1959 Ampeg Jet with 12ax7's!!!

Discussion in 'Amps and Cabs' started by NatStrat79, Oct 4, 2008.

  1. NatStrat79

    NatStrat79 Member

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    Recently picked up a 1959 Ampeg Jet that came from the factory with 12ax7's instead of the standard 6sl7's. I've seen tube charts on early Ampeg Jet's where 12ax7 was crossed out on the tube chart and 6sl7 was written in but I've never actually seen one that had the 12ax7's. The tube chart on mine list's the 12ax7's but the schematic pasted to the inside of the back panel is still for the 6sl7 equipped amp. Also the first 12ax7 seems to employ grid leak instead of cathode bias like ive seen on the regular 6sl7 jets so it doesn't really follow the schematic. Anyone know anything more? As much as I can find this amp doesnt exist.

    [​IMG]
     
  2. bunuel

    bunuel Member

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    In it's early days, ampeg definitely deviated from their standard tube lineups in the amps, based on tube supply. I've had several where this was the case & they were definitely stock like yours. Although this required tweaking the circuits as needed to accomodate the tubes, I've never seen where this was reflected in the printed schematics attached to the inside of the cab back (for obvious reasons--too much hassle). Pretty amazing to think that back in their early handmade period that they tweaked the circuits as needed, which is hard to imagine anyone but boutique builders doing now. All that said, I've not ever encountered an ampeg that used 12ax7 prior to the early 60s. Pretty rare amp you've got & I bet is sounds good, like all of those early ampegs that've been kept up to snuff!!
     
  3. NatStrat79

    NatStrat79 Member

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    It sounds great! Even with the 12ax7's it's basic tone is pretty much the same as my Ampeg Rocket and Mercury but it definitely has more overdrive on tap. It's so true though that these early Ampegs need to be kept up to snuff. Every one that I've owned has had horribly leaky coupling capacitors. Once they were properly serviced they became some of the best amps I've every experienced. The hardest part has always been finding good 6sl7's that aren't weak or microphonic. Having 12ax7's in the Jet takes care of that problem.

    I'd love to find someone else who owns this same amp but maybe its one of only a handful that were ever produced? Who knows how many have actually survived.
     
  4. NatStrat79

    NatStrat79 Member

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    Bump in the hope that someone might have some more info about this amp?
     
  5. tweedtwin

    tweedtwin Member

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    Hi I don't have any more info but my friend has a 59 Mercury with factory 12AX7's. Your's is the second I have ever seen!

    Cool amp!

    Tweedtwin
     
  6. teleharmonium

    teleharmonium Member

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    What's the basis of your dating the amp to '59, and do you have a pic of the front you can post ?
     
  7. NatStrat79

    NatStrat79 Member

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    1959 or early 1960 based on the speaker date code mostly. Jensen P12s, date code begins 2209.... The cabinet is covered in Navy Random Flair covering, only used 1958-1962. The grill cloth is the dark silver with lighter silver swirl pattern that would put it between 1958 and very early 1960 since sometime in 1960 Ampeg quit using the swirl pattern grill cloth. What was left of the logo was the chrome block letter style as opposed to the stamped tin logo with blue background used in 1958 and early 1959. The silk screen lettering on the chassis also matches up with the 1958-1962 amps.

    I took some more pictures last night. I'll upload a few when I get home from work.
     
  8. teleharmonium

    teleharmonium Member

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    Random flair covering and the swirl grille sound right for '59, but I thought the chrome logo was later. The tin plate logo you describe as I understand it was in use from late 59 to early 60 with the chrome coming later. P12S sound correct for an original speaker for a Jet of that time, but the solder on the tabs of the speaker looks crappy and so I wouldn't count 100% on the speaker being original.

    The Woodside address makes it unlikely to be any later than early 62, but we pretty much knew that.

    Maybe we can spot some other clues in your next pics, and if you can find date codes on some chassis parts it would help.

    It's definitely an unusual Jet. I've never met an old 6V6 Ampeg I didn't like.
     
