Tuesday, November 20, 2018

1950 (or so) Gibson BR6F

The first good small tube amp I bought was a Gibson BR6F. I found it at Guitar Exchange in Catonsville, Maryland back in 1992.


6SJ7 driving a 6SN7 phase inverter feeding 2 hungry little 6V6 tubes. 5Y3 rectifier. 10 watts into a 10" field coil speaker.

A word about the field coil speakers. They often sound lovely. Don't do what I did to mine: run a bunch of pedals into it and blast off for hours. I killed mine and once that speaker is dead, that's it. It'll never be the same. You want to treat the elderly nice and gentle, with respect. Leave those dumb ass pedals in the bag and learn to play better!

I probably could have had that speaker rebuilt, but I blew mine up in 1995. No internet in those days and tough to find someone to rebuild it properly

If you do blow it up, check these cats out:


his one was at Southside Guitars. It's long sold. I re-capped it and replaced the power cable. I hope the new owner just plugs in and plays it!

And a video of my friend Eric playing it.....


The amp:

1939 Kalamazoo KEH amplifier built by Gibson

Such a cool amp. This came from a good friend of mine. He bought it at a local shop as-is and it was dead.

I love them when they are dead. It's easier to fix a dead amp than one that sort of works. Example is the Oahu amp I bought in Dallas last year at the guitar show for $100. The power switch was dis-connected. Simple fix. The rest is just change caps and resistors as needed.

This was no exception. Dis-connected wire got it going. I had to re-cap it, ground it and change a couple super microphonic 6C5 tubes but that's it.

These early Gibson amps are exceptionally well made. Easier to work on than what they produced from the 1940s on forward. Odd, cause the early ones are service friendly like a Fender. They got worse over time where Fender just kept getting better. I like how you can simply unplug the field coil speaker in these. You just pull the chassis after that and do your thing.

Plus the looks:

This is one beautiful piece of equipment!

Tubes are 3 6C5 preamp tubes, a single 6L6 and an 80 rectifier tube. They do run rather hot. This one showed evidence of the transformers getting hot. I replaced the cathode bias resistor with a bit higher value. Makes things sound a little 'looser' but you know, I'd hate to see the output transformer die in this 80 year old amp.

Tube sockets were labeled right on the socket itself. Classy!

Yup. From the glory days of American manufacturing. These were factory built. Not cheap! You need to pay a builder to get this kind of quality today. Not cheap but come on, you're worth it!


DaVinci 2x12 "High Fidelity" amp built by Magnatone (model 260)

Here's one that was intimidating. A true barn find full of dead bugs and mouse faeces.... effing gross!

It was sold to my friend Dave at Sonic Circus for $50 a few years back. We weren't expecting much since it had spent so much time growing uglier due to neglect.

But once I cleaned it up, re-capped it, fixed the tears in the speakers it came back to life. And it has of course a gorgeous voice! I'm not a fan of the stereo Magnatone amps, too complicated, oddball expensive tubes, but these simpler ones are the bomb. It's about 25 watts with 2 6L6 tubes. Nothing expensive or difficult to find tube wise either. Just a 5u4 rectifier, some 12AX7 tubes and a 12AU7.

These 'stencil' amps built by Magnatone for other companies are a real bargain. Not exactly cheap but not what you pay for one labeled Magnatone. See my other post for the Panoramic amp I still have.

This amp is basically a Magnatone 260. It's now making music again at Sonic Circus. Dave has a beautiful Vox AC-30 with the copper panel. With the pitch shifting vibrato in the amp the 2 seem spiritually connected. Though, I prefer the Magnatone amps myself. Straight up Bo Diddley tone! Less noisy than the AC30 too, though, no diss on Vox. Those are amazing too.

Do notice the Celestion 'Guitar Center' model speaker I threw in. Not a bad choice but fortunately I was able to get the original speaker going again!

Bowl o' spaghetti construction:

And there you go! Get out there and try one of these. They have quite a sound! J

1965 Fender Showman amplifier. Killer bass or guitar head.

When I was in high school I had a cousin named Bryan. He had issues with telling the truth. But while I didn't trust him I loved the cat anyway. He wasn't a blood relative, just my god brother.

One day he showed up to my house with a Fender Showman, property of the Baltimore City Public School system. Yeah, he stole it.

But whatever. I'm sure they didn't notice it. The amp was missing tubes, badly neglected much like Bryan and that school system. It just needed help.

I was fascinated with the thing. I just wanted to get it working. I opened it up and shocked the hell out of myself on the still charged filter caps. It had power just no sound.

So I found a few tubes for it at Radio Shack and got some resistors that matched. I'm not sure if I even knew what a resistor was in those days. One just was burnt so I had to match it. Yes, Radio Shack in the Columbia Mall sold tubes! Good tubes. Not the crap made today.

