6V6 to 5581 or 6L6 in Princeton Reverb (Transformer Questions)

cs1botasky

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Hello guys,

May I ask if I wanna upgrade the 6V6s in my Princeton Reverb to 5581s or 6L6s, is it better to go for a larger OT and PT?

If so, shall I go with the OT and PT for Vibrolux Reverb or Twin Reverb and would there be more benefit if I go for something even larger?

Do you have any experience in Heyboer, Mercury Magnetics and Hammond OTs and PTs? Do they basically sound the same as long as the specs of the transformers are the same?

Do you think there would be a change of sound if rewiring a 110v transformer to 230v? Or using a step up transformer would yield best result for tone?

The power tubes (6V6) in the Deluxe Reverb are same as Princeton Reverb, but the Deluxe Reverb is a higher wattage amp. Are the OT and PT larger in a Deluxe Reverb than those in Princeton Reverb? If it's true, except getting louder and getting a larger headroom, would there be any other tonal change in upgrading the OT and PT of a Princeton Reverb to those in a Deluxe Reverb?

Joe Bonamassa upgraded his vintage 1964 PR with 5881 and put in his signature 12" Celestion JB-85 in there, it sounds pretty amazing!


Thanks much for your help in advance! :)
 

vampwizzard

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You'd have to do a bunch of things to swap in 5881's. Solid state rectifier, verify screen and grid stop resistors, add a grid stop to the phase inverter for starters. There are a couple of threads on here about this topic and worth a look.
 

Phrygian77

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You need a power transformer that has at least twice the VA of the stock transformer. One issue is that even the modern 100mA Princeton Reverb PTs have a 6.3V secondary that's limited to 2.25mA. That's just enough to run all of the heaters and a lamp.

You can make a Tremolux/Vibrolux PT fit by enlarging the cutout. It'll be tight, but it's doable.

 

archetype

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If you search this site there are many threads about doing this to a Princeton. The information you seek is already here if you look for it.

The basic question is "What are you trying to achieve?" Louder? Different tone? Different response when loud?

IMO, all of the following...

All of the things you're considering can be accomplished, but other than putting in a proper speaker and good tubes, anything you do to "improve" a Princeton will lead you away from Princeton tone. If you really like the way it sounds, but want that to be louder, you can't get there. Making it louder will also change the tone and response.

YMMV and others may have different opinions.
 

Lowerleftcoast

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Looking at the PR shown in the first post, there is a PT with extra laminations. Several companies make the *tall* PT to fit the PR footprint (higher voltage and current capability). The OT looks larger than the stock PR OT. I assume it is designed for the 6L6 family of tubes. It is hard to say what choice was made for the primary impedance. The PR uses an 8k primary when the Deluxe Reverb uses 6.6k. I would guess the OT has a reflected impedance in the typical 4k-ish range for 6L6 type tubes
If so, shall I go with the OT and PT for Vibrolux Reverb or Twin Reverb and would there be more benefit if I go for something even larger?
IDK if these transformers will fit in a PR. A Twin Reverb set would be overkill, imo.
Do you think there would be a change of sound if rewiring a 110v transformer to 230v? Or using a step up transformer would yield best result for tone?
The easy thing to do would be the step up/down tx. The sound/tone should be maintained as long as the B+ stays the same.

Where you live, it may be affordable to have a transformer rewound. Where I live, the price would not make sense as there are PT's available for less $. Depending on B+ and rectifier drop, the amp may sound/respond differently with a different winding.
Are the OT and PT larger in a Deluxe Reverb than those in Princeton Reverb? If it's true, except getting louder and getting a larger headroom, would there be any other tonal change in upgrading the OT and PT of a Princeton Reverb to those in a Deluxe Reverb?
Yes they are larger in a Deluxe Reverb. There are some circuit differences that account for sound/tone differences as well as the OT primary impedance differences. Then there are the different speakers with dB and sonic differences.
The Deluxe Reverb transformers are not beefy enough to use the 6L6 family of tubes, imo.

