My '63 Dumble-modded Princeton (?)
Moderators: pompeiisneaks, Colossal
My '63 Dumble-modded Princeton (?)
Hello!
I have an amp which I'd be grateful for some community input on (as someone who is entirely incapable when it comes to electronics, circuitry, etc), and which may be of interest to you guys.
I have a wonderful old Fender Princeton from late 1963 - it's a transitional "tuxedo" model, so the blackface livery with the brownface 6G2 circuit. It's a beautiful thing. I was told by the previous owner that it is actually the amp pictured on page 50 of the "First 50 Years of Fender Amps" book.
The amp sounds absolutely spectacular - guitars sound very "full" and very dynamic through it, and all sorts of overtones and harmonics jump out at higher volumes. It's truly wonderful to play. Anecdotally, everyone who's ever played it has offered to buy it on the spot!
I bought this 5/6 years ago, and have a printed chain of emails indicating that the amp was modified or "optimised" by Howard Dumble some years ago. I haven't given this too much thought over the years but decided to investigate this properly.
You can see my pictures below.
From some research, it seems that Dumble used to stamp his modded/rebuilt Fender amps "A.D.". This stamp is present in the main body of the 'cage'. I've also found some pics of an old Dumble Bandmaster, in which you can see the exact same stamp, with the faded first leg of the "A" and the weird backwards tick through the "D", here: http://www.amparchives.com/folder/2519/
There's also a number inscribed on the speaker in the same place and handwriting as I've seen on some other apparent Dumble/Fender mods.
I'd be hugely grateful for your thoughts. I put this on another forum and Rob Livesey from the UK, who seems knowledgeable on these matters, indicated that it has "all the hallmarks" of a Dumble-modded amp.
I have an amp which I'd be grateful for some community input on (as someone who is entirely incapable when it comes to electronics, circuitry, etc), and which may be of interest to you guys.
I have a wonderful old Fender Princeton from late 1963 - it's a transitional "tuxedo" model, so the blackface livery with the brownface 6G2 circuit. It's a beautiful thing. I was told by the previous owner that it is actually the amp pictured on page 50 of the "First 50 Years of Fender Amps" book.
The amp sounds absolutely spectacular - guitars sound very "full" and very dynamic through it, and all sorts of overtones and harmonics jump out at higher volumes. It's truly wonderful to play. Anecdotally, everyone who's ever played it has offered to buy it on the spot!
I bought this 5/6 years ago, and have a printed chain of emails indicating that the amp was modified or "optimised" by Howard Dumble some years ago. I haven't given this too much thought over the years but decided to investigate this properly.
You can see my pictures below.
From some research, it seems that Dumble used to stamp his modded/rebuilt Fender amps "A.D.". This stamp is present in the main body of the 'cage'. I've also found some pics of an old Dumble Bandmaster, in which you can see the exact same stamp, with the faded first leg of the "A" and the weird backwards tick through the "D", here: http://www.amparchives.com/folder/2519/
There's also a number inscribed on the speaker in the same place and handwriting as I've seen on some other apparent Dumble/Fender mods.
I'd be hugely grateful for your thoughts. I put this on another forum and Rob Livesey from the UK, who seems knowledgeable on these matters, indicated that it has "all the hallmarks" of a Dumble-modded amp.
Re: My '63 Dumble-modded Princeton (?)
Hello -
No Dumble expert so will defer to wisdom of others on whether it had crossed his bench. Upon an excess of time spent researching 6G2 in preparation for building anew based off that basic template, yours looks really clean and nearly stock. Ground swap switch has been modded into stand-by; some cathode bypass caps swapped, for what look to be stock values; and can see some changes around the tone pot. More better photos could aid people's attention and advice.
Best .. Ian
No Dumble expert so will defer to wisdom of others on whether it had crossed his bench. Upon an excess of time spent researching 6G2 in preparation for building anew based off that basic template, yours looks really clean and nearly stock. Ground swap switch has been modded into stand-by; some cathode bypass caps swapped, for what look to be stock values; and can see some changes around the tone pot. More better photos could aid people's attention and advice.
Best .. Ian
Re: My '63 Dumble-modded Princeton (?)
Thanks Ian! What woudl be helpful - clearer pics of the circuitry?
Re: My '63 Dumble-modded Princeton (?)
Cathode bypass cap at the right end (pointing with short arrow) looks identical to the tremolo one more in centre that's clearly a 25uF. Best to be certain it is. And there are components off the fiber board soldered directly to the pots (pointing with long arrow). A clean close-up of those will complete the picture for me. Others may well see stuff I missed.
Best .. Ian
Best .. Ian
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Re: My '63 Dumble-modded Princeton (?)
That orange drop tone cap to ground looks like either a Mallory PVC series polyester film/foil or a Sprague 225p PE f/f.
Re: My '63 Dumble-modded Princeton (?)
Here's some better gut shots - hope these help!
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Re: My '63 Dumble-modded Princeton (?)
I think this is not a mod, just a simple repair job. The orange drop, bias cap, and the two cathode caps are original values.
EDIT... Looks like he may have also replaced the cap can. I'd probably just call this a cap job.
EDIT... Looks like he may have also replaced the cap can. I'd probably just call this a cap job.
Last edited by sluckey on Sun Mar 07, 2021 7:48 pm, edited 1 time in total.
Re: My '63 Dumble-modded Princeton (?)
Hmm. The provenance I have with the amp says it was "optimised" by Dumble - not quite sure what that process might involve! The amp sounds spectacular though.
Re: My '63 Dumble-modded Princeton (?)
I agree!..The amp is stock and hardly been touched..Even if Dumble did refresh the bypass caps it's the 1st time I can remember him using the newer Black Spragues, he liked to use the older Jap Caps.
BTW. For the money there are much better alternatives out there.
Tony
" The psychics on my bench is the same as Dumble'"
Re: My '63 Dumble-modded Princeton (?)
Hello --
Thanks for the additional photos. Much is now clearer. Great little amp that perhaps seemed just perfect as-is, so no need to tamper or molest.
---
Best .. Ian
Thanks for the additional photos. Much is now clearer. Great little amp that perhaps seemed just perfect as-is, so no need to tamper or molest.
---
Agreed. Noting that another 25uF/25V cap was used for the bias filter. Original schematic and photos I've saved have 25uF/50V?
Close. An actual 5n0 stock value Sprague. That domino looks original.
True. What then would you recommend?
Best .. Ian
Re: My '63 Dumble-modded Princeton (?)
Most alum electrolytics from Japan are good quality. However if I had to pick one currently available for the money, it would be Nitchion PET.True. What then would you recommend?
Here are a few others
Elna:
Rubycon :
Panasonic
If money is no object "Audio Grade"
Elna, Silmic's
Rubycon's Black Gates
Nichicon Golds.
I've tried all of these and they are all wonderful
The (Silver) Sprague low ESR caps are also a decent cap but are not what I would consider Cheap..
Tony
" The psychics on my bench is the same as Dumble'"
Re: My '63 Dumble-modded Princeton (?)
The Tweedle Champ has the newer black Spragues.
And the Tweedle Dee has newer Ruby caps.
Aaron
And the Tweedle Dee has newer Ruby caps.
Aaron
Re: My '63 Dumble-modded Princeton (?)
I don't remember seeing these but here they are in the Champ.
Thanks Aaron Tony
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" The psychics on my bench is the same as Dumble'"