Found this online, and it's a wonderful step-by-step guide: at the website there are pictures to help guide as well. -Operator
www.geocities.com/SunsetStrip/Stage/4241/Run.html If any Questions.
RUNNING SOUND
Most PA systems, no matter how large or how small, are run in essentially the same way. Once the basic components of equalizer, soundboard, effects, microphones, amplifiers and speakers are in place, the basic principles for running a huge stadium PA are no different than those used for running a tiny coffee house system. This section will try to cover the basics of using all the major components of the PA, as well as getting all of them to work together as a whole to make the system operate at its best.
Turning it on
After you have it all set up and connected, the first thing you will probably want to do is turn it all on. This is trickier than you might think. Although turning it on seems simple enough, doing it improperly can cause damage to some parts of the system. Specifically, in addition to scaring the heck out of the people hanging out in the room, the loud "pop" that sometimes occurs when you flip the "on" switch has the potential to tear up the midrange horns. Although there is no way to avoid this popping altogether, there are a couple of things you can do to keep it to a bare minimum.
First, before you turn any knobs or switches into the "on" position, you should make sure that the master levels on the amplifiers and the soundboard are turned all the way down. If you don't make sure you check those levels, Murphy's Law might take effect and ensure that one of the levels is set incredibly high (maybe the slider got bumped in transit) which will cause horrendous and unexpected feedback immediately after flipping the "on" switch. That instant kind of feedback can easily blow a midrange horn. It's best to play it safe. The levels you should be most concerned with are the output levels on the amps (usually knobs), and the main outs (usually sliders) and monitor outs (sliders or knobs) on the soundboard. Once these levels have been "pulled down", it is safe to turn the system on. Other master levels such as those on the equilizers and effects are safe if left at or near their usual setting, but if you are in doubt (or haven't yet determined a "usual setting"), pull them down to zero as well.
Secondly, the components of the system should be switched on in the following order:
[Effects, EQ] then [Mixer] then [Crossovers] then [Amps (lows first, highs last)]
This order keeps the majority of the popping signals created by that initial power surge when each component is turned on from ever reaching the speakers. The main thing to remember is that the amps should be turned on last. The purpose of the amps is to increase the weaker line level signal to a high level signal that drives the speakers. If they aren't turned on, then there is no signal going out to the speakers. If the speakers don't get the high power signal from the amps, they can't "pop". Turning the amp on last reduces the number of "pops" from one for each piece of equipment you turn on to just one when the amp itself is switched on.
Thirdly, whenever turning anything on (or off) that is connected to the PA system (microphones, keyboards, acoustic guitars...), make sure that the "mon" knob and the "level" slider for the channel it is plugged into is pulled all the way down. Switches on active mics in particular make loud pops when being turned on or off.
Testing the System
Now that it is all turned on, the first thing to do is run the system through a series of tests to make sure everything is operating properly. There are a lot of things in a PA system to plug up, and it is very easy to make a mistake somewhere along the way. Running these simple tests will make it easier to quickly find and isolate these mistakes without any unnecessary aggravation. At first, it may look a little complicated, but once you get the hang of it you should be able to go through all the testing procedures in just a very few minutes.
Powered Mixer System
The powered mixer setup shown below is probably the smallest system that should be used for gigging. It is very convenient in that most of the components (Effects, EQ, Reverb, Mixer) are already built into one unit. This combining of components means that there are very few external things to hook up, and therefore there is very little likelihood of making an error when putting it all together.
The least complicated system is of course the easiest system to test. To test the system pictured above, you need only go through a few simple steps. The steps listed below are there as a guide to help you locate any problems. Often there are many possible diagnoses to any particular difficulty, and I have only touched on a few of them. If something in your system doesn't work properly, and the suggestions listed don't seem to be the problem, you should first go back to "setting it up" and make sure you wired it all together properly. If it turns out that everything is hooked up correctly, you should then check all your cords to make sure they are working. After you have determined that they are in good shape, it is then time to look at the possibility that something may be wrong with one of the larger components of your system.
To begin testing, it is a good idea to set all the knobs on the board to relatively neutral positions. To do this, set all of the EQ knobs on the input channels (Low, Mid, High) to the straight up twelve o'clock position, Set all the sliders on the main EQ to the center position (this is called "flat"), turn all the effects and auxiliary knobs all the way down, set all the "pan" (balance) knobs to twelve o'clock, turn all the gains on the individual channels all the way down, and make sure the main and monitor master levels are all the way down. The diagram to the right shows the knobs on input channel 1b in a typical system adjusted to the best starting positions. After these knobs are set, follow the steps below to make sure that the system is connected properly.
Mono (1 output channel)
1) Gradually turn the main (Volume or Level) knob or slider up to near its normal setting. On knobs, straight up at twelve o'clock is good. On Sliders, three quarters of the way up is good. These settings will vary depending on the soundboard, and the personal preferences of the soundman. It is a flexible setting that is inversely proportionate (when one is high, the other will be low and vice versa) to the final settings of the levels and gains of the individual input channels. Just make sure you don't turn it all the way up, or all the way down. Somewhere between one quarter and three quarters is fine.
2) If your mixer has one (some don't), turn the gain (or trim) knob on the lead vocalist's microphone channel up to about the nine or ten o'clock position. If it doesn't have a gain or trim knob, simply proceed to step 3.
3) While repeating the word "check" into the lead vocalist's microphone, gradually turn up the "level" knob or slider for that input channel until you can clearly hear your voice coming out of the speakers. If you don't hear your voice, recheck your connections and knob settings.
4) Now, have someone else check the mic (or you can do it yourself if the cord is long enough) while you go out to the speakers and listen to them to see if each is working. Make sure to place your head in front of the midrange horns and the individual speakers in each cabinet to check them individually. If a whole cabinet is not working, check your connections to that cabinet. If just a speaker or horn in a cabinet isn't working, and the others in that same cabinet are, check to make sure you plugged the cord into the "full range" input on the speaker. If it still isn't working, you probably have a bad internal connection inside the speaker cabinet or a blown speaker or horn.
5) If everything is working fine up to this point, check all the other input channels in the same way as in steps 2 and 3. Some channels may have instruments plugged directly into them instead of microphones. If so, instead of checking a mic, simply play the instrument while you turn that channel's "level" up. If one of the channels isn't coming out of the speakers, and all the others are, you either have a bad connection or cord, or something is wrong at the instrument end.
If your mixer is equipped with a powered monitor output channel, then proceed to steps 6 through 8. If the monitor output channel is not powered (ready made to plug a speaker into), then it will require you to use an external amplifier and equalizer. To test that kind of setup, skip ahead to the section called "The Single Amplifier Component System".
6) Turn the Main master slider or knob all the way back down. This will make it easier to hear your monitors independently of the mains while you make sure they are working correctly.
7) Gradually turn the master Mon (Volume or Level) knob or slider up to near its normal setting. On knobs, straight up at twelve o'clock is good. On Sliders, three quarters of the way up is good. Again, this isn't an exact science. Somewhere between one quarter and three quarters is fine.
8) Now, perform the same procedures described in step 3, step 4, and step 5, only this time make the adjustments to the "Mon" knobs or sliders rather than the main "Level" sliders or knobs.
Stereo (2 output channel)
The only visible difference between the mono powered mixer and the stereo powered mixer is the addition of a "pan" knob for each input channel and a master "pan" knob that controls the panning of all the channels at once. The "Pan" knob is basically the same thing as the "balance" knob on your car or home stereo system. Now having said that, here's the long, drawn out, semi-technical version of what it does in a stereo PA system.
A stereo setup has two separate channels going out of the system to the speakers. These are usually labeled either "left" and "right", or "A" and "B". Each of these channels has it's own independent amplification. In a powered mixer, this is all set up internally as part of one self contained unit. Using the "pan" knobs allows you to change the volume of channel "A" (or left channel) in relation to the volume of channel "B" (or right channel). In other words, when you adjust the "pan" knob toward the left, the left output channel will get louder in relation to the volume of the right channel, and the opposite will happen if you turn it to the right.
To test a stereo PA system, first follow steps 1 through 5 just like in the mono system, then procede to these next few steps.
5a) While checking a microphone, gradually turn the main "Pan" knob all the way to the left. You should hear the sound gradually move entirely to the left main speaker (from the audience point of view) as you turn the knob. If not, check your connections to see if the "left speaker out" is connected to the left speaker and the "right speaker out" is connected to the right speaker.
5b) Now, pan the sound with the main "Pan" knob all the way to the right. The sound should now move all the way to the speaker on the right side of the stage as it is viewed from the audience's perspective.
If, when you turn the "pan" knob to the left, the sound goes to the right, and when you turn it to the right, the sound goes to the left, all you need to do to fix the problem is check your speaker connections and make sure you plugged the right "speaker out" into the right speaker, and the left "speaker out" into the left speaker.
5c) Finally, set the main "pan" knob back to twelve o'clock. Then check the "pan" knobs on the individual channels using the same technique. If the main "pan" knobs are working properly, and an individual channel's "pan" knob isn't, there may be an internal electronic problem with the soundboard.
Once you have completed all of these steps with your powered mixer, and everything is working properly, you are finally ready to begin adjusting the sound of the system. You can skip the next several sections and go straight to "Input Signal Adjustment and EQing".
