18 marshall Vib Ef86?

[Rev D]

 Has anyone done a Marshal 18watt with vibrato and used the EF86 in the vibrato channel? I've had a liteIIB and currently have a TMB 18 and originally had built a Vib 18 and really liked the trem. Can you just substitute the 12ax7 in the VIB channel of the amp with a EF86? Ceriatone has done it on the vol/tone channel on a TMB but not the VIB, but I think I'd like it better on the other channel. Any problems with doing that? Any thoughts or experiences would be appreciated. Thanks.

Regards,

RD

Ps: Here's the scheme, the last few I've built were weber, and I thought I'd use this scheme and layout: https://taweber.powweb.com/store/6m18vib_schem.jpg
Layout: https://taweber.powweb.com/store/6m18vib_layout.jpg

[sluckey]

You can't do that. The 12AX7 and EF86 are totally different tube types.

[phsyconoodler]

You would have to look at the Ceriatone schematic and see how an EF86 is wired.
  A 12AX7 is a dual triode and the EF86 is a pentode.Totally different tubes.

The tone control would have to be totally changed and how you would get it to oscillate would be interesting.The existing trem circuit would not work with an EF86.

[Rev D]

 Fair enough, I'll mod my TMB via ceriatone's scheme and build the VIB stock. I do know the EF86 is a pentode and wired differently, just wasn't sure if it was possible, apparently not. Doesn't hurt to ask. Thanks for the reply's.


RD

[jojokeo]

Rev, w/ the appropriate modifications you can get r done. It just won't be as simple as you'd hoped that's all. Saying simply that it just won't work is hogwash. As Kevin Garnette says, anything is possible (except Celtics winning this year) - just look at Obama being president (doesn't mean he's any good). 

[sluckey]

Rev, w/ the appropriate modifications you can get r done. It just won't be as simple as you'd hoped that's all. Saying simply that it just won't work is hogwash.

Hogwash??? The 18W trem channel uses a twin triode 12AX7. One half is the preamp, the other half is the trem phase shift oscillator that also modulates the preamp half of the tube. How do you propose to use a single pentode to accomplish all that?

Besides all that, the original question was "Can you just substitute the 12ax7 in the VIB channel of the amp with a EF86?" No hogwash answers were given to that simple question.

[phsyconoodler]

I suppose you could install a bias-vary system like a Fender Princeton but you would still need an extra half-triode for an oscillator.
 
  Telling Sluckey it's 'hogwash' is BAD.Bad boy Jojokeo!

Rev D: You would have to basically gut the trem section and mod to the Princeton circuit,add a 12AX7 and change the values of the speed and intensity pot.Then another mod so it works with cathode bias. 
  Sounds a bit daunting but it can be done that way.
 

[jojokeo]

Sorry guys, I meant to imply that if there's a will there's a way. I didn't say that it would have to fit into the exact amount of tube sockets, in a certain existing amp chassis or anything like that. "With the proper modifications" there is a way to put a pentode in front of that design to get the desired result but not in subbing one tube/socket for the other - you are definately correct.