i was reading over this thread on diystompboxes.com about building an analog LFO circuit for some wild noise idea i’ve got brewing in the back of my head. i started messing around with some of the schematics on there and got a drifting saw wave out of it after a while. i was trying to take a picture of the wave itself on the oscilloscope which obviously didn’t turn out all that well. so many breadboards. yeesh.
Double the circuit for stereo. This is a breadboard representation of a single “channel.” Each channel will have its separate PCB with controls. This one lacks a volume pot, but the output was more than enough. 750mW after hooking up the gain path resulted in ripping the ear buds out of my ears in order to avoid total deafness. Sadly to say, I have about as much luck avoiding electrocution as I do cutting myself with knives. I’ll keep to the low voltages for a little while longer.
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.