The good, bad and ugly EL34/6CA7 list

organ

Since many of us here use EL34/6CA7 as power tubes in our amps, I thought it would be nice to share our experience with different tubes so we'll know which tube to buy next when we're looking for a different sound.

Here's my list starting from my favorite EL34:

1. Electro Harmonix EL34EH. According to Vaccum Tube Valley, they come closest to the best sounding EL34 by Mullard. After reading several posts about people running the EL34EH in triode and getting results which is as good as Mullard, I bought another quad which arrived today. The sound is KILLER. The EH is a Mullard copy. If you see pics of the old slim bottle Mullard, they look pretty much identical. My old quad of EH was getting weak. I was able to tell by the sound. The reason for this was using them to run my LSi9 a long time ago which I'm sure stressed the crap out of them and shortened their lifespan.

2. Svetlana (SED). In pentode, I'll have to say it's my favorite. So the SED is a tie with EH. The sound is much warmer than EH. However, I also used the SED to power my LSi for quite some time. One tube was pretty stressed out because the plate was slightly glowing. I'm planning to buy another set to play around in triode.

3. Electro Harmonix 6CA7. Direct replacement for EL34 even though it's a tetrode, it will work in pentode or triode. In pentode, this tube had a lot of power with great bass. Soundstage was large with a lot of detail. Not as 'romantic' sounding as EL34. Sounds smoother in triode but with less bass.

4. JJ E34L. I just don't get it. A lot of people love this tube but I didn't like them at all. The mids didn't have any bloom and the highs sounded dry to my ears. Their strength is bass output. Powerful and deep. IMO, this tube have no character unlike the others listed above.

That's it for now.

Please add what you hear in your EL34/6CA7 tubes even if I've already done so. Would be nice to see if we're hearing the same thing from these tubes. Just like speakers, different tubes have their own sound signatures.

I'm still waiting for a report from Madmax about the Shaguang tubes he purchased. He's still breaking them in.

Maurice

BlueMDPicker

Hi Maurice,

This looks like a good thread to keep alive given the interest in tube gear by several forum members.

I noticed your initial evaluation of the JJ/Tesla E34L was pretty dismal. After the tubes broke in, did you find them more pleasing? I really like them in the Dynaco-70 - more so than the Dynaco/Mullard EL34's. However, in my newly acquired DCM Lab 75+75 the Mullards are amazing. The DCM uses a .3 volt bias setting (versus the 1.5 +/- on the ST-70) and has a bias pot for all four power tubes. I don't know if that's the primary contributor to these Mullards coming to life, but they rock in this amp!

After reading through dozens of threads in various forums, I decided to get a quad of Ei thin bottle, pinch top EL34's. Should get them this week.

I also have a chance to buy a matched quad of original Tesla E34L's for $150 (versus the $200+ commonly seen on AudiogoN), but I think I'd rather have 3 or 4 quad of current production tubes to roll than tying up that much in vintage tubes.

And, of course, the new toy uses a quad of 12AT7's (about the only small signal tube I don't have in play between hifi and organ gear.) Had any experience with them?

Mike

organ

It's a funny story. I bought a quad of JJ E34L about a year ago when I was still running the LSi9 on my Dyna. That's when I thought they sounded like crap. They were so bad with the LSi that I didn't even bother to break them in. They had less than 10hrs of use. I just didn't know what all the hype was. And when I was ready to give them another try, the coupling caps on the dyna went loose and ate the JJ's alive.

Fast forward to Dec.... Again, I'm reading the archive on audioasylum.com to find out which EL34 I should try next and like before, everyone is talking about JJ. So I decided to give them a try again. But this time it was pure magic! I have a pair of Klipsch and they sound amazing. For some reason, I just couldn't enjoy them on the LSi.

Aaaah, I think your Mullards weren't properly matched. The bias pots on the Dyna are set up so that you need a matched set for each channel, so the one pot controls current to both tubes on each side. With the DCM you can adjust bias to all four tubes.

Let me know how the Ei sounds. I hear they have some very good mids. I'm thinking about trying out their "Big Bottle" EL34/6CA7.

Don't get the Tesla E34L. I hear the JJ is superior. Go to audioasylum.com and do a search on the tube forum. At least that's what I read. Plenty of discussions there.

Sorry, I have no experience with 12AT7's. Here's a healthy bunch of NOS and current production 12AT7. Great prices on NOS too... http://www.thetubestore.com/12at7types.html

Maurice

BlueMDPicker

Hi Maurice,

It's going to be hard to roll this Sylvania/Mullard/Dynaco quad out and put the Ei's in when they arrive. I got tired of dicking around with my ancient analog multimeter and picked up a digital VOM today. I dialed the bias in on the DCM amp down to the microvolt on each tube. I then rolled my Telefunken/RCA black plate 12AU7 duo, and RCA black plate 6X4, out of the preamp for a pair of Ei's and a 50's Tungsol 6X4. The sound is nothing short of amazing driving these SDA-SRS's. The bass is tight, extended and chest thumping. I never was too impressed with the PR's in the SRS's until I drove them with the ST-70 and, now, the DCM.

The former (and original) owner of the DCM claims the original Tesla's are the best tubes he ever rolled through the amp. But, my musical tastes are pretty different than his. And, what my ears crave is the warmth and dynamism of live music. I'm almost there.

