Which EL34 tubes for Hi Fi

[WE91]

Hi again BillEpstein. Thank you for clarifying! Yes your posting seemed a bit difficult to "read" ... Was it sarcasm ... Your "A" into "B" thing together with mentioning your age made me wonder ... Sorry if my answer was a bit harsh or provoked-sounding. You see - I must confess I did google some, - but just to back up on and stand by the recommended list ... 😉 Sorry to mis-read you, BillEpstein! I really genuinely want this thread to help people become concious about choosing their EL34's - and hopefully contribute to the manufacturers making good tubes for the right money!

If the consumers crave good tests and good quality at a correct price (the Shuguang Z's is sadly a bad omen as to prices vs quality) and this thread contributes to that, I'm very happy. This is really how simple the motivation for this thread is!

Best Regards Aril

 

[WE91]

Hi guys 🙂

First of all: Thank you all for your contribution making it possible to find a list of "the best current EL34's" and also to find a "system" as to how "measure" a new production tube's sonics; test'em against the true reference's!

I have much respect for this site (DIY Audio) because of "you guys" and your level of competence and experience. Because of this site's "weight" I hope people to take the list in this thread to be a truly serious suggestion in giving you the very best for your money in todays offerings.

"The List" once more (so you don't have to go back a page 🙂 )

The best current production - or available NOS EL34 type tubes!:
A four way shared 1st place goes to these:
*Gold Lion Genalex KT77 reissue
*Siemens NOS EL34
*SED "winged C" EL34
*EH-6CA7
Second place:
*Shuguang/Valve Art EL34

The first place is shared by so many tubes, because it is so much up to you and your preference. All the tubes in 1st place will give a balanced sound with very detailed and good imaging. Please choose the ones that you imagine will suit your needs/system best! Trusting our fellow DIY'ers comments, they should all be VERY good and possibly quite close, or even equal to our NOS reference tubes from "the golden age of tubes"!

- If you are rich and patient you can buy these:
Our reference NOS tubes are:
NOS Mullard XF2, NOS M.O. Valve Genalex Gold Lion KT77 and the NOS Sylvania 6CA7's.
- The question is if you would be more satisfied soundvise ...

Additional:
We may have something good coming soon that this thread haven't yet mentioned ...
In another thread on this fora I found "Johnm" quoting this:

" ... We are certainly “the spirit of Mullard” as most of us have been on site from the Mullard days. Yes the site is still in operation, wasn’t doing valves but is again now. They are not the same technology but the ethos remains.

Our plans currently have EL34 and EL84 in the roadmap for early 2009. Customer feedback of required types like yours is much appreciated as we don’t want to make all the variants; it’s not viable in the UK."

It's from this thread

Here's hoping that the prices doesn't become astronomical!!!
Hope Shuguang Z-prices will be only an attempt at "overpricing" that dies away because of lack of demand!

Small production, "higher end" and so forth - often accompanied by ... You guessed right - high prices (even if they're not justified). I guess they know there's a marked ...

I hope there will be tests/reviews of these new offering of tubes done the way suggested in this thread, so that we can know how they really come through!!!

Best Regards
Aril

 

[RJ]

Here's another vote for the EH 6CA7s.

Just put a matched pair in my Simple and that magic mid-range really came through even before break-in.

Pairs everywhere for $38; not much risk.

I bought 2 Quads of EH 6CA7's and was greatly surprised to find out that Mechans (from AudioGon) experience with them are the same as mine!

Mechans post The 6CA7 is also valuable because it is the true fatboy type. That tube is a tetrode whereas EL34s are often described as one tube. This is untrue they do sub for each other but the EL34 is a "beam" pentode. In my amps there is an astonishing difference in the sound. With true 6CA7s which are available from EH they sing gloriously, with great dynamics, slam and authority across the bandwidth, EL34s are a mere 98lb weakling by comparison.

Bill Epstein has also described the midrange magic I heard with these tubes. I'm really pleased to have followed this thread.

