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RE: Danny.........

I do not see your link for Fisher mods, but I will share exactly what I performed.

First I built a new RIAA with discrete components plus the fix for better low end. Frankly, I heard no difference from the stock RIAA.

I replaced all coupling capacitors with K40Y-9 including the phono section. I lowered the 7868 or 7591 with 220K grid resistors and changed the .047uF to .068uF at the power tube grid.

The power supply doubler changed to 2x 680uF 400 volt capacitors. Added a poly type 10uF capacitor on the doubler output. Change rectifiers to UF4007. Kept screen at 40uF, all others at 50uF.

Added two 3500uF for the bias supply & changed bias bridge rectifier to UF4007;

Used short plate Westinghouse 12AX7 or Brimar CV4004 in phono section. These tubes greatly clean up the phono section. Preamp section used RCA 12AX7 tall plate. Either black or grey are good with no noise issues like some black plates. Used vintage Tung Sol 12AX7s at phase inverters. RCA or Sylvania 7858 or 7591 finishes the tubes. Should mention a 12AT7 was used in the multiplexer output regardless if marked 12AX7.

After these mods, the clarity was greatly improved. The phono section was stunning- such a difference. It had a little chime in the audio that made it so musical sounding. Chime being like a church bell ringing if that makes sense.



Edits: 11/29/16

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  • RE: Danny......... - sony6060 17:45:16 11/29/16 (1)

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