The Humble EL34

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Cressy Snr
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#1 The Humble EL34

Post by Cressy Snr »

Of all the power pentodes I have tried in my projects, I keep returning to the EL34.
Other power pentodes may give slightly deeper bass or higher highs, yet the humble EL34 just seems to sound "right" and seems to play music rather than give hi-fi sound.
For several years now I've tried to get to the bottom of the sound of the EL34 and why it just does the biz. It is TONE; pure and simple.
The way it gives those vivid instrumental colours, the rich timbral palette, the way it serves up the harmonic beauty of acoustic or electric instruments, the sheer size of the presentation and how it just sounds so damned relaxed as it goes about its music making business, is the dog's danglies.

Not a fashionable valve for home hi-fi use; the mainstream valve amp industry seems to have moved onto the kick-ass characteristics of KT120s and KT150s in an attempt to emulate what it thinks is the sound of transistor muscle amps, leaving the music as an afterthought and bling and bluster as forethought.

How many of us started with building El34 amps and moved to "better" things?
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#2 Re: The Humble EL34

Post by Cressy Snr »

My Barbarik monos are once again running Tube Amp Doctor branded Shuggie EL34Bs and are currently doing nice things with Ronny Jordan's "A Brighter Day" CD from 1999 via my old Sony CDP-XB930 CD player.....Just lovely.
Last edited by Cressy Snr on Fri Jan 13, 2017 9:47 am, edited 2 times in total.
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pre65
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#3 Re: The Humble EL34

Post by pre65 »

Steve, can you remind me where you connect pin 1 (G3) to on the EL34 ?

I'd like to try EL34 in my KT66 amp. On the KT66 the beam plates are internally connected to the cathode and pin 1 has no connection.
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#4 Re: The Humble EL34

Post by Andrew »

EL34 is still very popular in the guitar amp world, I believe.

Perhaps they all know something we don't? Or have they settled on what they want in terms of evolution towards an ideal solution? Or, is it a lack of innovation in the market? Many of the classic guitar amp circuits seem similar. Are they aiming for standardisation? I'm curious, what drives, has driven, these design choices, anyone know?

Of course, the main reason could simply that EL34 is easily available new, but then which came first the chicken or the egg. Why not use other modern production?
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Nick
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#5 Re: The Humble EL34

Post by Nick »

Many of the classic guitar amp circuits seem similar.
I guess it depends on how wide you make the list of classics. Marshal started life as a Fender copy and was modified to suit UK parts and UK music at the time. Vox went a low feedback route, The Fender Twin (Black/Silver) was one type, the Bassman/Blues/Hot was another Fender design path. Then you had the early Fender and Gibson designs, some single ended, then the Peavy range. Then you got the high gain variants in the 80's. The Boutique types, and now there are a big range of modelling amps, some entirely solid state, some hybrid.
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#6 Re: The Humble EL34

Post by Cressy Snr »

pre65 wrote:Steve, can you remind me where you connect pin 1 (G3) to on the EL34 ?

I'd like to try EL34 in my KT66 amp. On the KT66 the beam plates are internally connected to the cathode and pin 1 has no connection.
Hi Phil,
On the bottom of the valve socket, you strap pin 1 to pin 8. Then you can swap beam pentodes and EL34s whenever you like.
Can't say for sure that you will like the sound with EL34, that's obviously something you have to make up your own mind about and be aware that I'm talking here about the El34 in push-pull pentode mode, with plate-to-grid feedback rather than single ended.
IMHO and IME, EL34 configured with plate-to-grid feedback, is the method that seems to get the very best sound out of it. The difference is not subtle, as Alex Kitic for one never tires of telling people. And he's right you know. I mean EL34 is a pentode so why not use it as nature intended? :wink:
In single ended triode mode, you can get a general idea of its tonal characteristics and if you like its sweetness (can be a bit syrupy in SET mode) and big tone, then you can develop it a lot further using Alex' Kitic's, Gary Pimm's or hell, even my ideas.
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#7 Re: The Humble EL34

Post by pre65 »

Thanks Steve.

I seem to remember (some long while ago) there was discussion on what to do with pin 1 on EL34, and it may have been our kid Paul Barker, suggesting pin 1 connected to ground ?

It may even have been on the old World Designs forum ?
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#8 Re: The Humble EL34

Post by Cressy Snr »

Yes,
You can ground pin 1 or as James D said a while ago, you could connect it to a low voltage DC supply so it can be set at a positive voltage slightly above the cathode. The sound may or may not change as a result. I have only tried the grounded supressor, not the raised above cathode version, but it was all a long time ago (ten years at least)
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#9 Re: The Humble EL34

Post by Cressy Snr »

It's interesting how European manufacturers who do offer amps with EL34s, for example Icon Audio and Primaluna, always offer KT88s as an "upgrade." The magazines also support this distinction. The EL34 is considered the introduction to valve amps whilst the KT88/120/150 is regarded as the real deal; the proper one that no self-respecting valve afficionado should be without. In comparison, the EL34 is a candle in a brown bottle.

In the DHT world the same thing happens with the 300B vs 2A3. The 300B is the one to have, though I can understand that in terms of output power into your average speakers.

I suppose the positive side of the EL34 being such a lowly valve in hi-fi industry terms is that it can be had pretty cheaply, unless you want NOS Mullards. :wink:
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#10 Re: The Humble EL34

Post by Mike H »

Pin 1 is suppressor grid. Which for some reason is a separate connection, unlike most if not all other o/p tubes where it's internally connected to cathode.

Somewhere I have or had a contemporary one-page piece of blurb from a magazine, by Mullard, flaunting their then brand new EL34 and everything it can do, circa 1953?

(One of the things it can do is take peaks of 800V on the anode, hence enabling 1 pair in push-pull to do 100W all by themselves.)

Anyway as such means it is a fairly modern development, and possibly the last big convulsive spurt of audio valve design before the transistors took over.


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Nick
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#11 Re: The Humble EL34

Post by Nick »

possibly the last big convulsive spurt of audio valve design before the transistors took over.
Frame grids?
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#12 Re: The Humble EL34

Post by IslandPink »

Cressy Snr wrote:[IMHO and IME, EL34 configured with plate-to-grid feedback, is the method that seems to get the very best sound out of it. The difference is not subtle, as Alex Kitic for one never tires of telling people. And he's right you know. I mean EL34 is a pentode so why not use it as nature intended? :wink:
Except when you've got the plate-grid feedback it's not really a pentode, more a triode/pentode hybrid :D
But anyway, I wonder if there's something special about the harmonic distortion profile of the EL34 ( and EL84 ) compared to some other output valves ?
What you need is a guy with a really sophisticated analogue analyser to get comparisons of a few common valves !
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#13 Re: The Humble EL34

Post by Cressy Snr »

IslandPink wrote: Except when you've got the plate-grid feedback it's not really a pentode, more a triode/pentode hybrid :D
I'll give you that! :lol: :lol:
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#14 Re: The Humble EL34

Post by Mudshark »

My fave valve CS..........Sub lime.

Mind you Ive only ever owned 3.

KT 88

RB 300

EL 34.
Last edited by Mudshark on Fri Jan 20, 2017 7:37 pm, edited 1 time in total.
Cressy Snr
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#15 Re: The Humble EL34

Post by Cressy Snr »

Mudshark wrote:My fave valve CS..........Sub lime.
Aye, its music personified. :D
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