1. Work behind the scenes continues. AK may go offline again for additional database and or Xenforo fixes.
    Dismiss Notice

Sansui AU-505 Rebuild: Is this little integrated within shouting distance of the best?

Discussion in 'Exclusively Sansui' started by patfont, Jun 8, 2018.

  1. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,791
    Location:
    South Jersey
    Got a Sansui AU-505 here that I rebuilt for myself!

    I always have my son come down to the shop and listen with me to my completed projects. When I tell him wow this sounds good, he always says is does but not as good as that little Sansui Amp you had here.
    That's always his kicker!

    The good:

    *Sounds so wonderful even at low volume
    *Has the image height depth and sound stage of a tube unit (yep I said it, as a tube unit)
    *The articulation of the low end is phenomenal, how is this thing not breaking up or clipping!!!
    *Great old school design, even after cooking this thing the heatsink is not really even hot, and all the outputs are within a 1/2 degree of each other temp wise.
    *It moves air like the big boys-you can feel the low notes in your chest as well as some times vocals.
    *Sure maybe something beats it in one category, but it will not be by much. This is an amp for people who listen to music not equipment. If it gets any better then this it could be scary!
    * I can hear it now, oh well my 22XX, or my 9090, or my 777, had em all here rebuilt by me and listened to them all.

    Please keep this info under your hat, don't want to drive up the prices on this gem.

    I'll get up some pics of the rebuild in some posts to follow.
     
    Last edited: Jun 8, 2018

     

    Please register to disable this ad.

  2. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,791
    Location:
    South Jersey
    Preamp tone board

    IMG_4264-3.jpg IMG_4265-1.jpg
     
    Hyperion and SansuiJavier like this.
  3. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,791
    Location:
    South Jersey
    Power Cap: screw terminal type IMG_4286.jpg
     
    Hyperion and stereofun like this.
  4. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,791
    Location:
    South Jersey
    For the preamp/tone section I used Nichicon FG and Elna Silmic II. I upgraded a pair of resistors to AMRG's and added some Wima films for the 1uf positions.
    I used a "High Ripple" Nichicon screw terminal cap for the power capacitor and used a Vishay 940C as a bypass.

    The high end on this little guy is clean, sweet and has no trace of high end hash or any electronic artifacts:

    *Coupling caps are bypassed
    *Power cap is bypassed
    *D001 is replaced with a modern dual diode rectifier.
     
    Last edited: Jun 8, 2018
    Hyperion and BLAH BLAH like this.
  5. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,791
    Location:
    South Jersey
    Man I soldered this board in without a pic, here's the new dual diode.

    IMG_4269.jpg
     
    Hyperion and BLAH BLAH like this.
  6. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,791
    Location:
    South Jersey
    The metal cover over the tone section is kinda flimsy-so just to be safe I added some vellum.

    IMG_4267.jpg IMG_4268.jpg
     
    Hyperion and BLAH BLAH like this.

     

    Please register to disable this ad.

  7. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,791
    Location:
    South Jersey
    IMG_4280.jpg Here are the bypass caps for the couplers on the bottom of the board. The couplers are Elna for Audio LAO.
     
    smurfer77, Hyperion and BLAH BLAH like this.
  8. stereofun

    stereofun Super Member

    Messages:
    1,223
    Location:
    Tucson, AZ
    You are preaching to the choir on my end. It is totally underated, but keep it quite please. The low end is incredible considering it's humble wattage. As Jim from QRX restorer used to say - it's a giant killer.
     
    Last edited: Jun 8, 2018
  9. ranch 22b

    ranch 22b AK Subscriber Subscriber

    Messages:
    2,196
    Y'all like the 505 better than the 505a?

    I've presently got a Lounge phono pre going into a Patfont rebuilt Harman Kardon 330B playing Band on the Run and I gotta say the bass is pretty darn killer.
     