  9. NatStrat79

    NatStrat79 Member

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    Here's a picture of the front of the amp. The logo is removed in this picture as it was broken hanging down and part of it was missing. I took it off until I can get a suitable replacement. I guess I'm not 100 percent certain on when the chrome logo was brought into use. I know sometime during 1960 as I have two other Ampegs a Mercury and Rocket both of which came to me with original Jensen speakers with 1960 date codes and the chrome block letter logos. They however do not have the swirl grill cloth. I guess I would assume Late 1959 to early 1960 for the Jet. The solder on the speaker terminals looks funny because I had the amp disassembled in order to glue down some loose vinyl and just give it a once over and check everything out. I was in a hurry and threw it back together for the pictures and probably should have taken more time to do it right. It is entirely possible that the chrome logo that came on the Jet was not original. My guess is still late 1959 to early 1960 but I'll poke around and see if I can find some other date codes later.

    Regardless of the date it would be interesting to know how many others like this were made if any? And why not a permanent switch to 12ax7's?
    [​IMG]
     
  10. wingwalker

    wingwalker Fuzzy Guitars

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    WOW!

    I've got a 60 model Jet...same tolex you have, different grill but mine has the more normal 6SL7's. Cool amp for sure, how's it sound??
     
  11. tweedtwin

    tweedtwin Member

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    I think my buddy's amp is a 59 because of the random flair and the swirl grillcloth. My 1957 Mercury is white with red swirl grillcloth but with a 6SL7 preamp and an original 57 Jensen P12R. A very early first year Mercury!
     
  12. 57special

    57special Silver Supporting Member

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    Yeah, you've got it dated in right era. I've never seen 12ax7's in a 50's Ampeg.
    Perhaps it went back to the factory at sometime in the 60's for 12AX7's?
     
  13. tweedtwin

    tweedtwin Member

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    Hi 57 there are no adapter plates from a mod in the 59 Mercury.
    They are factory stock! While it has more gain with the 12ax7's
    my 57 is fatter.

    tweedtwin
     
  14. 57special

    57special Silver Supporting Member

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    I love the late 50's Rockets and jets. A primitive, thick, wheezing, tone. Rare stuff, there. And you're talking to a man who has owned an Ampeg Superreverb and Superbreverb.:cool:
     
  15. GAT

    GAT Gold Supporting Member

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    Old Ampegs are great, I have a Jet that sounds killer. BTW, Hogy at Komet amps is sure good at fixing the old Ampegs.
     
  16. wingwalker

    wingwalker Fuzzy Guitars

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    This is turning into a very cool thread on these old beasts!

    Let me ask you guys...my 60 Jet's original P12S was long gone when I got it...whats a good speaker for these amps?? Im open to any suggestion as long as it'll fit in the cab!
     
  17. TungstenAmp

    TungstenAmp Gold Supporting Member

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    I dropped an older Eminence made Mojotone V30 clone into a 60's Jet and that amp just came alive.
     
  18. teleharmonium

    teleharmonium Member

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    Cool amp for sure.

    The possibility of a swapped out chassis had crossed my mind too, but NatStrat tells us the silkscreening on the control plate is also of the late 50s/early 60s style rather than the later style you would expect for an Ampeg with 12AX7s, and if this chassis had started out with octal preamp tubes, it couldn't have gone to 12AX7s without either new holes being drilled, or plates installed with smaller cutouts due to the difference in the size of the two types of tube sockets.

    The confluence of the silkscreening agreeing with the cabinet cosmetics, the tube chart, and the chassis itself being drilled for 9 pin preamp tube sockets seem to rule out this being a cobbled together or factory repaired amp with a later chassis.
     
  19. teleharmonium

    teleharmonium Member

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    I had the original P12S in my '60 Jet when I got it, but it was weak sounding (probably due to the mileage) so I replaced it with a similar era P12Q which I am happy with.
     
  20. NatStrat79

    NatStrat79 Member

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    For those of you wondering about a possible chassis swap. Here's a picture of the control panel. The silkscreening definitely fits the 1958-1962 era and not the later style.
    [​IMG]
     

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