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Old 27th September 2004, 06:19 AM   #1
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Default 2A3 SET Output Transformer opinions/recommendations

Hello All,

I'm in the process of choosing & assembling the parts for a SRPP 2A3 SET.
I'm having a tough time choosing and locating sources of good OT's.

This is what I've sourced out from the net so far:

Hammond ESE @ $32.00US ea.
One Electron UBT-3 @ $80.96US ea
Hammond 1627SE @ $85.00US ea.
MagneQuest TFA-204 @ $125.00US ea.
Tamura F-475 @ $143.00US ea. ($$$ for shipping)

I do have a budget that I'm tryng to follow so big $$$ OT's are kind of out....unless can convince my wife other wise

Thanks for your time

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Old 27th September 2004, 07:31 AM   #2
arnoldc is offline arnoldc  Philippines
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like you i started on the affordable side and got a hammond 125ESE (2.5K, 5K, 10K) for my je labs 2A3 (srpp). it sounds good for the amount i paid. i have moved on to a different iron now, which is a magnequest DS-025 (2.5K) and i believe it was a step forward in sonic improvement.

i have used a 1628 (5K) but that's for a 300B and now on my 807 amp, and it sounds good too.

if you ask my current favorite, that will be a Tamura F-475 (5K) which i used on my 245 amp. just be careful not to exceed the current rating of the transformer. if you bias your 2A3 at 45 operating point (34mA), the current will be ok for the F-475 and you get a gemini amp (2A3/45 switchable) with the proper cathode resistor, though not optimized for the 2A3 (less power).
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Old 27th September 2004, 10:36 AM   #3
SHiFTY is offline SHiFTY  New Zealand
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I was a little disappointed in the 125ESE, they were ok but not great... good to start with i guess.

I would recommend spending a bit more on the output iron first, you won't regret it...

Also I have tried the srpp and the loftin white and they didnt sound too good imho... The one I would recommend is the angela.com 2001 edition 2A3, its the best circuit i have tried so far.

SET amps are definitely good sounding tho, i would recommend them...
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Old 27th September 2004, 10:43 AM   #4
hacknet is offline hacknet  Singapore
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the tam seems to sound fantastic. it sounds light and dynamic. very detailed and fast.
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Old 27th September 2004, 12:23 PM   #5
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big $$$ OT's are kind of out....unless can convince my wife other wise
We can try...

Here goes, IMO the Hammond OPTs are good value for money but what good is it to save money on an OPT if you're going to be left wondering: What if I had....?
After all 85% of a classic tube amp's quality is determined by the iron it's made of, right?

From your list the Tamura is no doubt excellent but maybe too expensive.

Both One Electron and Mike Lefevre's Magnequest are no doubt among the best US winders I know of.

Then there are some superb European OPTs made by Bartolucci, Tribute, AE, Sowter and no doubt a few others that slip my mind right now.
Last but not least Luddahl from Sweden has an enviable reputation for good iron at a reasonable price.
The best source I know of (incidentally in my backyard so to speak) is Benny Glass' shop Aquablue in Antwerp.
More often than not he can offer the Lundahl xformers for less money than Lundahl themselves is selling for.

Feel free to mention my name in case you want to get in touch with him:


It's only a suggestion of course, I'm sure there's plenty of other good iron about.

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Old 27th September 2004, 12:45 PM   #6
KT is offline KT  United States
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Can't make any solid recommendations as I haven't used different transformers in the same 2A3 circuit. But these transformers are also worth researching: Electra-print and Audio Note.

I owned a Moth Audio s2A3 amp for a couple of years, and this used Electra-print OPTs. Sounded really good. Welborne Labs amps also use the Electra-print OPTs in their amps.

I also own the Audio Note Kit One. This is a 300B amp so there may not be a direct comparison here, but in a shootout for 300B OPTs in Vacuum Tube Valley several years back, the Audio Note OPT used in the Kit One was judged a best buy, sounding very good for the price. I agree!

I also have a Sun Audio SV300BE, again a 300B amp. This one uses Tamura iron and sounds very good, as well. Different circuit, so I can't directly say which is preferable.

In the 300B OPT shootout, it seemed that the big Electra-print unit they tested was much preferred over the other transformers, which included some units by Tango, Tamura, Audio Note, Bartolluci, One-Electron, Magnaquest (?), and a few others. Of course, other units from the same manufacturer may be better or worse than the shootout suggests.

Look into Electra-print and Audio Note, though.

Good luck,
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Old 27th September 2004, 04:02 PM   #7
jsn is offline jsn  United States
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Default tfa-204 thoughts

I have used the Magnequest TFA-204 and like it very much. The bass is better than I thought it would be, and the mids and highs are fantastic.

I am planning to upgrade the amp using the TFA-204 to parallel feed because I want to see how good it can be. for this I want to use the TFA-2004 parafeed output and a suitable plate choke, maybe EXO-003. This is more iron than your budget (and my initial budget) would allow, but I really dig this amp and want to see how far I can take it.

My suggestion is to be sure you leave room on the chassis for bigger transformers and perhaps a pair of plate chokes for parallel feed. That way you leave you options open for future upgrades. I am bummed because I am out of topplate real estate and ewant to add another pair of chokes, a 1uF paper in oil power supply cap, and a pair of Vitamin Q parafeed caps :( And my chassis is already 12" x 24" :) I guess I'll have to mount some of these beauties under the hood. Such a shame.

Oh, and if you buy "nice" iron, and want to upgrade, you should have no trouble selling it off to your friendly neighborhood tube nerds - so the upgrade costs can be fairly incremental.

Here is the amp in question:

This amp uses tons of surplus power supply iron, which can usually be found cheap. If you can get some good deals on stuff like this, it will leave you more money for output iron and plate chokes and stuff that you can't get surplus. I haven't bought a new power transformer in years, except for projects that must use readily available parts.

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Old 27th September 2004, 06:36 PM   #8
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Default output transformers

Electra-Print output transformers are some of the best. Jack will also work with you on whatever your needs are. He will make recommendations and answer questions if you have any doubts. His prices are very reasonable for custom wound iron. I highly recommend contacting him. Elecrta-Print phone no. 702-396-4909. E-mail electaudio@aol.com
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Old 27th September 2004, 11:14 PM   #9
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For the Hammonds i think you will find that Electro-sonic has the best prices (and are the Canadian distributor)


community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
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Old 28th September 2004, 01:43 AM   #10
arnoldc is offline arnoldc  Philippines
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Originally posted by SHiFTY
Also I have tried the srpp and the loftin white and they didnt sound too good imho... The one I would recommend is the angela.com 2001 edition 2A3, its the best circuit i have tried so far.
hi shifty, can you please tell me, if you still remember, the sonic difference between the SRPP (Steve's EZ-2A3) and this 2001 edition?

gang, other transformers that are possible alternatives include the Tango U-808 which i heard on a friend's "Darling" amp. and then Mike Le Fevre has these new "Robin Hood" series which is tempting at $75.

i have a friend with a Jack Elliano made DRD 300B and of course using Jack's OPT and they sound really clean when i hooked it up to my system must be the circuit or the OPT or both.
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