Further Tales From The Tonal Fringe: The Ampeg That Nearly Wasn't

A couple of weeks ago I had gotten an Ampeg jones and started trolling Craigslist for likely suspects. I found an ad that had just been posted from the Lincoln, Nebraska area and it was for a 1961 Ampeg M-12-the very amp you see in the pictures, and thereby hangs a tale.

I talked to the owner on the phone and I had his first name, phone number, and a place to meet in his smallish town north of Lincoln. So the Dragon Lady and me climbed into the Honda a/k/a Jackie Chan and headed west.
About 200 miles later we were there. I dialed the phone number I had been given and it was the fellow's work number, an answering service and they were completely unhelpful, didn't know anything and couldn't do anything until Monday. I then went through the Valparaiso phone book and called every Kevin in the book. No joy. I found the local public library and convinced the librarian to post a response to the ad which was still up on Craigslist, and went back to the meeting place.
Just as I was settling in for a good wait, I saw a red Dodge truck hurtling down a side road and it was our guy. His wife had intercepted the message and called him.
The amp was secured, cash was paid out, and I and the Dragon Lady retired to Lincoln for a repast at Five Guys.

How's it sound? It's clean, with a swampy vibrato, and cosmetically it is a peach. It is the early style 'random flair' vinyl covering with silver sparkles that predates the more common herringbone style covering. It sounds so good I'm seriously thinking about selling a couple of other amps I have here.

Vintage Parts Excursion Part IV: Son of Judybox Champion 600?

A friend of mine dropped off an early fifties Fender 5C1 Champ for an overhaul and it sounded so good I decided to make my own. Looking around the shop I found my Champion 600 reissue that has been lounging around with the occasional task of testing preamp tubes for excessive noise. I also gathered up a trio of tube sockets, some capacitors, a bit of perf board that had been used as a bookmark, and the main ingredients-a Stancor new old stock power transformer and a Thordarson output transformer, both of which had come out of the split window Dodge van. It took a few hours to gut the Champion 600 innards and repurpose it.

The first thing I did was ditch the speaker out jack and bore the hole out for a fuse holder. At that time I also installed a SPST power switch and, using a Greenlee type punch from Harbor Freight, installed a trio of tube sockets. Then a trio of 22 uf capacitors and suitable resistors completed the power supply setup. A test confirmed proper voltages at all the important places. Then, I wired up the 6V6 power tube and the 6SJ7 preamp tube.

It sounds remarkably like the old 5C1, but the speaker's a little more hi fi, so I'm looking for a nice period Cletron or similar fine speaker. The combination of the 6SJ7 pentode and grid leak bias is the tonal ticket. It'll slide right into a nice greasy blues tone, and with the right pickups it's a joy.

You could probably re-use the Chinese iron if you wanted to use a 6AX5 rectifier and reutilize the output transformer. But you might miss out on the magic.

To reproduce this project for you, it would cost you about $120 in parts and shipping for Magnetic Components iron, shipping both ways, and about $120 in labor. Tubes would be about $24 extra for a NOS rectifier and preamp tube and a vintage serviceable 6V6. If you like the idea, drop me a line.

UPDATE:

I did have a few issues with this circuit that it is worth knowing about. The lead between the 2-75k ohm resistors and the preamp tube is very sensitive to positioning and has a bad tendency to create oscillation.

After a few fits and starts and some blind alleys I ended up taking some hookup wire and wrapping about thirty turns around a pencil. I then stuck the lead through this coil and grounded one end. The Jensen Mod came in at about the same time so that got installed, offset a bit for clearance. The result's a lot cleaner and the volume can be maxed with no oscillation or interference. I'm still looking for an older 6" speaker-that'll really do the job of recreating a classic.