Noise on LS9 input channel

[sdauditorium]

Recently, we just started getting a bit of static-type white noise on Input 3 of our LS9-32. It persists whether or not anything is actually plugged in, so I'm assuming it's got to be something within the board itself and not the wireless receiver that's hooked up to it. It's not loud when brought up even past Unity, but it is definitely noticeable and present.

Anyone experience something like this, and if so, is it something I can attempt myself or would I be best to send it in to Full Compass or a repair shop? Thanks in advance.

 

[ThatsoundguyChris]

Does the gain effect it?

 

[FMEng]

Be sure to compare it with another channel under exactly the same conditions. That would include the same gain trim, same EQ settings, no VCA applied, and what it is connected to.

Any mic preamp will be noisy when it isn't connected to anything. To make bench measurements of the noise floor, it is common to terminate the input with a 150 ohm, metal film resistor. That simulates the source impedance of a mic without picking anything up acoustically. Or, take a careful listen to it with a dynamic mic plugged into it, keeping the mic in a relatively quiet location.

If the one channel is noisier than than the others, it needs to go in for service. Possibly a transistor or op-amp in the input stage is failing.

 

[TimmyP1955]

Although I doubt there is anything to be gained, save all your scenes and then initialize the console.