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Old 6th September 2006, 04:08 PM   #11
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I'll try to send you the schematic, but the basic rundown on the 45-845 IT parafeed amps I have (www.electronluv.com for pics/info) :

input transformer (600:15k I think) -> 45 (dc filaments, B+ somewhere like 200v) -> 1:1 5k IT (I forget if this is parafeed or not - could be either really), 845 output (900v b+) -> parafeed output trans/plate choke. Dual power supplies for the 2 tubes. AC or DC fils on the 845.

What transformers do you have already? The key in doing 45-845 in a 2-stage setup is getting enough gain, hence the need for a step-up input transformer.

-Ed
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Old 7th September 2006, 07:01 AM   #12
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Hi Ed

While I like the idea of just two stages, Gordon Rankin suggests that step-up transformers tend to compress the sound.
That of course would be in lieu of whatever negatives an extra stage would introduce.
What do you think of that line?

Do you recall how many mA on the B+? And does the schematic include the PS?

Cheers
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Old 8th September 2006, 02:44 PM   #13
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Hi Ed

> The key in doing 45-845 in a 2-stage setup is getting enough gain, hence the need for a step-up input transformer.

Ah, makes sense.

> transformers I have already?

Tamura F-2013

How did you go with the 45-845 IT schematic?
You can email me offline via the forum

Cheers
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Old 12th September 2006, 03:45 PM   #14
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Gordon has strong opinions about things, to say the least. ;-) he thinks that about all IT's or stepup trannies, I believe. My ears disagree with that presumption of his. But he is a smart guy, I tap him for advice on occasion too. he knows his stuff but take it with a grain of salt. still working on finding the schematic.

I'd take a good step-up (esp. @ the input) over a 3rd stage of amplification. The 2-stage will be quieter, all else being equal.

-Ed
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Old 12th September 2006, 11:36 PM   #15
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> Gordon . . thinks that about all ITs or stepup trannies, I believe.

I saw at the AA a while back, that’s one of his “top 10 peeves”

> I'd take a good step-up (esp. @ the input) over a 3rd stage of amplification.

Yes, I’m thinking eg ElectraPrint, James, Silk

(Doesn’t have to be parafeed) Does anyone have a 2-stage (ideally) 45 stepup 845 SE circuit?

Cheers
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