6L6 vs EL-34 output tube update

[myles_rose]

I deleted the image that was here as it caused much longer download times on this post.

 

There have been some test results published on the current EL-34 and 6L6 tubes recently.

Today on 3/3/02, we retested some of the tube types we had tested in the past with some new samples that we procured from various sources. This was after the distributor (who is on our mailing list) asked us to do so again, as they were surprised by the results.

 

In the process, we also did some out and out power comparisons, using the same set of parameters in the same circuit to look into this. There are now a number of amps which allow the user to swap the EL-34 and the 6L6. Keep in mind that the power supplies have to be capable of supplying two times the heater current for the EL-34, and other factors such as a mismatch of tube to output transformer impediance will result to a certain degree.

 

It is always best to know which tube your amp was optimized for, as a compromise in many cases is not all that great an idea generally.

 

Once again .... the "magic number" we are looking for is "72" on the 6L6 tube, and "100" on the EL-34, but for the second phase of this test, the 6L6 tubes were run at the same voltages as the EL-34 in a few tests. This will be marked or indicated.

 

As a comparison, we also retested the JJ EL-34 just for the fun of it.

 

Power output:

 

JJ EL-34 120.4 mA

 

Electro Harmonix EL-34EH 97.5 mA

 

E! Yugoslavia EL-34 94.3 mA

 

Electro Harmonix 6L6EH 81.1 mA (@ EL-34 settings)

67.1 mA (@ industry settings)

 

Chinese KT-66 91.0 mA (@ industry settings)

(this tube will exceed an EL-34 in output

using the EL-34 settings. This is a very

strong tube)

 

Sovtek 6550 120.2 mA (@ industry settings)

(The measurment on this tube should have been

140 mA, so these are not as strong as the

6550A USA GE tubes)

 

In brief ... if you are after high power and lots of headroom, the KT-66 is a great tube, but also has a very nice sound. The KT-66 is right up there with the "general" EL-34 tubes in output, and if you run them at higher voltages (which is well within spec), they will exceed most of the EL-34's in pure output.

 

If you want "balls to the walls" with your Marshall or an amp that uses these, then the JJ/Tesla offering is the way to go. These tubes by the way, were very consistant, and had gorgeous curve traces.

 

The curves on the Electro Harmonix offerings, in the last tested batch, differed from the Mullard's it was supposed to be patterned after. The Mullard's had a transconductance value of 11,000 while the EH offering were measured at about 8,100 for a 15 tube average, and all were very close to this figure. So .... if you want the Mullard sound, it looks like NOS is still the only way to go.

 

For those that missed the original tests, for the 6L6, the link here is:

 

http://acapella.harmony-central.com/Forum17/HTML/028064.html

 

.... and the EL-34 results were posted at:

 

http://acapella.harmony-central.com/Forum17/HTML/027432.html

 

Have a nice day .....

[Lance-a-not]

Thanks as always for the info Myles... You rock ! BTW I was sorry to see you go from the HC forum, although I definitely understand why ( so I signed up here too... all the more knowledge to absorb ).

 

Actually I have a question if it is not too off track. I have a Univalve, on your site I saw the importance of matching the sides of the preamp/ driver tubes as well. My question is does this make such a differance on the UV, or even a more pronounced difference?

 

Many Thanks,

 

Peace

 

Lance-a-not

www.mp3.com/lancebowzer

[myles_rose]

Originally posted by Lance-a-not:

Thanks as always for the info Myles... You rock ! BTW I was sorry to see you go from the HC forum, although I definitely understand why ( so I signed up here too... all the more knowledge to absorb ).

 

Actually I have a question if it is not too off track. I have a Univalve, on your site I saw the importance of matching the sides of the preamp/ driver tubes as well. My question is does this make such a differance on the UV, or even a more pronounced difference?

 

Many Thanks,

 

Peace

 

Lance-a-not

www.mp3.com/lancebowzer

Lance-a-not ....

