I've been thinking about trying out the Darkvoice 336, and looking at the schematic I've found that I have most, if not all, of the parts and tubes needed to build one. There's also an article on TubeCAD with some suggestions for mods that I've looked at, but I'm starting with figuring out the...

I have an old (late 70's) Koss Pro/4AA inherited from my father in law, but it's thin and boxy sounding with very little bass. I've also tried with a new pair of non-stock 50mm drivers but the sound didn't change much. Could it be the cans themselves? Are there any mods that can be done?

Rebuilt my "Brute Force" headphone amp. It was originally a mu-follower with paralleled 6SN7s into paralleled 6BX7s and sounded very good with high impedance headphones, but I wanted something that could drive low impedances without transformers. I found a schematic for an Aikido front end...

These are some of the most comfortable phones I've tried. Been laying around with a dead driver for years, so I ordered a pair of 50mm/150ohm drivers from Aliexpress, along with new pads. Yeah, that's a cat5 cable with Neutrik plug that I installed a long time ago :) Just started breaking in...

I built this some 15 years ago and just recently got it out again. I've cleaned up some wiring and changed out the tubes and it plays great, got rid of the hum and noise despite it still looking like a rat's nest underneath :) It's designed for 600Ω and I've been using 250Ω DT531s with it, but...