Adding volume control to simple LM383 based amp

[bancika]

Can someone tell me how to add simple volume control to LM383 based amp from GGG?
Thanks!

[shawn1]

trying to get to the post

[antonis]

R3

[Mark Hammer]

Wrong amp.  The correct one is JD Sleep's layout for the Craig Anderton practice amp that appeared in his DIY Projects book (and probably a Guitar Player column as well, IIRC).  The basic amplifier assumes there will be some sort of preamp/buffer/driver stage ahead of the input, where signal level being fed to the power amp could be adjusted.  After all, this is precisely what larger guitar amps do - volume is adjusted BEFORE the signal gets to the power stage.

On the other hand, as the schematic shows, the amp is essentially structured like a big powerful op-amp.  The range of possible usable values for feedback resistance and ground leg are shown.  If the goal is to simply reduce the maximum output level, without any need for intermittent adjustment, then the implied course of action is to reduce feedback resistance R2, and increase ground leg resistance R3.  So, for example, R2=4k7 and R3=22R would give highest gain and volume, while R2=2k2 and R3=270R would give much less gain and volume.

Make sense?

[Elektrojänis]

Changing the feedback parameters might work just fine, but there is usually a minimum gain where the amp chip is stable.

For that reason it might be more practical to wire a standard volume control to the input and choose the feedback resistors for the maximum volume you want for your input signal.

Btw. It seems that the original post is somewhat old.

[antonis]

It seems that the original post is somewhat old.