boost gain and volume

[Loggie]

I searching a pcb of a booster with 2 knobs "gain and volume" exist?

[MikeH]

lots of them exist.  you'll have to be more specific...

[Mark Hammer]

The gain can be adjusted on ANY booster.  Most of them simply fix the gain, and just use the volume control.  If you get a different tone from the circuit as the gain is turned up - and I am NOT talking about tone from the amp because of a boosted signal, but just tone from the pedal - then there is a reason to want to have both a gain and volume adjustment.  If there is no change in the tone of the circuit at different gains, then there is really no need to make the gain adjustable, or to have separate gain and volume controls.

[mountainking]

Some gain controls allow you to adjust the headroom of a circuit as well, which is also very useful.

[Mark Hammer]

Some gain controls allow you to adjust the headroom of a circuit as well, which is also very useful.

...if it results in an audible tone change.

[mountainking]

Mark, I was talking about a control that allows you to adjust whether the signal is distorted or undistorted, and when you said "tone" I quess I assumed that you were just refering to bass/mid/treble type tone. I realize now what you meant by "tone". Yes, if a gain control does nothing but adjust the amount of output the circuit will have, then it pointless. No need for two volume controls.