This was the contest at the European Triode Festival 5 years ago. Results are at the bottom of the page.
Enjoy.
Greg
Enjoy.
Greg
Yes - this was the ETF shootout. It doesn't really help since Tamura and Tango will be very hard to get hold of, and expensive. AE will have a long delay. So the only easily available OPT with a known very good square wave response is the Silk 3K.
Can anyone comment on it - any users?
There have been some pretty bad reports of quality control at Bartolucci - don't know if his is still the case.
I thought there was a good transformer winder in Serbia? Can't remember the details - can you remind me?
Serbian company is Trafomatic - not much info on their webpage:
http://www.trafomatic.com/eng_audio_tubeaudio.htm
http://www.trafomatic.com/eng_audio_tubeaudio.htm
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My experience with some se opts:
-Automatic electric europe made me many single ended transformers with double c core 0.05mm thick laminations and with amorphous core. I am very satisfied with their opt's sound quality.
-Hammond 1627. I don't like it. Bass is not enough, not balanced sounding. It was so heavy and has big iron but, sounding cheap.
-Transcendar audio. I borrowed 3,5k SE opt from my friend and compared it with AE Europe 3,5k SE opt. Transcendar sounds cheap and 2D when comparing with AE. So, i didn't like it's sound at all.
-Automatic electric europe made me many single ended transformers with double c core 0.05mm thick laminations and with amorphous core. I am very satisfied with their opt's sound quality.
-Hammond 1627. I don't like it. Bass is not enough, not balanced sounding. It was so heavy and has big iron but, sounding cheap.
-Transcendar audio. I borrowed 3,5k SE opt from my friend and compared it with AE Europe 3,5k SE opt. Transcendar sounds cheap and 2D when comparing with AE. So, i didn't like it's sound at all.
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Unfortunately the test at the ETF was not done correctly.
The measurement set-up is not good. The choke have to much influence on the measurements. They should have used a high quality ccs instead or even better: a tube.
So that's why all the measurements looks so bad for the upper frequencies in this test. Secondly the soundcard can not test frequencies till at least 500khz - 1Mhz. So ringing we can not see.
The sq test is much better. Now we see that almost every transformer has some ringing. The best is transformer no 10 (Tamura) but this transformer have a weak bass.
Here a link where you can see some nice measurements: Let's See Your Transformers!
The measurement set-up is not good. The choke have to much influence on the measurements. They should have used a high quality ccs instead or even better: a tube.
So that's why all the measurements looks so bad for the upper frequencies in this test. Secondly the soundcard can not test frequencies till at least 500khz - 1Mhz. So ringing we can not see.
The sq test is much better. Now we see that almost every transformer has some ringing. The best is transformer no 10 (Tamura) but this transformer have a weak bass.
Here a link where you can see some nice measurements: Let's See Your Transformers!
A link to some measurements from AE transformers.
Mededelingenbord
Unfortunately no copperloss measurments and no square waves but i expect (some) ringing if i look at the frequency response.
btw the 0,05mm cores they use are coming from a small batch which AE and Tribute bought some years ago from Zee electronics. It's not a large core so expect not the best low frequency response and/ or high copper losses (core geometry isn't the best either). It's a lovely core for chokes.
Mededelingenbord
Unfortunately no copperloss measurments and no square waves but i expect (some) ringing if i look at the frequency response.
btw the 0,05mm cores they use are coming from a small batch which AE and Tribute bought some years ago from Zee electronics. It's not a large core so expect not the best low frequency response and/ or high copper losses (core geometry isn't the best either). It's a lovely core for chokes.
Hi,
For example I paid 355 Euros to this:
Double c core open version, 3.5k to 8 Ohms, for 2a3 Tube.
I have designed a few very high quality output transformers that have proven superior to the best Tango and Tamura.
These can be wound on request for the ones that are really looking for some top quality OPT.
Very complex winding structure wound at very low speed and very high wire tension. Something that is out of reach in industrial production.
These can be wound on request for the ones that are really looking for some top quality OPT.
Very complex winding structure wound at very low speed and very high wire tension. Something that is out of reach in industrial production.
As I already said in other threads is very hard to evaluate audio transformers by looking at specs and measures.
Most of the people is fooled by the wider bandwidth.
But you can find VERY high quality OPTs with F-3 barely exceeding 20 Hz-20 KHz (like best Audio Tekne or Audio Note Japan OPTs)
or poorly performing output transformers with an upper limit well beyond 100 KHz.
Square wave can tell many things to an experienced eye.
But can be fooled by smoothing with compensation networks.
Good for the eyes not for the ears.
Of course horrible measurements can tell an OPT sucks but how will you tell the difference between high quality OPTs and excellent quality OPTs?
Experience and open minded listening are still fundamentals to make great audio transformers
That said, here are a few data for a 3K5 OPT of my design:
Bandwidth (-3 dB) is 7 Hz-70 KHz measured at 5 W. Good but not so impressing.
At 12 W / 20 Hz flux density is 0.7T (midpoint of the magnetization curve of the core)
working DC current 90 mA.
Total stray capacitance (after break in) is 150 pF or less. OK that is rather impressing, but still the important thing is how the stray capacitance is distributed in the winding, not is total value.
Weight 3.5 Kg
Here is a 10KHz square wave. New OPT: it will get smoother after break in. Absolutely no compensation network.
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Can you please elaborate? I suspect it has to do with interleaving. The more 'aggressive' the interleaving the better the distribution of capacitance throughout the winding, is that it?
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