 

[rknize]

I'm looking for more midrange from these KLF-10s. I'll give these EH 6CA7s tubes a spin next time I order parts from one of the vendors. I found the EH KT90 to have a more pronounced midrange as well.

Again, Mechan's comment about what the EL34 is is wrong, I believe. The EL34 was originally a true pentode while the 6CA7 is a beam tetrode. The EL34 lacks beam forming plates, which in turn means that when triode-strapped it acts more like a normal triode than a beam tetrode would, right? When triode-strapping a beam tube, you are ending up with a "beam triode", are you not? The beam forming plates are still doing their thing. The suppressor grid on the pentode is still there, but I don't imagine it is doing anything since there probably isn't any secondary emissions to worry about? That may be why the EL34 makes a nicer triode than some of the other big beam tubes....

 

[RJ]

I'm looking for more midrange from these KLF-10s. I'll give these EH 6CA7s tubes a spin next time I order parts from one of the vendors. I found the EH KT90 to have a more pronounced midrange as well.

Are the EH KT90's swapable with the EH 6CA7's??
I did a quick search and came up with very little info on the KT 90's.
Interesting comment on female vocals with the KT90's.
I use female vocals a lot to judge hi-fi setups.

 

[rknize]

Yes, they are just a bigger KT88 so they are pin-compatible with the EL34/6L6/KT66/KT88/etc types. They call these a KT90 probably because they resemble the old Ei one. They look resemble a giant EL34 with relatively long plates for their envelope size. I think they are an adapted sweep tube (PL509). They have a lot of fins on the plate. I can run them at 100mA and they don't even break a sweat.

 

[WE91]

Hi RJ and rknize.
Very nice, RJ, that this thread is helpful 🙂
My "checkup" (google) on the EH6CA7-EH told me that they vere close copies of the Philips and Sylvania fat bottle 6CA7's. A check up on those told me that they are pentodes, not beam tetrodes. There might be something I haven't found, - so please elaborate and tell if there's more to this. They have large plates, though - and have different characteristics to the ordinary EL34's. They will sound different. The EH6CA7 is supposed to be very close to the NOS tubes it copies. The sound is said by people who have A/B tested them (in the same circuit) to be as good as "the real deal" NOS types. In other words; this tube is a bargain. I believe the Watford review to be quite correlating well with all other findings on these tubes sonics.

Repeating my little statement conserning recent "developement":
We don't need the overly expensive "higher fidelity/new invention" kind of tube offerings from Shuguang (and Mullard?), when we have the tubes in this threads 1st. place ranking! These are as good as EL34's have ever been!
Prices near the reissue Gold Lion KT77 or NOS Siemens, their sonics being equal or possibly better (in a real test), - should be the "upper limit" for any such new "higher end" power tube! Then we could welcome them and buy them.
I'm not counter-productive or against positive drive and developement or people making money! We should welcome new developement, but not at an unreasonably high price! We, the consumers, must show the manufacturers through being concious 🙂 - We may risk a situation as for "the popular power triodes"; insanely high prices! Don't you think ...

Best regards Aril

 

[WE91]

I'm on a roll now So here's a bit more cannonfire
Todays marked giving highish NOS-tube prices makes manufacturers see bigger profit-margins if re-introducing or producing "new" NOS or "higher end" tubes often with an aura of mystique about them ...
Many are being fooled by good marketing and this "mystique" giving the effect of the consumer "believing" in a product being superior. If paying a lot for them and if they look "impressive" many will feel "confident" in owning "the highest end". Being caught in this may prevent you from actually discovering the *best sound your amplifier may be able to give! Is this to our benefit?
Price often says something about quality, but you must know when it's out of proportion! I feel a line ought to be drawn at/around 40 to 50USD as an absolute maximum for one tube for current production! (no matter how high a fad, number of "new" parts, black paint or "NOS name"). The pricing of the tubes in this threads list gives a reference as to level of performance/price ratio. If someone wants higher prices, they must prove the extra winnings/benefits in ways that will give us satisfaction that it is really worth it in sonics bettering real references!

