Tube DIY Asylum: RE: 5687 preamp by Stuben

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RE: 5687 preamp

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Stuben

In Reply to: RE: 5687 preamp posted by Tre' on December 23, 2016 at 19:00:45:

I started with the simple design. I had a terrible time with noise. Ended up on the second iteration with a 5687 CCS loaded into a Parafeed arrangement with LL1674 opt and a nice Parafeed cap. The LL1674 is basically wired backwards for the least amount of voltage gain and a lower output impedance of around 200 ohm. The CCS plate loads have a great PS noise rejection with great plate loading. Apart from dealing with a 4 core output transformer, it's very simple.Started the project with plate chokes, could not get the noise floor down to a palatable level.

Stuben

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Topic - 5687 preamp - sergio p 07:51:53 12/23/16 ( 13)

RE: 5687 preamp - GEO 13:32:44 12/28/16 ( 0)
RE: 5687 preampI - Jim D. 18:17:47 12/23/16 ( 0)
RE: 5687 preamp - Paul Joppa 17:24:35 12/23/16 ( 0)
RE: 5687 preamp - Triode_Kingdom 14:10:34 12/23/16 ( 0)
RE: 5687 preamp - dee eye why 10:27:45 12/23/16 ( 0)
RE: 5687 preamp - Tre' 09:48:24 12/23/16 ( 7)
- RE: 5687 preamp - Lew 12:09:08 12/23/16 ( 6)
  - RE: 5687 preamp - Tre' 19:00:45 12/23/16 ( 5)
    - RE: 5687 preamp - Lew 15:11:03 12/24/16 ( 2)
      - RE: 5687 preamp - Tre' 19:04:24 12/24/16 ( 1)
        
        RE: 5687 preamp - Lew 13:00:49 12/25/16 ( 0)
    - RE: 5687 preamp - Stuben 12/24/16 11:21:38 12/24/16 ( 1)
      - RE: 5687 preamp - Tre' 19:26:04 12/24/16 ( 0)