OTL Asylum

RE: How about an actual experiment?

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This Post Has Been Edited by the Author

In Reply to: RE: How about an actual experiment? posted by cnpope on August 26, 2011 at 12:04:23

"I am assuming one would insert a very low value resistor in series with the cathode of one of the tubes, and put the scope across that. This would give a direct view of the current flowing through that tube."
I'm not sure it would. I think AC current flows in a circle that includes all the tubes. I could be wrong about that.
"I agree that the outcome seems inevitable, since there simply isn't room for anything else to occur. I just feel that one clear trace showing the waveform of the current flowing in a single tube would put a stop to the endless debating about whether it is or isn't class A."
I couldn't agree more.
"What seems a shame in all this is that it detracts from the much more important point that it is a beautiful amplifier that apparently sounds superb. "
Yes it is a shame and the amplifier does sound great. It's just not Class A in the true sense.
Transcendent Sound, makers of OTL amplifiers, makes it clear that their amplifiers (and most other OTLs) are Class A/B.
The paper from Transcendent, while using some language that I don't totally agree with, makes the same points.
A Class A amplifier needs to idle at 1/2 the total needed peak current.
It takes 3.86 amps peaks to make 60 watts into 8 ohms so there needs to be 1.93amp idle current per bank or 241ma. per triode.
That just can't be done with a 6as7g.
Thanks for your input.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
http://www.transcendentsound.com/Transcendent/OTL_A_or_AB.ht (Open in New Window)

Edits: 08/27/11

Follow Ups:

RE: How about an actual experiment? - Jack Williams 15:40:04 08/26/11 (23)
- RE: How about an actual experiment? - Tre' 17:46:24 08/26/11 (22)
  - "Ask Kurt Strain about this issue." - kurt s 23:43:12 08/29/11 (7)
    - Thanks, Kurt... - Lew 13:29:50 08/30/11 (6)
      - Paul Speltz did the wrong thing - kurt s 18:10:04 08/30/11 (5)
        
        RE: Paul Speltz did the wrong thing - Lew 07:08:04 08/31/11 (4)
        
        Here is Paul Speltz' post on circlotron output Z... - Lew 07:40:22 08/31/11 (3)
        
        I see that really Paul almost did the wrong thing. - kurt s 20:02:04 08/31/11 (2)
        
        Output Z of cathode follower... - Lew 20:51:46 09/01/11 (1)
        
        RE: Output Z of cathode follower... - kurt s 00:42:47 09/02/11 (0)
  - In truth, Tre',... - Lew 23:42:21 08/27/11 (1)
    - RE: In truth, Tre',... - Tre' 08:01:36 08/28/11 (0)
  - King Ralph - GFL 06:39:53 08/27/11 (11)
    - Is this you again Tre', using a different moniker? - Duke 19:46:19 08/28/11 (10)
      - No, it is not me. - Tre' 21:33:06 08/28/11 (9)
        
        Uncanny resemblance in writing styles - Duke 22:05:37 08/28/11 (8)
        
        Hi Duke - Lew 13:17:54 08/30/11 (0)
        
        RE: this FAQ has been on the website for over a year. - Ralph 12:32:56 08/30/11 (2)
        
        RE: this FAQ has been on the website for over a year. - Duke 15:06:07 08/30/11 (1)
        
        RE: this FAQ has been on the website for over a year. - Ralph 15:31:42 08/30/11 (0)
        
        RE: Uncanny resemblance in writing styles - Tre' 22:12:02 08/28/11 (3)
        
        GoodFu++ingLuck - GFL 05:26:17 08/29/11 (2)
        
        RE: GoodFu++ingLuck = GFL? - Lew 17:34:32 08/29/11 (1)
        
        Bullying - GFL 06:39:56 09/05/11 (0)