.
 

wabashslim

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IMO You really should be looking for another amp that does what you want and leave that PR alone. You might spend less when all is said & done. It's not a job for someone who has to ask, if you get my meaning. Now, I put a DR output tranny in my '67 PR along with a 12" Weber speaker and am happy with the result. There's even a hole in the chassis for the DR's differently-spaced mounting screw, as if the factory at one time considered using it. You have to watch for speaker interference though; I had to make another baffle to move the speaker off to the side.
 

schmee

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Hello guys,

May I ask if I wanna upgrade the 6V6s in my Princeton Reverb to 5581s or 6L6s, is it better to go for a larger OT and PT?

If so, shall I go with the OT and PT for Vibrolux Reverb or Twin Reverb and would there be more benefit if I go for something even larger?

Do you have any experience in Heyboer, Mercury Magnetics and Hammond OTs and PTs? Do they basically sound the same as long as the specs of the transformers are the same?

Do you think there would be a change of sound if rewiring a 110v transformer to 230v? Or using a step up transformer would yield best result for tone?

The power tubes (6V6) in the Deluxe Reverb are same as Princeton Reverb, but the Deluxe Reverb is a higher wattage amp. Are the OT and PT larger in a Deluxe Reverb than those in Princeton Reverb? If it's true, except getting louder and getting a larger headroom, would there be any other tonal change in upgrading the OT and PT of a Princeton Reverb to those in a Deluxe Reverb?

Joe Bonamassa upgraded his vintage 1964 PR with 5881 and put in his signature 12" Celestion JB-85 in there, it sounds pretty amazing!


Thanks much for your help in advance! :)

The PR power transformer is weak to start with. So I would not do it. It's the same transformer as a little Champ.
The Vibrolux PT works great in a Princeton Reverb and has close to correct voltage. I have one.
(btw, this will give you more clean headroom, even with 6V6's)
The OT is also wimpy in the PR. And with 6L6's in there you will be at 4 ohms. You need to at least go with a deluxe size OT.
(as you mentioned, this is easier starting with a Deluxe)
A Deluxe uses bigger rated transformers, both of them.
 

Dacious

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Start with a Deluxe and you can get 25 watts biased up with plugin solid state rectifier module. The output impedance is not correct for 6L6s but it's no worse than a JTM45 or Blues Deluxe which run 6500 ohm output transformers. You will lose the dirty/sweet 6V6 overdrive thing. 6L6s just don't sound the same.
 

marshman

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If you really like the way it sounds, but want that to be louder, you can't get there. Making it louder will also change the tone and response.
I hate to be contrary, but here I go. I don't know what speaker you have in your PR, but a more efficient speaker will make it louder if the speaker you have has a low SPL rating. This may, dependent upon which speaker you choose, change tone and/or feel, but is very easily reversed and easily retried with other speakers.

It has also ben my very un-scientifically supported experience that super-closely matched tubes will feel a lot louder/cleaner than a loosely-matched pair, if that is, in fact, what you're looking for.
 

archetype

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I hate to be contrary, but here I go. I don't know what speaker you have in your PR, but a more efficient speaker will make it louder if the speaker you have has a low SPL rating. This may, dependent upon which speaker you choose, change tone and/or feel, but is very easily reversed and easily retried with other speakers.

It has also ben my very un-scientifically supported experience that super-closely matched tubes will feel a lot louder/cleaner than a loosely-matched pair, if that is, in fact, what you're looking for.

Understood. I wasn't clear. I was referring to changes to the circuit and components.

The speaker? Absolutely. A more efficient speaker that doesn't change the amp's character = a louder PR.
 

schmee

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My 71 Princeton Reverb has a Vibrolux PT, A Deluxe OT and an efficient speaker in it. It's a superb amp. very quiet at idle too. It retains the PR sound with more headroom. The PR circuit always has a bit more grit in the sound, but in a great way.
 

wabashslim

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So you can mod your Princeton, but no one else is qualified to modify theirs? If you get my meaning?
My mod was relatively minor, and the chassis was already set up for it - no metal drilling or cutting, no other component changes needed. Plus, I didn't have to ask someone more knowledgeable how to do it.

The OP was asking questions about "rebuilding" his PR into a whole different, bigger amp...a far more radical undertaking for which he didn't have the experience needed or he probably wouldn't have asked in the first place. Big difference, if you do or don't get my meaning.
 




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