Originally posted by EWong:
Thanks for the info ST
I guess the question is the signal to noise ratio on the "board" and the impact of increasing the board's output gain.
I just got back from a tour of the Mackie and Behringer sites. It seems that when they state specs for Signal To Noise ratios, these are usually done in three states.
- All controls down
- Channel faders down, Main at 0 dB (or Unity)
- Channel faders at 0 dB (or Unity), Main at Main at 0 dB (or Unity)
What this doesn't tell us in either case, is the effect on the signal to noise ratio as we turn down the main mix.
My speculative view is that almost all systems (one or more components strung together) have some self-noise. Some of that will be present no matter what we do, as long as the system is functioning. Some of that will be relatively fixed (e.g. that hiss that just won't go away), and some will be variable (that hum that rises and falls as you turn up the gain somewhere in the system). And then there is the signal that we want to hear.
Aha - that's how to explain it.
If you have experienced "that hiss that just won't go away", but noticed that if you turn up the volume, the real music seems to overcome the hiss and we don't hear it any more then maybe we can talk about the effect of turning down the output of the mixer.
If you have noise in the system up to and including the mixer, and it is of the kind that seems less troublesome as you turn up the volume, then it is really important to get an optimal match between the output levels and the L1® input levels. Optimal is - having the mixer running at the best position on the main output to have lots of good sound (signal) masking the bad sound (noise). I have found this is is usually when the mixer main output is at 0 dB (Unity).
If the overall level is too high for a good match with the input section of the L1® then we have to attenuate the signal somehow. If we do it with the main output of the mixer, we may be reducing the signal, but the noise remains. Just like turning down the volume in a noisy system. The music is lower but the noise becomes more apparent.
If we leave the mixer at its optimal settings but attenuate the signal with a pad just before it enters the L1® we stand a better chance of lowering the noise as well as the signal. This includes any noise we picked up between the mixer and the L1®.
I don't hold out that this absolutely correct, but it lines up with my general experiences wiring up gear.edit - grammar