EF86 Tubes

[NannerPuddin]

So I have seen from time to time that people like to use the EF86 as a preamp tube.  I have to plead ignorance, I know little about it, but I am curious.  I generally build Blackface type amps and am curious what one of these would sound like.  I believe the wiring is different, right? 

Thanks,

Doug

[HotBluePlates]

Well, it's a pentode not a dual-triode, so the socket wiring is different.

As a pentode, you can easily get much more gain out of it than a section of a 12AX7. But since there's 1 pentode in the bottle, and cascaded stage gains multiply, you can get more gain out of 2 12AX7 sections (1 bottle) than you can out of the EF86.

But they have the potential to sound quite different.

[bigdaddy]

It will give a BF type amp more of that highend gain like a Marshall or other Brit amps. When dialed in correctly it has a wonderful sound. The 5879 is very similar, less microphonic and has more mids but less of that highend sparkle.

Both great pentodes to use. In a push pull amp it's best as your first tube, in SE operation it works best as the driver tube IMO to dial in your gain structure.

One of the best amps I ever heard was an 18 watter with the EF86. Very musical, it had that magic in the sound.

[loogie]

I think both the EF86 and 5879 sound great when driven.  I prefer them in the second stage.  There's a region between clean and overdriven where both create some very interesting textures.  The EF86 has some definite sparkle.