*(footnote: "Best sound" is subjective).

 

[Ty_Bower]

The EH-6CA7EH is a close copy of the NOS Sylvania fat bottle 6CA7 and the Philips 6CA7 and they were made as a pentodes (true EL34 if you will).

I have a couple quads of Electro Harmonix 6CA7-EH. Unfortunately, they are at home and I am away so I cannot physically verify right now. I am about 99.9% confident they have beam forming plates, not a spiral wound third grid. My personal preference is to call tubes with beam formers something like "beam tetrode" or "beam power tube." I will refer to a tube with a spiral wound G3 as a "pentode". Technically, the beam tubes do have five 'odes in them, so they could be called a pentode, but that just confuses everyone. (As if they weren't confused enough.)

Again, Mechan's comment about what the EL34 is is wrong, I believe. The EL34 was originally a true pentode while the 6CA7 is a beam tetrode. The EL34 lacks beam forming plates, which in turn means that when triode-strapped it acts more like a normal triode than a beam tetrode would, right? When triode-strapping a beam tube, you are ending up with a "beam triode", are you not? The beam forming plates are still doing their thing. The suppressor grid on the pentode is still there, but I don't imagine it is doing anything since there probably isn't any secondary emissions to worry about?

I have read that some vintage 6CA7 had spiral wound G3. I have also read that some vintage EL34 had beam formers. I know for a fact that many vintage tubes were very clearly labelled with both designations "EL34/6CA7". So what does all that mean? I do not believe you can simply trust the label printed on the bottle to tell you what kind of construciton is inside.

As far as secondary emissions go, all vacuum tubes suffer from it to some degree. The impact is worse in triodes - their efficiency is lower as a result. Secondary emission was most likely one of the key motivating forces behind the development of multi-grid vacuum tubes. The reason for the occurrence of secondary emission is not because the screen and suppressor grids exist. It is the other way around - G2 and G3 exist to combat secondary emission.

My "checkup" (google) on the EH6CA7-EH told me that they vere close copies of the Philips and Sylvania fat bottle 6CA7's. A check up on those told me that they are pentodes, not beam tetrodes. There might be something I haven't found, - so please elaborate and tell if there's more to this.

See above. Again, I'm pretty sure the Electro Harmonix 6CA7-EH is a beam tube. One reasonably accurate way to tell (besides peering inside through the plate holes, or looking for the telltale structure poking above the mica) is to measure the screen current. One key feature (perhaps even a requirement?) of beam tubes is the alignment of the G1 and G2 grids. Screen current is typically much lower on a beam tube than on a pentode of similar class.

edit: I found a good photo of the 6CA7EH. Look in the plate holes - you can see the beam formers inside. Count the grid support rods poking through the top of the mica. There are only two, not three.

 

[Jeffrey Davison]

here's som interesting info to chew on....

I've built a preamp based on Pete Millets "Low Mu" design. It uses a 6SG7 / 6080 / 5998 / WE421 as the main triode output tube.

It uses an EL34 / 6CA7 wired as a CCS to load the tube.

In this application, the preamp requires a quiet tube.

I've been fortunate enough to have a genuine pair of NOS Genelex KT77's. Also on hand I have a pair of reissue KT77's and a pair of the EH6CA7.

As a CCS, the NOS GEC brought a lot of tube noise into the audio spectrum. The reissue was a lot quieter but still a bit of high ptched whistling was distracting me from audio bliss. I then tried the EH 6CA7's. The quietest of the bunch, still a bit of tube noise coming through, but not that distracting and very liveable.

Well, I had a pretty good tax refund this year and I was very intrigued with the construction and material choices of the Shuguang 6CA7-Z. It's a redesigned tube from the ground up with alot of thought put into it's design, construction and materials. True it's a bit pricey, but the quality IS there.

I know alot of people factor cost into their choice of tubes, but taking that factor out of the equation, I made some judgements based on the tubes themselves.

