Picked up a Massie 966 amp head

Discussion in 'Musical Instruments' started by dobyman, Jan 23, 2017.

  1. dobyman

    dobyman Turntable Addict

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    Thanks valvenator! I think I will try all AX7's later. See what happens.
    I honestly don't know which is the power transformer or output transformer. I'll get a better picture later too.
    What's your advice on trying a pair of 6L6's in this amp? I really have no way of knowing if these tubes it came with are even correct. It sat in a basement for over 30 years unmoved and 3 tubes were loose in the head when I got it.
    I know most vintage tube amps like Fenders used 6L6's. I thought 6V6's were mostly audio amp tubes..... but then I really don't know jack about it.
    And the front tremolo jack is an input jack. I plugged in and got sound, just no tremolo.
     

     

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  2. dobyman

    dobyman Turntable Addict

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    Didn't try the 12AX7's yet but I took a pic of the transformers. I am figuring that the output transformer goes to the speaker output jacks, so the lone tube is next to the output transformer.
    [​IMG]
    [​IMG]
     
  3. dobyman

    dobyman Turntable Addict

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    UPDATE: I changed all 4 small tubes to 12AX7's and a noticeable improvement in tone and volume, AND now the tremolo works as it should! :banana:
    Does anyone think I should try 6L6's??
     
  4. arts

    arts Super Member

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    The 6L6 has the exact same ''internal wiring'' as a 6V6,so can be used in the same socket without re-wiring.Also,they are similar electrically,so you won't do any damage by trying them.

    As I said earlier,the transformers on that amp are WAY bigger than what you would see in an amp meant for 6V6's.I would try 6L6's.
     
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  5. dobyman

    dobyman Turntable Addict

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    Thanks arts! I will see if I can find a pair!
     
  6. arts

    arts Super Member

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    Don't spend a lot or go for anything special Doby. Try a local music store (especially if they do repairs) and see if they have a pair of old ''pulls'' that still have some life left in them that you can use to try.
     
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  7. dobyman

    dobyman Turntable Addict

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    I actually just grabbed 2 new 6L6 tubes on ebay for $16 shipped. If they don't help I can always keep them for another project. Thanks again arts!
     
  8. arts

    arts Super Member

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  9. dobyman

    dobyman Turntable Addict

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    New 6L6's sound great! Thanks again to all for the info!
     
  10. Derka

    Derka New Member

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    I know this is a stale thread, but I just picked up this same amp. It looked like yours had the rectifier circuit modified to non-tube circuit.

    The schematic shows a 12AT7 for tremo which mine has but actually seems to work and sound a little deeper with the 12AX7.
    The schematic is available here...and seems to be mostly correct / complete compared to my head.
    http://www.prowessamplifiers.com/schematics/misc/Massie_Saint_George-Squire.html

    I checked mine out pretty thouroghly - drove it about 45 miles. Got it home and it still sounded good. But on second day about 10 minutes into playing it. The volume just suddeny dropped to like 5%.
    And from 0-10 on the pot is about like 0-5%.

    I started going through it methodically and am just about at wits end can’t figure out what’s going on.

    I checked all the stupid stuff - cables, guitar, powerstrip... etc.
    Checked / swapped all tubes.
    Simple test of power and output transformers.
    Checked resistor values,
    Chopstick test,

    All channels the same. So I assume something going on at inversion to power section. Tube power and B1,2,3 voltages all look good, bias good.

    Any thoughts on other remedies or ideas to get this thing cranking like it was?

    Thanks
     
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  11. Mystic

    Mystic We're all born mad

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    Speaker manufacturer code is upside down in the photo you posted, but the first three digits of the 6-digit code "look like 220" to me -- which was the code for Jensen. They ain' "blue bells" but if they are period-original Jensens... well, Jensens are Jensens.
     
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  12. dobyman

    dobyman Turntable Addict

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    I wish I could help. I did sell mine a long time ago, so I cant even guess.

    They didn't sound that good for sure. Like you said, Jensens.
     

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