BTW - I couldn't resist the urge to pop the chassis bottom of the DCM and explore a bit. Fantastic design and build quality. I was most impressed that the entire signal path on the PCB has its traces overlaid with silver wire reflowed to the trace. A work of art.

The amp came with AudioPrism 12AT7A's. I'm not familiar with that brand, and have no experience with the tube type, so I can't comment on what they might be similar to or who actually made them. I'm trying to grab a quad of NOS Mullard 12AT7WA's off eBay this week - simply to see what an all Mullard design tube lineup will sound like. I'll probably buy a quad of new production Ei's as well to try with the Ei pinch tops.

On the ST-70 front, I thought I was going to pretty much leave it alone until I heard the difference a dedicated phase splitter and gain tube per channel could make driving a quad of EL34's. I now think the old driver board is going. Just haven't decided which mod board to go with. A board with 4 small signal tubes is certainly going to grab my attention the quickest.

Love da' tubes!

Mike

BlueMDPicker

I'll try to update my listening experiences over time. So far, here are the rankings from EL34/6CA7 types I've tried:

1. JJ/Tesla E34L - Really bring out the best in my ST-70. Bass is tight and extended with real punch. Clear mids with exceptional definition and imaging. Highs are shimmering and vibrant without harshness or grain. They took aprox. 30 hours to burn in and open up. I haven't tried this tube in the DCM yet.

2. Vintage mixed quad of Sylvania/Dynaco/Mullard (all identical build structure) - In the ST-70 they have a warm and buttery mid range, yet not to the extent of detail loss. Bass is strong, but a bit loose. Highs roll off a bit early. In the DCM they are about all you could ask for. Makes you feel like part of a live musical experience.

3. Ei thin bottle pinch top EL34 - Still breaking these in with the DCM, but they have opened up nicely after approx. 24 hours. Best imaging tube I've tried, but quite thin in the bass and not much depth to the soundstage. I have my fingers crossed on this quad as they are well regarded in DCM designs.
Edit: At about 36 hours these tubes were starting to sound great. One problem - one of them started arcing on the cathode riser to the beat of the music in play. It didn't effect SQ at all (surprising), but it was obvious the tube was destined for a short life. I returned the quad for replacement and have not received the new tubes yet.

BlueMDPicker

Ei thin bottle pinch top EL34 follow-up
I received a replacement quad from the vendor. After initial biasing, a 45 minute warm-up, and re-biasing to spec I began a listening session. Two minutes into the second selection, one of the tubes blew in a quite spectacular fashion. I happened to be looking at the DCM amp from the listening position at the time. The plate of the tube went instantly cherry red and, as I jumped and ran toward the amp, popped its glass sleeve from the base - accompanied by the sound of a tug boat horn at close range from the right channel SDA SRS.

Back they went to the vendor, where I now have a credit. I haven't decided what to roll next. Perhaps the SED EL34's?

Tour2ma

Damn... Hope you were wearing your Depends...

BlueMDPicker

Originally posted by Tour2ma
Damn... Hope you were wearing your Depends...

Of course! I never change them until they're bagging down between my knees.

organ

Wow! Excellent reviews, Mike.

Sorry to hear your troubles on the thin bottles. I've been doing some readings and it seems they seem to be the 'weakest' out of all current production tubes. This is coming from guitar amp owners though.

Does the bias on your DCM drift with the line voltage? If the amp doesn't have a voltage regulator, this will happen just like the Dyna. So your bias voltage could increase at certain times of the day or night without you knowing about it. I know that a bias voltage that is too high will produce glowing plates.

I haven't decided what to roll next. Perhaps the SED EL34's?

Screw the SED for now. Get the Electro Harmonix EL34EH. I'm suggesting these tubes because you mentioned this on your earlier post...

my ears crave is the warmth and dynamism of live music. I'm almost there.

I still can't figure out which one I like better. I've been using both the JJ and EH and swapping them every few weeks. Both are amazing tubes but the EH are more 'lively' sounding than the JJ with almost a SS control on the bass. The SED sounds closer to JJ. However, the EH is not as warm as either the JJ or SED but they're certainly more 'lively' like I mentioned before. They have more 'snap'. Kinda like going from Polk to Klipsch.

Hey Tour,
Have you had the chance to try out the new Mullards yet?

BlueMDPicker

Thanks Maurice.

Well, the vendor sent me yet another quad of the Ei thin bottles after I returned the second quad - which was NOT our understanding. I gave him a call this morning to see what was going on. He said sorry for the mixup and if they gave me any problems just keep them and he'd refund my original purchase price and shipping. So, fingers crossed again as I break them in. The first quad was opening up nicely before one tube went "disco" on me. The imaging of these tubes is extraordinary. I know that Manley designs several of their amp lineup with Ei tubes in mind based on their own reliabilty and listening tests and availability as a current production tube.

The DCM seems very stable with its bias settings. I certainly hope I'm not experiencing line voltage drops, but it's an interesting consideration to explore.

I haven't tried the RF-3's with the ST-70 yet. I have the ST-70 setup in the MBR on another floor with SDA-2A's. And, I don't think I'll try triode strapping on that amp until I have the time to replace the original tube sockets (the rectifier socket is very loosey-goosey.) But, I agree that it will still have sufficient power - especially in that application.

Mike