here’s a small battery-powered guitar amp that i’ve constructed from reused parts. the housing is a busted computer power supply (some of which is in the No. 5) as well. i’ve got several options for this little fellow in mind, but, for now, it’s a tiny amp with a mean distortion. lo-fi enthusiasts should contact me if you’d like one custom built.
LightBox Prototype: a battery-powered guitar amp w/ distortion from abram on Vimeo.
She’s big and bulky, but you can’t ask for too much when you’re dealing with pre-printed PC boards. The 22k resistor in the gain path makes for extremely high output (in terms of headphones). The 100k stereo potentiometer on the output side should make the noise floor a lot lower unless the knob is cranked. That’s what I was going for hear since the application of this device will be mainly for when other loud instruments are being played in the room. A short trip to the electronics store should yield three more of these guys. After that, it’s onto the chassis.
This was my first attempt at building the circuit on the PC board. Unfortunately, I think I’m going to have to get a different board since this one isn’t quite big enough with two opamps. Soldering it is also a bitch considering it’s tiny and my iron tip isn’t as small as it should be.
The 1/8″ plug is the output soon to have a pot attached to it for volume control. I’ve been thinking about attaching an light meter to each channel, but I still need to know what the dimensions of the chassis will be before I jump that far into it.
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.
Abram Morphew is a musician, composer, inventor, theorist, technologist, self-taught engineer, and amateur scientist who lives in a '96 Jeep Cherokee with his wife traveling from place to place as the binary marketing show. This blog is a catalog of stuff that I make or bits of information that I think could prove useful later on when memory fails me. I currently hold an Extra Class Amateur Radio Operator license and transmit on the air as K2NXF.