mic preamp's input vs output gain knobs

R

richardosim78

New member
my dears,

whats the difference between mic tube preamp's INPUT gain knob and OUTPUT gain knob.
what each do in reality??
does input knob increase voltage and distortion/saturation of the mic signal and output knob outputs the loudness of it? like in a guitar amp operation...??
whats really going on there??

gracies.
 
richardosim78 said:
does input knob increase voltage and distortion/saturation of the mic signal and output knob outputs the loudness of it? like in a guitar amp operation...??
Click to expand...
Most of the time, basically, yes.

We'd have to look at specific schematics in order to say exactly how any given preamp accomplishes this, but it is basically so that you can run the preamp itself "too hot" and still send reasonable levels to whatever gear lives downstream.
 
It doesn't really have to be "very strongly", usually if you're actually getting saturation, overdrive, or distortion at all from a preamp, it means that the level must be quite a bit higher than "nominal" line level. Unless you also want distortion from later devices, you usually need to attenuate. OTOH, if you wanted to slam that already distorted signal into something else for even more distortion, you'd want to turn that output gain back up.

Like I said, though, it does kind of depend on the circuit itself. In some instances, the output control might interact with the output transformer, etc...
 
Like was said earlier, it depends on what preamp you are talking about. preamps with compressors or eq built in will have output controls so that you can counteract the effect of the compressor or eq.

This falls under the 'get the line level early and maintain it through the signal chain' umbrella.
 
i was talking about a mic tube saturation.. anyway..
so the final word is simply:
saturate mic tube preamp's input gain as much as u want, and then adjust output gain so that the second device in the chain doesnt clip/red..
right?
 
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I think this is a good question and I wish I knew the whole answer. I think impedance matching falls into the explanation somewhere.
 
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