K&K Audio / Lundahl Transformers

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K&K Audio / Lundahl Transformers

Interstage transformer GM70 amplifier

101.78.181.154

Hello!
This is an integrated amp for 845 but want to have GM70 instead, and intend to convert to standalone amplifier by replacing with higher step down ratio interstage transformer rather than 2:1 as the circuit recommended (so the GM70 will see much lower impedance from the driver section). Do you have anything for this application?

Also, we will change the output stage to parallel feed with LL9202AM OPT, any plate choke can you prefer?

Thanks!
2 stages 845 (Open in New Window)

Follow Ups:

RE: Interstage transformer GM70 amplifier - KevinC 13:05:52 03/15/16 (4)
Lundahl doesn't have any plate chokes that are large enough for your purpose. You should check with Mike LeFevre at MagneQuest and see what he has to say. He was much more involved in designing for parafeed operation than Lundahl has ever been.

Kevin Carter
K&K Audio
www.kandkaudio.com
- RE: Interstage transformer GM70 amplifier - Tubenstein 16:12:21 03/17/16 (3)
  BTW, do you have SE output transformer for parallel feed application with 5K primary? The output tubes would be KR-300BXLS.
  
  Thanks!
  - RE: Interstage transformer GM70 amplifier - Tubenstein 08:32:07 03/18/16 (2)
    Let put in this way, whether Lundahl has made a version of LL9202AMPPZ with 5K primary?
    
    thx!
    - RE: Interstage transformer GM70 amplifier - KevinC 10:32:54 03/18/16 (1)
      If you look at the data sheet for the LL9202, you will see that the closest you can come to 5K with the LL9202AM/PPZ is 6.5K.
      
      http://www.lundahl.se/wp-content/uploads/datasheets/1620_3_7_9202.pdf
      http://www.lundahl.se/wp-content/uploads/datasheets/1620_3_7_9202_AM.pdf
      
      Kevin Carter
      K&K Audio
      www.kandkaudio.com
      - RE: Interstage transformer GM70 amplifier - Tubenstein 02:53:38 03/19/16 (0)
        
        In Reply to: RE: Interstage transformer GM70 amplifier posted by KevinC on March 18, 2016 at 10:32:54
        
        Any AMPPZ (amorphous parallel feed) transformer from Lundahl made for 30-50W Power Range and primary impedance is a must?

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