Scott's PA System Tutorial: Running Sound

Page 5

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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.

Scott's PA System Tutorial Completed September 30, 1998