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sonofgroceries
10-23-2006, 01:42 PM
What is the function of a EF86 in an amplifier.

I know that Dr. Z is putting them in the Stangrays, and I've heard you can put them in the Hayseed 30s.

What kind of lineup are the tubes in when you have the EF86 in place?

iggs
10-23-2006, 01:46 PM
EF86 is a preamp tube. 9 pin pentode vs. 12AX7 which is a 9 pin dual triode.

Blue Strat
10-23-2006, 01:58 PM
What Iggs said.

The lineup can vary depending on the amp. Often, they're used as the first and only preamp stage, sometimes they're driven by a 12AX7.

donnyjaguar
10-23-2006, 02:38 PM
I'll just add that its possible to get much more gain out of a pentode than a triode. The hi-end guys tend to shy away from pentodes in the driver/preamplifier stages as they are technically not as linear as triodes. In my experience they work perfectly fine and there are truly useful tubes like the 7199, 6U8A and 6GH8A that can be used by themself to more effectively drive a pair of output tubes than a 12AX7/7025.

I've seen some power amplifiers that use a single 12AX7 section for a VA into a directly coupled Williamson style phase splitter which in turn drives the output tubes. There's only one problem with this (other than the complete disregard for all the work Williamson himself did) there's so little gain you can only run very minimal (or no) negative feedback. Some will say this is a good thing but I say it makes it difficult to get your money's worth out of the hardware. In my experience these type of shortcuts in design were made more for cost-saving than for the achievement of "killer tone".

DJ

sonofgroceries
10-31-2006, 11:48 PM
What type of guitars does the EF86 work well with?

marshallnoise
11-01-2006, 12:17 AM
Is that not the tube in the Super Champ as well?

Blue Strat
11-01-2006, 06:02 AM
Is that not the tube in the Super Champ as well?

No. You're probably thinking of a 6C10 which is equivalent to 1.5 12AX7s.

Blue Strat
11-01-2006, 06:03 AM
What type of guitars does the EF86 work well with?

All, apparantly. There are literally 1000s of amps with EF86 out in the field. I've known users with all types of guitars who like them.

YMMV.

iggs
11-01-2006, 07:33 AM
yeah ... to me, EF86 is like 12AX7 on steroids ... more gain, more dynamics, less compression, not saying it's better, but different ... seems like it can take a lot hotter signal on the input before it starts to compress and saturate.

Fretts
11-03-2006, 01:49 AM
The EF86 can sound kind of skanky and most of them are pretty microphonic, that's one reason they are not super popular. I've seen them with heatshrink on the top to try to minimize the microphonics.
As I understand it, their main appeal was that you could get so much boost out of a single tube that you could simplify your design and manufacture. I'd be surprised if they were used -back in the day- for their tone.
Having said that, I do like that rough sound, so no complaints here.

Damon
11-03-2006, 02:23 AM
I'd be surprised if they were used -back in the day- for their tone.


Vox AC15
Neumann U67
Ampex MX10
Quad II

The EF86 is one of my favourite valves. It translates a clarity and dynamic ease that can make a 12AX7 seem puffy and flat. Run as a triode it is one of the lowest distortion amplifying devices ever made. I guess it all comes down to circuit design and implementation!

Blue Strat
11-03-2006, 05:39 AM
The EF86 can sound kind of skanky and most of them are pretty microphonic, that's one reason they are not super popular. I've seen them with heatshrink on the top to try to minimize the microphonics.
As I understand it, their main appeal was that you could get so much boost out of a single tube that you could simplify your design and manufacture. I'd be surprised if they were used -back in the day- for their tone.
Having said that, I do like that rough sound, so no complaints here.

It's only MOST of the new production EF86s that are pretty microphonic. The NOS varieties are much better. Actually, there are quite a few new amps that use these including 65 Amps, Dr Z and Matchless.

ChickenLover
11-03-2006, 06:38 AM
yeah ... to me, EF86 is like 12AX7 on steroids ... more gain, more dynamics, less compression, not saying it's better, but different ... seems like it can take a lot hotter signal on the input before it starts to compress and saturate. My limited experience has been different with EF86s. I think a 12AX7 has more gain when you cascade both triodes and there is less compression. Regarding being able to take a hotter input signal...that I don't know about. I just know that when I've messed around with EF86 preamps the tone was more chewy and pliable (for lack of better words). If I wanted a big, clean tone I'm almost sure a single 12AX7 (using both triodes) would be better than a single EF86. But if you wanted a chewy/greasey type of tone, I think the EF86 might be better.

But that's just my limited experience with them and I haven't tried them as triodes (Damon's comment has gotten me interested in trying this). I've built two amps with an EF86 and the first one ended up with a 12AX7 in that socket. The second one is still a work in progress so I have an easy way to try it. But I have tried a number of different ways to run it (all pentode though).

Fretts
11-04-2006, 03:15 AM
It's only MOST of the new production EF86s that are pretty microphonic. The NOS varieties are much better. Actually, there are quite a few new amps that use these including 65 Amps, Dr Z and Matchless.

I do own a Dr Z Rt66 and I have to say it is my favorite amp, maybe of all time.
I have often played a tiny amp and wished that a big amp could act the same way. When I came across the Rt66 with its 3 knobs, I found what I was looking for. The 66 through a 4x12 loaded with greenbacks is a beautiful thing, at least in my world.
I also loaded up a Bassman 2x12 with Weber alnico Blue Dogs and it likes the 66 very much. Who am I to bust up a beautiful relationship like that?