Is your mixing console noisy? Here's why...
I sometimes browse audio forums to see what kinds of issues are troubling people. Mostly they are the wrong issues, when other issues would make far more difference. But today I found a genuine problem that would cause anyone concern...
The poster was complaining that his mixing console was noisy. Well, issues don't get much more troublesome than that.
I'm going to assume that the noise is a constant background hiss, rather than hum, interference or crackling noises of any kind.
Naturally, being a forum, many members were keen to dive in and tell the poster how deeply uncool his mixing console was and really he should have an XYZ brand. Preferably the late 1980s Mk. II version. But in reality the problem is more likely something to do with operation of the console.
Over the years I've tried and used many mixing consoles from cheap-as-chips Secks and Studiomasters, all the way up to Neve, SSL, Amek, Trident, and many others including mid-range Mackies, Soundcrafts and the like. What I can tell you is that if you're working with a console that is designed for pro audio, even home studio pro audio, then there is unlikely to be anything about the console that will hold you back from producing professional work. As long as there are no faults of course.
It's all down to the engineer. If you know what you're doing, then if your recording is noisy it won't be the console that is at fault.
A noise source that analog mixing consoles have that digital consoles and DAWs do not
One key difference between analog audio and digital is that digital audio can be 100% silent. If there is no segment in the timeline at a certain point in a recording, then there is no signal, and no noise.
This is not the case in an analog console. There is always a certain amount of noise present in each channel. So if you have twenty channels routed to the mix with faders up, you have twenty channels' worth of noise in the monitors. It should not be anything anywhere near being loud, but the more channels you add, the more likely it is that noise will become noticeable.
So pull down the faders on unused channels. That should lessen the problem. Well yes, it lessens the problem. But even just routing a channel to the mix adds noise, even when the fader is all the way down.
On an analog console, it is always good practice only to route channels that are being used to the mix.
(Having said that, to combat crosstalk, some console designs had all the channels permanently routed, even when the channel was muted. Particularly in broadcast circles, crosstalk is considered a worse problem than noise.)
Although there are many ways one could incorrectly operate a mixing console and cause a noise problem, this is certainly one likely scenario.
In summary, don't route unused channels to the mix. Oh, and while you're at it, you might have aux returns that don't have a routing button and always feed through to the mix. Make sure they are turned all the way down if not in use.