Testing the System
The Single Amplifier Component System
This system consists of the same components as the powered mixer system discussed in the previous section. The main difference is that these components are separated into individual units rather than being combined into one single unit. These separate units include; an equalizer, an amplifier, a mixer (soundboard), speakers, and microphones. Separate effects units can also be added, but they are not essential to getting the system working. Using effects is also a fairly large subject. It is large enough in fact to get it's own section later in the tutorial. For testing purposes, we can simply keep the effects knobs (send and return) turned all the way down. They can be tested and adjusted later.
Since the single amp component system is so similar to the powered mixer system, testing it is essentially the same. Simply follow the steps outlined below.
Mono
1) After setting the knobs on the board in the same configuration as described for the powered mixer (or like the picture to the right), the first thing to do is turn the volume knobs on the external amplifier (In some amps, they are on the front. In some, they are on the back) all the way up. This will ensure that you are getting all the power out of the amp that it is designed to deliver.
2) Now, make sure the equalizer is not in "bypass" mode. There is usually a switch on the front labeled "bypass" or something similar. Make sure this switch is in the "off" position. If "bypass" is turned on, the unit will route the signal it receives straight though it without running it through the electronics associated with the frequency adjusting sliders. In other words, the equalizer will be "bypassed", and any adjustments made to the EQ will have no effect on the sound of the PA system. That isn't good, so make sure it isn't bypassed.
3) Turn the "Gain" sliders on the equalizer up to about 3/4 from the bottom. This slider adjusts the input level of the signal as it enters the EQ. Leaving it adjusted at 3/4 gets the level high enough to work with while leaving a little headroom to turn it up later if it becomes necessary. If it is left all the way down, no signal will leave the unit and travel to the amplifier. As a result, no sound will come out of the speakers. In a sense, the gain on the EQ acts like another volume adjustment. Just remember that any extreme (too low or too high) in adjustment on any volume or gain knob can result in distortion or hiss in the speakers..
4) Now, follow steps 1 through 5 as outlined for testing the powered mixer system. The only real differences at this point are in troubleshooting any problems. Since there are more connections and more components, there are simply more places to look for errors. Tracking problems down may take a little more time.
5) One more test that I like to do is make sure the EQ is working. To do this, I adjust the sliders so that the high frequencies are turned all the way down. I then check a mic. Then I hit the "bypass" on the EQ and check it again. If the equalizer is working correctly with the system, there should be a noticeable change in the sound when it is set in "bypass" mode.
Since, in a non multi-amped component PA system, the configuration of the components leading to the monitor speakers is exactly the same as the configuration of the components leading to the main speakers (see Setting it up: Small Practical PA), it stands to reason that the testing procedures would also be the same. After testing the mains, follow the directions below to test the monitors.
1) Turn the main master level all the way down.
2) Follow steps 1 through 5 above, but apply it to the monitor system rather than the main. In other words, if it says "main", think "monitor".
Stereo
Running a system in stereo is nothing more than running two separate but identical signal paths out to two different sets of main speakers. To test them, all you need to do is run the same tests outlined in the steps above separately for each main output channel. Okay. If that didn't make sense, just follow the steps below.
1) Make sure all the individual "pan" knobs are set straight up at 12 o'clock.
2) If it has one, turn the master pan knob all the way to one side (Left or A, whatever the case may be). That will divert all the signal to only one of the main output channels. Basically, one side will be turned up while the other is turned down. Again, just like a car stereo. That means that during these tests, you should only expect one set of your speakers to be working at a time, depending on which way you have the pan adjusted.
3) If it doesn't have a master "pan" knob, it will have two different main master sliders, one for right (or B), and one for left (or A). Turn the left one (or A) up about 3/4 of the way, and leave the other one down. This accomplishes the same thing the "pan" knob did in step 2.
4) Now, follow steps 1 through 5 as outlined above for the mono system.
5) If it has one, turn the master "pan" knob the all the way to the right (or B). This should turn the left speakers down and the right speaker(s) up.
6) If it doesn't have a "pan" knob, turn the left slider (or A) all the way down, and the right slider 3/4 of the way up. This will pan the signal to the right speaker(s).
7) Again, follow steps 1 through 5 as outlined above for the mono system.
8) Around now, it's probably time to turn around and yell at your drummer for making all that blasted noise when you are trying to listen to the speakers. It won't do much good, but it will make you feel a little better. You will get to yell at the guitar player later, but he probably isn't there yet.
9) Turn the other channel back up to 3/4 or turn the master pan knob back up to 12 o'clock, whichever the case may be. Check to make sure that both sides of the stereo system are working by listening to both the speakers on the left side of the stage and the right side.
10) At this point, it would be really cool if you could take a little break, but chances are you're running late and don't have time, so take a deep breath or two, complain a little about how no one helps out like they should, and skip ahead to the section called "Input Signal Adjustment and EQing".
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The Multi-amped Component PA System
Although this system can seem very large and complex, for the most part testing it is the same as for the single amp component system. The only additional components necessary to make this system work are lots of extra amplifiers and speakers, and a crossover (or crossovers if you are running a stereo system).
Before running the tests for these components it is important to understand the function of a crossover and to adjust it properly.
Warning:
Failure to properly adjust the crossover can easily result in damage to your system, particularly the horns and the speakers. I recommend looking up the specifications for your specific models of horns and speakers to get the proper settings.
As defined in the "Words to Know" section of this tutorial, an electronic crossover is "a rack mountable unit used to separate frequencies leaving the soundboard into highs, mids, and lows with different outputs for each." The amount of each frequency (highs, mids, and lows) going to each amplifier and ultimately to each speaker is determined by adjustments you make with the knobs on the front of the crossover unit. These adjustments are called crossover points, which basically means the points at which no lower frequencies will be allowed to pass. Think of it as a low frequency filter. For example: Say you set the highs crossover point at 1000Hz. That means that only the frequencies higher than 1000Hz will be sent out of the high "output" on the crossover. In a sense, it filters all frequencies below 1000Hz from that particular output channel.
As the warning says, getting the settings wrong can be damaging to the speakers. This is particularly true of the high range horns and speakers since they aren't designed to be able to handle any low range frequencies. It is best (and safest) to consult your manufacturer's specs to find the right crossover points, but if none are available the following settings should be safe for most (stress is on most) systems.
Bi-amp crossover points:
• Highs - 1000Hz Tri-amp crossover points:
• Highs - 1000Hz to 2000Hz (2000Hz is a bit risky without the specs)
• Mids - 400Hz to 500Hz
These settings should be adjusted before you even turn the unit on. This will help avoid the possibility of accidentally sending a blast of low frequency signals to the high end horns.
To fully test the multi-amped PA system, follow the steps listed below.
1) Adjust all the knobs on the mixer to the same levels described and pictured for the powered mixer and the single amp component system.
2) If the crossover is equipped with knobs to adjust the volume(not the crossover points) of the outgoing signals (highs, lows, and mids), turn them each up to about halfway. This will leave you room to adjust them either up or down if it becomes necessary later.
3) Adjust the equalizer as described in steps 2 and 3 in the single amp component system test procedure.
4) Adjust the crossover points for the different frequencies in the manner described above, and turn the entire system on as described in "Turning it On" earlier in this section.
Here is where it gets a little different than testing the single amp system.
5) Turn the volume knobs on only the amp intended for the high speakers up all the way unless you are using an exceptionally powerful amp in which case you should turn them only part way up. This is because high frequencies speakers don't require as much power as the other speakers and may even be damaged if provided with too much wattage. Don't turn the other amps up yet. Since the high range speakers are the most delicate part of the system, we want to make sure that they are working correctly before we do anything else.
6) Gradually turn the main (Volume or Level) knob or slider up to near its normal setting. On knobs, straight up at twelve o'clock is good. On Sliders, three quarters of the way up is good. These settings will vary depending on the soundboard, and the personal preferences of the soundman. Just make sure you don't turn it all the way up, or all the way down. Somewhere between one quarter and three quarters is fine.
7) Turn the gain (or trim) knob on the lead vocalist's microphone channel up to about the nine or ten o'clock position.
8) While repeating the word "check" into the lead vocalist's microphone, gradually turn up the "level" knob or slider for that input channel until you can hear your voice coming out of the high speakers. You want to keep the volume low for now. The purpose of testing this way it to make sure no low frequencies are getting into the high speakers, and at very low volumes, they can handle the lower frequencies.
9) Now have someone else check the mic (or you can do it yourself if the cord is long enough) while you go out to the high speakers and listen to them to see if each is working. Make sure to place your head in front of each individual speaker. Also check to make sure no sound is coming from any of the other speakers. If there is sound coming out of the low or mid speakers, or if there is any problem in the way the high speakers sound (they should sound very high pitched, and should not be breaking up or distorting), then something is connected wrong, and you will need to retrace your connections.
10) Very gradually turn the same slider up while listening carefully for any unusual sounds coming from the high end speakers. If you hear anything wrong, like distortion or clipping, turn it back down immediately and check your connections, and gain and level settings.
11) Once the volume has reached the approximate level at which you will be running the system, and everything is still sounding a-okay, you can turn the slider level on the board and the volume on the high amplifier back down to zero and perform the same series of tests over again for the mids.
12) Once the mids check out, you can turn all the amps up to the appropriate levels (all the way for each of them with the possible exception of the highs), and proceed through the entire test sequence outlined for the single amp component system.
13) Jump up in the air, click your heels together, and shout "YeeeeeHaaaa!!!!!" or "WooooHooo!!!" or "@%$^~#*%$!!!" (Depending on where you're from) because you are finally done with testing. Now it's time to get to the actual "running" part of running sound.
