Pentode Tap on pushpull output trans

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Wragie
Posts: 5
Joined: Tue May 11, 2010 7:15 am

Pentode Tap on pushpull output trans

Post by Wragie »

Curious if anyone has ever tried using a pentode tap on a push-pull output transformer? It's a way you can use a single tube to drive it instead of a pair.

In my questo to try and reuse all the junk out of a reissue blues deluxe I ran across a reference on how to to this. The theory is it also gets everything into the sweet spot of the transformer so should sound better.

Just wanted to ask before I confirmed the guy who wrote that must have been in used car sales previously :D
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Phil_S
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Joined: Tue Oct 23, 2007 10:12 pm
Location: Baltimore, MD

Re: Pentode Tap on pushpull output trans

Post by Phil_S »

A single ended amp needs an air gapped output transformer to prevent premature saturation (and poo tone). I have no idea what you are asking, but PP and SE output transformers are very different. They aren't meant to be be interchangable.
Wragie
Posts: 5
Joined: Tue May 11, 2010 7:15 am

Re: Pentode Tap on pushpull output trans

Post by Wragie »

Thats actually from an old hammond tech note. It's rather a clever way of using the transformer single ended. No ide of how good or bad it sounds.
Was hoping someone else had tried letting the smoke out of things and would let me know before I am force to try it :D
Firestorm
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Joined: Fri Jan 25, 2008 7:34 pm
Location: Connecticut

Re: Pentode Tap on pushpull output trans

Post by Firestorm »

I think what Hammond was probably suggesting was using the center tap of a PP tranny as an ultralinear tap and wiring the other ends SE. It would be at 50% instead of 40%, but close enough. Still, unless the transformer was significantly heftier than called for, it would saturate pretty quick. I wouldn't try it with a tube more potent than an EL84 or a 6V6, even then.
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