You have to remember that I'm NOT using the tube as a power tube so my results probably have nothing to do with what most who are reading this will use the tube.

In my system, in my preamp as a CCS, the New $huguang is the absolute quitest,( no noise what so ever) and best sounding of the bunch. I haven't tried an EL34 NOS of any variety, nor any reissues there of. I really have no need to look any further as this is the right tube for the task I ask of it.

So guys, please keep an open mind about tubes and I know it's hard not to factor cost in but if it's build quality, construction and sonics, don't over look the Z.

JD

 

[Johan Potgieter]

A very interesting collection of facts/observations from a number of enthusiasts. This is what we need in these days of branding, cross-branding/cross-pollination/whatever. Ditto to the member remarking that in the hey-day there was enough demand so that reliable firms like RCA, Mullard, Sylvania et al could each afford their own manufacturing plants with resultant healthy competition quality-wise.

The sad fact is that only with time will reports of those 'that did not make it' duration-wise surface. I wonder if anybody here has used particular tubes for that long.

Just to illustrate the 'free' branding of tubes: I have a cut-open model of the argued-about 6CA7 - and it is decidedly a 3-grid pentode, resembling the classic EL34. So.

 

[rknize]

I have a couple quads of Electro Harmonix 6CA7-EH. Unfortunately, they are at home and I am away so I cannot physically verify right now. I am about 99.9% confident they have beam forming plates, not a spiral wound third grid. My personal preference is to call tubes with beam formers something like "beam tetrode" or "beam power tube." I will refer to a tube with a spiral wound G3 as a "pentode". Technically, the beam tubes do have five 'odes in them, so they could be called a pentode, but that just confuses everyone. (As if they weren't confused enough.)

I have read that some vintage 6CA7 had spiral wound G3. I have also read that some vintage EL34 had beam formers. I know for a fact that many vintage tubes were very clearly labelled with both designations "EL34/6CA7". So what does all that mean? I do not believe you can simply trust the label printed on the bottle to tell you what kind of construciton is inside.

True...what I said was a bit of a generalization. Perhaps my memory fails me, but I seem to recall the 6CA7 was supposed to be a ruggedized EL34 for the military. Maybe I made the leap in my head, but it seems like one way to do that is to eliminate one of those fragile grid windings. As time went on, I'm sure brands and designs began to cross-pollenate as manufacturing slowly consolidated and wound-down.

As far as secondary emissions go, all vacuum tubes suffer from it to some degree. The impact is worse in triodes - their efficiency is lower as a result. Secondary emission was most likely one of the key motivating forces behind the development of multi-grid vacuum tubes. The reason for the occurrence of secondary emission is not because the screen and suppressor grids exist. It is the other way around - G2 and G3 exist to combat secondary emission.

Yes, of course...I'm well aware that G3 is there to take the kink out of the tetrode the same way that the beams blast their way past it in a beam tetrode. 🙂 G2, as I understand it, was put there to shield G1 from the anode. The idea was to reduce Miller capacitance. Not trying split hairs...just wanting to make sure the facts are straight. However, the indroduction of G2 is what necessitated G3, so I guess you are right from that perspective. 😉

See above. Again, I'm pretty sure the Electro Harmonix 6CA7-EH is a beam tube. One reasonably accurate way to tell (besides peering inside through the plate holes, or looking for the telltale structure poking above the mica) is to measure the screen current. One key feature (perhaps even a requirement?) of beam tubes is the alignment of the G1 and G2 grids. Screen current is typically much lower on a beam tube than on a pentode of similar class.

I agree there...any Reflektor tube with round holes seems to be a beam tetrode. Also, if memory serves, beam tubes have larger plate structures in general because more space between G2 and the anode is needed to prevent too many wandering electrons that were not repelled back to the anode from reaching G2.

