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Project Notes

#098 Guitar Headphone Amp

An LM386 fixed-gain guitar headphone amp.

GuitarHeadphoneAmp_protoboard

Notes

Yet another LM386-based audio amplifier similar to the LittleGem/A386/Smokey series, this time adapted as a guitar headphone amp.

There are various “headphone amp” circuits based on the LM386. After trying many of the variations, I found that going back to basics performed just about the best (per the reference circuits in the datasheet).

Features of the circuit:

  • default 20x gain (no extra components required)
  • simple capacitive-coupling with ~50k impedence matching for a guitar input
  • ring of the 6.35mm connector is used to switch power - use with a standard mono cable
  • mono output is sent to left and right channels of the headphone socket

How it performs:

  • clean signal with a slight warm overdrive at maximum guitar ouput
  • performance can be a bit temperamental on a broadboard, but when I put it on a protoboard it performs quite well.

Construction

Breadboard

The Schematic

The Build

GuitarHeadphoneAmp_protoboard

Credits and References

About
Project Source on GitHub Project Gallery Return to the LEAP Catalog

This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is just my personal collection of projects. Two main themes have emerged in recent years, sometimes combined:

  • electronics - usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting
  • scale modelling - I caught the bug after deciding to build a Harrier during covid to demonstrate an electronic jet engine simulation. Let the fun begin..
To be honest, I haven't quite figured out if these two interests belong in the same GitHub repo or not. But for now - they are all here!

Projects are often inspired by things found wild on the net, or ideas from the many great electronics and scale modelling podcasts and YouTube channels. Feel free to borrow liberally, and if you spot any issues do let me know (or send a PR!). See the individual projects for credits where due.