Signal Adjustment and EQing
Finally!!!! You've gotten everything plugged up and tested, and it's all working exactly the way it's supposed to . . . Right?? Good. Now, we're finally in the home stretch and we can actually get down to the fun part of running sound. The following sections concern topics that are often misunderstood, sometimes misapplied, and many times simply ignored by rookie soundguys. If there ever was a time to pay close attention, it would be now. A thorough knowledge of the next few topics is what sets the great soundmen apart from the. . . well. . . lets just call them the not-so-great soundmen. I suppose we could call them "crappy", but that would be mean, wouldn't it?.
Signal adjustment
This section will deal with the relationship between the Gain (or Trim) knob and Level slider on each input channel and the master level slider or sliders (Main) on the soundboard. At the basic level, this will be done essentially the same for both a stereo PA and a mono PA. To get the incoming and outgoing signals adjusted correctly, follow the steps outlined below.
1) Begin by setting all the knobs in each channel of the soundboard to neutral positions. To do this, turn all the knobs to the position indicated by the picture to the right. Also make sure the main sliders or knobs are turned all the way down.
2) Now, make sure all your amps are turned up all the way using the knob (or knobs) either on the front or the back of the amplifier.
3) Make sure the EQ is not in bypass mode, adjust it's gain slider (or sliders) to around 3/4, and set its frequency sliders "flat" (in other words, slide them all up to exactly halfway).
4) Now slide the main knob or slider (or sliders if it is a stereo setup) up to where you will want it set when you are actually playing. Usually a good position for this is around 3/4 of the way up.
5) On the input channel where the lead vocalist's mic it assigned, slide the "level" slider up to where you want it to be positioned during the actual performance (I usually put it about halfway up). Although using the lead vocal mic isn't a necessity, I prefer to use it for all my initial setup and tests. This is because, since it is the one that will be used the most, I like to make sure it gets the most attention as I am setting up. This way I can insure that it will be the best sounding thing in the system. You can actually use any microphone channel you have hooked up for the initial setup and testing.
Before we proceed to the next step. . .
We need to look at output level indicators. In step 6, you will have to pay attention to both the sounds you hear coming from the PA and the output indicator lights or needle gauges in your mixer. Almost all boards have different ways of metering signals so it isn't possible to describe things universally, but whether they meter things with multi- colored LED lights or needle gauges, or they simply have an overload light, they all have one purpose. That purpose it to insure that the soundboard isn't being driven too hard. The meters are there so that you can adjust the strength of the output signal to it's optimum level. Generally, too high a level will cause distortion, and too low a level will cause hiss and noise in the system, but this can vary some depending on your individual equipment.
The LED lights will usually work something like this. The bottom light will light up when a weak signal is sent through the board at low volumes, and as the volume (intensity of the output signal) increases, the next light above it will light up, and as it increases even more, the next one above it will light up, and so on, and so on. Sometimes they work left to right instead of bottom to top. These lights are usually either green or orange or yellow or red. On my soundboard, the red lights are near the top and are indicators that I am at maximum allowable output signal. Basically, that means I can't turn things up any louder than that and still expect optimum performance from my system. For your board, you should check the owners manual for specifics on where your indicator lights should be for optimum performance. If you bought the board used, and you don't have a manual, look for notation on the board itself. Even if nothing is written in words, there should be something on the gauge to indicate the best level. It may be a darker bolder marker line at the right level or it may simply be that the color of the lights is different. Usually, the lowest dark red light indicates where the signal level should be set. Ideally (at maximum volume), you want this light (or the light located at whatever level the manual suggests) to flicker on and off only during very high volume spikes. If you have the output level set so that during a performance the signal spikes a little below that light most of the time and the light is flickering only occasionally, then things are set just right. Once you have it set, you can back off on the volume if necessary. This will cause the signal lights to peak a little lower, but now you will be aware just how high your volume can go.
A needle gauge meter (VU meter) works in basically the same way as the LED meter does. It will swing only slightly when presented with a weak output signal, but as the signal increases, it will point farther and farther to the right. The area where the needle is pointing is usually marked with numbers and/or multicolored regions. This works exactly like the LED meter. Usually, there will be an area marked to the right side of the gauge that is colored red. This it similar to the red lights on the LED gauge. For ideal performance, you want the needle to occasionally swing into the red area only during high volume spikes. If the needle usually spikes a little to the left of the red, and only bounces into the red once in a while, then the output level is set correctly. Some gauges might not use a color code but will instead have numbers. To know where the best level for these is, you will need to check your owner's manual. Once you have it set, you can back off on the volume if necessary.
Some boards will also include an overload or "clip" light. When this light is on, it means that the internal electronics of the soundboard are having to electronically reduce the outgoing signal. This is a safety feature that is supposed to keep the signal under control even when you aren't. Setting the signal on this kind of board is simple. If the clip light is flickering, turn the levels down just a hair until it stops. This will derermine your maximum signal level on the board. You want to avoid clipping whenever and wherever you can. Constant clipping anywhere in the system can cause damage to your speakers.
Now. . . back to step 6
6) Now, while checking (literally saying "check" over and over) the lead mic, gradually turn the gain (or trim) knob up until you begin to hear the vocal coming out of the main speakers. Don't forget to keep an eye on the output meter. Continue turning the gain up until the sound reaches the approximate volume level you will be wanting to use during the performance, or until the output meter reaches the maximum allowable output level as described above. If you reach the desired volume without exceeding the allowable output level as indicated by the LED or VU meter, then proceed to step 7. If the allowable output as indicated by the meter is reached first, you have 3 choices; 1) Keep the output signal in allowable range and run your system a little quieter than you prefer, 2) Go buy some more powerful amps and speakers, or 3) Crank it up anyway regardless of the gauges and risk destroying your system. I heartily recommend going with numbers 1 or 2. Option number three can get really expensive.
7) Once this is completed, repeat steps 5 and 6 for each vocal microphone channel. If all your vocal mics are the same model, the gain knobs and level sliders should all end up in very similar positions for each different channel. If they are not, your level sliders should all be in the same positions, but the gains (trims) may end up in different ones. Once the gains are set, you won't need to touch them again for the remainder of the gig, but the sliders will probably need further adjusting later. From this point on, the sliders will be what you adjust if you need to turn something up or down in the front of house (FOH) or main mix.
8) Now, repeat steps 5 and 6 for the other microphones (horn mics, mics on guitar amps, drum mics, and basically any instrument you have miced) except instead of checking the mic verbally, check it with the instrument that it is micing.. You will notice a drastic difference in some of the gain settings for the instruments as compared to the vocals. This is normal. You would expect a kick drum, for instance, to put a lot more volume into a microphone than a simple woohoo from the singer. One more thing to note is that active microphones will put off a much stronger signal than passive mics. The gains on active mics will probably have to be turned much lower in order to keep the level slider in its desired starting position.
9) Now, repeat steps 5 and 6 again for any direct inputs you have into your board. Those often include bass guitars and keyboards. Again, do these checks by playing the instrument (or having someone else play it) while you adjust the knobs appropriately. If none of the direct inputs is from an acoustic instrument (like a guitar or, heaven forbid, a banjo), then this step can be put off until after the system has been EQed. Keyboards don't and basses don't tend to feedback much in the PA, so they don't really need to be included in the upcoming EQing procedure.
10) Take a deep breath and proceed to "EQing".
Notes on signal adjustment
With the exception the use of the gain knob, adjusting the monitor levels will be essentially the same. However, I prefer not to adjust the monitors until I am completely finished EQing and adjusting the mains. Later, when the time comes to adjust the levels in the monitors, it should be done by only the use of the master level monitor slider (or knob) and the individual monitor level knobs on each channel. Don't use the gain. Just put the master monitor knob or slider to 3/4 of the way up and adjust the individual monitor knobs on each channel to the volume level you want. Some boards also have meters for the monitors, and the same rules apply to them that apply to the mains. Remember not to use the gain knob when adjusting the monitors. Although adjusting the gain knob will effect the monitor signal, doing so will undo everything you just did to the mains.
In a nutshell, here is how all these knobs are related to one another. This won't be a deep electronic technical explanation ( I don't have one of those), but it will at least show what each does.
----The gain knob adjusts the signal (whatever it is) as it comes into the board. It's purpose is to control or level out (or match) all the incoming signals so that they are nearly the same when they get to the other controls. This is done by either turning it up to boost the incoming signal a little or by turning it down to reduce the signal a little. Turning the gain knob up or down on a channel effects everything in that channel whether it is mains or monitors.
----The level slider on each channel adjusts the level of the signal as it leaves that particular channel on its way to the main slider.
----The main slider adjusts the entire level of all the signals as they leave the soundboard on their way to the main speakers.
Adjusting any or the above knobs will effect the levels shown on the main output level meter. It's a delicate balance that should be watched throughout the gig. Gradually turning all the levels up during a gig can result in too much output power and the clipping that goes with it. Be careful. Watch those meters and adjust the level and main level sliders accordingly.
----The monitor knob on each channel adjusts the level of the signal as it leaves that particular channel on its way to the master monitor slider or knob.
----The master monitor slider adjusts the entire level of all the signals as they leave the soundboard on their way to the monitor speakers.
Adjusting either of these (or the gain) will effect the levels shown on the monitor output level meter. Again, watch those meters when making any changes to the mix and adjust the monitor knobs and master monitor level slider (or knob) accordingly.
Now that your signals are all adjusted properly, click on "Next Page" to continue on to the EQ section.
Signal Adjustment and EQing
EQ Defined
An EQ (short for equalizer) is a device used to filter out or boost specific frequencies in a PA system or any other amplification system (such as a guitar amp, home stereo, TV set, etc). In a sound system, it has two primary purposes. One is to help control feedback, and the other is to help achieve the specific sound you are looking for when you are performing.
