McIntosh MR 71

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  • Skisoverboards
    Junior Member
    • Dec 2005
    • 6

    McIntosh MR 71

    ;x( To anyone who restores, I just got myself a McIntosh MR 71 stereo tuner, all i know about it is that it is awesome. it is in great shape aside from being very dirty! Anyone who has good DIY restoration advise PLEASE HELP I REALLY want to see what this thing can do!
  • Karma
    Senior Member
    • Nov 2005
    • 801

    #2
    HI,
    I found this from a google search. It is from the 1965 Lafayette Radio catalog.

    NEW DELUXE MODEL MR-71 FM STEREOPHONIC TUNER

    All-Electronic Automatic Stereo-Mono Switching. FM Multipath Reception Indicator. Magnificently engineered by McIntosh to bring you outstanding of FM monophonic and FM multiplex stereophonic broadcasts. Features new improved tuner circuits: A new computer designed filter reduces noise from stations broadcasting subcarrier music sources; automatic all-electronic stereo-mono switching that is clickless; stereo light activated by 19KC carrier only. Two D'Arsonval signal strength and tuning meters of high sensitivity which do not need zero adjustment; multipath indicator to eliminate multipath distortion; double tuned input circuits before Nuvistor R.F. amplifier; 5 I.F. stages. Also has "Panloc" system for ease of custom installation. Sensitivity: better than 2.5 microvolts, response: +/- 0.5 db 20 cps 20KC. Capture ratio: 1.5 db; Hum: better than 70 db below 100% modulation: Separation: better than 30 db; Distortion: less than 0.5% at 100% modulation. Anodized gold and black panel. 16W x 5 7/16H x 13" D. For 105-125 volts 50/60 cycles AC. Shipping weight 37 lbs. $19 monthly, Net $399.00. Wood Cabinet for MR71, oiled walnut. Shipping weight 11 lbs. Net $25.00.

    You have found a GREAT FM tuner, one of the best ever made. I am very jealous. When I owned and operated my high end audio repair shop I restored a few Mac machines. They were always a labor of love because I could not charge what I actually put into them.

    Obviously, you need to give it a good cleaning inside and out. Use a compressor to blow out all the loose dirt and dust. Then using any implement that seems to suggest itself, remove the stubborn stuff, inside and out. Mark the tubes with their location (I think each is identified with a V number next to the socket). Then carefully clean the chrome chassis top using Windex, Q tips and soft paper towels. Use nothing stronger. Be very careful. The silk-screened information is somewhat fragile and will not stand up to a good scrubbing. Even so, you will probably loose some of it.

    You may have dirt trapped behind the front panel. It should be removed and cleaned. At this time replace ALL the lamps even if they still work. You may want to order these from McIntosh since long life is important.

    Electronically, assume the tubes are weak. Test all the tubes. The Nuvistors used in the RF front end may be hard to find. Google them. There is a problem if you have to replace (likely) any of the RF or IF tubes. The tuner will need to be realigned which is a technical job most folks or repair shops can't do. Additionally, the large cans on the chassis are electrolytic capacitors used in the power supplies. These gradually go bad with age and may need to be replaced. The problem here is that each can contains multiple capacitors. These can be hard to impossible to find especially with the right physical configuration. Remember, this tuner is 40 years old. Lots of things have changed.

    I suggest you contact McIntosh and request a quote for a complete electronic rebuild. It won't be cheap. I would consider asking McIntosh to replace the large electrolytic capacitor even if it is still functional. Tubes should not be problem. They are the most qualified and have the parts, knowledge and test equipment. When you get it back you should have a tuner that is as good as new and something to be very proud of.

    Consider buying a complete set of spare tubes. Day by day most tubes are becoming harder to find. Tubes in a tuner usually have a long life but you never can tell. Get a Manual. McIntosh manuals include a complete schematic.

    I should warn you that the state-of-the-art has advanced since 1965. The specs of the tuner will not match some of the new tuners now available. But none of the new units will sound as good as yours mostly because of the tube design. No matter. Don't hesitate. You have a classic.

    If you decide you don’t want to proceed, contact me. I may want to take it off your hands.

    Good Luck, Sparky
    Last edited by Karma; 14 December 2005, 15:22 Wednesday.

    Comment

    • Skisoverboards
      Junior Member
      • Dec 2005
      • 6

      #3
      WOW, thanks ALOT that was VERY helpfull, i will definatly give all those things a try! I really look forward to restoring this beauty, I have been a self diagnosed audiophile for some time and after furnishing my home with all the modern audio I could handle, I decided it was time to venture into the past (see what my gramps is talking about when he says my 10s of thousands of dollars has bought junk lol) I was given a mint condition onkyo a-7070 stereo amp, dont know everything about this guy yet, that kick off my interest in vintage audio, 3 weeks later a diff customer droped this mcintosh in my lap, it would apear snowball effect is going to drag me all the way back! Now I just need to give the mr71 some tlc, and see what seperates will compliment it! anyone with more suggestions on restoration or just what will compliment it, please, my ears are open! ;x(

      Comment

      • Skisoverboards
        Junior Member
        • Dec 2005
        • 6

        #4
        One more thing, anyone know where to get a cabinet for the mr 71, mine does not have one and i very much need one, let me know if you can still buy them and where?
        Thanks in advance

        Comment

        • Karma
          Senior Member
          • Nov 2005
          • 801

          #5
          HI Jay,
          You can try all the usual sources (ebay,etc) but don't hold your breath. In 1965 the MR71 was a VERY expensive tuner. The only tuner I know of that was more was the Marantz 10B (around $700) which had a built-in oscilloscope!! It's actually my favorite tuner.

          The bottom line is McIntosh didn't sell that many MR71's. The odds of finding an empty case are nil. Consider building a new one or do without. You must admit that it's pretty handsome with the chassis showing. Many people used them just that way.

          Jay, I'm having second thoughts about you working on your tuner. When I was running my business I would almost never give advise to walk-ins who wanted to work on their own equipment. My reasons were simple. I felt that if someone is asking questions about the most simple technical issues, they did not have the knowledge to work on equipment. It is not trivial. You could really screw it up. Plus, there are potentially LETHAL voltages inside. Tube circuits use high plate voltages that should not be messed with by beginners. And there are other traps which are too many and complicated to discuss here.

          If I'm wrong about your technical skills then go ahead. But if my hunch is right you should have the work done professionally. For most people, electronics is not a do-it-yourself activity.

          Sparky

          Comment

          • Skisoverboards
            Junior Member
            • Dec 2005
            • 6

            #6
            Thank you, Sparky, for the input. I like it. I have been in the tinkerin buinness for quite some time, so i think i can handle it. Restoring it is what i will do, and i mean no disrespect, but that is all the input i need. Im not hawking this piece of awesomeness. However, forget gettin rid of it, cause i mean to missbehave!!!!

            Comment

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