 

[WE91]

No, no, no, no, Jeffrey Davison ... 😉

In my system, in my preamp as a CCS, the New $huguang is the absolute quitest,( no noise what so ever) and best sounding of the bunch. I haven't tried an EL34 NOS of any variety, nor any reissues there of. I really have no need to look any further as this is the right tube for the task I ask of it.
- So guys, please keep an open mind about tubes and I know it's hard not to factor cost in but if it's build quality, construction and sonics, don't over look the Z.

😎 😉 😉 I've been quite tough in what I've said about these. It has all been about the price - and the attempt Shuguang does to make it "special" so it can justify the pricetag ... What's behind the black "paint" and what does these looks do to the "mystique" ... With this price they should(!) be very well made tubes with really excellent sonics, far outclassing all others. What you are saying here, Jeffrey Davison, is most welcome!!! Contributing to give a "picture" of the new, pricey Z's performance. A great comparison to the EH6CA7-EH, allthough, as you say, it do not tell much about the Z's sonics as an output-tube. - I would love to have these Z's compared to other current high quality tubes! (But DO NOT like what this "trend" Shuguang is contributing to with Z's may do to "pushing the price envelope" of high quality EL34's).
Nice to hear about the low microphonics in the EH6CA7 too ...

Very nice, Johan Potgieter! The EH6CA7's are built like pentodes then ...

Just to illustrate the 'free' branding of tubes: I have a cut-open model of the argued-about 6CA7 - and it is decidedly a 3-grid pentode, resembling the classic EL34. So.

This might give som explanation to 6CA7's ... And this datasheet from Duncanamps
- And this too ...

 

[ja2dhc]

The attached photo compares 6CA7 made by Matsushita in 1963
and ShuGang's EL-34B made in the 21st century.

The constructions resemble each other and plate currents
are identical in my amplifier. At 1963 time frame, Matsushita
had a technical joint from Philips therefore its 6CA7 was
considered to be the same design with Philips's. 21st century's
EL-34B by ShuGang seems to take the original Philips' design.
I think this construction contributes to good sonic.

 

[WE91]

Arigato gozeimasu, totemo, ja2dhc 🙂
I guess we're on to something ... The whole 6CA7 beam-tetrode/pentode thing seems a bit "unclear" - as there's testimony to both tetrode and pentode construction ... I guess I will let the reader find out if this is something you want to investigate on your own. A new thread on this maybe?
Suffice to know that the tubes recommended in this threads list all are fine in an EL34 amplifier!!! Here's wishing everybody the very best sound for their money!
Matane, ja2dhc
Sayonara😉

Best Regards Aril

 

[Wavebourn]

Logically thinking, 6CA7 should be a ray tetrode, while EL34 -- pentode. Why? Legal issues, patent right. 6CA7 was made using modified 6L6 technology and documentation developed by RCA engineers in 1930'th. Manufacturing development and setup in pre-CNC era was costly for production of a totally different tube.

 

[WE91]

So it seems that an aswer to the beam-tetrode/pentode question might be given here by Wavebourn ... it seems so plausible.
I will bow out of this now, but I'll be back (as Schwarzenegger says) in this thread if talking about ranking of tubes or when I get my audio up and running and doing my comparisons of the better EL34/6CA7's (some time into the future) ... I've got quad's of several 1st. position ones - and also a bunch of different NOS 6SJ7 and 6SN7's.

Please post if someone knows of good tests of the much talked about Shuguang Z's or the new "real" Mullard EL34's

-with Austrian (-Norwegian?) accent:I'll be back 🙂

 

[Johan Potgieter]

In my previous post I was not trying to 'polarize' matters regarding the 6CA7. It is obvious that they come both with G3 and without it - too much evidence of that.

To perhaps recap briefly (apologies to those in the know): The screen grid was added to a triode with a dual purpose: To shield the anode from the g1 because the position without it (triodes) became impossible in r.f. due to the high anode-g1 capacitance. The second purpose was to provide a constant current characteristic, so that the constancy of the electron 'stream' was not influenced by anode voltage (as in triode). It is this second feature that brought on the problem of secondary emission - electrons 'bombarded' off the anode by the arrival of high speed electrons all the way from the cathode. It was not a problem with triodes because they merely returned to the anode - the only positively charged element in the vicinity. But with an equally positive (or sometimes more so) g2 in the area, the screen current would increase abnormaly with the anode going lower in voltage than the screen during positive g1 swings.