If set correctly, an EQ helps in the control of feedback by making each frequency coming out of the speakers reach the threshold of feedback at as near the same time as possible. . .
Did I just hear someone say, "Huh?"
Let me explain. . .
First, we need to understand what a frequency is. A frequency is a tiny piece of sound that, based on its pitch, can be pinpointed at a specific spot in the entire spectrum of sound. Frequencies can be separated electronically and then assigned to different individual controls on the equalizer. On most graphic EQs (The ones with sliders), the lowest frequency will be assigned to the leftmost slider, and the second lowest to the second from the left, and so on all the way up to the highest frequency range which is assigned to the rightmost slider. These sliders will be marked in hertz. Hertz (cycles per second) is a measure of frequency where the lower the number, the lower the tone. Therefore 20 hertz would be a really low frequency, and 20K (20,000)hertz would be a really high frequency. It's not absolutely necessary that you know this, but it can definitely help out when trying to identify problems in the equalization or specific instruments.
In a PA system, or any system that creates sound, some frequencies will tend to dominate the sounds leaving the system. In the case of PA systems, we are mostly concerned with the way the different frequencies are proportioned as they leave the speaker. If a PA system is used without an equalizer, some frequencies will come out of the speakers much more prominently than others. These frequencies, since they are in essence louder, will be the first frequencies to feedback as the system is turned up to higher volumes. This is one reason why we need an EQ. An equalizer makes it possible to, well. . . "equalize" all the frequencies so that they all reach the threshold of feedback at the same time. In other words, you can use the EQ to make it so the highs will feed back at exactly the time as the lows as you increase the volume of the entire system. You do this by using the individual sliders on the EQ to turn the naturally louder frequencies down to the same level as those frequencies that are naturally a little quieter and vice versa.
Adjusting the EQ
Although you can start with either the mains or the monitors, I prefer to set up the EQ for the monitors first. This is because, due to their proximity to the microphones, monitors are much more likely to feedback. That means EQing them is a more delicate operation than EQing the mains and will require a little more time and attention. At gigs, time is not always a luxury, and you may have to start before you are completely done adjusting things to your satisfaction. I find that since they aren't responsible for most of the feedback, the mains are a lot easier to adjust "on the fly" after the band has started if it becomes necessary. Monitors aren't so easy to adjust once the band has started playing, so I like to adjust them first to ensure that the greatest source of feedback will get EQed. This helps keep my feedback problems to a minimum.
"Ringing Out" the Monitors
To adjust the EQ in the monitors, follow the steps outlined below. Since this procedure involves listening for small amounts of feedback "ringing" in the speakers, it is sometimes referred to as "ringing out" the monitors.
1) First make sure there is no one on the stage that will be making any noise that will go into the PA. Ringing out the speakers will require you to increase the volume level of the system until it is right on the edge of feeding back. If someone yells into a microphone while you are doing this, all kinds of uncomfortable things that may cause ear damage could result. Not to mention, you may want to beat the guy up. This of course could lead to the band breaking up. Then you might have to cut your hair off and go get a day job. You don't want that, so it's best to just keep everybody clear during this part of setting up.
2) Now, if you haven't already done so, adjust the levels of the mic and instrument channels (in the monitors) to approximately where they will be set during the performance. (See Input Signal Adjustment)
3) Adjust the sliders on the graphic equalizer so that they are all just a little low of center as illustrated in the diagram below. You will be individually adjusting these upward as you adjust the EQ, so you need to have a little extra room to slide them up while still leaving some room to adjust them downward if necessary.
This is where it gets tricky. . .
4) Now very gradually slide the master monitor slider (or knob) up until you hear the faint beginnings of feedback. Don't turn it loud enough to allow that feedback to take over, but you want it to be right on the edge. If it is feeding back continuously, pull it back just a hair until it stops. Don't let it get out of control, or it can damage the speakers.
5) Very carefully and slowly slide the far right slider on the monitor EQ (highest frequency) up until you begin to hear faint high frequency feedback coming from the speakers. This is the "ringing" part of ringing out the monitors. Once you hear that sound, pull that slider down very slightly until the feedback subsides. Don't slide it up any farther. That would cause continuos loud feedback that could damage both speakers and ears. Even worse, it could make the early arrivals in the audience shout out rude and annoying things at you. That of course could cause you to shout rude and annoying things back at them which could in turn cause you to lose the gig, and again you could be looking at a haircut and a day job. So be careful with that slider.
6) Now, move over to the next slider to the left and follow the same procedure described in step 5. The only difference is that the pitch or frequency of the ringing feedback will be a little lower since you are adjusting a lower frequency slider.
7) Working your way from right to left (high to low), perform the procedure outlined in step 5 for the remaining sliders on the EQ. Some of these will go all the way up without feeding back. It's OK for a couple of them to do that. When that occurs, just return the sliders that don't feedback back down to halfway (flat), and adjust them by ear (until they sound right) after you are done ringing out the rest of the EQ. If a lot of them are going all the way up without feeding back, you need to slide the ones that do feedback down even farther than they were when you started and then begin the whole thing over again from step 4. That will make those frequencies that you pulled down lower feed back at a higher level on the master slider thus allowing the overall volume to increase. This increase in volume will get the frequencies that weren't feeding back to a higher level thus helping them to achieve enough volume to reach feedback levels, then those frequencies can also be "rung" out.
Note:
As your ear gets used to hearing these different frequencies, you should get to a point where you can identify the approximate frequency of the feedback you are hearing and then match it to the corresponding slider on the equalizer. Once you learn to do this, you will be able to hear feedback and then, by ear, pinpoint the slider you need to adjust (turn down) in order to eliminate that feedback. This will make ringing out the monitors easier, because instead of starting all over as described in step 7, you could simply turn the master monitor slider up and identify (by ear) which frequency feeds back and turn it's slider down. In essence, you would be doing the procedure in reverse. You'd be making the feedback happen with the master slider and then reducing the offending frequency at the EQ instead of finding the upper feedback threshold by increasing the individual frequencies with the EQ.
8) Once you have all (or at least most) of the frequencies as high as they can go without feeding back, then turn the master monitor volume slider or knob back down to the level you will be using during the performance.
9) Now, check a microphone and see what you think? If it sounds good, then finish adjusting the individual levels of the individual input channels (mics and instruments), and you will be ready to move on to adjusting the mains. If it doesn't sound the way you want it to, you can now adjust the monitor equalizer's sliders to your personal preferences. The thing to remember, however, is that if at all possible, you should make your adjustments by reducing frequency levels rather than raising them. This is especially true of the sliders that did cause feedback as you adjusted them in step 5. The ones that didn't cause feedback can be adjusted all the way up or down without causing any feedback problems in the monitors so you may want to concentrate your efforts there.
10) Pat yourself on the back and move on to adjusting the mains.
EQing the Mains
In smaller rooms,, the mains can be EQed by applying the same procedures described for the monitors to the mains. Whether to leave the monitors up while I do the mains is something that I still haven't decided. I see good points and bad for each way. If you turn the monitors down while you work with the mains, you know you are getting sound that is coming from nowhere but the mains, but on the other hand, if you leave the monitors on while you do the mains, you get a full blown picture of what things will be like once the whole system is running. It's a hard call. I'm not sure which is best, but I usually leave the monitors up and running while I do the mains so that I won't get any surprises when I have everything on later. I'll leave this one up to you.
In larger rooms, and outdoors, ringing the mains out isn't very practical. Oftentimes, not enough sound will come back to the stage from the speakers to cause much, if any, feedback to occur, and if some sound does make it back to feedback, it won't necessarily be an accurate representation of what is really coming out of the speakers. I know of only two ways to EQ the mains. One is very scientific and requires the use of some expensive equipment involving a microphone on the dance floor and some funky "pink noise" generating device. It also takes a little extra time to do it this way. Most people don't really have either the time or the money to spend on this system, so they have to resort to the old fashioned way of doing things. That way relies primarily on your ear and a lot of common sense. In other words, you have to listen to the speakers and see if they sound right to you and then, if they don't, you have to know how to adjust them to sound like you want them to. Try as I might, I can't think of a step by step method of adjusting the mains, so instead, I've listed (in no particular order) some tips and ideas below.
-----One good bet for getting the mains to sound good is to start from a consistent setting on the EQ. Some schools of thought say that you should start by setting the EQ in a smiley face and others say that you should set it up to look like a sine wave. Through a lot of experimentation, I've found that (for me at least) the best starting place for the EQ is to set it up something like the diagram of the EQ below. I came up with this setting through experimentation before anyone had told me about the sine wave or the smiley face way to do things, but by comparing, you can see that my method falls somewhere in between the two. You can experiment on your own to find the starting place that is best for you. Don't forget, though, that it is only a starting place. Once everything is up and running, you will most likely need to make adjustments and changes to some frequencies in order to make the front of house speakers sound as good as possible.
-----The most common problem feedback frequency I've discovered is the 2K band. It may be a good place to check when you are hearing a high end squealing feedback. Don't forget that more often than not, feedback problems will occur in the monitors before the mains.
-----Each input channel can be individually EQed to some degree by adjusted the EQ knobs (high, mid, low, etc.) assigned to that channel. This is a tremendous aid when dealing with different brands of microphones and different vocal tones. For instance, some singers and some microphones will naturally have a lot of lower tones. Instead of fixing the problem of too many lows in that mic by changing the main equalizer and thus changing the whole mix, try adjusting some of the knobs assigned to that channel alone.