 

On your Univalve, it won't make a bit of difference. The output stage in the Univalve is class A, but also not push-pull, and open ended. What this means to keep things easy, is that the output tube in the Univalve has no crossover notch, no crossover notch distortion, and is conducting all the time. The driver tube (V2) only has one job ... and that is to push one tube ... not a pair.

 

So... experiment all you want, but in the case of the Univalve, spending extra money on a matched anything... preamp or power tube, is not necessary at all, and will not yield anything useful.

 

The Univalve also loves output tubes that are worn out and out of spec from other amps. It it works at all, it will work great in a Univalve. Try to get your friends to give you their "old and worn out" tubes!

 

Regards,

[dale661]

This is a pretty cool place Myles. I like it. I've come here from HC as well.

[Lance-a-not]

On your Univalve, it won't make a bit of difference. The output stage in the Univalve is class A, but also not push-pull, and open ended. What this means to keep things easy, is that the output tube in the Univalve has no crossover notch, no crossover notch distortion, and is conducting all the time. The driver tube (V2) only has one job ... and that is to push one tube ... not a pair.

 

So... experiment all you want, but in the case of the Univalve, spending extra money on a matched anything... preamp or power tube, is not necessary at all, and will not yield anything useful.

 

The Univalve also loves output tubes that are worn out and out of spec from other amps. It it works at all, it will work great in a Univalve. Try to get your friends to give you their "old and worn out" tubes!

 

Regards,[/QB]

 

Thanks Myles,

 

I did try a worn out a OLD 6l6 from my girlfriends Mark 1, and it sounds fantastic !!

 

Muchos Kudos

Peace

 

Lance-a-not

www.mp3.com/lancebowzer

[LesPaul59]

Myles,

 

It looks like some of us are following you from the Harmony Central... Keep up the great work!

 

I'm glad to see the JJ E34L's being the way to go with Marshalls... I've tried Svetlanas EL34 and JJ's and the E34Ls seemed to complement my amp better...

[Sylver]

I've been checking out the HC forums as a lurker since Miles has told us that he posted there. I found that the members there seem to be very hostile, and there is a lot of in fighting. Jeez. Like I need to be pissed off when I'm surfing. Anyway, welcome aboard, all, hope you'll find MP forums rewarding.

 

Jack

[myles_rose]

Originally posted by dale661:

This is a pretty cool place Myles. I like it. I've come here from HC as well.

dale661 ....

 

Welcome to this forum. I hope you have a good time here. It is not as active as Harmony Central, but I am sure over time it will grow.

 

Regards,

 

Myles

[myles_rose]

Originally posted by Lance-a-not:

I did try a worn out a OLD 6l6 from my girlfriends Mark 1, and it sounds fantastic !!

 

Muchos Kudos

Peace

 

Lance-a-not

www.mp3.com/lancebowzer [/QB]

Lance-a-not ....

 

What you'll also find, is that a lot of those old tubes come back to life after putting them in a continuous duty cycle of a class A amp.

 

Regards....

[myles_rose]

Originally posted by LesPaul59:

Myles,

 

It looks like some of us are following you from the Harmony Central... Keep up the great work!

 

I'm glad to see the JJ E34L's being the way to go with Marshalls... I've tried Svetlanas EL34 and JJ's and the E34Ls seemed to complement my amp better...

LesPaul59 ...

 

The JJ's to a lot of folks seem to compliment the Marshall amps even more than the Svets for a lot of folks. They are a lot stronger than any other EL-34, and some of the 100 watt Marshalls have been scoped at 150 watts. The 50 watt heads typically put out at least 70 watts with these tubes.

 

Joe Perry, Joe Walsh, and Billy Gibbons use these tubes, and in a C-85 Matchless they are pretty amazing. The version they use is the Groove Tubes EL-34LS which is slightly different in plate construction than the JJ version.

