Sunn Concert Slave (later red knob version) ohm rating?

Discussion in 'Amps [BG]' started by BlkHeli, Jan 27, 2014.


  1. BlkHeli

    BlkHeli

    Joined:
    Feb 2, 2013
    Location:
    Boston, MA
    I've been using my Sunn PB-10 preamp into a Sunn concert slave head to push two ampeg svt 610 cabinets. Each cab is 4 ohms for a total of 2 ohms.

    The rig sounds great but since I was unsure of the ability of the head to handle a 2ohm load, I upgraded to a sunn coliseum slave which is known for its 2ohm capability.

    Problem: despite the lower wattage, the concert slave sounded better.
    I also ran a Crown 1000xls and still prefer the souns of the Concert Slave.

    If the concert cannot handle the load, I'd consider getting a second identical one for a dual concert slave setup so each is running at 4ohms. The head sounds great with a single cab as well.

    My question: can the concert slave reliable handle 2ohms?

    Second question: anyone into doing a straight trade 70's black knob coliseum slave or Crown 1000xls for 80's red knob concert slave?
    :)
     
  2. nashvillebill

    nashvillebill

    Joined:
    Oct 13, 2002
    Location:
    Nashville TN
    I do not think the Concert can reliably handle 2 ohms.
     
  3. BlkHeli

    BlkHeli

    Joined:
    Feb 2, 2013
    Location:
    Boston, MA
    I don't think so either. Can't seem to find a person or a resource that can confirm that as fact.
     
  4. Steve Dallman

    Steve Dallman Supporting Member

    Joined:
    Mar 5, 2006
    Location:
    East Central Wisconsin
    Looking at the schematic, and the four 3055 output devices as well as the lousy heatsinking, it's 150 watts RMS would be at 4 ohms, not 2 ohms. There is no protection for shorts, or overheating as with modern amps. At 2 ohms, the power amp would try to develop more power than the components are rated for.

    The power amp is the same as the power amp in the Concert Lead and Concert Bass amp. You are right, info is sparse.
     
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  6. nashvillebill

    nashvillebill

    Joined:
    Oct 13, 2002
    Location:
    Nashville TN
    I concur; though I sold my Concert Bass years ago, as I recall there isn't much of a heatsink. Trying to run four 2N3055's into 2 ohms would likely put them well outside their SOA.
     
  7. BlkHeli

    BlkHeli

    Joined:
    Feb 2, 2013
    Location:
    Boston, MA
    Thanks folks. I'll take those 3 opinions to the bank.

    Is there a way to circumvent the onboard preamp on a sunn concert bass head to make it a slave head?
     
  8. ryco

    ryco

    Joined:
    Apr 24, 2005
    Location:
    97465
    This is a good place to go for info on all things Sunn.
    Great guys on this forum! Can answer all questions as a lot of them worked for Sunn.
    Lots of specs and schematics, too!

    http://sunnforum.ampage.org
     
  9. nashvillebill

    nashvillebill

    Joined:
    Oct 13, 2002
    Location:
    Nashville TN
    Yes, you can just use the power amp section by bypassing the preamp: there is a switching jack on the back, I think it's labeled "Power Amp In". Plug your preamp into it.
     
  10. BlkHeli

    BlkHeli

    Joined:
    Feb 2, 2013
    Location:
    Boston, MA
    Thanks guys! That label is confusing. Gonna grab a nice concert amp off FeEBay now. Oddly enough they're easier to find than the slave versions.
     

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