-----In any equalization situation, it is always preferable to turn something down rather than to turn something up. For instance, if your system sounds too rumbly and muddy, rather than trying to turn the highs and mids up to get a crisper sound, try turning selected frequency bands in the lower ranges down to achieve the same end. You cannot cause feedback by turning something down, but turning things up can easily set your speakers to squealing.
-----If you are having troubles hearing the vocals, rather than simply turning them up try adjusting the EQ so that there are a little less lows and mid lows and a little more high mids and highs. Most of the clarity in the vocals comes from the higher midrange frequencies. If they are pulled way down, you will never hear the vocals very well no matter how loud you turn up the volume. Think of it like this, if you put a pillow over a boom box speaker, you would be able to hear the rumble of the low end (some guitar, bass guitar, and drums), but you wouldn't be able to distinguish the words of the song being sung. That is because the low frequencies can resonate through the shell of the box, but the mids and highs can't. Move the pillow, and all the highs and mids come out fine, and you can again hear the vocals. Think of the pillow as if it was the slider controls for the highs and mids. Turn those mids and highs up, and you get vocals, turn them down and they go away.
-----When adjusting the EQ, you may want to play a CD through the system. Choose music you are familiar with so that you know how it is supposed to sound. Also choose something that has a similar sound to the band that is about to use the system. Use the Equalizer to make that CD sound great, and it won't take much adjustment to make things sound good once the band starts playing. I personally prefer to use thick heavily produced music like Kansas or Floyd. That way, I'm sure I'm using a good well EQed CD.
-----The goal when adjusting the mains is to achieve a good fullrange sound. Be careful not to over do it on the lows or the mids. Too many mids will wear your audience out (ie. "my ears hurt") and may even run them off, and too many lows will give you a distorted rumbly sound that makes it impossible to hear the nuances of the music.
-----If possible, find someone who can give you a second opinion on how it sounds. Just a casual, "How's it sound?" can yield an opinion that might just point out something you hadn't noticed.
A Final Word on EQ
In my observation, improperly adjusting the EQ is probably the most common mistake made by soundmen in local venues. It is very tempting, especially when you are pressed for time, to skimp in this area. It's also a very huge mistake. The EQ is essential to getting a good sound in the front, and it is the only real weapon you have against feedback. This is especially true in the monitors. Properly using an equalizer can double your potential volume and clarity on stage, and can virtually eliminate feedback. If you get it all set right before you start, you won't have to worry about that feedback at all, and you can spend your sound engineering time doing things that are much more fun like playing with the effects and sculpting the sound to each particular song. This brings us to the next and final section of this tutorial. Click on "Next Page" and we will take a look at adjusting and operating the effects.
Effects
Since it would take an entire book to explain all the details and applications of the multitude of effects and effects units available to use in a sound reinforcement system, this section will deal mostly with the commonalities related to all (or at least most) of those effects units.
Signal Adjustment
In the signal path of the effects loop, there are as many as six different knobs that ultimately determine the amount of effects you hear coming out of the speakers in your PA system.
Listed in order of signal path, these include:
1) An "Effects" knob on each individual channel of the soundboard which adjusts the amount of (output) signal that will be sent from that channel to the master effects knob on the soundboard.
2) A "master" effects send knob that turns all the signals received from the individual channels' effects knobs up or down as a group. Some boards will have this and some boards won't.
3) A signal level "input" located on the effects unit itself which adjusts the level of the signal as it enters the effects unit from the soundboard.
4) A "Mix" knob on the effects unit that lets you balance the amount of original signal to leave the unit with the amount of "effects" to leave the unit.
5) An "output" knob on the unit itself which adjusts the level of the signal leaving the unit on its way back to the soundboard.
6) An Effects "level" knob that adjusts the level of the signal as it enters the soundboard from the effects unit.
The illustration below illustrates this signal path.
Adjusting the levels for the effects properly is similar to adjusting the input levels on the input channels of the soundboard. An effects unit usually has some kind of LED, clip light, or gauge on it that indicates the strength of the signal it is receiving. To get optimum performance from your effects, you want the gauge to read right at the upper edge of the allowable levels. The gauge is usually marked clearly with either words or a red area to show you the maximum input level it can handle before it begins to distort. To adjust this input level, you need to strike a balance between the channel effects knob and master effects knob on the soundboard, and the input knob on the effects unit. Below is a step by step method that can be used to achieve this end.
1) Get the entire system up and running. Adjust the input channels on the board and EQ the mains and the monitors.
2) Turn all the output signal controls for the effects signal path to around halfway. You could actually leave them all the way down to set the input signal, but you will probably find it comforting to actually hear the effects while you are going through this process.
3) Turn the "Mix" knob (if the unit has one) about halfway up. Again, this is more for your comfort than out of necessity.
4) If the effects unit has a "bypass" button, make sure it isn't in bypass mode.
5) Turn the "master" effects send knob on the soundboard to about halfway.
6) Turn the "input" knob on the effects unit up to around halfway.
7) Now, while checking the microphone, gradually turn up the effects knob on that mic's input channel until you see the gauge on the effects unit reach the proper level. You should start hearing the effects coming out of the system at some point along the way. Ideally, you would want the channel effects knob to end up at around halfway when the signal reaches it's proper level. This is so you will have room to adjust it either up or down if you need to later. If you find that you have to turn it all the way (or almost all the way) up to get enough signal, back it off a bit and turn either the "master" effects up on the board or the "input" up on the effects unit. If you find that you get a strong signal when it's turned almost all the way down, try turning either the "master" effects down on the board or the "input" on the effects unit down.
8) Once you have the balance between the those three knobs set to an acceptable level, go to the next channels and adjust them using only the "effects" knob on each individual channel. The "master"on the board and the "input" on the effects unit should already be set.
9) Once all the channels are set, turn the "master" effects knob on the board or the input level on the effects unit down just a hair. They both do basically the same thing at this point, so the choice is yours. The reason for this is so that you can have a little headroom to adjust the individual channels up some later if it becomes necessary.
Once the input levels are set, you can follow the next few steps to set your effects to your tastes.
10) You can adjust the effects volume to the mains by using the "effects level" or "return" knob on the soundboard.
11) Use the "mix" knob on the effects unit to adjust the ratio of original signal to raw effects that leave the effects unit. In other words, turned all the way one way, you get nothing but effects (if it was echo, you'd only get the echo, not the original sound), turned all the way the other way, you'd get no effects at all, just the original signal.
12) Some soundboards have a "monitor effects" knob. This is there so you can put the effects in your monitors. Adjust it as necessary. It's just another control for the return signal of the effects, so it won't effect any of the input adjustments you just made.
Notes on Effects
Without going into too many details, here are some tidbits concerning effects, plus several alternate ways to hook them up.
-----You can use your"Aux" inputs and outputs in exactly the same way you would use "Effects Send" and "Effects Return" . They do the same thing only with different labels. You just have to remember what knobs correspond to what jacks.
-----You can loop your effects back into a spare channel in your mixer instead of into the "effects return" jack. Your final level adjustment will then be on the slider of that channel and your monitor effects adjustment will be on the "mon" of that channel. You can also EQ your effects by using the EQ knobs assigned to that channel. You need to make sure though, that you keep the effects knob on that channel turned all the way down because if it is left up, there will be an internal feedback loop that will cause awful potentially damaging sounds to come out of the speakers.
-----You can hook effects up in sequence, one after the other, but you have to pay careful attention to the signal meters on each one in the line and make adjustments to the input levels as necessary.
-----On some boards, you can hook up effects to only one channel at a time by using the sends and returns assigned to that specific channel, or you can place the effects directly in line between the instrument/microphone and the soundboard.
-----Some effects are often placed in line somewhere between the soundboard and the amplifiers. This is sometimes done with compressors. The drawback of doing it this way is that you don't get individual control over each vocal and instrument. Instead, any adjustment you make will effect everything in the mix equally.
-----Some common effects include reverb, delay, chorus, compressors, and noise gates. -----Be careful not to fall into the trap of turning your effects way up to "make it sound better" or to "cover up" bad musicianship or vocals. Effects are there to lightly enhance the sounds being made. If they enhance a good sound, then they can easily make it an even better good. If they enhance a bad one, then it can just as easily make it a better bad, and a better bad is really a worse. . .right?
-----Sometimes, when effects are very loud, they can contribute so feedback problems, so keep an eye out. It may not be the EQ that will fix things in every instance.
-----Be careful not to fall into the trap of turning your effects way up to "make it sound better" or to "cover up" bad musicianship or vocals. Effects are there to lightly enhance the sounds being made. If they enhance a good sound, then they can easily make it an even better good. If they enhance a bad one, then it can just as easily make it a better bad, and a better bad is really a worse. . .right?
-----Sometimes, when effects are very loud, they can contribute so feedback problems, so keep an eye out. It may not be the EQ that will fix things in every instance.
This concludes the section on the basics of running sound. From this point on, I will be adding information to this site from the inside out. The main sections are now complete in their basic form and content; however, the world of PA systems is a large one and there is a lot more to know and to tell. For me, the key has always been to experiment a lot and to ask a lot of questions. I'm still asking, so I'm sure I'll have more to add as time goes on.
Setting it up
Part 1
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Interact with other musicians and soundguys on the PA tutorial's Message Board.
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PA Systems come in many different shapes and sizes, ranging from the very elaborate systems used in large stadiums all the way down to a simple microphone patched into your home stereo. Listed below are several of the most common setups.
