'71 Marshall 50 watt Soundcheck

Discussion in 'The Squawk Box' started by Mouse, Dec 5, 2017.

  1. Mouse

    Mouse Senior Member

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  2. Cjsinla

    Cjsinla Premium Member

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    Dude. Was that snow falling in front of your camera lens or were you knocking dust from the ceiling with all that volume?
     
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  3. Pwrmac7600

    Pwrmac7600 Premium Member

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    lol yeah close the door, we wouldn't want the sound to get out of the room! :rofl:
     
  4. cherrysunburst00

    cherrysunburst00 Senior Member

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    SWEET!
     
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  5. Mouse

    Mouse Senior Member

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    Second part of your question is correct
     
  6. Mouse

    Mouse Senior Member

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    Thanks Cherry !
     
  7. Mouse

    Mouse Senior Member

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    Just pushing dust particles out my window :cool2:
     
  8. Oatie

    Oatie Junior Member

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    [​IMG]

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    I will share my pics...

    Jan 14, 1972 build
    47K NFB ( Germany build with NO polarity switch and Selectable Voltage Switch ).

    I don't use Facebook so I could not see your video, do you have it on YouTube?
    I would love to see you make it snow in da house. Rappers make it rain , Rockers make it snow and look pike a Kate Bush video.

    Big smile for that 1971-72 sound, Mullards and time capsuls. Two Jan 1972 JMP50 BUILT 3 DAYS APART , always covered since new chassis plating still like new.
    Covers and storing in the home preserved them well. Jim signed the inspections and inside the speaker cab along with Ron the speaker builder.

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    This is the Jan 17, 1972 build with the Super Lead Spec. 100 NFB ( USA build we with the polarity switch)

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    102/3 Pulsonic Greenbacks, my favorite speaker can be used with all my gear now thanks to the Power Station. Even a Tweed Deluxe sounds amazing through the 4 Greenbacks.

    I know many of you have seen my 1972 Twins before, but many new members have not seen the beauty. This half stack was $ 950.00 back in 1972, as much as a one year old used car.

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    My 1970 small box with PEC Lar Mar MV,
    The famous Bean Dealer was one of the first Marshall Dealers in the USA.

    [​IMG]
     
  9. Oatie

    Oatie Junior Member

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    My 1970 JMP50 SMALLBOX with PEC Lar Mar. MV, mil spec silver tinned shielded Teflon wire. Remove the polarity switch and you can either leave it connected inside the amp fastened with a small metal bracket or use a plastic cable zip tie to hold it to a wire, be sure to cover it if you leave it in the amp to retain the original b solder joints. I removed mine as it was not virgin factory connected. The polarity switch location is a great place to install a master volume.The Lar Mar is cool because it had the 2.2 Meg resistors installed to act as backups if the PEC pot fails, and also if you turn the master all the way up, it's just like having the stock circuit installed. Both the quality PEC pot and the film 2.2 meg resistors and the shielded silver tinned Teflon wire make a quiet signal at idle dimed. Two pieces of the 3 wire cable makes a clean install. The old Plexi was wired with the purple NFB wire to the speaker jack tap, not the 8 ohm select button location. That is the way they were wired, us your 1971 wired with the purple NFB wire to the speaker jack? The amp had ceramic snubber caps and I installed Sprague Vitamin Q .22/1000v. Snubber caps in the amp and it's very quiet at idle. One of my favorite player amps.

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    Best shielded wire for master volume and mods, real silver tinned copper - Teflon coated Military Aviation Wire (eBay 3wire)
    22 Ga 20 Ga 18 Ga all work well, mine is 22 Ga.

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  10. Leña_Costoso

    Leña_Costoso Senior Member

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    You're missing the retaining nuts on the board studs.... might want to correct
     
  11. jojo

    jojo Senior Member

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  12. Oatie

    Oatie Junior Member

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    That's funny, I took that pic just before I installed the Welwyn 1K7 screen grids and the 5K6 grid stoppers, also had to clip the white wire to the bridge rectifier and route to the standby switch. That was a factory mistake on the late 71 to 1972 amps. The way the amp was wired in that photo the standby was not working and the amp would power up simply by turning on the power switch. The solution is to add 3" of white wire after you cut it off the rectifier terminal then connect it to the standby switch. Both of those amps were closet finds and I had to do the same to both amps. You seldom see old Plexi amps with factory clean plating in the inside, most are rusted or well worn. Mouse must be loving his 71 because these amps have the best components. Its the amp everyone wants to copy.
     
  13. Mouse

    Mouse Senior Member

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    Yes 71 is very potent amp.
    These days i'm playing more this one a JTM45 kt66 built with very nice components and custom winded transformers by myself. It just sings on the lower decibels and sounds thick with that very complex middle. This is with single 12'' Marshall Heritage G12 (98dB, 55Hz cone, 70 watt). Open Back cab
     
    Last edited: Dec 14, 2017 at 12:04 AM

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