MC252 and preamps

Discussion in 'McIntosh Audio' started by Big Mac, Jun 27, 2018.

  1. Big Mac

    Big Mac Well-Known Member

    Messages:
    759
    I've read that the MC252 does not 'play well' with certain preamps due the amps specs?

    Obviously McIntosh preamps will be fine for the MC252, but what other other manufacturers preamps?

    I am specifically looking to mate a Shindo Aureiges or Shindo Monbrison with a MC252.....any problems on the horizon?

    Thanks in advance!
     
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  2. Chubba

    Chubba Active Member

    Messages:
    414
    Location:
    StCatharines Ont Canada
    I have used a Sonic Frontiers SFL-1 for about seven years and really like the sound.I did have a McIntosh C-2300 demo unit for a week which was very good but I like what I have just as much.Cheers
     
  3. ddude003

    ddude003 New Member

    Seems the Shindo Monbrison may be the better of the two being a dual mono design... Remember to check the matching preamp out to amp in impedance... This Shindo tubed pre and McIntosh ss power amp sounds like a delicious combination...
     
    Last edited: Jun 27, 2018
  4. Chubba

    Chubba Active Member

    Messages:
    414
    Location:
    StCatharines Ont Canada
    I would like to hear that combo and and the differences.I have recently bought a new to me SFL-1 that has been rebuilt by one of the fellows that wroked there and the sound from this one sounds real.I wish I could have kept the first one as well for second system.
     
  5. twiiii

    twiiii Addicted Member

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    5,641
    Location:
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    Most tube pre-amps unless specially designed are not good at driving the low impedance of modern SS amps, and remember a MC 252 requires close to 2.2 volts to reach full dynamic out put. Sounds like no real problem, but remember the low !0,000 input impedance. A lot of tube pre-amps are shy on output current. Remember Modern Mac tube pre-amps are hybrids with SS buffer amps allowing them to drive anything with out compromising the tube performance. Tube pre-amps are easily compromised by connecting cables in addition to the amplifiers load. Not so with Mac Hybrids or SS pre-amps.
     
    Last edited: Jun 27, 2018
  6. Chubba

    Chubba Active Member

    Messages:
    414
    Location:
    StCatharines Ont Canada
    twiiii,great post.The manual for the sonic frontiers says 320 ohms out min 10,000 for the amp . it is also a hybrid which puts out up to 20 volts.
     

     

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  7. Big Mac

    Big Mac Well-Known Member

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    759
    I have used both the Shindo preamps mentioned driving a MC225, a MC250 and a MC2125.....and yes, they sound sweet! The MC2125 has the preamp matching switch in the back and I set it for 2.5....seems to work with no problem with one meter ICs.

    Just a bit worried about the MC252 if I move to that unit as I want to keep the Shindos.
     
  8. Chubba

    Chubba Active Member

    Messages:
    414
    Location:
    StCatharines Ont Canada
    Should be good then.
     
  9. Chubba

    Chubba Active Member

    Messages:
    414
    Location:
    StCatharines Ont Canada
    Big Mac Sorry about going overboard on the SFL-1.
     
  10. Big Mac

    Big Mac Well-Known Member

    Messages:
    759
    No problem Chubba..

    Does anyone on the forum have the combo of an MC252 and a Shindo preamp??
     
  11. ddude003

    ddude003 New Member

    Do you have the spec sheet for the Shindo Monbrison??? What is the output impedance??? The spec on the Shindo Labs website sez:
    "Output(RCA Pin Jack ) Impedance:5V/1KΩ X 2."
     
    Last edited: Jul 5, 2018

     

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  12. Big Mac

    Big Mac Well-Known Member

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    Thank you ddude, that is most helpful.
    I suppose I should contact my Shindo dealer about the specs and ask if he thinks the combo would work well.
     
  13. Big Mac

    Big Mac Well-Known Member

    Messages:
    759
    My Shindo dealer says it's not a good idea....but I have used both Shindo preamps on other McAmps....MC2125, MC250.....

    Somehow I just don't get this input impedance business.

    Any other opinions would be appreciated.
     
  14. damacman

    damacman Blown and Injected Subscriber

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    Location:
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    If what ddude003 posted is correct, that is fine.

    Input Impedance of amplifier / Output Impedance of preamp should be 10:1 or greater.

    10,000 Ohms / 1,000 Ohms = 10:1
     
  15. ddude003

    ddude003 New Member

    Yes, rule of thumb is Input impedance of the amp should be roughly 10X higher than the output impedance of the preamp...

    My concern is that the posted specs may not be accurate or match this example of this particular preamp... Things may have changed since his preamp was built and Shindo Labs web posting spec... Also, as I understand it, some of these preamps may be customized by Ken Shindo so I am wondering about the provenance of this particular preamp re the web spec... Anyway, 10X is just a rule of thumb and there is lots of wiggle room... Volume/gain adjustments and distortion are issues when falling too far outside of the thumb... ;^)
     
    Last edited: Jul 8, 2018
  16. Big Mac

    Big Mac Well-Known Member

    Messages:
    759
    Looks like the older Aurieges, the one I have, is 5K ohm output impedance.....found this on an old post from J. Halpern, Shindo importer.

    That makes it MC252 at 10K ohms and Aurieges at 5K ohms....looks like 2:1...ouch.
     

     

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  17. damacman

    damacman Blown and Injected Subscriber

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    Personally, I've never understood why preamp manufacturers don't strive for an output impedance of 50 Ohms or less. Such a preamp could drive any number of any amp on the market.
     
  18. ddude003

    ddude003 New Member

    Voodoo, Synergy or Basic Electronics...
     
  19. jayvis

    jayvis Well-Known Member

    Messages:
    591
    Location:
    Iowa
    The MC252 is an outstanding amp. Get yourself a modern McIntosh preamp and your problem is solved.:thumbsup:
     
  20. ddude003

    ddude003 New Member

    Your Shindo Monbrison and MC252 will sound delicious... Just do it and your done...
     

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