EF86 question

[Philoffline]

Is there a good reason not to put a 12ax7 driving a tone stack, Lightning-style, after an EF86 preamp?

Every EF86 example I can find basically goes straight to the PI, with just a volume pot and usually some sort of top cut option. The venerable AC-15. I understand that you can't drive a tone stack with an EF86 because it wants to see higher impedance. But add a gain stage>cathode follower>T/B stack, and you should be in business, right?

Thanks for your help; I'm figuring this stuff out as I go along (obviously).

[Dr-Joned]

I think I saw a Dr Z amp or matchless that used the ax7 after an EF86. I don't think there is any issue with doing it that way. Usually the EF86 is setup to have so much gain that there is no need for another stage before the PI.

[tubeswell]

I think the answer is basically what Dr-Joned said.

FWIW I have a similar project in the wings here (albeit SE) altho' I've been away from home for 2 1/2 weeks, so it got stalled. Obviously you could set up the EF86 for lower gain and then use as 1/2 12AX7 as a recovery/driver stage.

http://music-electronics-forum.com/t23037/

[M Fowler]

The Dr Z Prescription has the EF86 in second position.

Mark