Hello,
During the last European Triode Festival, aside the "transformers shootout" , I could perform measurements on 30 output transformers for Single End 300B ampliifers.
The document with the measurements is downloadable at the bottom of the page:
European Triode Festival - ETF2009 Shootout
look for: "see the measurements here".
direct URL:
http://forums.melaudia.net/attachment.php?aid=1228
Best regards from Paris, France
Jean-Michel Le Cléac'h
During the last European Triode Festival, aside the "transformers shootout" , I could perform measurements on 30 output transformers for Single End 300B ampliifers.
The document with the measurements is downloadable at the bottom of the page:
European Triode Festival - ETF2009 Shootout
look for: "see the measurements here".
direct URL:
http://forums.melaudia.net/attachment.php?aid=1228
Best regards from Paris, France
Jean-Michel Le Cléac'h
Anyone want to buy a pair of the original Hammond 1628SE's? You know the ones with the built in 16 KHz notch filter. Good 12 pound paperweights, or maybe parafeed chokes......I didn't think so.
surely someone down in Miami needs a boat anchor. (or um.. kayak anchor)
About the lundahls, I was reading a chinese forum where they tested tx's and also wrote about their subjective thoughts on them..
the lundahls did test as the best and were good subjectively, but they all seemed to prefer the ones that didn't test quite as well...
I guess then we're getting into the whole liking some sorts of distortion aspect, which we don't need to talk about! 🙂
About the lundahls, I was reading a chinese forum where they tested tx's and also wrote about their subjective thoughts on them..
the lundahls did test as the best and were good subjectively, but they all seemed to prefer the ones that didn't test quite as well...
I guess then we're getting into the whole liking some sorts of distortion aspect, which we don't need to talk about! 🙂
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Just a minor correction - Lundahl uses a single C-core (core-type construction) while most of the other companies that use C-cores employ shell-type construction.
John
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Well, there is some risk 🙂
Such a grumpy post from me -- in my defense, due to improper grounding on my part I had just blown some mosfets in someone elses amp that not only needed to be replaced, but that needed to be Vgs matched w/in ~1mV.
Tough to beat those old Tangos, though. 🙂 A friend of mine has a nickel NY series Tango that exceeds anything I've heard yet.
For me, low odd-order distortion is most important.
John
Well, I was the one who actually bought a bunch. Fortunately it was about 5 years ago when I could actually afford it. The winners were easy to sell, just mount them to an amp (Tubelab SE's in that case) and loan the amp to friends. The good ones wound up sold. The big heavy one that sounded like someone put a blanket over the speakers kept coming back. I haven't yet found a way to make those transformers sound good.
All of those experiments taught several things, but the one that doesn't seem to show up here, is my observation that the OPT should be matched to the speakers and the anticipated use. If you have very high efficiency speakers and your average listening level is far below a watt, big OPT's will just rob you of detail. If you have low efficiency speakers (like my 87db Yamahas) where the average listening level is in the 5 watt+ range, the little OPT's (Hammond 125CSE and Edcor XSE15-8-5K) will saturate on bass heavy music.
I took some amps to a friends house who has 106db Lowther based horns. The big Hammond 1628SEA's (the good ones) sounded lifeless since too much energy is used up in the 10 pound iron core. The big Edcors did better, but not great. The little Edcors gounded great, but the "10 Watt" Electra Prints were the best. No I won't sell those! All were fed by a 45 tube at less than half volume.
On my 87db Yamahas the big Edcor CXSE25-8-5K's are the best followed by the Electra Prints, the old Transcendars, and the One Electrons in that order. The last 3 are nearly identical and many people can not distinguish them.
The big Hammonds have the best bass by far and they flat shake the house when fed by a cranked up KT88 based Simple SE running into 15 inch Silver Iris OB speakers (96db). You can hear the bass inside the house across the street. Overall sound quality is very good. The big Edcors have a little more detail and give up a small amount of bass under the same conditions. The big speakers will bring out the saturation in any of the small OPT's since their impedance stays low down to about 45 Hz. You need big OPT's if you want to drive 15 inch speakers at low frequencies.
Save yourself the agony of the opt and go for an otl amp
Forgive me, I could not resist with my corny humour, its Friday
Forgive me, I could not resist with my corny humour, its Friday
I couldn't resist, it was too easy. I have been chained to my computer at work for a week of 12 hour days. Put the chip into the test socket, push the button, read some meters, listen to 5 sequential noisy 1 KHz tones and evaluate them for sinad (niose and distortion), look at two spectrum analyzer plots and decide whether to send the chip to a prototype product, or the scrap bin. Repeat. 1800 times. Yes, I have silicon on the brain this week. I finally finished the last chip about 7PM tonight. Back to real engineering next week.