Thus a g3 was introduced with little effect on the fast travelling electrons of the primary stream, but enough effect on the much slower travelling secondary electrons bounced/dislodged off the anode. (A g3 would be seen with much wider space between windings than other grids.)

The beam tube advantages came about when an alternative had to be found to a pentode as mentioned before (patent matters etc.) Here it was found that a space charge of electrons formed near the anode with the anode further away from the another electrodes than before. This was, with the right electrode distances, found to be sufficient to replace g3 action, with some advantage in efficiency. The beam forming electrodes were added to prevent stray electrons at the sides to find other ways of going around because the grid-anode geometry did not exist there because of mounting posts etc. It is stated in original notes that beam tubes may or may not also have G3s. The extra efficiency resulting from g2 lying 'in the shadow' of g1 windings (same pitch) is another feature, not really related to the space charge-g3 matter.

Thus (in the early days, anyway) such 'pentodes' could exist with/without beam forming electrodes, and independently, with/without G3. The common beam tube topology emerged historically as the preferred way; the point is that one could have, say, the 6CA7 with/without g3, or with/without beam confining electrodes.

As far as I know this is the only tube where this variation exists in practice. RCA Tube Manual lists the 6CA7 as equivalent to an EL34 with identical characteristics; they call it a pentode, thus with g3. I think it has been evident that, probably in the interests of economy, the Russians are now marketing more kinds of 'generic' structures. Thus the about 9% difference between KT66 and 6L6GC is ignored, and the identical structure is used in both tubes; some are even marked KT66/6L6GC. The ideal curved anode structure has also been dispensed with, apparently with little adverse effect. (Original KT66s had a flat anode, original 6L6s a curved one.)

Above basic notes come from RCA Tube Manual and other early works on tube development. Again apology for hopefully informing some of what must be old hat to others.

 

[Johan Potgieter]

The mainly sounding and measuring difference is that the tetrodes have a much sharper clipping and more high order odd harmonics, than the soft clipping EL34 pentodes.
The percentage of the optimum screen-taps for ultralinear operation also differs. Normally 40-43% for tetrodes and 25 - 30% for pentodes.

Johan (namesake!)

This is basically so, but in practice depends on the circuit design. Clipping, yes; but hopefully one does not normally listen there; that is in overload! (excluding guitar amps where this characteristic may be used as part of the guitar sound). Distortion patterns before overload depends on circuit parameters.

Then similarly, one will find that the chosen % screen tappings also depend on design features. I am sure you are aware that EL34 (pentode) designs in fact largely use 43% taps. Outputs are slightly higher the lower the screen taps, but 'triode' typical characteristics appear somewhat more prominent with increased tap %. Very generally maximum outputs start to decline notably with taps >45%, so that UL advantage then begins to disappear. Again this is tube-specific; the above is general.

 

[rknize]

I'm looking for more midrange from these KLF-10s. I'll give these EH 6CA7s tubes a spin next time I order parts from one of the vendors. I found the EH KT90 to have a more pronounced midrange as well.

Just wanted to check-in and say that I did pick-up those EH 6CA7s not long ago and have been listening to them. They sound great in the SSE! They pick-up enough of the bass that the EL34 lacks and have a nice midrange like the KT90s. I haven't done any "critical" listening with the SSE in a while, but I've been listening to lots of live Knopfler stuff while doing other work in the room (finally getting to some remodeling). I was using the TSE before, but it just can't fill the room and have good bass response at the same time with those 45s. The SSE is perfect and plays live rock music the way it should be. The 6CA7s sound really nice as triodes. I'll have to sit down "in the spot" with some female vocals to see how they really compare.