50L6 amplifiers

My humble setup

These little amps are the culmination of time working at Coffman Labs, where I’ve built the CypherLabs Prautes 50L6/25L6 headphone amp for the last eighteen months or so. Damon Coffman sold and gifted me parts to build five amps of my own, so these are the first two— Damon designed the chassis and I’m skinning them in different ways. They are extremely similar to the Prautes electronically, as it is the same circuit, and the components are the same except for the interstage/splitter transformers; my amps use the Edcors used in the original Coffman Labs H1-K, whereas the Prautes has more expensive autoformers which image better. My amps are built differently internally, being based off a stand-off isolation cage inside; also, I opted to use different wire in some places, as well forgo the use of some switches (including the bass-boost circuit). Like Prautes, everything is point-to-point wired and soldered, no circuit boards. Although these are technically speaking only meant to be headphone amps because they can only produce ~1.5W, they work amazingly as an integrated unit for driving efficient speakers (loudly enough to get one evicted at least).