Example 1: The Bare Bones
The above example is about as basic a system as you can get. Hooking it together is relatively simple. The most important thing to remember when hooking up any size PA is the direction of the signal. This is indicated above by the red arrows. The signal starts with your mouth (or drum, or horn, or whatever), then goes through the microphone into the system, then routes its way through the amp, and finally into the speaker where it leaves the system as a much louder sound. A good rule of thumb is to remember that when plugging something in (like an amp), whatever you plug into the input should be coming from the direction of your mouth while whatever you plug into the output should be heading toward the speaker.
An easier way to think of it might be to think of it as a river, the microphone being upstream, the speaker being downstream, and the amp being a reservoir in between. As the water (the signal) flows from upstream (the Microphone), it must enter the reservoir (the amp) through an input, and then exit the reservoir through an output until finally, it reaches the downstream side (the speaker).
So, that's the theory (complete with a picturesque metaphor). Now here is the reality. In the example above, you would plug things up in this order.
1)Plug the mic cord into microphone (There is only one place to plug it in. Technically it's an "output").
2) Plug the other end of the mic cord into the "input" of the amplifier (remember, input is coming from the microphone).
3)Plug the speaker cord into the speaker "output" of the amplifier (the signal is flowing out of the amp toward the speaker).
4)Plug the other end of the speaker cord into the "input" on the speaker (the signal is coming from the microphone through the amp to the speaker.
And there you have it. You have successfully hooked up your first basic PA system. Of course, although it will amplify the sound, this particular system won't be of much practical use to you in any real life playing situation. It still lacks three essential ingredients.
Example 2: The Essentials
With the addition of a mixer (soundboard), an equalizer (EQ), and a set of full range speaker cabinets, we have created a small PA system that can be used both for rehearsal and for some gigs. The principle of signal direction stays consistent. As the arrows indicate, the signal again starts at the microphone passing through each component in turn until it reaches the speakers where it exits the system as an audible, much louder sound. It is important to note the order in which the components are hooked up. No matter how many more components (such as effects or compressors) are added, these basic building blocks should always line up in this order relative to each other. The EQ should always be connected somewhere between the output of the mixer and the input of the power amp. The microphone should always be on the input side of the mixer, and the speakers should always follow the amplifier.
Keeping in mind signal direction, the system shown in example 2 should be hooked up like this:
1)Plug the mic cord into microphone (only one end of the cord will fit).
2) Plug the other end of the mic cord into any "input" channel of the mixer (input comes from the microphone).
3)Plug a high Z cable (patch cable) into the "main out" of the mixer (the signal is flowing out of the board toward the speakers).
4)Plug the other end of this cord into the "input" of the equalizer (the signal is flowing from the microphone).
5)Plug one end of a high Z cord into the "output" of the equalizer (the signal is flowing out of the EQ toward the speakers).
6)Plug the other end of this cord into the "input" of the power amp (the signal is flowing from the microphone).
7)Plug two speaker cords into two speaker "outputs" on the power amp (the signal is flowing through the amp toward the speakers).
8)Plug the other ends of these cords into the "inputs" of the speakers (the signal is coming from the microphone to the speaker).
Warning:
Never plug anything other than a speaker into the output of a power amp. A "speaker out" connection carries a very strong signal that can and probably will cause damage to the other components.
Example 2a: The Powered Mixer
The powered mixer (pictured in the center of Example 2a) is very handy in that it combines the amplifier, the equalizer, the mixing board, and some limited effects into one relatively compact unit. These can be very convenient in some situations. They are especially useful for smaller acts (like acoustic bands), and great for rehearsal. In general, they are smaller and easier to transport, and easier and faster to hook up. Also, in many cases, buying one combined unit like a powered mixer can be considerably less expensive than buying the pieces separately. On the down side, they generally have less power than you can get using separate amps, and they often lack some controls on the EQ and Mixer, so if you are in a big loud band in a big loud room, you probably don't want to use one of these.
Stereo to Mono
You may have noticed that you have more than one channel in some (or all) of the components of your system. These are usually labeled in one of three ways; A and B, 1 and 2, or left and right. Each or the two channels will have its own inputs and outputs. What this means is that the component is stereo. Basically that means that it contains two completely separate pathways for two completely separate signals to flow through.
The system examples so far, for simplicity's sake, have been mono systems, but the principles are the same for stereo. A stereo PA can easily be used as a mono PA by simply running through only one channel in each component. For instance, If you wanted to use only channel "B" in your EQ, you would use the input and the output for channel "B", and leave the channel "A" inputs and outputs open. Of course, when you actually use the EQ, you have to remember which channel you hooked up so you can know which one you will need to adjust to change the sound of the PA. Moving the channel "A" knobs won't do anything if only channel "B" is hooked up.
The sound board is a little different in that you need only be concerned with the outputs. There are many inputs in a soundboard coming in from the many microphones on the stage, but a stereo board will have two separate "main" output channels. You need only choose one of these to use it in mono. Just remember which one you choose and adjust the knobs on the board accordingly.
The real draw back to running your stereo PA system mono is that you end up using only half of that expensive piece of equipment you bought. That isn't that big of a deal with an EQ or a crossover, but with a power amp, only using one channel means you only use half of its power. Only using half of a 500 watt amp results in only getting 250 watts of power, and that just plain sucks. This problem can be fixed by the use of "bridging", but it's a variable and sometimes complicated setup that can be hazardous to the health of your equipment. If done right, it's great. If done wrong, it's disaster. Therefore, I've decided to leave bridging out of this tutorial (liability and all). However, I did find a complicated technical description of it on the Peavey homepage. If you are interested in bridging, try looking there. If you're not, just do what I do and keep on truckin' without it.
Now that we have covered the basics, we are free to put together a complete and practical gig-ready PA system. . The system below is great for smaller venues, and has the added bonus of not taking up too much room in the equipment truck.
Example 3: Small Practical PA
In example 3, we have added monitors and effects. The monitors are the speakers that face back toward the stage so that the people there can hear themselves singing. They require a separate equalizer and amplifier and are hooked up in the same configuration as the mains (mic to mixer to EQ to amp to speaker), except that the cord running to the input on the monitor EQ is coming from the "Monitor out" channel on the soundboard rather than the "Main out". Basically what has happened is that the signal that has left the microphone has been split by the internal electronics of the soundboard into two separate signals. One signal is then routed through the "monitor out" into the monitors while the other is routed through the "main out" into the mains. This makes it possible to adjust the sound coming out of the monitor speakers separately from the sound coming out of the main speakers.
Note:
If you are using a stereo equalizer, you can run the mains through one channel of the EQ (say channel "A") and the monitors through the other (channel "B"). Just remember which channel you assigned to the mains and which you assigned to the monitors.. That way you know which sliders and knobs adjust each part of the system. Doing this avoids the need to purchase a separate EQ, and allows you to fully utilize the equipment you already have.
This same principle can be applied to any stereo components in the system such as amplifiers, compressors, and crossovers, etc.....
The effects help to thicken out or modify the sound that is going through the PA system. There are many different kinds of effects including such things as delay (echo), reverb, and chorus. These can be hooked up "in line" or directly in the path of the signal, but are much more versatile when hooked up in an "effects loop". An effects loop is created when a signal is sent out of the soundboard into and through whatever effects you are using and then "loops" back into the soundboard. Once this loop is set up properly, the effects can then be adjusted individually for each input channel (microphone, keyboard, etc...) on the soundboard. This means you could put a lot of echo on one guys vocals while adjusting another guys to have almost none. On the other hand, a digital delay (echo effect) in line with the mains....say, between the mixer and the EQ....would effect everything coming out of the main speakers equally, and everyone would have the same amount of echo.
Now that we have examined the concept, here's how you plug it all in:
Mains
1)Connect everything together as described in example 2. This is essentially the signal path for the mains.
Monitors Remember, signal path flows from the microphone toward the speaker.
2)Plug a high Z cable (patch cable) into the "Monitor out" of the mixer
3)Plug the other end of this cord into the "input" of the monitor equalizer.
4)Plug one end of a high Z cord into the "output" of the monitor equalizer.
5)Plug the other end of this cord into the "input" of the monitor power amp.
6)Plug two speaker cords into two speaker "outputs" on the monitor power amp.
7)Plug the other ends of these cords into the "inputs" of the monitor speakers.
Effects loop
8)Plug a patch cord into the "effects send" or "effects out" of the soundboard. This is where the signal leaves the mixer (you are sending it out of the mixer).
9)Plug the other end of the cord into the "input" of the effects unit.
10)Plug another High Z cord into the "output" of the effects unit.
11)Plug the other end of this cord into the "effects return" or "effects in" on the soundboard. This is where the signal returns to the mixer thus completing the effects "loop".
Multiple effects
You will probably want to run several different effects at the same time. This can be done by either using a multiple effects unit that will run many effects simultaneously within a single unit, or by putting several different effects units in line within the same effects loop. "In line" simply means hooking them up in a row such as in the following example.
Example 3a:
In this case the signal flow is coming from effects send and flowing toward return. Remembering that the inputs are always on the upstream side of the flow, the "inputs" in this situation will always be coming from the effects send jack, and the "outputs" will always be going toward the effects return jack. Thus we have a signal path like this:
Effects send (from the board) to Input (on the delay) to Output (on the delay unit) to Input (on the Reverb unit) to Output (on the reverb unit) to Effects return (on the board)
Some soundboards are equipped with more than one effects channel. All you need to remember is that if you used the effects send from channel "A", you have to use the effects return for channel "A". If your board has more than one effects channel, you can set them up totally independent of each other. This gives even more control when adjusting the sound to the individual mixer inputs (microphones, etc...).
