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More of a question than answer

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In Reply to: Quality of Scott 222c output transfomers compared to Dynaco Z-565? posted by youropinioncounts on October 4, 2006 at 17:39:05:

I once saw a web page describing measured characteristics of output transformers from virtually every significant piece of vintage gear. All measurements were performed under similar conditions. Measurements included frequency range, distortion-free power at 30 Hz, and shape of 10 kHz square wave. With regard to the last characteristic, all transformers were divided into five groups. Group A was flat plateau; B, single overshot w/o ringing; C single undershot w/o ringing; D, uner-or overshot with fast decay ringing, and E, bad complex ringing. Transformers from Group A were few, all from very respected gear. Names included Peerless, Marantz, Macintosh, and few others. Tango transformers also do not ring in the 10 K square wave test (from a different study). One Scott model that he measured (as I remember, 299C) was there too. Because all Scott iron came from the same manufacturer, I guess all these transformers have very similar characteristics. I have 222C and 233 (233 uses the same iron as 299C) and their transformers have the same size (though different numbers). Scott transformer also measured -3 dB at 43 kHz and 3 W at 30 Hz.
Bottom line: Scott transformers are as good as they get, among the best of the best. Based on what I know about Dyna, I am not sure it is anywhere close. It is more likely the level of modern Hammond transformers that are all in the Group E.
I could not find that web page. If anybody knows, please post.

Follow Ups:

Actually, the Dyna stuff also did well in those tests.... - JimL 08:41:20 10/12/06 (0)
mostly group A and B, although somewhat less high frequency extension than the Scott transformers tested. I would say they are roughly comparable.
Re: More of a question than answer - Kyle K 19:02:54 10/04/06 (5)
You talking about John Atwood's transformer tests?
http://www.one-electron.com/Trans_Tests.html
- http://www.one-electron.com/Trans_Tests.html (Open in New Window)
- One Test to Add - Triode_Kingdom 22:44:01 10/04/06 (3)
  Here's the result that I got a couple years ago with my 211 prototype using a Magnequest FS-100. Some of you may have seen this before. The test was performed at 1kHz, rather than 10kHz, so it's difficult to compare with John's tests directly. Still, it looks pretty darn good. Mike really knows his stuff!
  - well... - Sector-7G 17:22:23 10/07/06 (2)
    Hey-Hey!!!,
    Seems to me that if you cut the period to 1/10-th that you're going to have that ringing through most of wave-form. Now if it looked that good with a 10k signal, you'd have something...:)
    Now with the Atwood testing, the Z565 got an 'A' even though the slope of the leading edge of the square wave was not as steep as a 'B' output. It is just a test...if you want to try to get more out of it, examine the raw data yourelf.
    cheers,
    Douglas
    
    Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
    - Wheat and chaff - Triode_Kingdom 21:17:43 10/07/06 (1)
      > if you cut the period to 1/10-th that you're going to have
      > that ringing through most of wave-form.
      The frequency and amplitude of the undesired energy render it inaudible. This is excellent performance for a transformer of this type.
      > Now with the Atwood testing, the Z565 got an 'A' even though
      > the slope of the leading edge of the square wave was not as
      > steep as a 'B' output.
      Perhaps Atwood was acknowledging that a 10kHz square wave isn't entirely relevant.
      TK
      - maybe... - Sector-7G 07:15:05 10/08/06 (0)
        
        In Reply to: Wheat and chaff posted by Triode_Kingdom on October 7, 2006 at 21:17:43:
        
        > > > The frequency and amplitude of the undesired energy render it inaudible.
        That is a matter of opinion. Atwood certainly thought testing at 10k with square waves was useful. It is certainly easy enough to claim that testing at 1k is just as good as testing at 10k.
        That same argument can be extended to the LF performance...can't hear it, speakers won't reproduce it...so why bother?
        Better parts make better amps. I don't quite believe the arguement that just because I shouldn't be able to hear it, that I won't hear it.
        cheers,
        Douglas
        
        Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
- Yup, that's it, thanks! nt - sser2 19:16:17 10/04/06 (0)
  nt

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