Tube DIY Asylum

Some pics of recent build: KT88 PP

172.11.32.65

Chip647

PP KT88 Triode

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LL1660S/AM/PP
Lundahl Amorphous Core Transformer Phase Splitter
Blog with Pictures (Open in New Window)

Follow Ups:

RE: Some pics of recent build: KT88 PP - cellailuca 10:18:24 06/27/25 (0)
Very, very, very nice!

Omnes feriunt, ultima necat.
RE: Some pics of recent build: KT88 PP - GEO 06:09:22 06/27/25 (0)
Very nice job!
RE: Some pics of recent build: KT88 PP - Triode_Kingdom 07:34:03 06/26/25 (2)
Nice job! That chassis must be pretty heavy with the dual mono supply. I built my last amp as monoblocks to make it easier to move around. Would be interested to see the schematic of your design.
- Schematic - Chip647 10:33:12 06/26/25 (1)
  This kinda evolved over time. It was originally designed for a 6V6GT driving the phase splitter, but the 6SN7 seemed more elegant in this role as it really does not have to drive any A2 grid current and the Lundahls are speced at 20mA.
  
  It has a lot of gain (probably too much), so the cathode bypass caps are not needed. Running it with the KT88s at 27 watts dissipation each (60 mA at 450v)
  
  The hum at the speaker terminals with inputs shorted is 0.2mv.
  
  When I get the better OPTs I am going to add a second set of inputs to bypass the input stage as an option for use with higher gain preamps.
  - Thanks! (nt) - Triode_Kingdom 13:12:17 06/26/25 (0)
    nada aqui
RE: Some pics of recent build: KT88 PP - Joe Appierto 05:25:28 06/26/25 (3)
If looks are any indicator, it must sound very nice. Good job!

Joe
- RE: Some pics of recent build: KT88 PP - Chip647 06:32:43 06/26/25 (2)
  Thanks. It is very quiet and the Lundahl interstage transformers were a big upgrade to the sound. I will replace the output transformers with the AM core Lundahl's when I feel like spending a bit. It does sound pretty good, does bass very well.
  - RE: Some pics of recent build: KT88 PP - Joe Appierto 06:56:10 06/26/25 (1)
    You're welcome. KT88 output tubes are very musical sounding in my opinion. Are those 6SL7 and/or 6SN7 input and phase spiltters on the front end?
    
    Joe
    - RE: Some pics of recent build: KT88 PP - Chip647 10:22:53 06/26/25 (0)
      Both 6SN7. The schematic is posted above now.

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