I've seen the volume pot added before the preamp, sometimes after the preamp, sometimes between the gain stages in the preamp.
Is there a preferred position that gives a better performance or is it dependant on the preamp design? Does the same also apply to added tone controls or equalisation?
Is there a preferred position that gives a better performance or is it dependant on the preamp design? Does the same also apply to added tone controls or equalisation?
It's usually a trade-off between noise and overload headroom.
If you put the gain control pot right at the input, then obviously you get the best immunity to clipping, but all the stages after the pot are operating at max gain and each will be adding noise.
Conversely if you put the pot late in the signal chain, then as you turn down the volume, you are also reducing the noise. The problem is that a high-level input could cause stages before the gain-control to clip.
That's why the control is often about half-way down the chain! Wherever you put it, be careful that the stages before the pot aren't going to clip. (perhaps by giving each input its own input-level setting pot.)
If you put the gain control pot right at the input, then obviously you get the best immunity to clipping, but all the stages after the pot are operating at max gain and each will be adding noise.
Conversely if you put the pot late in the signal chain, then as you turn down the volume, you are also reducing the noise. The problem is that a high-level input could cause stages before the gain-control to clip.
That's why the control is often about half-way down the chain! Wherever you put it, be careful that the stages before the pot aren't going to clip. (perhaps by giving each input its own input-level setting pot.)
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