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Vintage threads from the first ten years

Boogie Princeton

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10/3/1997 7:24 PM
Bob	Boogie Princeton I have a 73 silverface Princeton and had read about how the early Mesa Boogies were derived from these amps by using the chassis with a tweed Bassman components. Has anyone done this and if so where can I find instructions on the re-do? Thanks . Bob

10/4/1997 2:25 AM

When I first heard about Randall Smith stuffing a 60 watt Bassman circuit with an extra gain stage into a Fender Princeton cabinet, I was thinking it was the ever-present Princeton Reverb amps, which isn't a tiny amp. But I later read that it was the earlier Princetons (no reverb), which were just a step up from the Champ amps. He replaced both transformers and completely rewired the amps so I think the cost would be prohibitive at this time.
.. Dan Torres has come up with several mods for pre-1980 Princeton reverb amps, and is designing a new Torres amp called the PrinceTone which is based around these mods, which include a redesign of the driver circuit with an added direct-coupled tube stage to increase the voltage and current of the signal going to the output tubes. I think the price of the full mod is between $150 and $200 if you do the work yourself. He used to have lower priced mod kits for the Princeton, but he may be phasing them out.
.. You might want to give him a call or send him a fax requesting his current catalog, newsletter and any info he may have about his Princeton mods.

Phone: 1-415-571-6887 or 1-415-571-1507]
Fax: 1-415-571-0849

P.S. I've been looking for a good, cheap Princeton myself just so I can add the mod to it!

10/7/1997 1:29 PM

Steve:

I had one of those "mild-mannered" SF Princeton amps. There was an article in GP magazine (a year or so ago) called the Prince-O-Wails. It was written by John McIntyre of Musitech Electronics. If you remember the Bassman "Bluesmaker" mod, it's the same guy. I decided, after talking with John, to buy a kit of small parts from him rather than trying to source small quantities of parts myself.

This mod makes use of the triode in the tremelo circuit and the triode split-load phase inverter and reconfigures them into a high gain cathode coupled phase inverter, for added gain. The now unused tremelo controls are turned into midrange controls. Some of the pots are replaced with ones having push-pull switches used for various tone-shaping options. The output section has a cleverly engineered cathode bias and a swtch to open up the bypass capacitor for a "soft clipping", as John calls it. The power output is now closer to that of a Deluxe Reverb, and the stock 10" Oxford wouldn't have held up very long. So I built a new baffle for a 12" speaker, which was an 80w lead (celestion copy) Eminence. The speaker had to be mounted off-center so the larger magnet didn't foul the tubes. The original grille cloth and chrome logo were put on the new baffle.

This amp now has much better tone, and is even a little "rude" when turned up. For reverb, I use a Boss RV-3 ahead of it. The outward appearance of the amp is completely stock after the mod. I love that "sleeper" look!!

So far, everyone who's tried this amp really likes it. I would highly recommend digging up the article in Guitar Player and considering this worthwhile project.

Respectfully submitted,
Doc

10/4/1997 8:52 AM

I turned my Princeton Rev into a 40 watt amp with a 12" spkr years ago.It was quite a learning experience as I rebuilt it over and over again to try and get it right.I used a Bassman power transformer and a Fender output transformer for 2 6L6's into 8 ohms.Also added a choke.This is a major rebuild and pretty much entails gutting the whole chassis and starting over.Hard to get all those parts on the Princeton circuit card.I used a shortened Twin Rev circuit board.Takes some juggling to get a 12" spkr in the box with the larger output transformer,and some large frame spkrs wouldn't fit.Mine is basically a Pro Rev cct with solid state rectifier.I'm not a high gain guy .No room for a rect tube.If you don't need tremelo(I do)it would be easier.Follow the layout and schematic of your favourite amp and you can't go too far wrong........

10/4/1997 3:24 PM
Charles	Bob!.... Imitation is the sincerest form of flattery... Seriuosly.. once I can get my hands on a PR, the conversion will go ahead. I don't think there will be any trouble documenting it for later use, just in case you're interested. Charles

10/7/1997 2:22 PM
Doc	Bob: This doesn't answer your question, but there are pictures of Santana's "Priceless" boogie amp at website www.santana.com/carlos/guitar.htm. It looks like a SF Vibro Champ, but the cabinet appears slightly taller to accomodate the 12" JBL speaker. Doc

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