www.hagamps.com
Wish it was available as a kitHalf Watt - Tube Amplifier
HALF WATT is an all-tube micro-amp intended for practice or studio work. It will easily drive any speaker cabinet (or none at all) without impedance or stability issues. A convenient headphone output allows for quiet practice (or for connection to DAW or PA).
I did something like this with a 12AU7 for the power stage and I didn't like it enough to continue pursuing, maybe I'll take a swing at a 12BH7 output stage. I just built a tube headphone amp for bass a couple days ago and I really like 12BH7 as a power tube for that.I bet Mr. Sushibox (@vigilante398) could do something like this. I think we should encourage him. This would be perfect for the garage testing rig!
Way too expensive, with that low of power I'm going to be running an SMPS for the high voltages. Also I've been shocked at the price of the little Hammond "universal" output trannies for a pretty sub-par frequency response. The output tranny Hag uses can be had off the shelf for $20, half what a Hammond universal runs. I'll do it on a PCB for easy build with minimal and clean offboard wiring, most of the parts will be available from Tayda, and I'm trying to cram it all in a 1590XX like the Hag.
Correct, half of the 12BH7 is unused. I thought about throwing it up front for a clean boost, but the plate current of 12BH7 is pretty high, I figure I'll leave it out and just let it be a clean amp. Weird that he's claiming 4 to 16Ω on a single jack, the output tranny is rated for an 8Ω output, but I guess you generally have enough tolerance that you're not going to kill a transformer or a speaker by mismatching within a handful of ohms like that., especially at low power like we're talking here. So it's not atuo-matching or some technological miracle, it's just "eh, you'll probably fine".
Yup, the Firefly. That's the 12AU7 build I did before that I wasn't thrilled with. It uses a 12AU7 in "self-split", which is kind of like push-pull but without a phase inverter, but not very efficient. It didn't sound bad, but it was a one-trick pony. I'm a fan of pedals (obviously), so any amp I build needs to be able to do a clean pedal platform thing, and the Firefly has a great sounding overdrive, but no good cleans.
I was curious how Mojotone did their push-pull set up, looks like theirs is also a self-split, no phase inverter.
Pretty much any Blackheart is killer for the prices you can get them for. Little Giant was the very first amp I ever modded, they're great stock but also excellent modding platforms.
