In love with capacitor coupled output sound



  • corticocortico Posts: 593
    Here are a couple more pics...

  • corticocortico Posts: 593
    edited March 2018
    I am approaching the end of the project. This 1060 phono preamp sounded phenomenal even with the old caps.

    I started to replace the resistors and electrolytic, the plan is to replace it all.
    As on the other boards the original films and polystyrene capacitors will stay, no need to replace those.

    The original green Nissei films are good sounding and the polystyrene capacitors last forever, have low distortion and 1% tolerances.

    The transistors 2SC458 become noise with age, it’s recommended to replace it with KSC1846 type. I have to do this latter, I need a transistor tester to be able to match transistors gain for left and right channel

    Before photo
    Progress photo:

  • mhardy6647mhardy6647 Posts: 24,507
    Lots of hard work -- maybe you should fabricate a couple of Plexiglass tops to show it off! :)
  • corticocortico Posts: 593
    edited March 2018
    Thank you mhardy6647! I find these vintage circuits very aesthetically pleasing.

    Walnut case Vs acrylic case? ....
  • afterburntafterburnt Posts: 6,276
    edited March 2018
    All of this electronical talk is sexy, especially the "soiled state" stuff
  • corticocortico Posts: 593
    afterburnt wrote: »
    All of this electronical talk is sexy, especially the "soiled state" stuff

    there’s more than 100 hours on it, sounds so good!!! I can’t believe it is coming from this little amp...

    It would be fun to do a blind test and AB it with a higher end piece... :)
  • pitdogg2pitdogg2 Posts: 15,545
    Very nice i bet it sounds great
  • corticocortico Posts: 593
    edited March 2018
    One upgrade that is worth mentioning, Marantz had implemented this mod on later unit.

    To protect output transistors, a pair of diodes (UF4004) per were installed on the back of each power amplifier to function as flyback diodes for the output stage of each channel.
  • corticocortico Posts: 593
    I consider this project successful, thanks to all the mentors at AK Marantz forum for their invaluable source of knowledge and kindness!

    These little amps totally deserve restoration, it’s a great piece. The service manual can be downloaded at Hi-Fi Engine, It has the schematic dwg, full part list broken down by type and locations, also the board layouts which was very helpfull to plan the work.

    The transistors have modern substitutions. It’s highly recommended to replace all 2SC458 transistors with KSC1845. Also, power supply H801 can be replaced with KSC2383YTA. There are a couple on the phono board.

    These are some equivalent transistors:
    H001-H004, 2SD217 On Semi
    H705-706, 2SC371Y = BCS47
    H707-706, 2SA562Y = BC221 or B327
    H709-710, 2SC959 = 2N3440CS
    H711-7712, 2SA606 = 2N5415 or 2N5616

    I read that there’s eight 2SC1000 transistors on the preamp that can be replaced with 2SC1815 in case originals become noisy. It’s also recommended to upgrade diodes H802 and H803 with a fast soft recovery UF4005. There are another 2 diodes on the power amp that should replaced.

    The amp plays several hours daily since rebuilt. It is difficult to turn it off. I understood the importance of “burning in time”, there was noticeable changes throughout the process.

    It superseded all my expectations, sounds much better than the original without loosing its identity.

    There is a sense of joy and accomplishment when I listen music through it. I don’t know what else to say without using the usual cheese adjectives :)

    I never heard the original unit when new, but I like to believe that this one maybe sounding close to what it sounded when new.

    I have been considering increasing the scope and maybe replace RCA jacks, speaker terminal and the skinny old power cord.?!

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