It's Alive!!! First amp build lives...

[rfgordon]

Guys,
My first amp build, which I mentioned in previous posts, mated a standard Matchless Lightning board to a pair of cathode biased 6L6s. I went this direction for two reasons: 1. I played a Lightning last summer in Vegas and I liked it. 2. I took the PT & OT out of a '65 Harmon-Kardon office PA amp that ran, you guessed it, 2 6L6s cathode bias. The 5AR4 in there now is vintage from the HK. I figured I'd keep it simple. Besides, you don't see too many cathode biased 6L6 amps any more, except from a few of the boutique guys.

So, I finally fired it up late Saturday morning and....nothing. Zip, zero, nada, nyet. Hmmm, what next? Lots of visual checking, poking, voltages all OK. I tried again after a couple of hours of this. I really cranked it and could hear the OT vibrating in tune with the guitar--so I knew then that the amp was "playing."

The Harmon-Kardon had conventional 4-8-16 ohm taps plus a 25v distributed speaker line. I went back to the HK chassis and studied whence the wires had all come. Turns out I had picked the wrong wire for speaker ground. Swap wires and, shazaam! It's alive. Bummer number one fixed, which revealed bummer number two: Muchisimo 60Hz hum.

I went back to Gerald's books, reread a bunch of posts on various sites, moved the OT, did a whole bunch of stuff. Today I found a hifi diy site whose ground instructions finally "clicked" in my head. Came home tonight and moved grounds, cut some wires, reflowed ALL the joints to ground, (oh, yeah, I had 100k instead of 100 ohm resistors on the artificial ct for filament.). Then tried again, and, shazaam: quiet as a church mouse. Well, a church mouse that roars!!

This baby is a monster! The hi input rocks, grinds and sings from the gate, and the lo input sounds maaaaaaahvelous with single coils, extremely sweet. The HK OT has GINORMOUS low-end. I think I could use this thing as a bass amp with the right cabinet. Low A and E string telecaster riffs are truly badass thru this thing. The cathode biased power section is sustainiation to the max.

Now I need to pick a good speaker for it. I've got it thru a spare V30 right now, though I'll audition some other speakers. I've got a Weber in my '66 Gibson GA20-RVT that sounds great, and a Tone Tubby ceramic in my Mark IV that I really love. Any suggestions would be welcome.

My next build will be for my rhythm guitar player. He wants a loud clean amp for jazz rhythm with a quartet of 6V6s.

Dudes, I am seriously infected with the amp building bug now! I'll try to post photos this weekend so you can all sneer at my spastic wiring and layout. This will definitely be heard on Burley Maple's next album!

Later,
Gordo
www.burleymaple.com

[tonelab2]

Congrats!How about pics and sound samples.

[UR12]

Rich

Congrats on the build from one bald guy to another I checked out your webpage, pretty cool!. Are the VWs for sale?

[rfgordon]

Dana,
Thanks for digging our tunes. The VWs are in a junkyard. We went looking for a trashed Cadillac, since we have the song "Cadillac Girl." The only one in that junk yard was soooo far in the woods there was no way to photo it, much less get Amber to scramble to it.

Here are some pics of my amp. Things ended up kind of smushed up against the front of the chassis--the Geraldian mantra, "keep grid wires short" kept ringning in my ears.... Next time I'll use a 3" tall chassis vice 2" for a bit mo' room.

Just for hoots, today I ran the scooped Metal Zone pedal thru it--earth shaking thunder!! That vintage tranny is a monster!!

So far, I like it best with my Weber 12" speaker.

So now I gotta start on the cab for the thing....

Happy trails.
Gordo

[rfgordon]

I stuffed the amp into an old Boogie head cab and gigged with it Saturday. Did great, though it lacked headroom. Kind of angry from the gate. So today I raised the plate voltage on the 6l6s from 405 to 430, and now it has tons of really nice headroom, but not too much.

I built the combo cab for it yesterday, and it's all done except the tolex. Still waiting on that. Sounds truly great thru the 12" Tone Tubby ceramic, which has had a year or so to break in with my Mark IV.

I think, though, that I'll experiment with the value of the bright cap on the volume (it's a Matchless Lightning circuit). I've got 200 pf on there now, but it lets a wee bit too much finger noise come thru.

Is a homebrew amp ever really done?

Cheers,
Rich (aka Gordo)

[skyboltone]

Congratulations Mister:
I love to scrounge too. We used to find old tube amps all over the place but no more. I keep waiting for the garage sale McIntosh 275 in mint condition. Rip that baby up and make two guitar amps!! Just kidding.

Good job.

Dan

[Bob-I]

Is a homebrew amp ever really done?

Cheers,
Rich (aka Gordo)

No

[rfgordon]

Fellow tube junkes,
Here are some happy snaps of the thing all cabbed up. I found a signs/engraving place that made my nameplates for 45cents a square inch. Not sure if I'll have 'em do a faceplate for mine, but I'll put one on the amp I'm starting for a friend.

Back in 1980-81 I met, played with, and learned a lot from an old black Piedmont bluesman called Big Boy Henry. In his honor I call the amp endeavor the Big Boy Amplifier Co.

What you can't see in the pics is that I mounted a fan down in the cab, as well as an outlet box to power the amp and fan. The amp chassis plugs into that outlet, then the power cord that comes out is from that. Once upon a time I had a drunken reveler come on stage, catch a foot in the cord and proceed to drag my prized Bandmaster Reverb head all over the place, tearing the connections inside all to hell. This current set up is about as drunk-proof as I could think of.

We've started doing some recording again, so not too long from now I'll try to post something with this amp onto our website.

Cheers,
Rich