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Old 28th September 2002, 11:34 PM   #21
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Join Date: Dec 2006

Well I put out the cash for the iron today. All will come from Jack at Electraprint in Nevada. Talked to him on the phone and all is well. Having the power trannys custom built, chokes and the power trannys are stock fare. Opted for The ST3KB ouput tranny. Read a review on the web from VTV and they rated Electraprint tranny's very warmly. 3 to 4 weeks for delivery. Now I fell like the women in the T.V. comercial for Mervyn's department store, " OPEN!, OPEN!,OPEN!". Just need to source the rest of the parts as funds permit. Will keep you posted. Cherio!!!

Paul A.
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Old 1st October 2002, 12:05 PM   #22
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Default OTL


While Paul is doing the building...

heck, I still need to make my 6080/6AS7 OTL
Excuse my curiosity here.
Have got anything particular in mind ?

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Old 1st October 2002, 04:34 PM   #23
Colt45 is offline Colt45  Serbia
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not exactly sure.

I had an idea.

i dont even know what you call it. its like SRPP, but the phase is inverted for the top tubes(or is it the bottom tube..).
4 sections on top, 4 sections on the bottom(so 4 tubes total).

futterman topology, i guess its called.

i was thinking of a 7025 paralleled for gain, and a 6S4 for cathodyne.

+60v on the top, -60v on the bottom, so that you dont need coupling caps on the output. (or 120 on the top, ground the bottom, and use output coupling cap(s) )

got most of the idea from my friend Tim, but he says his design needs a little fixing up.
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Old 1st October 2002, 04:58 PM   #24
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Default OTL


Regardless the voltage on the output tubes (60Vdc either way,seems very low to me) in principle you will not need an output cap.
A lot of transistor designs work around the same principle and although some have a coupling cap in the output stage you normally will not need that.
OTL+OC seems like heresy to my ears?
A half decent OPT would at least present the advantage of not changing its characteristics over time?
Don't get me wrong here though.
I like OTL amps since they can put out an amazing amount of current into a reasonable speaker load and if I can get rid of yet another superfluous and costly component I will prefer that road.
I've said it before:I await the day someone can manufacture complementary tubes.

Thk you for your kind response,
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