Dynaco/Hafler P/P Plexi.

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FuzzFaceBuilder
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Dynaco/Hafler P/P Plexi.

Post by FuzzFaceBuilder »

I wanted to field thought and opinions on using Dynaco P782 and A470 for a mean high B+ P/P plexi. SS rectified and KT-77's for a >100w P/P amp. Was thinking of using the C354 (1.5H) choke. Should I look into a C1999?

The p782 is 800v ct @ 200 ma, 6.3v @ 5A. 5V recto tap for a Dumble-style "mega boost". The 800v rectified down should give me ≈565v max.

The A470 is self explanatory. 4.3k primary, 30 to 15 KHz at 70 watts. Also I found reading around TAG (the bold in the quote is my emphasis):
talbany wrote:I've used the real Dynaco A470's in several builds (mostly 34's Express) and are no doubt KILLER!! iron. ...Although they were designed for a pair of 34's or 6550/88's these transformers were 100% over spec and can easily handle 100 watts on a bad day..
A 470 weight pushing 10lbs

Tony




Any other insight or advice would be greatly appreciated! :D
Last edited by FuzzFaceBuilder on Mon Nov 04, 2013 12:39 am, edited 1 time in total.
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M Fowler
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Re: Dynaco/Hafler P/P Plexi.

Post by M Fowler »

Does this mean that the 200mA rating of the p782 is under rated as well since for a 100w amp we should be looking at 400mA to 500mA rating.

Perhaps the p782 is happy unless we stress it. :)

Mark
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FuzzFaceBuilder
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Re: Dynaco/Hafler P/P Plexi.

Post by FuzzFaceBuilder »

M Fowler wrote:Does this mean that the 200mA rating of the p782 is under rated as well since for a 100w amp we should be looking at 400mA to 500mA rating.

Perhaps the p782 is happy unless we stress it. :)

Mark

Thanks Mark!

If things work out, I plan to stress it! :shock: :D

The charts for the p782 specify 800v @ 200mA, but "will deliver up to 300 ma continuous, albeit at a slightly lower voltage". Rated 780v @ 300mA continuous on the spec sheet. AND if what Tony said about Hafler/Dynaco stuff being 100% over spec holds true, we should be able to get closer than we think!

Even if we come up shy of 100w, an optimistic 75-80 watt P/P marshall ain't so bad!
Last edited by FuzzFaceBuilder on Mon Nov 04, 2013 12:39 am, edited 1 time in total.
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M Fowler
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Re: Dynaco/Hafler P/P Plexi.

Post by M Fowler »

Yeah about 75 or 85 watts maybe and 300mA should be darn good.

Those Dynaco transformers are nice and I've used a lot of those A470-S Dynaclones in different types of builds but not that high of wattage. :)

I was thinking about trying a pair of KT120's with that p-782 PT and using 1k2 100w OT.
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