Wright Sound Company WPA 3.5 with "gold" output transformers

Steph · 7238

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Offline Steph

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I recently acquired a second pair of the WPA 3.5 (to use in a tri-amped
setting) and am trying to figure out what the story with the second set
of amps might be.

Most of the ones I have seen have a serial number and the initials of the
assembler along with a date (month/year). For example, my first pair have
the following info:

Serial number: 417 L 417 R
Assembler / Date: SH 5/01

The second pair have the following markings:
Serial number: 042 R 042 L
Assembler / Date: SM ROHR

It would stand to reason that the second pair were number 42, whereas
the first were number 417. What stumps me is the possible meaning of
the "ROHR" (in place of a date).

I am also interested to know which output transformers were used. On
the second pair, they are a gold color, whereas on the first pair, they are
black. From what I have read, various OPTs were used by George over
the years: MagneQuest, Sowter, and O-Netics have all shown up in various
searches. I've seen DeYoung come up, as well.

I have asked the gentleman from whom I purchased the amps about this
andhis reply was "Over the years I have owned many of his amps, pre-amps
and phono pre-amps. The 3.5s that I sold to you were used by George as an
experiment to see what the gold transformers would be like versus
Magnequest. George preferred the gold transformers but they were too
costly--he would have had to charge more for his amps and he didn't want
to do that."

Any ideas on who might have made the "gold" transformers or to what the
"ROHR" designation might refer?

Any insights / leads would be appreciated!

Steph


Offline Jim R.

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Reply #1 on: March 22, 2013, 11:42:01 AM
 Most of the gold color transformers I've come across were made either by Bertolucci of Lundahl, but this was supposedly a more champagne gold than real gold plating.  The only real gold plating I've seen has been on some elektra print transformers that Sy Brenneman used in some of his higher end amps.  Come to think of it, I believe the James transformers are also available in a champagne gold color, but those would not have been more expensive than the others you mention.  If I were you, I'd go with Lundahl and start looking there.

No idea what the rohr is, sorry.

Hope this helps,

Jim

Jim Rebman -- recovering audiophile

Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).

s.e.x. 2.1 under construction.  Want list: Stereomour II

All ICs homemade (speaker and power next)


Offline Doc B.

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Reply #2 on: March 22, 2013, 11:54:17 AM
I'd guess they are Electra Prints. Gold plated end bells were an option for a while. You might check with Jack.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline Steph

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Reply #3 on: March 23, 2013, 05:32:22 AM
Thank you for the reply / replies. Not sure who this will be in reply to as I'm not familiar with this forum design! But I do appreciate the comments.

I put the word gold in quotes because I intended to emphasize the color. It's not just the end plates and it's unlikely that they are gold plated. The term champagne seems apropos here. I will try to post picture of innards and outtards tomorrow after a friend and I look into these and give them a listen later today.
« Last Edit: March 23, 2013, 05:35:24 AM by Steph »

Steph


Offline Doc B.

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Reply #4 on: March 23, 2013, 06:23:16 AM
OK, those don't sound like they are ElectraPrints. Not sure what else they might be. I know George tried Sowters for a while and they are on the higher side price wise (and sound very good) but I don't know if Brian makes anything with a gold finish. When it comes to George's amps, every one was a one off to some degree. And the only schematics I ever saw were a couple that George gave me many years ago. So it's a little hard to make a definitive guess about any of the parts!

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline Steph

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Reply #5 on: March 24, 2013, 05:17:39 AM
Thanks for the replies so far. I'm still figuring out this site's software, so if you don't mind slumming it at the Asylum for a few moments please take a look at the link for some exterior pics.

http://www.audioasylum.com/forums/set/messages/7/72784.html
http://www.audioasylum.com/forums/set/messages/7/72784.html

I didn't bother with posting pics of the innards because I had three different pairs to look at and they (as Doc suggested) are all somewhat different in their layout. Also, it turns out the serial numbers appear to be meaningless, as they don't line up chronologically with the stated production dates!

The "RORH"  designation in place of a date on the 042 units remains a mystery.


« Last Edit: March 24, 2013, 05:21:19 AM by Steph »

Steph


Offline Doc B.

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Reply #6 on: March 24, 2013, 06:23:42 AM
The end bells are brass, not gold and those look to be MagneQuest TFA -2004s. What's curious is they appear to have permalloy laminations, which should be used in a parallel feed circuit, which that amp does not appear to be. Perhaps the lams are M4 or M3, or perhaps George was just wingin' it on the design of that one.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline Grainger49

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Reply #7 on: March 24, 2013, 07:17:57 AM
Since the laminations are "gold" I expect that the transformer was painted.  I posted this in Mikey's thread.  These are my TFA-2004 transformers with polished/lacquered end bells:

http://www.bottlehead.com/smf/index.php/topic,2865.0.html



Offline Doc B.

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Reply #8 on: March 24, 2013, 07:32:28 AM
The lams in the photos are a nickel color, or perhaps the color of m3 lams. And Mike did quite a few transformers with raw, unpolished brass end bells, which those look like to me, as I have some myself.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline Grainger49

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Reply #9 on: March 24, 2013, 09:03:42 AM
I think in the middle picture the lams look more silver than gold.  I didn't pay that much attention to it.  In the other two the lams look more gold.  But you are probably right.  I don't remember that my end bells looked gold before polishing.  That probably has something to do with how long the end bells have been around.



Offline Steph

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Reply #10 on: March 24, 2013, 09:11:42 AM
Thanks, guys! Not ignoring other responses ... just don't know how to navigate this forum, yet.

Does this work?

http://gallery.AudioAsylum.com/cgi/gi.mpl?u=6942&f=417_inside.JPG

Steph


Offline Doc B.

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Reply #11 on: March 24, 2013, 10:05:37 AM
I still think it's a permalloy or M3 TFA, but I wasn't paying attention to the stack before - it's a TFA-204 not a 2004. The lams are stacked and gapped for series feed and you can see that is how it is wired underneath. Probably permalloy lams, and George was probably assuming that the 3.5W 2A3 power output would be OK in series feed with the permalloy. Not sure about that, because I don't know how much DC current he was running through the core.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline Steph

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Reply #12 on: March 25, 2013, 08:24:20 AM
I still think it's a permalloy or M3 TFA, but I wasn't paying attention to the stack before - it's a TFA-204 not a 2004. The lams are stacked and gapped for series feed and you can see that is how it is wired underneath. Probably permalloy lams, and George was probably assuming that the 3.5W 2A3 power output would be OK in series feed with the permalloy. Not sure about that, because I don't know how much DC current he was running through the core.

We have a winner! Thanks to all for your efforts. Upon some dissection, we found the following handwritten marks on the core:
60 MADC
10x10 TFA
204 NAG

The core in the 042 unit (all black) was simply stamped "TFA".

Still wondering about the meaning of the RORH designation on those units.

Steph


Offline Doc B.

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Reply #13 on: March 25, 2013, 09:06:59 AM
You could ask Mike what some of that means. Not sure what 10x10 means. I would have guessed that is the number of lams in alternating layers in the stack if it looked pinstriped. NAG might mean Nickel Air Gapped.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline Steph

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Reply #14 on: March 25, 2013, 10:23:07 AM
You could ask Mike what some of that means. Not sure what 10x10 means. I would have guessed that is the number of lams in alternating layers in the stack if it looked pinstriped. NAG might mean Nickel Air Gapped.

Thanks for all the help, Dan! I'll touch bases with Mike.


Steph