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Post by asattwanger on Oct 2, 2008 15:47:35 GMT -7
I have been thinking about this. I have a Musicmaster Bass amp I modded and migt as well puch a bit farther. TopHat has a Portly Cadet that the 6v6 model has a 12ax7 in the front end and a EL-84 model that they put a Ef-86 in. So this got me thinking
What kind of mods does one need to do to replace a 12ax7 preamp tube with a Ef-86?
Thanks Dave
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Post by John on Oct 3, 2008 5:44:15 GMT -7
From what I know, it would take MAJOR changes in the amp. It's not a simple change in resistor or cap.
The 12ax7 is actually two individual units inside one glass container. The EF86 is one unit...and they operate differently. So even if you were to get the pins to work with the ef86, chances are you'll run into big problems because your amp will need that second side of the 12ax7...but it won't be there because the ef86 only has one operating unit inside the glass.
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Post by ruger9 on Oct 4, 2008 6:06:10 GMT -7
Didn't someone have a plug-in convertor for this? Or maybe it was to put a 12AX7 in an EF86 slot? I think Myles posted about it a year or so ago...
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Post by John on Oct 4, 2008 7:04:45 GMT -7
Didn't someone have a plug-in convertor for this? Or maybe it was to put a 12AX7 in an EF86 slot? I think Myles posted about it a year or so ago... There is a thing...I think they're called yellowjackets by THD. Used for taking an el84 and adapting it to a 6l6 or el34 power tube jack. The Doc said something like: "If you use one of these firecrackers, you'll void your warranty."
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Post by brad737 on Oct 4, 2008 8:34:33 GMT -7
There's also something like the Yellowjacket that will allow you to use a 12ax7 in the place of an EF86. Personally, I don't see the point. The 12ax7 has WAYYYYY less gain, so your tone will suffer. And if you're going to go to the trouble of carrying something extra to the gig, why not bring the correct tube instead of a little tube jacket doohickey? BTW, John is absolutely right. The dual-triode to pentode swap might make for some "interesting" changes to your amp...like the smell and appearance when it starts burning.
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Post by dixiechicken on Oct 11, 2008 12:50:16 GMT -7
DC here!
That wont work at all - I dont think even a yellow jacket gizmo can make it work properly.
The 12AX7/ECC83 tube is a double triode tube (two triodes) contained in one glassbottle. The EF86 is a single penthode contained in one glassbottle.
It is not only that the pin configs are completely different - the specs and data and requirementsof the EF86 penthode and the triodes inside the 12AX7 are very very different.
DONT MESS WITH IT - it is not a good idea - get yourself another amp if you want something different.
Cheers: Dixiechicken!
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Post by asattwanger on Oct 12, 2008 7:52:14 GMT -7
Ok I was thinking it might be an easy mod, but from the sounds of it it's not.
DAVE
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strat-les
New Member
"Don't play as well as you think you can.....Play better"
Posts: 32
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Post by strat-les on Oct 13, 2008 12:54:15 GMT -7
I had asked the same question about doing the tube switch in my Tube Driver pedal. Myles agreed - definitely a NO-NO ! Kinda like putting a Chevy engine in a Ford ..... for what it would take to rewire everything.........not worth it. Want a Ford to run like a Chevy?.....Buy a Chevy ! My $.02 Skipp
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Post by asattwanger on Oct 13, 2008 14:46:26 GMT -7
Skip that isn't exactly true. My MMB doesn't run like a Z, but that isn't what I was after. The value of the amp is low, but the modded sound is alot better than any other amp in the $200-250 range. Good enough that I don't feel bad about using it from time to time.
Anyway to break it down. I like the way the Ef-86 responds. I like to play with this amp and modding it some more would be ok by me. Would like to get it tube rect'ed and a Ef-86. Basicly saying hell with keeping it a MMB. I have about $200 invested in the amp with the Weber. Another $100 in modds if it makes a difference would be ok by me.
DAVE
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Post by myles on Oct 14, 2008 9:39:51 GMT -7
Didn't someone have a plug-in convertor for this? Or maybe it was to put a 12AX7 in an EF86 slot? I think Myles posted about it a year or so ago... GT had an adaptor to allow a 12AX7 to be used in an EF86 slot. It sounded very different than the EF86 and that was not the intension but turned out to be the reality. I personally thought it sounded awful. The only time I would have considered it was if you had one of the adaptors sitting around and your amp had it's EF86 tube fail at a gig and you needed to "get home". It would be cheaper and better to carry a known good spare EF86.
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Post by myles on Oct 14, 2008 9:41:02 GMT -7
There's also something like the Yellowjacket that will allow you to use a 12ax7 in the place of an EF86. Personally, I don't see the point. The 12ax7 has WAYYYYY less gain, so your tone will suffer. And if you're going to go to the trouble of carrying something extra to the gig, why not bring the correct tube instead of a little tube jacket doohickey? BTW, John is absolutely right. The dual-triode to pentode swap might make for some "interesting" changes to your amp...like the smell and appearance when it starts burning. You are 150% on target .... have a spare correct tube.
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