I have been fortunate to have had long conversations/correspondence with Great Guru Baxandall, Peter Walker and worked with Ted Ashley (who designed the last of the great LEAK valve amps)
Ted said that, although he could pontificate at length over why the LEAK design was better than the Radford, the real reason for their good performance was cos Radford made their own transformers and LEAK had a good relation with Drake who made their transformers.
These gurus were unanimous. "The guy who designed the transformer was far more important than the snake oil used to pot the windings."
If you want to become a transformer guru, have a look at RDH 4, articles on valve amps and transformers in old Wireless World and a JAES article by old man Sowter just before he died. Don't expect instant epiphany. If you study these works diligently, you might achieve your aim in your old age.
In the 90s, I needed a transformer for a completely different application. The Drake sample had better THD, saturation bla bla compared to the other contenders yet was half the weight (and hence cost competitive)
Today, I think only Sowter has this real expertise. Perhaps also Lundahl .. though my experience with them was for other types of transformers. The others just copy old designs and add snake oil.
I'm probably doing 'modern' transformer makers a disservice as I've been a real beach bum this century 🙂 If anyone has evidence of transformer design & manufacture expertise for these, please post the evidence.
Anecdotal is OK but not, "I replaced a Dynaco ST-70 trannie with a Virgin OPT from Unobtainium Transformer Co. Clarity & definition was so much better, all the BS fell out of my speakers."
Ted said that, although he could pontificate at length over why the LEAK design was better than the Radford, the real reason for their good performance was cos Radford made their own transformers and LEAK had a good relation with Drake who made their transformers.
These gurus were unanimous. "The guy who designed the transformer was far more important than the snake oil used to pot the windings."
If you want to become a transformer guru, have a look at RDH 4, articles on valve amps and transformers in old Wireless World and a JAES article by old man Sowter just before he died. Don't expect instant epiphany. If you study these works diligently, you might achieve your aim in your old age.
In the 90s, I needed a transformer for a completely different application. The Drake sample had better THD, saturation bla bla compared to the other contenders yet was half the weight (and hence cost competitive)
Today, I think only Sowter has this real expertise. Perhaps also Lundahl .. though my experience with them was for other types of transformers. The others just copy old designs and add snake oil.
I'm probably doing 'modern' transformer makers a disservice as I've been a real beach bum this century 🙂 If anyone has evidence of transformer design & manufacture expertise for these, please post the evidence.
Anecdotal is OK but not, "I replaced a Dynaco ST-70 trannie with a Virgin OPT from Unobtainium Transformer Co. Clarity & definition was so much better, all the BS fell out of my speakers."
Alas, Partridge was gone by the time I became seriously involved in amp design.
I should clarify that. They went bust in 1997. But by the late 80s/early 90s, they supplied mainly guitar amp makers and didn't really have a design office. I should ask my friends at Celestion if they know more but I think those who would have are gone. 🙁
They were important in the Williamson, Mullard 5-20 days for high quality amps. ... as will be seen in the articles I recommended.
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yes, thank you very kindly, dear gorgon53.
I read of them before. (As of non-existing anymore Welter).
Reinhöfer's current (???, or from 2013): https://www.roehrentechnik.de/html/gegentakt.html
For me the difficulty is: to find the best one, which is but relevantly the best.
It would be nicer, if every company would mention full technical quality data,
which maybe still is partially irrelevant, when only perceived sound quality is of importance.
thank you again. will read a bit.
My model is my mechanically/optically most "sauber" built BRAUN CV11.
(since I never did much testing with diverse loudspeakers, so no experience,
it is difficult to speak competently on sound 'quality' for that one.)
A german recording studio engineer from a top quality studio found it a bit 'näselnd'.
With my LE1s I find it nice, though some crackling either from the LE1 or the CV11 tube sockets, or else ?
thank you, bye.
german Aufgeräumtheit and Solidität:
Transformer brochures . . .
I think that they were usually written by Marketing.
My top 2 rules about what Marketing says:
1. Believe Marketing
2. Trust, but Verify
I was tasked with checking every specification of 4 page brochures of Tektronix spectrum analyzers, priced from $20,000 to $85,000.
I also checked the specified performance requirements that was listed of Request for Bid documents of the US Government, We had to meet the specs, or be found in violation, ending the opportunity to sell to Uncle Sam.
Someday, I plan on purchasing a pair of Monolith Magnetics push pull output transformers.
Of the listed data of several SE and push pull transformers . . . I found One spec, of One transformer to be in error (Typo?).
