In my attempts to recently mod a Peavey Classic 30, I’ve been researching audio amplification like a demented mad scientist scheming to destroy the world. I’ve understood the conceptual model of amplification for a while, but I’ve never actually plunged into the crafting part of it before now. After changing out some tone caps, I couldn’t help but wonder how something like capacitance could actually affect the way the electrical signals are converted back into mechanical sound even though it’s pretty obvious.
A while ago I came across a schematic that included a simple 8-pin IC as the workhorse of the circuit. It’s called the LM386, and it’s got to have near a thousand uses judging by the amount of information about it. My cohorts and I have been toying with the idea of headphone sessions, a improvisational mixing session where the four of us write and play music while being conscious of the stereo field. This of course requires the purchase of a headphone amp. Why buy one when you can just build one.
I played with the LM386 for about five hours. It was mostly blind experimentation since I was just using parts I could pull off other dead devices. I had also purchased a shitload of resistors earlier in the day which I was also dying to play around with. I could only get it to sound clear enough at lower volumes through a .5 Watt speaker with a tear in the cone. It seems ample enough for headphones. I figure four dual PCBs with essentially 8 tiny amps attached to a pot on the jack should just very well do the trick. I’ll make a better effort to document as well.
lm386 amp made with random caps from abram on Vimeo.