Not much has changed from my previous build, I got occupied for the last week or so with building a new desk while waiting for some JRC386D chips to arrive. I also configured a smaller breadboard host to reduce the necessary desk space required to test my ideas out. Initial tests are showing that the JRC386D IC amplifies far cleaner than the LM386N-1 IC. It can be driven by my previous op amp and FET buffers at full volume without...

A few days ago I was lamenting, in a rambling sort of way, about being unable to get the distortion channel working on my test design. After redesigning and breadboarding the circuit many times I finally came across the core issue – I was configuring the op amp in a non-inverting format which was having unexpected results with the feedback loop. Once I realized my mistake I quickly whipped up a new version. Note that this is an...

In my quest to figure everything out myself, instead of just blindly following pre-designed circuits, I’ve come up with a pretty good clean sounding 1/2 watt power amplifier as well as an effect loop and more recently a switching setup for dual channels using a DPDT switch and some nice tone shaping. For the most part, it’s been about 60% research and theory and 40% just trying things out and learning from the resultant epic...

The design is slowly starting to take shape for my guitar amplifier circuit.  Here is the power amplifier stage with the simple effects loop and the tone stack portion of the pre amp that I will be testing next:   This is essentially the same three knob tone stack found in most big name amplifiers. I’m still working on tweaking some values and have not yet wired this one up. Using the very useful Duncan Amps Tone Stack...

  After studying some other LM386 based 1/2watt guitar amplifier designs I noticed that where I had a 10KΩ resistor on the output, all other schematics have a 10Ω resistor there.  I delved a bit further and found that the data sheet also specified the 10Ω resistor, so despite working – I was clearly mistaken. I played around with some other component values, referencing the data sheet, and created a version of the circuit that...

I have been playing with some various circuits to deal with the pre amp stages and effects loops for my miniature guitar amplifier design.  The circuit presented here is a revision of my previous core amplifier schematics. Other than a few component changes, the main difference is that I have added an N-FET transistor (MPF102) buffer to the input stage. This should prevent improper impedance loading on any pedals in the effects loop stage...