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Hooking up 2 amps on a MX110Z?

Discussion in 'McIntosh Audio' started by bobivxx, Oct 20, 2015.

  1. bldozier

    bldozier Active Member

    Messages:
    103
    what if using a pair of mb amps, left and right, would the input rules still be relevant, I've read folks using mc 30/60/75 paired,
    but there issn't any mention of that here.

    i've also read the mx110 does not adhere well in multi-amp configurations, could anyone who has used it in this way expound.

    Id like to use two mb for a front stage + L+R for a sub, just due diligence 1st as i'm seeing conflicting statements.
     

     

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  2. 62caddy

    62caddy Trust but verify Subscriber

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    The input impedance of the amplifier(s) needs to be determined.
     
  3. bldozier

    bldozier Active Member

    Messages:
    103
    ok i will be sure to verify the imp is over that of the mx-110.
    if using a 4 way active network, do the same laws apply.
    how would the preamp see the amps through the active network?
    series or parallel, if its a series would the laws of impedance still apply to the preamp
     
  4. bldozier

    bldozier Active Member

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    103
    any help please?
     
  5. 62caddy

    62caddy Trust but verify Subscriber

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    Need info on the active network device.
     
  6. KentTeffeteller

    KentTeffeteller Gimpus Stereophilus!

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    Better yet, feed the main out of the MX 110 to the C20 tuner input, then you have the MX 110 tuner and the entire preamp section at your disposal too.
     

     

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  7. 62caddy

    62caddy Trust but verify Subscriber

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    Well you may need to change your pants Tony :D - turns out the early MX110 has exactly that. Only recently learned this myself.

    http://mcc.berners.ch/tuner-pre-amps/MX110EARLY.pdf
     
  8. whoaru99

    whoaru99 Epic Member

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    The preamp does not "see through" something like that. It works with the input impedance of the connected device(s).

    I suggest you perform the measurement suggested a few posts back (post #16) to ascertain the approximate output impedance of the MX110. It might spare you a bunch of angst looking for something that "matches" because a lot of gear these days does not have 100k or higher input impedance. I've done that sort of test, but used a high value potentiometer instead of a resistance decade box. Start with the pot at max then dial down until the voltage is 1/2 of starting. Disconnect the pot (do not change adjustment) then measure the resistance of the pot. That is your approximate output impedance.

    Generally speaking, as long as the connect load impedance is 10x or more the output impedance of the preamp there is no problem with the "match".

    In other words, if you do the test and find the pre out impedance is, for example, 500 ohms (or whatever) as long as the input impedance of the connected device is 10x (5000 ohms) or more this example, it should work fine.
     
    Last edited: Jan 6, 2018
  9. rollcentre

    rollcentre Boom-tizzz

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    I find it interesting that they decided to get rid of the 2nd pair of main outs for the Z series. While on the C20 they added them on the later models.
     
  10. 62caddy

    62caddy Trust but verify Subscriber

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    Given the 10:1 impedance requirement, would it be correct to assume MX110's actual output impedance is ~ 10,000 ohm since Mc says it should be used with input of 100,000 ohm or greater? :idea:

    In any case, my own experience with the MX110 there is noticeable gain loss when paired with an MC2155 (which is 50,000 ohm input). I will add however there doesn't seem to be much loss to SQ but the volume needs to be set higher. Of course the 0.75 V input sensitivity setting helps quite a bit, although you get an increase in noise floor.

    Bottom line is that I tend to agree with Mc's recommendations regarding amplifiers the MX110 will be happiest with. Of course, YMMV.
     
  11. whoaru99

    whoaru99 Epic Member

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    I’d be extremely surprised, to the point of doubt, the output impedance is anywhere near 10k.

    Why is the magic number 100k? Perhaps that happens to nicely align with other Mc offerings.
     

     

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  12. bldozier

    bldozier Active Member

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    from my gathering so far the external actives, work well with all gear.
    input impedance of 50k & output of 4K MAX.
    an output RL of 50K
    Quoting from hifiengine. pionner d23.

    output for the mx110 is 100k, thats specified on page 1 of the thread.

    if the input impedance is 50k for the active crossover,
    would that figured be added to each amplifier connected w/ it.
    would each one of the 4 stages been seen independent by the preamp.

    my thought was the distribution amp already existed within the active crossover...

    EDIT:
    the preamp impedance could possibly be lower then stated, i do not have 1 ATM to test it.
     
    Last edited: Jan 7, 2018
  13. 62caddy

    62caddy Trust but verify Subscriber

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    I don't know...tube models in production when MX110 was being produced were 250K; first gen SS, 200K ohm which ran roughly through the late 70s. (MX110 production overlapped SS models for the first 2 years of being introduced)

    Maybe someone can definitively answer the question because I'd like to know myself.
     
  14. monkboughtlunch

    monkboughtlunch Super Member

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    So - is there any definitive answer about impedance compatibility? Can one use a vintage MX110 with a brand new 2018 MC275 VI with no ill sonic effects?
     
  15. whoaru99

    whoaru99 Epic Member

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    That is the recommended maximum load impedance, not the output impedance.

    It was common at the time to have high input impedance in amps but how well the MX110 would work with lower input impedance depends on output impedance of the MX110. Without someone measuring one then it's just a guess. My guess is it would be fine well below 100k loading, but that's just me...
     
  16. gmfgmfgmf1

    gmfgmfgmf1 Active Member

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    I have a C-20 with two mains - one runs my main amps to main speakers full range - the other runs a subwoofer amp low passed
     

     

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