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PA Gain Structure: Aux Send / Aux Return Levels?

Zooberwerx

Gold Supporting Member
Dec 21, 2002
23,315
28,109
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Virginia Beach, VA
I've just installed a DigiTech Studio Twin FX processor (POS but it was free and does have some usable reverb options) in one of our four available Aux Send / Return loops. I'm dealing not only with two separate controls for send and return levels but also dry / wet and input levels on the DigiTech unit itself. My primary objective is to maintain a variable FX saturation while preserving the highest possible signal / noise ratio.

If anybody can suggest a logical way to address this, I'd be most appreciative. FWIW, I have noticed that the Digitech in its "dryest" setting is a bit of a tone-sucker.

Thanks

Riis
 
Pump the Send up until just before the Digitech unit clips. Set it to 100% wet. Pump the Return up until you have the desired level of effect.

Using any dry signal on the effects unit could lead to phase issues, when the dry signal from the effects unit mixes with the dry signal from the channel when they go into the summing portion of the mixer. You use the mix control on an effects unit when it's inline (ie: in an insert, between the mixer and the power amp, etc.).

EDIT: Oh, just realized that you've also got input gain on the Digitech. For best signal to noise ratios, you want as high of a signal going into the Digitech as possible without it clipping. Attenuation later down the chain means a lot less noise than multiple moderate gain stages. I'd set the effect unit's input gain to minimum and the send on the board to maximum to start with, and bring down the send if you're getting distortion, bring up the gain if you're not getting a hot enough signal. That is, unless the input gain is just a trim control (ie: no amplification tied to it, just attenuation), in which case, start with it topped out and bring it back if need be.
 
Pump the Send up until just before the Digitech unit clips. Set it to 100% wet. Pump the Return up until you have the desired level of effect.

Using any dry signal on the effects unit could lead to phase issues, when the dry signal from the effects unit mixes with the dry signal from the channel when they go into the summing portion of the mixer. You use the mix control on an effects unit when it's inline (ie: in an insert, between the mixer and the power amp, etc.).

EDIT: Oh, just realized that you've also got input gain on the Digitech. For best signal to noise ratios, you want as high of a signal going into the Digitech as possible without it clipping. Attenuation later down the chain means a lot less noise than multiple moderate gain stages. I'd set the effect unit's input gain to minimum and the send on the board to maximum to start with, and bring down the send if you're getting distortion, bring up the gain if you're not getting a hot enough signal. That is, unless the input gain is just a trim control (ie: no amplification tied to it, just attenuation), in which case, start with it topped out and bring it back if need be.

Well, I messed with it before reading your edit. Didn't even turn on the power amps; I used the LED's for guidance. I found that if I started with the individual mic channel Aux level and master Aux Send level at "0" unity gain and set the DigiTech's input at 50%, I got a decent response with no clipping.

Riis