George - do you get the customer chant that "my holidays are sacred, but you have none"? It seems that the s*** always breaks loose here just before a major U.S. holiday (most of our customers are in the Far East).... On another note - a spoon full of silicon helps the medicine go down (tee, hee)...
There is few european transformer companies more...
Bartolucci from Italy:
Ricerca e Sviluppo - Bartolucci Transformers - Welcome to Ricerca e Sviluppo - Bartolucci Transformers
trasformatori bartolucci
Welter from Germany:
Welter Audio Electronic Seit 1975
This Finnish company; RPM Developments delivers Welter transformers:
RPM Developments Oy - Webstore
Danbury Electronics from England:
Danbury Electronics
Valves And Transformers (Contents)
Bartolucci from Italy:
Ricerca e Sviluppo - Bartolucci Transformers - Welcome to Ricerca e Sviluppo - Bartolucci Transformers
trasformatori bartolucci
Welter from Germany:
Welter Audio Electronic Seit 1975
This Finnish company; RPM Developments delivers Welter transformers:
RPM Developments Oy - Webstore
Danbury Electronics from England:
Danbury Electronics
Valves And Transformers (Contents)
I work in an advanced development group that designs circuits and chips for furure products. Our customers are the product development teams, and two of them are in countries that do not have the same holidays as us. Our schedule is built with time off at Christmas, but theirs isn't. As with all leading edge technology, issues crop up that must be addressed, so guess where the extra time comes from. Our new chip is something that has never been done before, so the wafer fab does no testing at all. I designed a simple screening system (yeah, $300K in test quipment) to check for functionality, so I have been rewarded with the additional duties of being "chief chip tester". This wasn't bad when we got lots of 50 chips, but 1800......that sucks!
Yeah, but it is a bit crunchy and still tastes bad!
Anyone tried the Plitron toroid SE OPT yet? Yes, I have one 3.5K used in my 300B monos. It has very flat and wide frequency range upto 80kHz.
Also, I used the Lundahl SE OPT as well for 45, and 2A3 SE amplifier. They sound very nice indeed. Good price and great performance.
Cheers - Merry Christmas and a Happy New Year.
I have sold a pair of Hammond 1627SE to my friend. Once I used the Lundahl, the Hammond is out of the game. However, I would say 1627SE is a good performer. It is just not as good as the higher end ones.
Johnny
Also, I used the Lundahl SE OPT as well for 45, and 2A3 SE amplifier. They sound very nice indeed. Good price and great performance.
Cheers - Merry Christmas and a Happy New Year.
I have sold a pair of Hammond 1627SE to my friend. Once I used the Lundahl, the Hammond is out of the game. However, I would say 1627SE is a good performer. It is just not as good as the higher end ones.
Johnny
I haven't tried their SE OPT's but I have a pair of absolutely huge 400 watt P-P toroids. They too have a flat response out to 70 KHz and down below my measurement threshold of 5 Hz. They are rated for 400 watts at 20 Hz. Sound good too, but a little intolerant of DC imbalance.
If you are serious make me a reasonable offer for the pair. They have been connected into several amplifiers but never mounted or had the wires cut. I had thought about wiring them up to an 833A and using cathode feedback to attempt to smooth out the notch, but never got around to it. I don't have much time any more, so these and a lot of other projects that never got finished need to go. The rent on the warehouse goes up again in January.
Hi Pete!
Indeed - unless you wish to dish out the premium for Tamura Permalloy core transformers for single-ended use with DC bias, Lundahl comes in very close - the silicon iron core models, that is - amorphous core transformers with large air gaps keep the disadvantage of amorphous core materials (early saturation) without reaping the benefits - after all, the air gap largely dominates the game... remember Per's remarks on the 27-NOV.
As for PP, the Lundahls aren't half bad either - here amorphous cores can play out their benefits (after all, there are zero transitions in the magnetisation)... so, for low distortion before NFB they are worth considering...
Best regards,
mb-de
===
PS: Gerd Reinhoefer is doing good quality stuff too - his 53.85 is a killer for 2A3 etc. in push-pull...
Indeed - unless you wish to dish out the premium for Tamura Permalloy core transformers for single-ended use with DC bias, Lundahl comes in very close - the silicon iron core models, that is - amorphous core transformers with large air gaps keep the disadvantage of amorphous core materials (early saturation) without reaping the benefits - after all, the air gap largely dominates the game... remember Per's remarks on the 27-NOV.
As for PP, the Lundahls aren't half bad either - here amorphous cores can play out their benefits (after all, there are zero transitions in the magnetisation)... so, for low distortion before NFB they are worth considering...
Best regards,
mb-de
===
PS: Gerd Reinhoefer is doing good quality stuff too - his 53.85 is a killer for 2A3 etc. in push-pull...
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