Tuesday, September 6, 2016

Formerly A Knight KB83

I bought this Knight stereo amp years ago at an auction. I tried to rebuild it to its original state but the voltage was soaring and the circuit boards were a brittle nightmare. They were not taking to the constant work. I called it quits. My good friend Chris Hornbeck was kind enough to draw up a fresh more modern schematic. The chassis tubes and transformers were great so that is all we kept.
Forget what I said fortunately Chris chimed in with a comment:
Chris Hornbeck
Signal path is all push-pull, differential input with CCS, cathode follower drivers, plate and cathode loaded triode connected outputs, separate cathode resistors with 1000uF bypasses to 0 and 32 Ohm taps, 8 Ohm tap to signal ground. No long-loop feedback, extensive decoupling to input stages.

Power supply is dual GZ34's to 10uF Solen/ factory choke/ 4x100uF to outputs, then 20Hy/C/R/C to inputs. Bottom of supply lifted by 5V for CCS supply.
 This amp was a kit and has never worked properly until now. The orginal builder just never got it to work so I got all nos tubes with it. That is four EL37 and two GZ34 rectifiers. All mullards  except the 12AX7 amperex and 12AU7 also mullard are just from my stash.
 If I ever get the schematic corrected I'll post but it was very challenging getting everything to fit in the snug chassis. I'll always afford myself more room than this... I don't like rebuilds but prefer scratch... 

Anyway it is quiet on my 107db1w1m Klipsch Jubilees so what else could one ask for but just a few easy mods and it be done lol....

8 comments:

  1. Nice big output transformers. Looks great.

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  2. Is the other large box an isolation transformer for the power supply?

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    Replies
    1. 1 power transformer
      2 output transformer
      1 power supply choke underneath
      2 small chokes for 12ax7 an 12au7 supply

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  3. Hey Iain,
    What do you mean by chokes? capacitors? pardon my ignorance.

    Doug Y

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  4. Beauty! And look at those Mullards, drool.

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  5. Signal path is all push-pull, differential input with CCS, cathode follower drivers, plate and cathode loaded triode connected outputs, separate cathode resistors with 1000uF bypasses to 0 and 32 Ohm taps, 8 Ohm tap to signal ground. No long-loop feedback, extensive decoupling to input stages.

    Power supply is dual GZ34's to 10uF Solen/ factory choke/ 4x100uF to outputs, then 20Hy/C/R/C to inputs. Bottom of supply lifted by 5V for CCS supply.

    Chris

    ReplyDelete
    Replies
    1. Thank you. The post is ammended 8-)

      Listening to William Onyeboer and Cholita Sound....

      Thanks again it sounds great.

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