I had posted a while back when I was interested in buying a new amp in the Fender '68 series models. I was concerned about the the wattage excess of the Custom and wanted low end power to have that surf sound, ect.
I looked at the Princetons and was hung up on the fact the speakers were not 15".
Here was my original post:
https://surfguitar101.com/forums/topic/35353/

Many thanks to Synchro and Tqi for their inputs!

Well, I had finally decided that what I really wanted was just a new tube amp head.
I had made a custom speaker cabinet a few years ago and it was excellent build of birch ply and housed a 15" Canibus Rex. The tube amp head I had been using was a Peavey Classic 20watt, but this has ability to switch with attenuator to 5W. It never had that classic 'Fender' driven sound tho. I did customize the color to match!

After much thought, and winter boredom, I decided to buy a used Princeton '68 and 'Chop-Shop' it into a new amp head to match my cab. I read where this has been done before and of companies that sell the amp head chasis.
But my skills are worthy to build it myself.
When checking the dimensions of cabs, I was surprised to see the Princeton depth and width would match my existing speaker cab perfectly. It was meant to be!

While I was at it, why not get a custom made speaker, from Weber?
After much research on that, I got a California 15" 80 watt, light dope and aluminum cone for ultra sparkle!

Here it is finally complete!
I was torn thru several aesthetics. The original cabinet has a cool fish cut out. That was fun, and I can still insert it.
Another idea I started with was a rip-off copy of a Tone King face with that white truncated form.
But after the Prinecton Silverface was under way, there was no other obvious choice but to match the silverface looks with drip-edge trim!
That was hard to find material, and although not quite the perfect match of brushed aluminum vs, polished chrome, its very cool indeed.
Funny how that turquoise grill cloth matches the Princeton graphic too!

Synchro had gone into detail regarding the different amp choices I had inquired thru the '68 lineups between the Reverb Deluxe , 40 watt Custom Pro and the Princeton, and got into the 'negative feedback' circuits, how the early breakup of these amps occur. ect.
Well, I don't know, or understand enough about that tech stuff, but want to report that perhaps of my selection of over-watt choice of speaker, and the aluminum cone design, that this setup stays super clean all the way to 11! (if I had that)
Honestly , this is the best cleanest sounding amp I have ever played.

And for you Tqi, how does my gear match now!

This was a brief trial of possibility, not a Fender look tho..

This was my original "Fish Amp" design I had for many years

Last edited: Feb 13, 2023 15:23:01

I still have the original P-cab and could insert the rack and have it all work like it did before....less the drip edge I cut.

Iceratz, that is absolutely gorgeous. A single 15 should make for a good, solid sound.

If you ever feel the need to increase headroom, you can put a 5.6 kilohm resistor in parallel with R 10, which will cut the resistance of the negative feedback circuit to 2.8 kilohm, which is essentially identical to the 2.7 kilohm resistor used in the ‘65 PRRI. I wouldn’t bother, unless you find that you need more headroom.

I’ll sorta miss the old fish amp.

The artist formerly known as: Synchro

When Surf Guitar is outlawed only outlaws will play Surf Guitar.

IceratzSurf wrote:

Thanks Synchro and Tqi!
I still have the fish panel that simply slips over the current opening.

I would like to know more about the many modifications that can be made to this Princeton amp circuit.
One such mod is the conversion you mention for removal of the negative feedback.
But another I saw was where this can be switched and use the footswitch jack port to install a simple toggle.
I won't be using the footswitch which BTW is causing issues. Something is not working and grounding where it shouldn't.
But the Reverb and Trem work great from the front panel.
I also have a big pedal board I use as well.

I wouldn’t recommend removing the negative feedback, unless you want to lower headroom. The negative feedback resistor on the ‘68 Princeton is 5.6 kilohm, which reduces the amount of negative feedback, in comparison to the negative feedback resistor on the ‘65 PRRI, which is 2.7 kilohms. If you add a second NFB resistor of the same value, in parallel, you can regain that level of negative feedback, and the higher headroom that goes with it.

The artist formerly known as: Synchro

When Surf Guitar is outlawed only outlaws will play Surf Guitar.

Tqi wrote:

Yeah, aluminium dome speakers don't typically like distortion so much so removing nfb is a dangerous move on your amp. But screw it - why not have the option?

Though possible alternative which is very surf - why not add a presence control? Rob Robinette has some designs in his Silverface mods and amp voicing pages?

If one is not adverse to adding some switches, it would be easy enough to have a switchable NFB resistor, although at that point you would have to de-solder the NFB resistor from the circuit board. If you just place another resistor in parallel, you can solder it to the leads of the existing resistor.

A Presence control would be über cool.

The artist formerly known as: Synchro

When Surf Guitar is outlawed only outlaws will play Surf Guitar.

Not tried recording and don't really delve into more than looping.
I will mic for outdoor jamming though.

Synchro and Tqi,
I like the idea of Presence control!

Last edited: Feb 14, 2023 17:53:57

fenderfan wrote:

Your skills most definitely are worthy.
I have played a million gigs with my California 15, and can't imagine using any different speaker for what I play.<

Hey that's great to hear! I do love the crisp clean sound of the Cal 15"

The folks at Weber were all keen with compliments as well, and then sent out pics on instagram.