[fuzzroffe]

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 driving a White cathode follower so I ripped out the old circuit, keeping the regulated 300V power supply, and just built it. So externally it's identical, with the same tubes, but with a completely different circuit underneath

My 5Y3 was acting funny and not giving enough voltage so I put in a 5R4 instead. There's some noise when I get past 12 o'clock on the volume. I know there's a ground point I have to fix and I may have to re-run some wiring, unless the noise comes from the regulator tubes... So far it behaves good even with 32 ohm Grados. I have a couple of 6BL7's so I might put a 4PDT in to switch plate/cathode resistors for them.

 

[fuzzroffe]

Fixed the noise with a decoupling cap on the 6AS7 grids and some better ground points. The bass is far better than the old circuit, lower and tighter and it just sounds "snappier" overall.

 

[HiGHFLYiN9]

Looks great, nice work!

 

[fuzzroffe]

Thanks!
I just put in new output caps, got a pair of Kemet 330uF/350V to replace the old junk box 200V caps I had. They have less than 1/10th of the ESR so they should be a bit better, and I bypassed them with 2.2uF film caps. I have a pair of 10uF Solens too but it might get a bit cramped in there.

 

[HiGHFLYiN9]

You should post some pics of the inside when you have a moment. Audiophiler caps might be smaller than the Solens if space is an issue.

 

[ScornDefeat]

Very interested in seeing pics of the internals, as well!

 

[fuzzroffe]

Well, the inside is a hot mess, but it’s way way better than with the old circuit. This was my first ever tube project, years ago, so the socket layout was only based on what looked cool from the outside. But at least it’s noise free

 

[ScornDefeat]

Awesome! Noise-free is what's most important!

Plus, I'll take classic DIY point to point wiring over PCB any day for cool factor.

I might have to look up the schematic for this and take a shot at it, myself . I'm in the preliminary process of a fully-balanced 4-board Beta22 build and it's no joke!

 

[fuzzroffe]

More mods: I changed caps in the power supply, it should take the ripple down from 20mV to 8mV according to the PSUD simulation. It's probably overkill since it's before the regulator, but I had some better quality parts so I might as well use them

 

[HiGHFLYiN9]

You've got plenty of space! Potentially check out some NOS Russian PIOs. Those are all pretty large but are reasonably priced and sound great. You could parallel a few if you need.