I got it working. I remember it sounding like it was underwater, not in a bad way, it was just so warm.

Thus started my fascination with tube amps. And my fascination with the Fender Showman. I think I traded that chassis in on something I bought at Angela Instruments a couple years later. Early on when Steve had his shop in Savage Mill, or maybe in his house. Those were the days!

I did buy a working one when I was in Berklee. I used it for a while. I think I was fascinated as well cause a Marshall Plexi was intimidating to me. A Marshall seemed like an exotic nuclear power source. Yet, when I watched Jimi play Monterrey in the film, he had his Marshall and a glorious Showman amp too. Seemed more manageable to me.

So this one was from Indigo Ranch and had been sitting neglected for a couple or more decades. Simple re-cap, re-tube and there you go. I replace the (either 500pf or .1000pf) cap that feeds the phase inverter with a .002-.005. We're using the amp for a clean 80 watt bass amp. The Showman is 8 ohms, whereas the dual Showman is 4. I prefer these.

Such a beautiful sound......

Old caps. It's dumb but on an amp like this I re-use the sleeves cause they have the dates on them. But folks, do change the filter caps. It's just stupid not to!

Did the usual. New grounded cable yadda yadda..... Transformers are all original and this amp is no longer sad and neglected, its cutting tracks once again at Sonic Circus in Vermont!


70's Traynor Bass Master. Prog rock EVIL!!!!

This was a fun one. At Sonic Circus they have 3 amazing Ampeg B-15 amps of varying vintage. They have an early cathode bias model, which is out favorite, a later fixed bias from around 1966 and a more powerful 70's one. They all record so nicely.

We were cutting tracks and believe it or not I was getting a bit bored of the B15 Fender Precision bass combo. Some of Dave's material is venturing into Prog territory. He's a great guitar player, his son is a great everything player, so I felt like just kicking back and playing bass, acoustic guitar and some saxophone.

So anyway, I pulled this neglected old Traynor off the shelf. Another fine amp from Indigo Ranch Studios...

It's no B15, that's certain. It's aggressive, nasty, impolite.... sounds like Geddy Lee or John Wetton rather than James Jamerson! All are outstanding bassist. Both inspire me!

Amp is about 50 watts with 2x EL34 tubes and 3 12AX7 tubes. Single 15" speaker. EVIL SOUND!

Another simple Re-cap, changed the output tubes. Sadly the Mullard RCA stamped tubes were shot.

These are a bargain. Great for guitar as well. Hand wired, Hammond transformers, Mullard Mustard caps in the signal path, and built like a tank. Go get it! You won't regret it!

40's - 50's Rickenbacher "Electro" amplifier

Here's an extremely rare amp. An old Rickenbacher metal amp from the 1940's.

No idea what model it is, there is one that looks like this called the M10 but this has a 12" Jensen PM speaker rather than a 10".

It looks like a space heater!

With this speaker grill and metal box we were expecting a not good sounding amp! Though the circuit is oddly similar to my main amp that I built: 2 6V6 tubes fed by a 6N7 phase inverter with a lovely 6SJ7 preamp. 5V4 rectifier tube.

What does it sound like? This was the closest we could get to the AC/DC sound. Raw, raunchy and open. I'm usually not a fan of the old Jensen PM speakers, too mellow for me, but not this one! It was perfect!

Re-capped it, changed the power cable and took out the death cap. This was another Indigo Ranch Studio amp that had been sitting on a shelf in Vermont for the last 2 decades. Now it's back in service.

I love that it lived in Cumberland Maryland and belonged to "Jaguars International"! I'm a Maryland native. I just wonder what music was made on this peculiar amp?

Matching grey power transformer!

I'm a fan of the 6SJ7 preamp tube sound. They're cheap as chips for a good NOS one. Lots of harmonics and a big open sound. This is an amp I'd like to find another of for myself. But then again I can always visit my friends at Sonic Circus and cut tracks on this one anytime.


Ancient Gibson amplifier circa 1930's

Here we have a real gem, an ancient Gibson amp from the early or mid 1930's. I know very little about this one, I don't know what model it is. What I do know is it's ultra simple. No power switch, no volume control. And inside no signal capacitors either. It's 100% transformer based in the signal path.

I replaced the ancient electrolytic capacitors, put a grounded power cable on and left it at that. It has a lovely voice with it's 10" field coil speaker. It's about as loud as an old Gibson J45 being strummed good and hard so it's actually kind of perfect for playing in acoustic situations.

Silkscreened logo:

Ancient super cool "Goat" tube shield:

Speaker shots. Jensen field coil. I love wrinkle black paint. It's my favorite. 30's look!

Interior shot. Simple!

This was another amp from the legendary Indigo Ranch recording studio. It had been sitting for the last 20+ years at Sonic Circus in Vermont. Now it's cutting tracks again at their studio. Real blessing to be able to work on such a rare and interesting piece!