18 Watt Lite .. 12AX7 vs. EF86?

[Crabman]

I’m considering building an 18 watt lite head to leave at the place where I jam. I have an extra cab there but I’m kinda growing tired of dragging my Trinity 18 watt head back and forth.

I was thinking of building the EF86 version. Have never played through an amp with a pentode at the front. Wondering how different this is from the classic 12AX7.

Any opinions?

[JMPGuitars]

I like both a lot, and I made modern versions of both (Lite 2b(ish) = 12AX7, Lite 2p = EF86).

If you want more preamp dirt and a different sound compared to your other amp, I'd choose the EF86 variant. However, you could also build one with the parallel/cascade mod, and that could be fun too. Or the Superlite TMB which also has a nice cascaded preamp.

More considerations: 1. tube availability; 2. tube microphonics.

The 12AX7 tubes usually cost less, and are less likely to have issues with microphonics. If you build my Lite 2p version, I've found that to be less microphonic than the original EF86 Lite with the more Voxxy preamp design. It's less of an issue as a head vs. combo.

BTW- you should also look at the Russian 6J32P which is essentially the same as an EF86. I've had good luck with those too.

Thanks,
Josh

[Crabman]

Thanks for the feedback. Didn’t give much thought to availability and cost. I see that I can pick up the EF86 for about US $30 but not a lot of choices.

It’s hard to evaluate the tone compared to the 12AX7 variants from youtube videos. Although it would appear that a pentode up front has a fair bit of harmonic jangle going on which is very cool.

Im aware of the shortcomings of the Vox EF86 circuit from reading Merlins books and his recommended setup appears to align reasonably well with the lite 2P … which is what I would follow.

Looking at the schematics I noticed that 56K grid stoppers are used at the EL84s. Was this needed to tame highs a bit?

[JMPGuitars]

I think I used Merlin's site for a starting point on the Lite 2p updates, and tweaked to taste from there.

I think that's accurate about it being more harmonically rich.

IIRC the 56k grid stoppers might have been partially for that, but more likely to avoid oscillation issues.

Which EF86s were you looking at? Don't buy a JJ.

Thanks,
Josh

[Crabman]

The JJ EL86 isn't an option for me anyway. I know what you mean .. there have been some major QC issues with that brand of late. The 2 options I would have at the US $30 price point are Electro Harmonics and Winged C (6J32P type that you mentioned). I generally go through the Tube Store since it's Canadian and doesn't run me into trouble with shipping duties.

I guess I could also dual channel the build with 12AX7 and EF86 inputs, but that would take away from the wonderful simplicity of the Lite format.