MusicMan HD-130 Preamp

[Blackboarcult]

For those who don't know these amps, they were made by MusicMan in the mid-to-late seventies under Leo Fender's supervision. While the poweramp stage was valvular, the whole preamp stage was solid-state, allegedly in search of the cleanest, highest headroom.
This series of heads and combos (all very similar, topologically) was used by Buck Dharma (Blue Öyster Cult, they recorded Don't Fear The Reaper with this amp!!!), Johnny Winter (who played through the 410 combo until his death), Mark Knopfler, Eric Clapton (late 70's) and Albert Lee among others.
So while dicking around from forum to forum on a study break, I read all this, and checked the schem: seemed pretty easy to lay out.
I breadboarded the preamp section (the two channels are almost identical, no need to to both), and it sounds pretty great. Nice clean sound, nice breakup thanks to the odd (at least to my noobie eyes) clipping section, and takes ODs and boosters greatly. A TS9 and the gain maxed, and I was in full-on BÖC-Godzilla territory!

Thought it might be a great pedal platform for those toying with SS poweramps, so here's the layout, unverified as I'm waiting for veros from Musikding.
I did it some days ago but didn't double check until today. Should be safe to do, but until I verify it, check it against the schem just in case.

Enjoy and ROCK ON!


EDIT 06/28/19: now VERIFIED!!!!

[doxasound]

Ooo, interesting to see a good preamp without any JFETS! Thanks for the layout!

[anders]

I'll second that. Looks really interesting for sure!

[Blackboarcult]

layout updated above!
No changes, just the "verified" tag, it was good to go.

I may try different transistors later on, but a priori BC549Bs fit rather well here.
I spent 15 minutes stupid-debugging it: I was getting breakup way too early on the gain pot, until I realized I was testing it with a Dimarzio superdistortion humbucker . Switched to my Vester strat-knockoff, and the cleanness reappeared. So much for my hungover brain...

[tvas22]

Any chance you’ve got a clip of this in action? I have a small class d power amp and I’m looking for something very clean to pair with it, and this looks ideal.

Also, it probably makes no difference to the sound, but I think the input resistor should be 34k, as the 68k resistors are wired in parallel - regardless of which channel you’re in the signal will only see 34k.

[Silver Blues]

Neat, I didn't know this existed. Thanks for the nice work, I'll probably be trying this sometime in the future too.

[punkrawkgeek]

Awesome to see this up here! I have a HD-130 head... This amp is my doom machine. I love this amp. I will have to throw this together and try it through some of my other amps. :D
Thanks~