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Single Ended Triodes (SETs), the ultimate tube lovers dream.

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RE: Measurement of 30 output transformers for SE300B

Posted by Jmmlc on January 4, 2010 at 09:45:26:
Hello Dave,

Paul reply is correct for the most, IMHO.

The gap of the OPTs having a dominant 2nd order distortion component operates near the knee (in the low linearity part near the saturation) of the BH curve, this surely induces some dynamic compression + H2 dominant distortion that may be euphonic, but...

I may add that it is probably a good thing that 3rd order generally dominates considering that the 2nd order distortion component will be mainly brought by the 300B itself. Higher order harmonics may be due also to intermodulation products and to the input/driver tube(s).

The difficult "art" is then to find the proper mix of all parameters to accord to your loudspeakers (it depends a lot on their efficiency for sure... this means that IMHO there is no universal solution to the question of the better choice of an SE OPT)

Here in France the SE OPT subject lead to very hot discussions between the tenants of the use of the best measuring transformer and the tenants of the "listen and choose" solution.

It is very funny that during ETF2009 shoot-outs I voted very often for the "looser" and that when the results were known I could see that those "loosers" were -for most of them- the best measuring transformers. I could see few "known" audiophiles (known at least from me) that voted the same...

But the majority voted for OPTs having a frequency response having very few bass frequency extension and an extended frequency response in the high frequency range with a rising slope. (those OPTs sounded bright to my ears). All in all this was an interesting experience but more related to anthropology than to audio ;-)

Best regards and an Happy New Year 2010 from Paris.

Jean-Michel Le Cléac'h