Crossovers
Up until now, we have dealt with PA systems that use a single amplifier to power a set of full range speaker cabinets. In addition to speakers and horns, these cabinets are equipped with internal passive crossovers. Basically, crossovers are little electrical devices that receive a fullrange signal and divide it into separate outputs of midrange frequencies, lowrange frequencies, and highrange frequencies. That way, the highs are sent only to the speakers designed for the highs, the lows are sent only to the speakers designed for the lows, and the mids are sent only to the speakers designed for the mids. Passive crossovers do this by dividing the signal after it leaves the power amp while active crossovers do this by dividing the signal before it gets to the power amps.
Passive crossovers (located inside full range speaker cabinets) are good in that they make it possible to provide a full range of sound using only one amplifier, but they are a little inefficient. Since all the speakers are working from the same source, the low speakers, which require more power, will tend to rob power from the higher frequency speakers and horns.
Active crossovers (plugged in-line before the amplifiers) are good in that they make it possible to power the mids, lows, and highs from different amplifiers. This way you can use a big super-duper amplifier for your lows, and use a smaller amp for the mids and highs. This is a much more efficient use of power, and it gives you the ability to acquire a much more powerful and full sound. The catch is that using an active crossover requires a lot more equipment and expense.
Using an active crossover in a system is sometimes called bi-amping or tri-amping. Below is an example of tri-amping the mains in a mono system.
Example 4: Tri-Amping the Mains
With the exception of the signal path to the main speakers, example 4 is exactly the same as example 3. The effects loop and the monitor system should be connected in the same way as before, but now the mains have been turned into a tri-amped system. To do this, a crossover, three separate amplifiers, and three separate sets of speaker cabinets must be used. Each of these amplifiers as well as each set of speaker cabinets must be designated to a specific audio frequency. Which frequency goes where is determined by the outputs on the crossover. The "low out" should go to the input of the amp with the highest wattage because the low end speakers will require the most power, and the "high out" should go to the amp with the lowest wattage because the horns will need the least power. Just remember that it takes a lot more energy to vibrate the great big cone on a fifteen or eighteen inch speaker than it does to move the tiny diaphragm in a midrange horn.
Warning:
Never plug a high end speaker or horn into the amp that is plugged into the "low out" of the crossover. These speakers are not designed to handle such low frequencies and will be damaged very quickly if hooked up incorrectly.
To hook up the system in example 4, follow steps 1 through 15:
Monitors and Effects
1) Connect these together as described in example 3.
Mains (Keep in mind that even though the signal flow splits inside the crossover, it still flows from the mic toward the speakers)
2) Plug a high impedance cord into the main "output" of the mixer.
3) Plug the other end of this cord into the "input" of the main equalizer.
4) Plug another high Z cord into the "output" of the equalizer.
5) Plug the other end of this cord into the "input" of the crossover.
Lows
6) Plug a high Z cord into the "low output"of the crossover.
7) Plug the other end of this cord into the "input" of the highest powered amp.
8) Plug a speaker cord from each "speaker out" of this amp into the "input" of each low speaker (one cord to each speaker).
Mids
9) Plug a high Z cord into the "mid output"of the crossover.
10) Plug the other end of this cord into the "input" of the middle powered amplifier.
11) Plug a speaker cord from each "speaker out" of this amp into the "input" of each midrange speaker (one cord to each speaker).
Highs
12) Plug a high Z cord into the "high output"of the crossover.
13) Plug the other end of this cord into the "input" of the least powerful amplifier.
14) Plug a speaker cord from each "speaker out" of this amp into the "input" of each Midrange/high horn (one cord to each horn).
15) Take a break. That was a lot of work.
To see how a large super-duper stereo PA system with multiple effects loops, monitors, and compressors is hooked up, simply click on "next page". Be patient though. The diagram is a little bit on the large side and will take a little time to load up.
Below is an example of a large stereo tri-amped PA system.
Example 5: The Works
With the exception of the compressors, the additions incorporated into this system are simply a doubling of the system components covered in previous examples. At this point, you should have a pretty good grasp of how to hook it all together, so rather than listing a lengthy step by step, I have listed a brief description of each addition included in this example.
Two Monitor Mixes
Running more than one monitor mix can be very useful in that you can provide different monitor mixes for different parts of the stage. I have found that the drummer often wants to hear different things in the mix than the rest of the band. With two different monitor mixes, this is easily accomplished. Simply assign one monitor mix (channel A) to the drummer and another (channel B) to everyone else. This way you can adjust what the drummer hears independently of what everyone else on stage hears. In order to do this, your soundboard needs to be equipped with more than one monitor channel. These channels, usually designated as "Monitor A" and "Monitor B", will be controlled by separate knobs and will have separate outputs which must in turn be hooked into separate equalizers, amplifiers, and speakers.
Multiple Effects Loops
The same concept applies to the effects loops. To hook up two effects loops in a mixer that is equipped for it, all you have to do is run one loop through "Effects A" and another separate loop through "Effects B". Some boards come equipped with several different available effects loops that may be labeled "Effects 1", "Effects 2",etc. Sometimes the effects will be labeled as "auxiliary". You can run as many separate effects loops as your mixer is equipped to handle provided that you have enough separate effects units to pull it off. One possible use for this set up is that you could assign nothing but a long delay (echo) to Aux 2 and your general effects to Aux 1. Then when a song required a long echo on a certain part, all you would have to do is turn up the slider or knob for Aux 2 to get your desired echo without changing to rest of the effects at the same time. Then when the echo wasn't needed anymore, you could simply turn the Aux 2 all the way down effectively removing that effect from the mix.
Note:
The effects send, monitor out, and auxiliary out channels are essentially nothing more than specifically labeled line out channels. This means that as long as you pay close attention to where you plugged things in and you properly re-label your knobs, you can use them interchangeably. Usually, the only reason to do this would be to acquire another monitor mix in a board that is equipped with only one monitor channel but has an extra unused auxiliary channel. To avoid confusion, I would recommend doing this only as a last resort. Also, don't forget that in order for your effects to work, they must return to the soundboard to complete the effects loop.
Mains in Stereo
Running two separate channels for the mains is what is known as running a stereo PA system. To do this, you need a stereo mixing board. This board will consist of two output channels for the mains. These will be labeled either "left" and "right" or "A" and "B". The sliders for each input channel on the board will control both channels simultaneously, but there will be a "pan" knob above each that will allow you to pan the volume from left to right just like the "balance" knob on your car stereo. The output sliders on the board will operate the outputs for channel "A" and "B" independently of one another. Hooking this system up is essentially the same as what you did when hooking up two monitor mixes. Simply run the left channel "A" out to it's own equalizer, crossover, amplifiers, and speakers, and then do the same for the right channel "B". This is where those stereo (two channel) components come in handy. For instance, you can hook the "left out" from the board into the channel "A" input of the equalizer and hook the "right out" from the board into the channel "B" input of the same stereo equalizer. This principal can be followed all the way through the crossover, and the amplifiers.
Note:
When using a stereo amplifier in this way, make sure the switch in the back is switched to "stereo" mode.
Compressors
Compressors are an effect that is usually run in-line in the main signal path. They make a subtle change in the sound of the entire system that amounts to "taking the edge off". There are a lot of technical descriptions for what they do, but my best description is to say that they do just what the name implies. They squash (or compress) the sound together to create a more compact and clean sound. Be careful with these, they can be used for either good or evil. Set to a moderate level, they can add to the quality of your overall sound, but set too high, they can take the life right out of your performance. Honestly, I am not the biggest fan of compressors, but I think I am in the minority, so I felt I should incorporate them into at least one example.
Example 6: The Snake
At some point you may want to use a soundman to run sound from somewhere other than the stage. In order to get the board out in front of the stage and across the dance floor, you will need a PA snake.
The PA snake is used like an extension cord that connects all of the things on and behind the stage to all the things the sound man will be using in the sound booth on the other side of the room. The snake should have at least as many low impedance (low Z) channels as your soundboard, and at least 2 to 4 high impedance (high Z) channels depending on whether you are running a stereo setup or not. When setting you system up this way, the soundboard should be placed at least 30 feet or farther out in front of the main speakers so that the sound engineer will be far enough away to get a clear idea of what is coming out of the system. Also, the equalizers, the compressors, and the effects should be located along side the soundboard while the amplifiers and the crossovers should be located on or behind the stage. The on stage end of the snake will be a big box with individually numbered High Z inputs and Low Z outputs. The end of the snake toward the sound booth will have high Z outputs and Low Z inputs with numbers corresponding the inputs and outputs on the stage end. The ends toward the sound booth will be loose and look like the ends of microphone or instrument cords.
To properly hook up the snake, simply plug each of the loose low Z ends into the channel on the soundboard that corresponds with the number printed on that end, then plug all of your microphones on stage into their regularly assigned channels at the box end of the snake. For instance, the loose end marked "1" should be plugged into input channel number 1 of the soundboard. Then, on the stage you can plug microphone number 1 into the number 1 input on the box end of the snake thus assigning microphone number 1 to channel number 1 of the soundboard.
The high Z inputs and outputs are there to provide an extension between the compressors (if you're using them. If not, insert the word EQ for the word "compressor") at the sound booth and the crossovers on the stage. To do this, simply plug one of the high Z loose ends of the snake into the output of the compressor, and then plug a cable between the corresponding high Z channel on the box end of the snake and the input of the crossover located on the stage. This same principle applies to both the monitor channels and the main channels.
