Little gem... how can i clean it up?

[ejbasses]

Ive built the little gem and im using it on headphones

my question is how can make the little gem sound clean thru the whole rotation of my volume knob

any help will be appreciated

thanks!!

[Peter Snowberg]

The LM386 on 9V has a pretty low headroom so the only way to stop it from distorting is to use an attenuator on the input.

This gets a little tricky for tonal reasons because the 386 has an input impedance of roughly 50K which is already so low it's eating the highs. For distortion it's good to have some of the highs removed, but the same is not so for clean tones. If the impedance were more like 1 meg you could just add a 1 meg pot for a "max" volume control to the input and be done with it. At 50K, adding a pot will load down the guitar even more and kill more of the highs. Nothing comes easy does it?

The best advice I think I could give would be to add a JFET buffer to the front end (see the Ruby schematic for this) and use the volume control between the buffer and the 386 to set the maximum level so you don't get clipping. The JFET raises the input impedance so the tone isn't getting killed and it does it without clipping.

Add a JFET, a couple resistors, a cap or two, and a pot and then you'll have a small and clean amp.

Beware that the 386 is not very loud when it's running clean. Just so you know....

Take care,
-Peter