just picked up a MC752; It's convincing me I now need a Mac pre-amp.

Discussion in 'McIntosh Audio' started by isotopesope, Jan 26, 2017.

  1. AdamAnt316

    AdamAnt316 Collector of heavy things Subscriber

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    I have yet to compare them side-by-side, but I think the MR73 likely has the edge performance-wise with its extra IF stage. It appears to use a 4-gang tuning capacitor, compared to three on the 2110, so it should be more selective on the FM end of things. Feature-wise, the meters and 'magic eye' tube on the MR73 might not be as fancy (or fun to watch) as the 2110's oscilloscope tube, but the fact that you don't have to switch between modes to use them is a definite plus. Besides, it should be about listening to the music being received, not watching the squiggly line dance around the screen.
    Well, I wouldn't be as drastic as that, but it's definitely something to keep in mind. I've sprayed DeOxit into rotary potentiometers used in my preamps and receivers, and they weren't destroyed. As long as you're careful, they should be fine, though it'd be a good idea to apply some FaderLube afterwards to restore the lubrication within. Of course, there are definitely exceptions out there, as I discovered to my horror when I attempted to clean the volume control on my Zenith Royal 500H transistor radio. The quick spritz of DeOxit utterly destroyed the notoriously-delicate carbon track inside the tiny potentiometer; I'm not sure that using FaderLube instead would've saved it, but it's definitely food for thought..........
    -Adam
     
  2. AlTinkster92

    AlTinkster92 AK Subscriber Subscriber

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    Thanks mrz, I finally sent the 114 off to Audio Classics, going to have the whole thing gone thru..:)
     
  3. isotopesope

    isotopesope AK Subscriber Subscriber

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    a little update: just got my MX113 back from my local shop's service dept... they USED to be a Mac dealer, but haven't been for awhile, but their main tech has worked there since their Mac days... Anyways, they got all the pots cleaned and got the FM working again, and really made it sound a ton better. Most importantly getting rid of a slight hum. however, even after replacing the bulb, though they could not get the Stereo light to work, despite it pulling in stereo FM.

    any ideas?

    however, one caveat: when I first got the unit back from them, I hooked everything up, (all inputs except Phono 2 are in use) and gave it a test listen... everything sounded great, except NO FM! AM was still working as before... So, i gave them a call and asked about it....

    When i first got this unit, it came with 4 of those grey input caps... since only Phono 2 was open in my setup, i put the caps into that input... then just threw the 2 extra into the SP1 and SP2, just because. the tech asked about the "shorting caps" as he called them, and told me to make sure they WEREN'T installed in the SP outputs... well, once I removed them, FM worked again! it's really only SP1 i think that does this, the other SP output doesn't seem to do it.

    Is this NORMAL?
     
  4. isotopesope

    isotopesope AK Subscriber Subscriber

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  5. c_dk

    c_dk Addicted Member

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    I think your SP1,2 is TP1,2. They are test connections for a piece of test gear like a oscilloscope. So shorting them out will kill the FM.

    As to Jon's issue being yours also, could be. You need to check voltages against he schematic.
     
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  6. isotopesope

    isotopesope AK Subscriber Subscriber

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    ah, yeah i'm sure i'm a bit mistaken how they are labeled. good to know that is normal though! thanks.

    i'm pulling FM in, so that's probably good enough for me at the moment, as I mainly just play records. i think eventually I'll take it back in and have them look at the LDR. I printed out that SB info from that thread, so that'll be a big help.
     
  7. c_dk

    c_dk Addicted Member

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    I think Jon's issue was a failed transistor not the old, old school,LDR.

    Your tech can use a KSC1845 instead of the discontinued 2SC2240, unless he too has some 2240s left in a parts drawer since Mac parts sent them out in the 80s as replacements.
     
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  8. isotopesope

    isotopesope AK Subscriber Subscriber

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    well well well... just got this L52 cabinet for my MX113!! stoked!

    also, is this stackintosh stackrilege? my amp is barely covering the vent from the preamp... it doesn't seem to get very warm, so i feel inclined to not worry, and just love the bomb....

    [​IMG]
     
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  9. 62caddy

    62caddy Trust but verify Subscriber

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    The only "sacrilege" is that the MX113 isn't paired with its stablemate MC2505! ;)

    All's well otherwise. Enjoy. :music:
     
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  10. isotopesope

    isotopesope AK Subscriber Subscriber

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    hahaha maybe that's my next McInGoal, though i might miss that extra 25 WPC? i do love those blue gauges, and would love to have a headphone jack, despite the fact i have terrible headphones. I'm currently running an Adcom GFS-1 just so i can switch my speakers off and have a headphone jack for the rare occasions i am not playing jams thru the speakers.
     
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