Pentode (EF86) pre-amps and combo's?

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Re: Pentode (EF86) pre-amps and combo's?

Post by rexracer »

I think you also get better tone out of a dedicated tone cabinet, combo cabs are just for convenience imho.
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Re: Pentode (EF86) pre-amps and combo's?

Post by Isaac Stuckey »

Finished mine yesterday. Sounds great, except need to reduce the el84 cathode cap from 18watt value (500uf) to 250uf like in a ac15, and a couple small tweaks, but it sound great, maybe the fact that I used original Celestion Blue (Vox Silver Bulldogs) speakers for playing, in a 2x12 cab... ;-) Guess that helps, but sound really great though.
Anyway, Yea in a head cabinet it sounds pretty good. I had to take the tube shield off of it as it rattled, and it really only is as Microphonic as a bad 12ax7, so its pretty reasonable. And no problems with it right on top of the cabinet. I played it through a little 1x12 with a WGS reaper in it and that was great too. It squeals with my tele, when you dime it, so I gotta try some other guitars too, as It's just that that guitar is a little microphonic itself, as the pickups arent potted. but they are pretty good.
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Re: Pentode (EF86) pre-amps and combo's?

Post by tubenit »

The 5879 pentode is a nice alternative to the EF86. We've used this in V1 in numerous builds including the HoSo56 which originally had EL84's.

http://www.el34world.com/Forum/index.php?topic=6176.0" onclick="window.open(this.href);return false;

and in overdrive sections of amps like this one:

http://www.el34world.com/Forum/index.php?topic=9636.0" onclick="window.open(this.href);return false;

With respect, Tubenit
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Re: Pentode (EF86) pre-amps and combo's?

Post by katopan »

I've got the AC15 EF86 preamp as a second channel in my 18 Watt head. Works fine except for the EF86 in there at the moment has gone noisy (it crackles) and needs replacing. I've never had microphonic issues with it.
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Re: Pentode (EF86) pre-amps and combo's?

Post by Ingo »

Hello

another very good option is to use a used EF804 from Telefunken. The differences to the EF86 are very small and it is a really very stable tube with less micro phonics than the today available 12AX7A, even selected. I have build some custom amps with that tube and the sound is really wonderful.

Best regards
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Re: Pentode (EF86) pre-amps and combo's?

Post by Isaac Stuckey »

Tubenit,
That tweed OD special schematic looks really interesting, I liked the tone, slightly interested in building one now. That would be cool.

Also, Ingo, You mentioned the EF804, is that a direct replacement for the EF86 pinwise? Does it have the same gain properties? Like would it be less gain kind of like the difference between a 12ax7 and a 12ay7 or is it similar?
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Re: Pentode (EF86) pre-amps and combo's?

Post by CurtissRobin »

I looked for the EF804 and found that it's a tube the sellers are very proud of. i.e. $$.

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Re: Pentode (EF86) pre-amps and combo's?

Post by JMPGuitars »

I use EF806S which is a direct replacement for EF86 and they sound fantastic.
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Re: Pentode (EF86) pre-amps and combo's?

Post by Isaac Stuckey »

The EF806s isn't too cheap either, but definitely would be nice to experiment a little further. I'm hoping to build another AC15 soon, so when I get another EF86, I'll have to try another variant or two...
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Re: Pentode (EF86) pre-amps and combo's?

Post by AC Cobra »

I got a new tung-sol ef806, so Ill see what that will do in a head. A little off topic, bit somewhat realivant... dose anyone know of a good way to tone controll schematic? I was thinking of the matchless/orange style rotary tone controll, although with the right coupling cap I would be happy no tone controlls. Just gain and volume. :lol:
I will be using mearlins values for the ef86 section, which Im sure Ive seen zaphood refrence at one point
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Re: Pentode (EF86) pre-amps and combo's?

Post by Isaac Stuckey »

My favorite for a single knob simple tone control so far, is like a tweed deluxe... Look up the schematic for the 5e3.
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Re: Pentode (EF86) pre-amps and combo's?

Post by Ingo »

Isaac Stuckey wrote:Tubenit,
That tweed OD special schematic looks really interesting, I liked the tone, slightly interested in building one now. That would be cool.

Also, Ingo, You mentioned the EF804, is that a direct replacement for the EF86 pinwise? Does it have the same gain properties? Like would it be less gain kind of like the difference between a 12ax7 and a 12ay7 or is it similar?
Hi Isaac

The EF804 from Telefunken is a long living version from the EF86 and is less microphonic. It is a direct replacement pinwise and has the same electric values as the EF86. Even this tube is more expensive, it´s worth a try

Best regards
Ingo
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Re: Pentode (EF86) pre-amps and combo's?

Post by Isaac Stuckey »

That's very cool, will have to try one of those eventually.
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Re: Pentode (EF86) pre-amps and combo's?

Post by JMPGuitars »

I'm curious about them too, but the JJ EF806S is $30 compared to the EF804 for $70...and I'm happy with the EF806S. I think it's funny that I don't want to spend that much on tubes considering what some people pay for NOS. ;)
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Re: Pentode (EF86) pre-amps and combo's?

Post by Isaac Stuckey »

Is your EF806s basically the same thing as Ingo described?
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