• Item: SRPP 12AU7 preamp  
  • Type: retro-thermionic “Noir”  
  • Posted: 6 February 2021  
  • Builder: mwhouston  
  • Country: Australia  
  • Comments: 0  


A new preamp all completed in record time. Should be Ive probably made eight like this. Gooda lub the obby

Apart from having to replace a faulty RCA (Jaycar’s new RCAs - from last year - don’t solder. I think the center pin is steel and solder just balls up and won’t get a grip). I have put in a complaint but I didn’t think anyone looks at them. My last complaint never got answered.

Back to the preamp. Sounds detailed, laid back and smooth with the Psvane 12AU7 TIIs. Worked at first on.

Voltages are;
HT = 247V
bias = 2.44V
current = 5mA.

Im using a Radi0kit external PS kit. Regulated 12V and electronically smoothed HT. Turn it up and it’s dead quiet no hum, buzz, crackle, snap or pop. Looks and sound extremely good. Called it “Noir”.

Alps pot on the output, Russian PIO output caps and SRPP topology. Metal film resistors. Wood cheeks have been finished with a finishing oil. They really have lifted. Epoxy enamel paint on top of etching primer. Enjoying it now with my 2W 6L6 SE UL wine box amp.


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