Marantz SR2285B Receiver : Phono Stage Model Response - diyAudio
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Marantz SR2285B Receiver : Phono Stage Model Response

Posted 19th March 2013 at 07:02 AM by rjm
Updated 20th March 2013 at 02:54 AM by rjm

Mid-range 1970's stereo receiver.

I was curious to find out a) what the phono circuit was, and b) how tight the RIAA response might have been.

The answer is "four transistors" and "pretty damn good", respectively.

We are impressed. These Japanese engineers knew a thing or two. I would like to see some of these old circuits resurrected as discrete phono stages with modern components to see just what they are capable of.
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Comments

  1. Old Comment
    6L6's Avatar
    Wow, that looks simple and good!
    Are there any suitable transistors in TO-92 or something thru-hole?
    permalink
    Posted 31st March 2013 at 09:49 PM by 6L6 6L6 is offline
  2. Old Comment
    rjm's Avatar
    Well, it's simple at least...

    It should also be reasonably tolerant of substitution of the transistors. TO-92 size will be fine, low noise preferable, the trick though is the originals are quite high voltage, -90 Vcbo from the front and -150 Vcbo for the rear set. Since the voltage rails total 80 V, this is not an optional requirement.

    Perhaps someone could suggest some candidates. The 2SA992 2SC1845 come to mind...
    permalink
    Posted 1st April 2013 at 09:47 AM by rjm rjm is offline
 
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