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Vintage threads from the first ten years

Princeton Reverb

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1/6/2000 11:23 AM

Princeton Reverb

My Princeton Reverb wasn't cutting it for live situations so I rebuilt it. Deluxe Reverb Transformers, NOS RCA 6L6's, ss rect, long tailed pair splitter, cathode bias, EVM-12S spkr, 3-spring reverb - this amp sounds awesome except.... it hums all the time (too much for recording) and when I turn the reverb up past 3, that makes alot of noise too (a hum -type noise). Oh, and I forgot to mention the star grounding that I put in didn't help much. I can't tell if the hum is AC or DC (is there a proof positive test), and I've replaced almost every component in the reverb send and return stages, I also have shielded wiring on almost every grid in the amp. What's the next thing to try? Any ideas out there?

1/6/2000 4:56 PM

Did you replace the original filter cap can? (Maybe one of the sections has died.)

Does the filament supply use a secondary center tap to ground or a pair of 100 ohm resistors to ground arrangement? (It should use one or the other, or there will be filament-induced hum).

Are the output tubes matched reasonably well?

Is the wiring neat, with signal-carrying wires separated from power-supply wires?

1/6/2000 5:07 PM

I have a 69 Princeton Reverb that works just fine for smaller gigs (with a drummer), and I didn't have to do nearly the amount of hacking you did.

I replaced only the OT with a DR unit. To get maximum output, I just did the PI voltage mod so that both sides of the outputs could be driven fully, no need for a long-tail mod. I still have the tremolo working. I stayed with 6V6s, but I put in the most efficient 10 incher I could find. Still looks and sounds just like a Princeton, only louder. I find those 3-spring pair reverb pans to be a bit much. I also dropped the value of the coupling cap at the PI input to keep it from farting and getting too muddy at high volumes. Great little amp now, without seeing the resale value go down the sewer.

1/6/2000 5:39 PM

Benjamin Fargen

John,

Not to be the bad guy here.......but just because the guy converted his amp to what he wanted doesn't mean the guy did a "Hack" job.
You seem to really get fired up over any kind of mod that hurts resale value. I could see if this was a original tweed amp or maybe even a blackface......but who
cares if the guy has a silverface fender he wants to learn on.
You always have great input that I'm sure everyone appricaites,(including myself:>)
but why do you get so hard core on a guy that's just trying to learn about tube amps and get the tone he want's out of something?
If he paid a tech and had a hack job done......that's a little different........but this is not the case.
Clue me in?

Benjamin.

1/6/2000 6:31 PM

Ben, I must disagree with you. THAT much surgery/modification is a hack job.

That is a hand-wired, point to point amp. They don't make them any more. Even the SF era amps are now experiencing price appreciation. A lot of guys here dismiss butchery of an SF era amp as a "who cares, there's lots of them". That thinking is outdated. There's really not so many. Each year a few are destroyed by natural disasters, and others are butchered. Either way, there's fewer and fewer originals. If someone has an old p-p wired Fender amp and he's grossly unhappy with it's performance, he needs a different amp. Silverface amps are not sacrificial animals to the amp butcher shops, like many feel. If the guy wants to learn about amps, that's great, but hey, there's the AX84 project, Allen kits and several other avenues other than hacking up an old Fender. There's really no effective difference between paying some jerk tech to Torres-up an amp or doing it yourself. The end results are identical. I suspect he could have come close to what he wanted with a much lesser degree of modification. The DR and PR use completely different sized power transformers, so if the PT was replaced, there was most likely some metal cutting involved, and hence, the mods are not reversable.

From reading his original post, my impression is that he was not getting enough volume. You'd be surprised at the whopping volume increase you can get with just putting in a VERY efficient speaker and doing the simple PI voltage mod. My PR will hold it's own with any stock DR now.

Not really "hard-core", just reality check. No flames, no profanity. Thank you for your consideration.

1/6/2000 7:29 PM
Benjamin Fargen	John, I respect your opinion and you do have some very valid points!Maybe everyone needs to start having a fresh outlook on silverfaced fenders. Thanks, Benjamin

1/7/2000 12:53 AM
Bob	Dear John Stokes, Thanks for contributing to the conversation. You're right, I did cut metal to get Deluxe Reverb power transformer in the chassis. But no, you're wrong , I didn't do it for more volume alone. Please read my rant on preservationism. Remember, now we have the Net, lots of part places, chassis galore: it wasn't always like it is now. Bob

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