A friend came around with a 1965 Fender Princeton Reverb today...

H

HamishR

Well-known member
A genuine 1965 Princeton Reverb. Quite something to behold because it was so pristine. He had only just bought it so wanted me to check it out for safety and set up. It had a replacement stand-up PT for our 240V wall voltage but it was installed using the original screw holes and was actually a really neat job. Whoever replaced it knew what they were doing. The AC cord had also been replaced and although it wasn't strictly to code it was done well. The ground wire should have been longer and it was attached to a lug on the PT mount.

But the rest of the amp was PRISTINE. I should have taken photos! I have never seen an original Fender in such untouched, clean, perfect glory. I was amazed that the original caps all worked just fine. No sign of bulging or leaking gunge. Really low noise floor - way quieter than any PRRI I have heard. It had two different brand 6V6s in it but they were perfectly matched - the plate voltage was identical on each tube. Everything worked except that the reverb tank was a bit sproingy. The bias tremolo sounded lovely, the bass stayed nice and tight until the volume was well up. Surprising amount of clean headroom with my Strat which has fairly hot pickups.

Overall it was so much quieter, better sounding and tighter than every reissue I have heard it's crazy. My friend will be using it at a gig this weekend.

So the only thing we have done is to replace the stock ceramic speaker with a Celestion 10" Gold. It has made a huge difference - much louder, fatter and betterer. The stock speaker will be kept to sell with the amp if/when the time comes.

It was such a pleasure to see such a time capsule of an amp. BF Fenders are not really my thing but this one was so well built it was good to see. I love old amps, especially one as perfect as this.
 
That's great. Was the original speaker a Jensen?

I've read that regular use helps extend the life of the electrolytic caps so if you have one with leaking or bulging caps it probably wasn't played much.
 
@cdwillis : "I've read that regular use helps extend the life of the electrolytic caps so if you have one with leaking or bulging caps it probably wasn't played much."

Yes, regular use will extend the life of electrolytic caps (not so much for oil-in-paper caps). 'Bulging' is caused by over voltage and or current in-rush at start up. In the states, over voltage can be a problem as our average utility AC voltage supply has increased from 105VAC in the early 1950's, to 115VAC in the early 60's and so on. I currently average 126VAC at my house. Accordingly, and amp designed to produce 440VDC on the tube plates using 115VAC in, will produce 482VDC at my house (10% increase). If the filter caps are rated at 450VDC, they will begin to budge and self-destruct.

I recently replaced the bias cap on my 1964 Fender Vibroverb (designed for 115VAC), because it was rated at 50VDC and my bias range was -70VDC to -40VDC (currently set to -52VDC). Needless to say, my bias supply was leaking to ground and causing problems.
 
Electrolytic caps can blow at any time when they approach 40 years old (and make a royal mess). And as odd as it sounds someone on a different forum just got rid of the radio reception by replacing theirs. Most people also notice tone improvement after replacing as well.

On a completely different tangent, I just finished blueprinting a repro BFPR chassis last night in Visio, all measurements were within 1/64th of an inch, much smaller than a mm. I was surprised to only find about 5 of them were an odd number, like 29/64 or 53/64.

Still working on a 59 Bassman now, but this is next. Probably. Got everything purchased to build a 2203 too, but I'm leaning towards the BFPR next.....

BFPR V07.24.24 inside chassis dimensions T.E.jpg

It's important to be sure where all the holes are before designing a layout, which is why I start by blueprinting the chassis.... This is going to have a set bias as well as a bias balance so matched tubes won't be as crucial. Set the balance, then play with hot and cold till you get it right.

BFPR V07.24.24 T.E.jpg
 
So jealous. You could make the case that as important to the sound of the early Marshall is to rock and roll, the early Princeton's did much of the heavy lifting. Especially in the studio. I've only had the pleasure once and had to be dragged away kicking and screaming :)

OK, truthfully the speaker was pooched and I got a chance to let' er rip thru a fresh WGS.
 
Gonna take an original pristine 65 Princeton out and gig with it? I mean, I get it, but damn. I would have recapped it anyway unless he’s using a brown box or variance, the caps might just let go.
 
jimilee said:
Gonna take an original pristine 65 Princeton out and gig with it? I mean, I get it, but damn. I would have recapped it anyway unless he’s using a brown box or variance, the caps might just let go.
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I wholeheartedly agree. If you're going to be out on a stage, in the sun, the interior of that amp is going to be exponentially hotter than indoors. And of course you have to play loud to be heard above the drummer.

That's the perfect conditions to make 60 year old caps go BOOM and maybe take some vintage tubes, or even transformers with them. Think of it this way. How many 60 year old *anything* do you have that still works?

I know because I've read the posts from the poor souls that ask if anyone knows a good tech to replace the transformers and do a recap job on their vintage amp.

It's also an extremely good idea to add backup diodes to the rectifier tube socket. If the tube shorts it can let A/C into the DC feed and ALL the electrolytic caps go off like firecrackers! This is shown with a scrubber cap to also deaden the pop from the standby switch.


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cdwillis said:
That's great. Was the original speaker a Jensen?

I've read that regular use helps extend the life of the electrolytic caps so if you have one with leaking or bulging caps it probably wasn't played much.
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Hard to tell. It doesn't look like any Jensen I have seen so we suspect it's an Oxford. I googled "1965 10" Oxford Speaker" and it looked much like that. It sounded ok but a bit timid and mid-scooped. The Celestion Gold sounds amazing in this amp.

We tested with a 5U4 and a GZ34 and the 5U4 gave us 440V exactly on the plates of both tubes. The GZ34 got us exactly 549V on the plates of each tube. I thought there would have been a greater difference.
 
I've played a 79 Princeton reverb. Magical. The owner is moving out of state and was trying to decide if he should sell his Deluxe Reverb RI or the Princeton. I just looked at him like he was from another planet.

I had a 79 Vibrolux Reverb that I sold off earlier this year. I hated getting rid of it but 35 watts through 2x10's was wayyyy to much juice. But could it sing when you get it into it's sweet spot. Man.
 
The amp I'm playing all the time right now is a home-brew 6G3 brown Deluxe clone. I've been watching a lot of Psionic Audio Youtube clips so used a lot of his grounding tips and man it runs quiet. So it was super interesting to see how the grounding was done in the '65 Princeton. It's a lesson in how to make an amplifier.

Tone-wise I really prefer my brown Deluxe but once the Princeton had the 10" Gold in it the sound was impressive. It sure didn't sound like an amp with a 10" speaker any more. Some of the first amps I had back in the early '80s were Rivera-era Fender "black face" amps like the Princeton II and Concert II. Compared to this old Princeton they lacked low end and sounded boxy. So that's why these great old amps always impress me. But they are very rare here.
 
@HamishR "I have seen so we suspect it's an Oxford". I don't know many people who liked the Oxfords (CTS) in Fenders. The Jensen's, JBL's and Utah's (Pyle) all have their followers.

@Spiff4565 "'ve played a 79 Princeton reverb. Magical." Below started life as a '78 Princeton. I bought it sans speakers, circuit board and transformers in the 90's (just a cab and bare chassis). I installed a 12" speaker, some 1967 Schumacher transformers from a Bassman and did my own point-to-point 6lL6 thing. It is heaven and can be quiet or loud and maintain tone.

AMI Lil Giant front 2.jpg AMI Lil Giant Inside 1.jpg AMI Lil Giant 11-4-2023.jpeg
 
I worked on a 65 RI today that had a gacked reverb. Bone stock other than fresh tubes and was a very friendly little amp but not very close to the old originals I've played. Still a nice amp though.
 
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