Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: crashtm1 on May 10, 2010, 09:07:50 pm
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OK.. Here's the plan.... I've got most all the parts ready, just need a blank chassis...
Starting with a Princeton reverb.... solid state recto, 4x6l6, JTM 45 PT with a Vibrolux OT, master volume and preamp control..
I'll post as I build....
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Are you sure the Vibrolux OT is up to the task? I bought a BF bandmaster that was toast, someone had tried running 4 6L6GCs, same transformer. I also don't think the Princeton style PI will drive 4 big bottles. Is the JTM 45 PT even up to it? Maybe try 4 6V6 tubes, is that what you meant.
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Maybe try 4 6V6 tubes, is that what you meant.
That's what I was thinking, too....??
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Is this a first time build?
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I bet he meant 4-6V6's.You might consider cathode bias too.Nice touch responsive amp.
The JTM45 PT will kick out pretty high voltages with a solid state rectifier.Might want to think it through a bit more.Depends I guess on what you are looking for.
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With the parts you are using, are you shooting for the Diaz CD30?
I presume the princeton is just being used for the chassis carcass, no?
(If so, remember, the CD30 used long tail PI, not a princeton style concertina.)
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Transformer view.
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Yes that's exactly what I'm shooting for... CD30...
And the chassis is carcass only.. I've got
some drawings and pics from when I owned one ,,, shooting in the
dark otherwise ... ;)
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Hey Topbrent...
Care to elaborate on your comment?
(If so, remember, the CD30 used long tail PI, not a princeton style concertina.)/quote]
I've read up on the net, but no one has really explained it in laymen terms...What's the difference? Tone? Voltage? Can it be applied to any circuit like a 2204? ???
Greatly appreciated..
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He's talking about the phase inverter on that amp using the more modern long tail type.
Long tail pair is a phase inverter topology that has a single resistor connected as a pseudo-current source from the junction of two tube cathodes, with the outputs taken off the individual tube plates, one in phase with the input signal, and the other out of phase with the input signal. The circuit gets it's name from the "tail" resistor connected to the cathodes.
Concertina phase splitter is the name given to the single-tube phase inverter in which the in-phase signal is taken off the cathode and the out-of-phase signal is taken off the plate, with equal-value plate and cathode resistors. This phase splitter configuration has excellent balance, but only unity gain. Also called a "split-load" phase inverter.
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safe to say that he was injecting a Marshall power section into a princeton reverb circuit with master ?
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Yes and no...
From the component values in the phase inverter, it is more like your basic longtail, silverface twin reverb, 4 6L6 power section.
- .01uf input, 330k-470-330k-22k tail - .1uf 820-100 nfb. Fender bandmaster/pro reverb OT.
About the only thing "marshall" about it is the 50pf or 100pf smoothie cap across the PI 100k plate resistors.
(The amp is very "fender" overall. Look at the vibrato channel in a aa270 twin reverb for inspiration. Remove the normal channel and vibrato itself )
If I had to venture a guess, the master volume is probably a Ken Fischer type II. Wire routing supports this guess.
- Known in the current vernacular, LarMar MV.
There is a guy (groovtubin) over on ampgarage that used to build these amps for Diaz. He currently runs Omega Amps.
If you asked nicely, he might give you some build tips.