Those were just the kind of things I found on my job, when I was checking Tektronix Brochures (I knew the specifications intimately, so I could find the error(s) in 5 minutes, before the ink dried).
I have heard a few different models of Monolith Magnetics output transformers.
They "Sounded" excellent.
Or, I could be convinced to purchase Hashimoto, Purvis, or other excellent PP output transformers.
Current production interests me, I do not want to purchase Obsolete-ium, Unobtain-ium, or nonsensically Overpriced-ium.
That way, if anybody wants to build an amplifier I designed, they can find current production parts to duplicate it.
$0.03
PS.
I was able to listen to my low power balanced amplifiers on a pair of very good, very efficient loudspeakers in a large restaurant / bar. The 2 combined audio clubs liked the "sound"
At home, I use them to drive ProAc 2000 Tablette Signature speakers, and a single JBL 12 inch subwoofer; I am enjoying them a lot!
Now . . . the truth, the triode Wired JJ 5881s are driving lowly Hammond 5k Ohm 15 Watt output transformers, selected for low power, good square wave shape, p-p impedance; and no global, no schade, and no output transformer-to-cathode negative feedback modes.
I think that they were usually written by Marketing.
My top 2 rules about what Marketing says:
1. Believe Marketing
2. Trust, but Verify
I was tasked with checking every specification of 4 page brochures of Tektronix spectrum analyzers, priced from $20,000 to $85,000.
I also checked the specified performance requirements that was listed of Request for Bid documents of the US Government, We had to meet the specs, or be found in violation, ending the opportunity to sell to Uncle Sam.
Someday, I plan on purchasing a pair of Monolith Magnetics push pull output transformers.
Of the listed data of several SE and push pull transformers . . . I found One spec, of One transformer to be in error (Typo?).
Those were just the kind of things I found on my job, when I was checking Tektronix Brochures (I knew the specifications intimately, so I could find the error(s) in 5 minutes, before the ink dried).
I have heard a few different models of Monolith Magnetics output transformers.
They "Sounded" excellent.
Or, I could be convinced to purchase Hashimoto, Purvis, or other excellent PP output transformers.
Current production interests me, I do not want to purchase Obsolete-ium, Unobtain-ium, or nonsensically Overpriced-ium.
That way, if anybody wants to build an amplifier I designed, they can find current production parts to duplicate it.
$0.03
PS.
I was able to listen to my low power balanced amplifiers on a pair of very good, very efficient loudspeakers in a large restaurant / bar. The 2 combined audio clubs liked the "sound"
At home, I use them to drive ProAc 2000 Tablette Signature speakers, and a single JBL 12 inch subwoofer; I am enjoying them a lot!
Now . . . the truth, the triode Wired JJ 5881s are driving lowly Hammond 5k Ohm 15 Watt output transformers, selected for low power, good square wave shape, p-p impedance; and no global, no schade, and no output transformer-to-cathode negative feedback modes.
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kgrlee,
$0.03 is not overpriced. It accounts for Inflation.
Yes, there are many excellent obsolete output transformers.
I added lots of information, when I edited my Post # 47, AFTER you read it.
You might enjoy re-reading it for my updated informational edits.
And in Honor of old output transformers, I have re-used Fisher 500C output transformers, originally made to work with 7591 outputs in Pentode mode, and a 12AX7 gain and phase splitter tube, and global negative feedback to the driver cathode. The 12AX7 was probably not fully up to the needed performance,
Do you think the Fisher engineer knew anything? Positive Synergy? Dumb luck? Those output transformers are great!
The 500C required the good output transformers in order to work well, given the topology and the driver tube.
My various amplifier designs used the output transformers completely differently than the original 500C circuit, and used different driver and different output tubes.
I also have re-used the Dyna Stereo 70 A470 output transformers in other circuits.
$0.03 is not overpriced. It accounts for Inflation.
Yes, there are many excellent obsolete output transformers.
I added lots of information, when I edited my Post # 47, AFTER you read it.
You might enjoy re-reading it for my updated informational edits.
And in Honor of old output transformers, I have re-used Fisher 500C output transformers, originally made to work with 7591 outputs in Pentode mode, and a 12AX7 gain and phase splitter tube, and global negative feedback to the driver cathode. The 12AX7 was probably not fully up to the needed performance,
Do you think the Fisher engineer knew anything? Positive Synergy? Dumb luck? Those output transformers are great!
The 500C required the good output transformers in order to work well, given the topology and the driver tube.
My various amplifier designs used the output transformers completely differently than the original 500C circuit, and used different driver and different output tubes.
I also have re-used the Dyna Stereo 70 A470 output transformers in other circuits.
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