Tube DIY Asylum

• Bingo, you nailed it! - Jim Hagerman 16:16:51 03/23/07 (0)
  In Reply to: I believe I've discovered my problem with SEt...it has to do with how much voltage is measured AT THE PLATE ... posted by Iczerman on March 21, 2007 at 15:21:54:

  These tubes are almost always driven with too much voltage on them. Hey, it's recommended in the data sheet, right?

  Well Iczerman, you used your ears and came up with a better result. I congratulate you for that.

  jh
  
  

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• What is the measured plate current on each? - richardl 15:38:31 03/22/07 (0)
  In Reply to: I believe I've discovered my problem with SEt...it has to do with how much voltage is measured AT THE PLATE ... posted by Iczerman on March 21, 2007 at 15:21:54:

  It sounds to me like you are running the tube at higher current at 250v and that you are getting less current at 275v. Your power transformer may be running out of juice. What is the design spec of the power tranny?

  To compare apples to apples you must look at the same current with the two voltages. Take a look at this chart and see where you are with both and check to see your current situation.

  http://www.mclink.it/com/audiomatica/tubes/2a3.htm
  
  

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• Re: I believe I've discovered my problem with SEt...it has to do with how much voltage is measured AT THE PLATE ... - zarniwoop 09:15:26 03/22/07 (0)
  In Reply to: I believe I've discovered my problem with SEt...it has to do with how much voltage is measured AT THE PLATE ... posted by Iczerman on March 21, 2007 at 15:21:54:

  how much Pout do you get with 200V on a 2a3? 2W? I know there are people that like the 1W 45 amps and the like, but I personally wouldn't go below 5W unless speaker effeciency was 103dB or higher.
  
  

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• I am using my Sun 300BE SET at operating points of close to your description and I... - hagustos 00:34:40 03/22/07 (2)
  In Reply to: I believe I've discovered my problem with SEt...it has to do with how much voltage is measured AT THE PLATE ... posted by Iczerman on March 21, 2007 at 15:21:54:

  don't think in the near future I will ever need any other amp other than for DIY fun.
  About 300V B+,250V Plate V,55ma current,880R cathode resistors,3,5K Output Tranny and 5Watts of power.
  As a bonus,even though I have a pair of Vaic C37 300B spares, I am in no hurry to change my early production JJ300B tubes that I have been using for 6 years.
  And don't think this operating point is a compromise, because if you see Western Electric performance graphs of 300B,this OP is close to one of very low distortion ones.The only drawback is less wattage.
  Regards,
  Hakan
  
  

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  • Re: I am using my Sun 300BE SET at operating points of close to your description and I... - RC Daniel 01:11:52 03/22/07 (1)
    In Reply to: I am using my Sun 300BE SET at operating points of close to your description and I... posted by hagustos on March 22, 2007 at 00:34:40:

    Perhaps I am looking at different data or have guestimated the figures incorrectly, but that power output seems a little high - I would have thought less than 4W, but I could be (very) wrong.

    Not surprised you are happy with the way it presents music tho. Many believe that the low power DHTs sound better when run at half to two-thirds max dissipation and higher than 'optimum' loading. For my 300B project, I will probably opt for 300V or 350V and 50 - 60mA with a 5k load for about 4.5W (or less) or 6W respectively...

    Regards
    Raymond

    PS. Your system looks very nice - enjoy!

    
    PS. Your system looks very nice - enjoy!
    
    

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    • Re: I am using my Sun 300BE SET at operating points of close to your description and I... - hagustos 02:45:54 03/22/07 (0)
      In Reply to: Re: I am using my Sun 300BE SET at operating points of close to your description and I... posted by RC Daniel on March 22, 2007 at 01:11:52:

      Hi,
      I am not at my home computer but as far as I remember, 4,6Watts from calculations on the loadlines.I don't know the actual measured value.
      Thank you for kind words for the system.
      Regards,
      Hakan
      
      

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• Hear's the Dealio: Tube plate voltage is generally... - Thomas Martens 17:02:11 03/21/07 (3)
  In Reply to: I believe I've discovered my problem with SEt...it has to do with how much voltage is measured AT THE PLATE ... posted by Iczerman on March 21, 2007 at 15:21:54:

  specified BETWEEN THE PLATE AND CATHODE --NOT between the plate
  and ground. With a cathode biased tube, the voltage from the plate
  to GROUND is the sum of the operating "plate voltage" of the tube
  and whatever bias voltage is being developed by the bias resistor.
  To say it another way: If you measure the voltage between plate
  and ground, and then measure the voltage between cathode and ground,
  then you can subtract the cathode voltage figure form the plate
  voltage figure, and this gives you the ACTUAL PLATE VOLTAGE which
  the tube is operating at. It is quite common for people to become
  confused about this. I'm not suprised your amp is sounding better
  as you upped the B+.

  Good Luck,

  -T.M.
  
  

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  • Hopefully the post clarified things anyhow, furthermore... - Thomas Martens 09:32:34 03/22/07 (0)
    In Reply to: Hear's the Dealio: Tube plate voltage is generally... posted by Thomas Martens on March 21, 2007 at 17:02:11:

    He must have an impedance mismatch issue if increasing his B+
    had an adverse effect on the sonics.

    Thanks for pointing out a trifling oversight on my part with
    such zeal --I guess.

    -T.M.
    
    

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  • Um, actually he said the sound got worse as he increased the voltage. nt - JimL 20:00:50 03/21/07 (0)
    In Reply to: Hear's the Dealio: Tube plate voltage is generally... posted by Thomas Martens on March 21, 2007 at 17:02:11:

    .
    
    

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  • You did not read his post (nt) - Chris O 17:13:26 03/21/07 (0)
    In Reply to: Hear's the Dealio: Tube plate voltage is generally... posted by Thomas Martens on March 21, 2007 at 17:02:11:

    
    _______________________________
    Long Live Dr.Gizmo

    
    
    

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• Re: I believe I've discovered my problem with SEt...it has to do with how much voltage is measured AT THE PLATE ... - Tre' 15:47:13 03/21/07 (3)
  In Reply to: I believe I've discovered my problem with SEt...it has to do with how much voltage is measured AT THE PLATE ... posted by Iczerman on March 21, 2007 at 15:21:54:

  Talk to me about the PP electraprint transformers.

  Tre'
  Have Fun and Enjoy the Music
  "Still Working the Problem"
  
  

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  • Electraprint PP 2a3 output transformers.. - Iczerman 07:52:09 03/23/07 (2)
    In Reply to: Re: I believe I've discovered my problem with SEt...it has to do with how much voltage is measured AT THE PLATE ... posted by Tre' on March 21, 2007 at 15:47:13:

    3K primarys

    70ma per plate

    6 ohm secondary

    silver wire used for secondary windings.

    If I do a single-ended project and it SMOKES the PP2a3...I'll let you know!
    
    

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    • Electraprint PP 2a3 output transformers..How much did Jack charge you...? - -3db 14:45:15 03/24/07 (1)
      In Reply to: Electraprint PP 2a3 output transformers.. posted by Iczerman on March 23, 2007 at 07:52:09:

      I may get a pair, or, I may have them wound for 45's.
      Thanks,
      -3db
      
      

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      • Very reasonable.. - Iczerman 20:49:56 03/24/07 (0)
        In Reply to: Electraprint PP 2a3 output transformers..How much did Jack charge you...? posted by -3db on March 24, 2007 at 14:45:15:

        $650.00 for the pair!
        
        

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