Many of us have had feedback issues at a live show and have been given the following advice from a fellow sound guy: ‘If you turn down your input gain and turn up your output, you will get better gain before feedback.’
It was one of the first things I was told by a veteran engineer when I started mixing monitors.
The truth is that this is simply incorrect. Feedback depends on the total gain and response of an entire circuit. Gain in series is additive, it does not matter where in the circuit it is applied. It’s the total amount that matters. 20db of gain at the input is exactly the same as 20dB of gain at the output.
There is one caveat. If you start taking components beyond their limits they could potentially start adding distortion to the circuit, thus changing the entire circuit response. The solution to this is simple: don’t drive things into red!
Jamie Earle is Clearwing’s Chief Audio Engineer. He started working in the shop of a PA company 10 years ago, cleaning sick off of cables and painting speakers. Since then he has toured as Band Engineer and Systems Engineer. He was brought up in a small 8000 pop coastal town in the South East of England and has spent time living and working in Prague, Czech Republic, where he met his Minnesotan future wife. They moved to the US in April 2014.