Hi!
I'm Marco from Italy.
I would like to build a Tweed Princeton (5F2-A) clone amp.
I'm a bit in trouble with the trannys.
I've seen on the schematics that Fender used PT 66079 and OT 265.
Does anybody of you know the specs of these trannys?
Does anybody of you know some equivalent trannys I can use?
Thanks in advance for any reply you will post.
Donations
OT and PT for a Tweed Princeton (5F2-A)
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goneracin
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PhatTele
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I believe Princetons share the same power transformer as Champs. I'm not as sure about the output transformers, but it's more than likely that they're the same as well...letting the tube configuration dictate the output. A Champ generate 4 ohms, but that due to using only one 6V6. A two 6V6 push/pull amp wil generate 8 ohms (like a Princeton).
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Newt
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Since the 5F1 Champ and the 5F2-A Princeton are the same except for the Princeton's tone control, I suspect they used the same trannys.
Your choice of trannys will be determined by your budget, desire for authenticity, and availability in your area.
If you are wanting to build a nice small amp and are not set on the 5F2-A, kits for the AX84 P1 are available in Europe from www.madamp.biz for good prices.
A PT for a 5F2-A will need to provide 50-60ma of high voltage current with a secondary voltage of 220-300, center-tapped; 2 amps @ 5 volts; and about 1 amp at 6.3 volts(allows for a 6.3-volt pilot lamp). There are several Hammonds in the 37X series that will fit the bill.
Any OT with a primary impedance of around 5k will serve.
Your choice of trannys will be determined by your budget, desire for authenticity, and availability in your area.
If you are wanting to build a nice small amp and are not set on the 5F2-A, kits for the AX84 P1 are available in Europe from www.madamp.biz for good prices.
A PT for a 5F2-A will need to provide 50-60ma of high voltage current with a secondary voltage of 220-300, center-tapped; 2 amps @ 5 volts; and about 1 amp at 6.3 volts(allows for a 6.3-volt pilot lamp). There are several Hammonds in the 37X series that will fit the bill.
Any OT with a primary impedance of around 5k will serve.
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spunky78
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"Do you think that these values are too much? "
Your rectified raw B+ will be approximately (1.414 X 330) -50 =416 volts. You probably don't want to run a 6V6 much over 375, so, depending on the drop across the OT primary, you might be a little high.
A 5Y3GT only needs 2 amps of 5-volt current.
For your 6.3, you will need 450ma for the 6V6 and 300ma for your 12AX7, plus 125-150 for a pilot light. So you could get by with 1 amp there.
That PT is more than you need, but should work. And you could use it for something else later, or add tubes for higher gain or tremolo.
Your rectified raw B+ will be approximately (1.414 X 330) -50 =416 volts. You probably don't want to run a 6V6 much over 375, so, depending on the drop across the OT primary, you might be a little high.
A 5Y3GT only needs 2 amps of 5-volt current.
For your 6.3, you will need 450ma for the 6V6 and 300ma for your 12AX7, plus 125-150 for a pilot light. So you could get by with 1 amp there.
That PT is more than you need, but should work. And you could use it for something else later, or add tubes for higher gain or tremolo.
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markd
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First let me say, I think your choice of the tweed Princeton circuit is a good one. I have a few White Higher Fidelity amps(made by Fender in the 50's) and they have the same circuit. They are great sounding recording amps. That single ended power amp distortion sounds so smooth and the clean sound is good also.
Since you are in the European Union, you might try Shinrock transformers in Germany. I know he makes an OT for your project. If you don't mind ordering from the states, email Weber VST. They sell good, and inexpensive, correct Fender trannies. I know they have an OT, and perhaps a PT, that would be right on. The voltages on the PT are going to be critical for the best tone.
hth, markd
Since you are in the European Union, you might try Shinrock transformers in Germany. I know he makes an OT for your project. If you don't mind ordering from the states, email Weber VST. They sell good, and inexpensive, correct Fender trannies. I know they have an OT, and perhaps a PT, that would be right on. The voltages on the PT are going to be critical for the best tone.
hth, markd
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