  10. richardpp

    richardpp Active Member

    Messages:
    108
    Location:
    Adl, Australia
    I'm a big fan of the AU-505, it makes the bass end sound so good. Great pics and information on the rebuild, beautiful job!
     
    patfont and quadmatrix82 like this.
  11. The Fuxtor

    The Fuxtor AK Subscriber Subscriber

    Messages:
    2,548
    Location:
    Calgary, Alberta
    Love the Patfont rebuilds!!
     
    patfont, stereofun and ranch 22b like this.

     

    Please register to disable this ad.

  12. quadmatrix82

    quadmatrix82 Active Member

    Messages:
    273
    Very under rated small Sansui integrated everyone raves about the 555a but this is just as good fiction anything I think the bottom end is nicer
     
    patfont likes this.
  13. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,791
    Location:
    South Jersey
    trying the power cap "with out" bypass cap now.


    IMG_4289.jpg
     
  14. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,791
    Location:
    South Jersey
    Here is a shot of the amp board:

    IMG_4284.jpg
     
    Hipocrates, Hyperion and richardpp like this.
  15. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,791
    Location:
    South Jersey
    When you replace the transistors on the amp board you need to bump the 1K Ohm bias trimmer to 2K. What happens is you can only usually get it down to 14-22 mV.
    This goes for the 555A also.
     
  16. Leestereo

    Leestereo Super Member

    Messages:
    2,048
    Location:
    Ottawa, ON
    As always, very nice work Pat.
    Interestingly, later production AU-555As employed the same F-1266-1 Main Amplifier board as the AU-505. You might consider implementing a Baxandall Diode and a Vbe Multiplier By-pass capacitor, details can be found here: Sansui AU-555A Power Amplifier Modifications
     
    richardpp and Hyperion like this.

     

    Please register to disable this ad.

  17. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,791
    Location:
    South Jersey

    Thanks Ben!

    I did know about this from Conrad's 2000X page have read it many times. I will ask a question though in your thread.
     
  18. smurfer77

    smurfer77 AK Subscriber Subscriber

    Messages:
    1,409
    Location:
    San Francisco
    Pat, great descriptions on the first post. Yes, you often have to increase the VR values... this is common on a lot of amps as you work on them. I keep flip flopping between the 555A and 505 as to which I prefer. The general consensus seems to be the 505 may have an edge in warmth/bass and the 555A may have an edge on clarity/space, but I'm sure the variations are subtle at this point and quite dependent on particular caps/parts used in rebuilds or condition of stock amps etc etc.

    All in all, yes, the 505 is a well kept secret. Still, I think your 777 should beat it :p
     
    patfont likes this.
  19. kevzep

    kevzep Its all about the Music Subscriber

    Very nice!! Very thorough and interesting work.......
    Do you use a formula for working out what value to use for those by-pass caps on the output, or is it a trial and error kind of thing...?
     
    patfont likes this.
  20. patfont

    patfont AK Subscriber Subscriber

    Messages:
    2,791
    Location:
    South Jersey
    What you are seeing here is an almost finished rebuild, well what do I mean?
    Certain locations and cap selections are done 1 at a time where I am inserting different caps and then listening usually to a "Direct to Disc" LP so I can hear every detail a change may bring.
    The "power cap" for example, 1st try was a Nichicon KG, the Nichicon KT screw terminal is the 2nd try, listened back and forth a few times. The Nichicon KT has lost the bypass cap-sounds better.
    Amp board C801/C802 1st try C0G caps, changed to Wima films-fit perfect sound smoother in the high end.
    C807/C808 were Nichicon ES bipolar, switched to Silmic II sounds better.
    *******When I say sounds better it means to me it blends best with the units sonic signature and strong points, and still sounds cut from the same cloth.
    C803/C804 I tried Sonicap Gen II's like the stock caps better.
    I do not just do wholesale changes on units to what should technically go in a position as the best part. I do try them but then I listen and compare.
    The couplers were tried with and with out bypass caps, the bypass caps stay on, lowers the noise floor.
    These are just some examples............

    Answer to your actual question, the bypass on the power cap was a Vishay 940C .01uf same as the original.
    And yes I do take time to let a said component break in to sound it's best before a change out.
    I am impressed by this little 505 so took my time with almost all decisions on it.

    Hope this helps.

    Pat
     
    richardpp likes this.

Share This Page