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Accuphase P-600

Discussion in 'Kenwood-Trio/Kensonic-Accuphase' started by Ds2000, Feb 11, 2017.

  1. Ds2000

    Ds2000 All About every cool stereo component. Subscriber

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    So here is a journey related to this amplifier. It sat for 15 years in a shop, my buddies shop. He was never really able to get to the project beyond perfunctory looks and prodding. So I finally got to getting it back as his abilities are something of yesterday. Tom B, this is headed to you. Follow the story here as it should be interesting. I cleaned it up thoroughly today.
    It has a new transformer I installed while working at CSA, but the startup circuit is not in good shape after a spike, or this is what I was told. I'll look forward to it working again.
    IMG_4140.JPG IMG_4139.JPG IMG_4138.JPG IMG_4137.JPG IMG_4136.JPG IMG_4134.JPG
     
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  2. FootFungus

    FootFungus Super Member

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    Do you have any close shots of the circuit boards? I've been underwhelmed with the construction on the lower/mid-line Accuphase units. I've always hoped their statement amps were more substantial.
     
  3. nj pheonix

    nj pheonix AK Subscriber Subscriber

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    I know nothing about it but it looks pretty industrial (read built like a tank) to me!
     
  4. Ds2000

    Ds2000 All About every cool stereo component. Subscriber

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    Boards on cards.
    IMG_4146.JPG IMG_4145.JPG IMG_4144.JPG IMG_4141.JPG
     
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  5. FootFungus

    FootFungus Super Member

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    Thanks. Much better PCBs than are what are in my P300L and V.
     
  6. Ds2000

    Ds2000 All About every cool stereo component. Subscriber

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    All glass epoxy, heavy traces, etc. It's a very well put together amp.
     
    Last edited: Feb 11, 2017

     

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  7. nj pheonix

    nj pheonix AK Subscriber Subscriber

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    That's a lot of chips:idea:
     
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  8. Ds2000

    Ds2000 All About every cool stereo component. Subscriber

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    All related to the 12 bit A/D converter for the digital metering system. The rest of it is a linear AB amp, hand built with discrete components.
     
  9. FootFungus

    FootFungus Super Member

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    Are the drivers bipolar, or 2SK405/2SJ115?
     
  10. Ds2000

    Ds2000 All About every cool stereo component. Subscriber

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    Not entirely sure, they're difficult to see, and the schematic is still at the old techs place.
     
  11. FootFungus

    FootFungus Super Member

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    The pictures in the Accuphase show Hitachi 2SK400/J114. Very similar devices to the 2SK405/J115, with better Vds (+-200).
     

     

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  12. Ds2000

    Ds2000 All About every cool stereo component. Subscriber

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    Those are they.
     
  13. Ds2000

    Ds2000 All About every cool stereo component. Subscriber

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    The main branding on the transistors are NEC, Hitachi, and the outputs are Sanken.
     
  14. Alan0354

    Alan0354 Super Member

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    It looks like to have 4 pairs of Sanken 2SC2922/2SA1216 type of big transistors on each side. You have schmatic for the power amp?

    It's a very nice high end amplifier.
     
    Last edited: Feb 11, 2017
  15. Ds2000

    Ds2000 All About every cool stereo component. Subscriber

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    There's 14 of the Sanken transistors in the output section per channel. I do have the full schematic and parts list, but it is in the morass back where I picked it up. I'll need to beg, borrow, and steal to find a new one and the SM if it's lost.
     
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  16. Ds2000

    Ds2000 All About every cool stereo component. Subscriber

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    Interestingly, in some ways it is similar to the Onkyo M-510 I have, but then it is also a world apart. The Onk kills it in sheer ability and power supply, it weighs nearly twice the Accu, but they are rated the same per channel at 8 and 4 ohms.
    Now the Onk will do 1,200w into 1 ohm continuously, 2,100 peak because of its dual 1.2 kva transformers, the Accu needs one to switch in the low impedance circuit to achieve around 450w into the same load.
    No dismissal, the Accuphase is one very nicely built machine.
     

     

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  17. Alan0354

    Alan0354 Super Member

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    I just got the manual for it and has the simplified schematic. Really looks like a very high end power amp. Must be very expensive. Those transistor are very powerful ( much better than the TO-264) 7 pairs works as good as 10 pairs or more of the regular transistors. Clever they use FET as driver. Here is the link to the manual:http://www.accuphase.com/cat/p-600en.pdf

    The circuit has a lot of similarity to the amp I design, but I use all BJT instead of mixed FETs. I use current mirror load on the IPS but the P-600 use resistor. But the P-600 use cascode VAS on top of darlington VAS, I only use darlington, no cascode. The one that is better is P-600 use 7 pair of the superior transistor. I use 9 pairs of regular MJL1302/3281. The P-600 win out on this.

    You going to keep it after fixing it?
     
  18. Ds2000

    Ds2000 All About every cool stereo component. Subscriber

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    I am not sure. I may keep it, it is a really nifty piece of audio history, and something I lusted after as a kid. At the end of it's run, it was $5,000.00+
     
    Last edited: Feb 11, 2017
  19. Ds2000

    Ds2000 All About every cool stereo component. Subscriber

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  20. nyhifihead

    nyhifihead Well-Known Member

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