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centraltexastubeguy 27th April 2013 11:22 PM

Best PP OPT 30-100W range
 
Howdy, Folks:

For the amplifier currently in the conceptual stage, I'll want a new manufacture PP output transformer, and for budget reasons it should be an off the shelf as opposed to a custom (unless someone knows of a competent custom winding house that is competent compared to off the shelf).

The topology is still up in the air but most likely it'll require separate screen windings with about a 20-30% ratio relative to the plate windings. Not ready to specify the complete transformer yet, just wanted to give y'all an idea of the class. This is for HI FI.

So, the question: who are the off the shelf providers out there with whom any responder has experience and what are the respective opinions about each?

Thanks!

Rene

mctavish 27th April 2013 11:31 PM

A given would be Electraprint. Not exactly budget but quality in spades and more than competent...

Drewaudio 27th April 2013 11:48 PM

I agree, i've found my 20w PP Electraprint's to be outstanding. I've also got a pair of PP 80w transcendar's that I'm yet to use that were half the price of the 20w Electraprints. I see a lot of posts on the forum based on projects that use SE Transcendar's but none using the PP variant....

sootboots 28th April 2013 12:07 AM

I have a pair of 30W PP Transcendars on the way for an EIclone. I will report back when I finally get it put together. The one I hope to build is a clone of the Eico Hf-87 as per the diytube.com website. My reference will be the JE Labs 300b mono blocs which sound beautiful but not enou power right now. WAF prevents true high efficiency speakers....

JP

45 28th April 2013 12:56 AM

Quote:

Originally Posted by centraltexastubeguy (Post 3470660)
Howdy, Folks:

For the amplifier currently in the conceptual stage, I'll want a new manufacture PP output transformer, and for budget reasons it should be an off the shelf as opposed to a custom (unless someone knows of a competent custom winding house that is competent compared to off the shelf).

The topology is still up in the air but most likely it'll require separate screen windings with about a 20-30% ratio relative to the plate windings. Not ready to specify the complete transformer yet, just wanted to give y'all an idea of the class. This is for HI FI.

So, the question: who are the off the shelf providers out there with whom any responder has experience and what are the respective opinions about each?

Thanks!

Rene

Depends on what "for budget reasons" means. Custom made transformers with those specs are not going to be cheap.
Off the shelf you can buy the Sowter 8994 that is a replica of the Acrosound TO-350. Of course if you can find a pair of original Acrosound OT's they still are very good as well, although modern magnetic materials are a lot better.
A pair of Sowter 8994 cost about 500 British pounds!
Primary impedance is 6.6K plate-to-plate with separate UL windings at 43%. The Sowter is rated 100W (but the frequency is not specified), the Acrosound was specified for 100W from 20Hz to 20KHz, FR 7Hz to 70 KHz +/-1dB, max DC current for each tube 175 mA, max DC unbalance 10% of the previous value.
These transformers where specifically designed for tubes that could not withstand high screen grid voltage like the 6146, however I think that the separate winding is beneficial for any tube....

MelB 28th April 2013 01:44 AM

Hammond Mfg.-"Classic" Push-Pull-Easy Wire-Tube Output Transformers - (1608A-1620A, 1645A & 1650A Series)
Order any of them from Digikey. They have been making output transformers forever...
They sound pretty good to me.

centraltexastubeguy 28th April 2013 02:22 AM

Thanks, All. I hope the input keeps coming. I have deliberately not introduced any of my opinions so far, interesting how at least 2 of the names I'd expected to show up right away have not. Maybe in a couple of days!
Rene

prairieboy 28th April 2013 03:29 AM

Quote:

Originally Posted by mctavish (Post 3470667)
A given would be Electraprint. Not exactly budget but quality in spades and more than competent...

I agree, get a quote ... he does know what he's doing.

DeathRex 28th April 2013 03:57 AM

Edcor, they are next door in Carlsbad, NM.
I think it's $70 set up + price of transformer for a custom job. PP 60 watts are $70, 100 watts are $92.

Head to head edcors are some very good transformers, and you can't beat the price.

45 28th April 2013 10:13 AM

Looks like there is some misurdestanding here: separate windings for UL is not the same thing as UL taps.
Separate windings are usually called tertiary windings and, as the name suggests, are indipendent. This allows to apply a different DC voltage to screen grids. This is not possible with the vast majority of UL output transformers, regardless of their cost and performance. As the winding geometry becomes more complex and the work nearly doubles the cost increases accordingly.....


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