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Just found this forum. Thank you for letting me post my question. I have what I believe to be a '65 Jet serial# 2478.
It has two 6BK11s , two 7591s and a 5Y3 rectifier tube. The tube chart says J-12-A but the "A" is scribbled out and a "T" is penciled in there. This amp does have tremolo. Does anyone have a schematic for this? I can't seem to find one online. A J-12-A has 6SL7s. A J-12-B is close but has 6V6s instead of 7591s. This amp also has only 3 foot pegs, 2 in front, 1 in back. Any insight would be greatly appreciated. I love ampeg amps and am happy to have found this forum.
Merriam Shoals
dmorrre@gmail.com
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Thanks for the reply Liquids. I think the first link was probably it at one time. The pdf will not open, and I also found that on the music-electronics-forum and the pdf would not open from there as well... The second link is a J-12 that has 12AX7s instead of 6BK11s. There are schematics out there for the J-12-T reissue, but for some reason the original J-12-T schematics are difficult to find online. I have a partial schematic glued on the inside of the back cover, but half of it is missing. Still looking...
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Looks like we need to track down someone with an original schematic (if there ever was one) and get a scan!
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I just posted the J-12D schematic in "Docs"
It has 7591s and 6BK11s, I assume there are only minor differences between that schematic and the J12-T
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Thanks Hangman! That looks close pre and power tube-wise. My J-12-T has a 5Y3 rectifier tube and this "D" schematic looks like it has a solid state rectifier. I also have a 1966 J-12-D so this might come in handy some day. I appreciate your help on this... I think I am just going to have my local tech work on the J-12-T for me. (it has developed a slight hum) He probably can figure it out. On another topic, what is your take on the 3 foot pegs vs 4 foot pegs? My J-12-T has 3 footpegs, and the J-12-D has 4. Do you think Ampeg thought that the odd number of footpegs would help the cabinet resonate better?
-Merriam Shoals
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Yeah, I imagine the rectifier is one of the only differences. Otherwise it should be pretty much the same. Any good tech shouldn't even need a schematic to work on that one.
The footpeg issue was likely ampeg trying to keep costs low rather than make the cabinet resonate better. The jet was their entry level amp.
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Thanks Hangman. Customers must have complained about the missing foot because my other Jet(the 1966)has 4 feet and is stable. The '65 can be a little wobbly...
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yeah, I've worked on a number of them and it always bugs me. I'm surprised Everett Hull would have allowed that. He didn't appear to be the kind of guy would would be ok with cutting corners.
