Hi all,
I have an Allen & Heath Zed14 mixer, and recently had to take it into a space in which I had to patch its output into a basic Mackie's input, to connect to the existing installed system. Given the installation it was impossible for me to steal the outs directly. Anyway - we've used this same procedure multiple times with this and other boards with no significant issues. On this occasion, however, we were getting an excessive amount of noise, and a hum that both seemed to get louder at times. (Power for the entire system was coming off of the same circuit). And furthermore, upon using a Roland m200i thereafter in the same fashion, it sounded clean.
Anyway, this led me to check to measure the voltage of the outputs of the console (my intent was to see if I had dropped a shield pin... though I'm not certain that this is at a ll a valid way to diagnose this). What was interesting was, when measuring voltage across pins 2 and 3, with a 400hz sine wave, with channel and main outs at unity (panned center), and the gain boosted until the output meter read zero, I got a voltage of something like 2.2V on the left chanel and about 1.7 on the right. I also measured across pins 1 & 2 on each out, and got roughly the same difference between them. Is this an indication of a logical problem (either with the above situation or something else)?
I know that whole thing is very wordy - my apologies. Let me know if there is anything I can clear up for anyone.