In this actual circuit, I think I used a JFET preamp stage. The thing with JFETs is that they can amplify signals starting at a much lower initial level, like the high impedance signal from a guitar pickup. That means I have reasonable signal integrity and quality to work with.

The LM386 uses bipolar output transistors, and this results in rather bland sounding clipping of the waveform. This is like most entry level guitar effect pedals or the sound from typical cheap amps. It has no warmth and sounds almost like digital static in the distortion effect.

“Good” guitar sounds come from nonlinear clipping of the waveform. It is still bad audio, just less rigidly bad. Tubes clip the signal in a nonlinear fashion as do germanium diodes and transistors. These are the elements that can be added to make a better sound. A preamp stage that includes a couple of germanium diodes before the amp will make the tube-like warm distortion that most people like.

Then follow this preamp stage with a second that passes the signal through a couple of piezo transducers with a loose spring mechanically connected to both elements and the second piezo used as a pickup. That makes a spring reverb and gives the signal depth like it is being played in an auditorium.

Overall, the noise floor is what you might consider bad in headphones audio, but is very typically ignored with even the most pricey guitar amps. The BJT output clipping of the LM386 is digital and flat if over driven. The spacial depth of such a simple circuit is flat like all other mini amps that have been around for decades. In this instance, the output is clear and clean at lower levels due to the JFET preamplifier topology. Without a reverb circuit, the sound is too clean to the point of flatness and makes any undesirable nuances more prominent. Overall, it is about like listening to a decent quality FM radio station on a boombox from the late 90’s.

If anyone is getting into this kind of thing, look up open source circuits for guitar effects that uses germanium diodes. Then get an old powered subwoofer from a cheap surround sound system. Inside, you will find a low pass filter circuit using some op amps for the sub. Reverse engineer the op amp stages and hack in your geranium diode distortion and add a JFET preamp input before the first op amp stage. This will sound like a decent mid level guitar amp. You can buy germanium diodes pretty easily, but they are on some old TV circuit boards for salvage from common curbside junk, (buying is way easier as old TVs are hit or miss and might have 1 germanium diode). JFET transistors are a little harder to find and are easily damaged by static. A little more than half of through hole electret mic modules use a tiny JFET inside. It is a pain to use one of these in practice, but it is usually a free option for salvage in the most common consumer level junk.