Congratulations!!!
You now have the ability to hook up any system you are likely to ever need. Anything bigger or anything more is just icing on the cake or overkill or the product of someone with way too much money. Of course, if you are going to be playing at Woodstock or in the Superdome, you might need to have a larger system, but at that point you will probably be able to afford to pay someone else to do all this stuff anyway.
WORDS TO KNOW
This section deals with some words and phrases you are likely to hear and maybe even use while running sound. It helps to be at least somewhat familiar with most of these so that you can better impress you friends with your high tech lingo. Some of the definitions are taken right out of the dictionary, while others are interpretations taken directly from personal experience as a sound man and a musician.
Active/Inactive Microprones - Scientific definitions aside, active microphones generally sound better than inactive ones, but they generally cost more. They also require the use of either a battery or phantom power while inactive mics need only be plugged into the mic cord in order to work. In most playing situations, the subtle improvement in sound quality from an active mic isn't worth the extra cost and hassle. One possible exception it the headset mic. Put simply, inactive headset mics just plain suck. Active headset mics put out a much stronger signal and feed back much less.
Amplifier (Power amp, Head) - It's the part of the sound system that actually magnifies or "amplifies" the sound. In other words, it makes stuff louder.
Attenuator (Pot) - The electronic dohickey under the knobs that increases or reduces the strength of the signal running through it. When these get old and dirty, they can make popping noises or rumbles in your PA (As in "my pots are dirty").
Balanced input/output - A "balanced" connection is one that has three wires to move the signal. One is a ground, and the other two (called conductors) carry signals of equal value. This is why they are called balanced. Low Z cables and connections are the most common example.
Balls - 1) The depth and thickness of a sound, usually on the bottom end of the EQ (as in "needs more balls"). 2) The strength of the voice on the mic (as in "check it like you have some balls").
Bass - 1)The lower frequencies. 2) On the soundboard this should refer to the bass guitar channel, not the bass drum.
Bottom - The bass frequencies (as in "needs more bottom end").
Cable, 1/4 inch - An unbalanced cable most often used for instruments and patch cords. Commonly referred to as "guitar cords".
Cable, TRS - A less common balanced cable that has 3 different contacts on its 1/4 inch connectors. Most headphone jacks are a good example of a TRS (Tip-Ring-Sleeve) connector. These are sometimes used instead of the more common XLR connection.
Cable, XLR - A balanced cable used for low impedance microphones and sometimes for connections between some parts of the PA. Commonly referred to as a "mic cord".
Channels - These are divided into two separate categories. Input channels are those channels coming into the soundboard such as microphones and direct lines. Output channels are those leaving the board such as monitor and main outputs.
Chorus - Common type of effect that makes sounds fuller and thicker.
Clean - Describes a distortion free sound with few effects.
Compressor - Effect used to squash the sound together. Used properly, it can take the edge off or your sound. Used improperly, it can take the life right out of your system and make it sound like an MTV mix.
Crisp - Describes a good clean high midrange sound. It can be good or bad depending on the look on the face of the guy who said it.
Crossover, Active - A rack mountable unit used to separate frequencies leaving the soundboard into high's, mids, and lows with different outputs for each.
Crossover, Passive - Used inside of full range speaker cabinets to separate highs, mids, and lows and send them to their respective speakers within the each cabinet. These are not as efficient as active crossovers because they require all frequencies to draw from the same source of amplification.
Cord (Speaker, Mic, Instrument) - Used to connect a sound system together. Each type of cord is made for a specific purpose and should not be used in place of another type of cord, not even if they look alike. Also see "cable"
Delay (Digital, Analog) - 1)Effect used to create echo...echo...echo...echo...echo... 2)In more advanced systems used in very large venues, delay can be used to time the arrival of the signal to the speakers in the back of the room so that people in the back hear the sound coming from those speakers at the same time that the sound coming from the speakers in the front of the room arrives.
Direct box - Used in line to convert a high impedance signal into a low impedance signal.
Distorted - The way your PA sounds just before it blows up. Fuzzy and scratchy. If you hear this, it either means you have something hooked up wrong, or something in the system is going bad. It could be anything from your super expensive soundboard to a five dollar patch cord.
Dry - Describes a sound coming from the PA with no effects on it.
Effects - Electronic boxes (usually rack mounted) added to a PA system to subtly change and enhance the signals going through it. Examples include; Reverb, Delay, Compressor, Chorus.
Equalizer (Parametric,Graphic) - This is used to filter out and adjust specific frequencies in the PA. This is the part of the PA where you have the most control over the band's overall sound. It is also the number one weapon against feedback.
Feedback - This occurs when the sound coming out of the speakers goes back into the microphones, then back out the speakers, then back into the mics.... and so on. This can build very quickly to a point where everyone in the room is holding their ears and screaming at you. It can also cause damage to the PA.
Flat - Refers to the frequencies on the EQ when they are arranged in centered neutral positions.
Folded Horn - A speaker design where the speaker points back into the cabinet and bounces around finally coming out large ports in the front. It is intended to maximize low frequencies in a relatively small cabinet.
FOH (Front of House) - Refers to the speakers that face toward the audience. Also called the "main" speakers.
Frequency - Practically speaking, high frequency means high pitch and low frequency means low pitch.
Front Loaded - A speaker cabinet where the speaker faces out toward the front.
Full Range - Describes a sound which covers all audible frequency ranges. As in "full range speaker cabinets."
Gain - Knob usually found at the top of each input channel on the soundboard. Used to set input levels of the separate channels to relatively equal positions.
Ground Adapter Plug - Adapts a three pronged electrical plug to a two pronged wall outlet. This bypasses the ground and may create a hum in the system. A lack of a good ground can cause mild electrical shock when touching a microphone.
High Impedance Cord (High Z) - A big word for instrument cable. These cords generally have quarter inch male ends. they tend to loose signal strength at lengths longer than 25 feet.
Horn - The part of the speaker that emits midrange and higher range frequencies.
Jack - Anywhere you plug something in.
Kick Drum - PA lingo for bass drum. This eliminates the confusion between the bass drum and the bass guitar.
Level - Sets output volume of individual PA input channels. Usually positioned as sliders at the bottom of the soundboard.
Loop (Effects Loop) - A signal path separate from the main signal paths where a line signal is routed out of the mixer through a series of effects units, and then returned back to the mixer. The electronics within the mixer can then be used to individually control the effects on each input channel.
Low Impedance Cord (Low Z) - A big word for mic cable. These cords lose very little signal over distance, and can thus be made very long. PA snakes are constructed mostly of Low Z cords because of their need to be lengthy.
Line In (Input, return) - Where a signal enters the board or component.
Line Level - A low level signal such as the signal in a guitar cord. Most parts of a PA require a line level signal. Remember, however, that speaker outputs are not line level. Plugging speaker outs into line ins will result in damage to the equipment
Line Out (Output, Send) - Where a signal leaves the board or component.
Mains - The speakers facing the audience along with the system of amps equalizers and effects attached to them.
Microphone (Mic) - I'll bet you already know this one
Monitors - The speakers facing back onto the stage and the system or amps, equalizers, and effects attached to them.
Monitor Mixer - Larger systems often use a completely separate mixer for the monitors that only adjusts the sounds that are heard on the stage.
Muddy - Describes a low end muffled sound lacking highs and mids, and possibly having too much effects.
Pan (Balance) - Knob on the mixer that adjusts the relative volume between left and right (or A and B) in a stereo setup. Just like the stereo in the living room.
Patch Cord - A very short high Z instrument cable.
PFL - These buttons allow you to boost or isolate individual channels in the headphones.
Phantom Power - When this is turned on in the soundboard it will power the active microphones in the system. It should be turned off when no active mics are hooked up.
Polarity - The direction of flow of electricity either negative to positive or positive to negative. Matching polarity between different amplifiers can greatly reduce hum and the risk of elictrical shock. Most amps come equipped with a "polarity switch".
Potentiometer (Pot) - See "attenuator". For our purposes, they are the same.
Power Strip (six way) - Allows you to plug a lot of things into one power outlet.
Power Supply - Basically, a rack mountable power strip that costs a whole lot more, but hey, some of them have cute little lamps that light up the face of your rack.
Reverb - A most basic and necessary effect. Think of it like this. If you stand in a big empty warehouse and shout, "Hey!", you will hear a sort of "reverberation" surround you. It's sort of like an echo, but not exactly. Think of it as audio afterglow.
Slider - Usually found on an EQ of a soundboard. These turn things up or down by a "sliding" movement rather than the rotary movement employed by knobs.
Snake - In large systems, this long bundle of cords connects the things on the stage (amps, mics...) to the things at the sound booth (mixer, effects, EQs.....).
Speaker - The part of the system that physically produces the sound.
Speaker Cabinet - The box that holds the speakers.
Speaker Out - A high power signal leaves the power amp through this jack on it's way to the speaker.
Submix - Used on larger mixing boards when selected channels are assigned to specific sub-channels before their signals reach the main slider. For Example, you could assign all the drum channels to one submix (all on one slider) so that you could turn them all up or down at the same time.
Sum - This sends a line level signal out of the board. Heck if I've ever found much of a use for it.
Tinny - Used to describe a sound with too many highs and mids and not enough lows.
Unbalanced Input/Output - These cables contain 2 wires inside of them. One is a ground (shield) and the other carries the signal. The most common of these for PA uses are the 1/4 inch high Z instrument cables and connections.
