Tube recommendation for '66 Princeton

Mattbedrock

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I have a very delightful '66 (PK) Blackface Fender Princeton that I use as my main practice amp. It currently has two Groove Tube 7025's for pre-amp. I have both GT and Raytheon (black) 6V6's for the power section. The rectifier is a Mulllard GZ34/5AR4. While I love the clean sound, I would like to try preamp tubes with a little more gain to see if I could get a little breakup out of her. Does anyone have a recommendation of a hotter set (or single) preamp tube for this fine machine?
BFFenders.jpg


I do usually run a distortion pedal (MXR or TS-9) on the front end for lead tones.
 
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That's a tough order to fill. I have a 65 Princeton NR. To get the kind of gain, you're talking about. I have to use a V-Stack. These particular amps have one less gain stage than a PR and are the cleanest amps this side of solid-state (anybody remember transistors?), and are highly desired for that quality. I only use it when I have to get that particular tone for recording-occasionally I put a Greer Razor Burn Fuzz in front of that(for additional Hendrix/70's grit). On the other side, I use Scumback 12" speakers through Hermida Audio z-Cabs. When I use it clean, the Scumback SA10M provides clarity, tone, and unsurpassed fidelity.
 

mbratch

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You won't get much of a gain difference by changing brands of 12AX7 or 7025.

However, there are some simple mods that can give it a bit more grind. The simplest being to disconnect the global negative feedback loop. I've done it on my Princeton, and it works. I ended up taming it just a little with a higher value resistor than the stock NFB resistor. With this change, you'll also find that the bass is a bit boomier, and there's some added presence.

You might also consider the Stokes or Paul C mods.

Or, trade with someone the 60's BF Princeton for an early 70's SF Princeton Reverb. They're approximately 1-1 in value. :)

After all that, though, it's clean tone isn't quite the BF Princeton tone it was before the mod. So you might want to consider a low gain pedal, like a Barber Silver LTD, Timmy, or something like that.
 

NotWesYet

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I am using a Mullard 12AT7 in the V2 position of a BF Pro Reverb as it gives me a lower output, so I assume it would breakup earlier by having to turn the amp up. I am going to try a RCA 12AT7 to see if there is an appreciable difference. I would think a AT7 in your V1 position would do the same...(but maybe an expert can chime in here.)
 

jcs

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8,093
i have a late 65 princeton, you be surprised how much difference there are in 12ax7 in these amps.

i've horded tubes for years and after much trial and error, i have a sylvania 7025 long plate in the pi slot that tests very strong in my b&k 600 (as strong as any 12ax7 i've ever tested in terms of transconductance).

this tube made a big difference in dynamics as well gain, it helps to make certain your 6v6 are biased at or near 70% dissipation.

i have blackplate rca 6v6gt in the amp at the moment and an amperex bugleboy 12ax7 in v1 as well as a mullard gz34 rectifier,the speaker at the moment is a weber 1230-75 celestion copy with pre rola doping (i changed baffles), this is the best sound/response i've achieved with my princeton, i am very pleased and wont change a thing!

a nice od pedal is all i use now to push it just a bit.
 

Mattbedrock

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Thank you all for the good advice. I think I'll try a little tube swapping today.
 

Mattbedrock

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I tried out a variety of different 7025, 12AX7 and 12AT7's. Definitely much lower gain with the AT. The 7025's and AX's sounded fairly close to one another. One AX had a particularly interesting ratty tone on 10, but I ended up with the same GT 7025 that I started with - seemed to have the best overall tone and consistency from 4 - 10. I was trying all of them with a LP Classic w/ 57 Classics in it, but just for giggles, I got down my Explorer 2 with Dirty Fingers in it. Man, that amp roared with those hot pickups.
 

danef

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101
I have a 78 Silverface Princeton (non-reverb). Just wondering about suggestions for 6v6's for maximum volume and headroom. Probably going to convert the baffle for a 12" speaker as well at some point. Oddly, the tubes currently in the amp seem to be smaller than current-sized 6v6's. Is this normal? They are 6v6's, but the glass seems smaller...
 




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