 

On the last test we finished this weekend, out of 10 of the JJ EL-34's the spread was less than .4 .... and that again was 0.4 milliamps between the entire set of all ten tubes. What that also tells me, is that their quality control is pretty advanced, as these tubes came from 5 sources ordered as duets for either a JCM 800 Marshall or a Rivera Knucklehead 55 watt amp. We told the suppliers to send us tubes in the middle range, the same if possible as a Groove Tubes #5 set.

 

I also hope to see more of the good folks here from Harmony Central.

 

Regards,

[Chipotle]

Myles, I enjoy your tube information tremendously. I was wondering if the JJ EL-34 the same tube as the Groove Tubes E34LS?

 

Thanks again.

[dave123]

hi myles,

 

i've moved over here from hc too. i want to learn something and not get flamed for it.

[myles_rose]

Originally posted by Sylver:

I've been checking out the HC forums as a lurker since Miles has told us that he posted there. I found that the members there seem to be very hostile, and there is a lot of in fighting. Jeez. Like I need to be pissed off when I'm surfing. Anyway, welcome aboard, all, hope you'll find MP forums rewarding.

 

Jack

Jack ...

 

I used to post in both forums, generally here first. In the future I will be posting only here. I think the people over at harmony central that were some of the great ones, would find benefit in this forum.

 

By limiting my activity and help to this forum, I will be able to give more indepth and personal help to the folks in this forum. The personal email support will continue for the folks here, as will the phone call support that some of you have experienced.

 

Regards

[6AM]

I only wish I knew what all those test results mean!

[duderanimous]

Originally posted by Sylver:

I've been checking out the HC forums as a lurker since Miles has told us that he posted there. I found that the members there seem to be very hostile, and there is a lot of in fighting. Jeez. Like I need to be pissed off when I'm surfing. Anyway, welcome aboard, all, hope you'll find MP forums rewarding.

 

Jack

You are correct about the HC forums... there seems to be a lot of adolescent behavior there. I don't think it's too much to expect decent, courteous interaction on these types of boards, but I guess it's all up to the individual users, and what the moderators (or lack of in HC forums case) will allow.

 

Hey Myles... Nice to see that you are still accessible!!! Another great post, Sir. I look forward to reading many more of yours, as well as everyone elses here.

[myles_rose]

I was INCORRECT in my original answer to this question from Chipotle. I have just corrected this reply in another post in this topic, so perhaps scroll down.

 

Originally posted by Chipotle:

Myles, I enjoy your tube information tremendously. I was wondering if the JJ EL-34 the same tube as the Groove Tubes E34LS?

 

Thanks again.

Chipotle ...

 

There are two JJ EL-34's ... one is the 25 watt version and one is the 30 watt version as the GT EL-34LS.

 

Some folks claim they are different, and that Groove Tubes has some say so at the JJ factory. I am still trying to find an answer to this, as in my tests, the curves are identical. Bob, over at Eurotubes, is the importer for JJ, and visits the factory often over in Prague. He is a pretty astute fellow, and I think if there were a difference, he'd be aware of that.

 

I don't think there is a difference, but Bob is probably more of the expert here than I am. You may want to ask him the same question. You can find his phone number and contact info on his website at www.eurotubes.com

 

Regards,

[myles_rose]

Originally posted by dave123:

hi myles,

 

i've moved over here from hc too. i want to learn something and not get flamed for it.

dave123 ....

 

Welcome.

 

Myles

[myles_rose]

Originally posted by 6AM:

I only wish I knew what all those test results mean!

6AM ....

 

I will try to keep it a little more simple in the future. Sorry for too much techo mumbo jumbo ...

 

What I will try to do on future reports is have an overall area where I will list the strong points and weak points of tubes maybe ... or perhaps the best picks for particular amps or applications. I'll have to think this through.

 

If anybody here has ideas as to a format you'd like to see, I am open to any suggestions.

 

Regards,

[myles_rose]

Originally posted by duderanimous:

Originally posted by Sylver:

I've been checking out the HC forums as a lurker since Miles has told us that he posted there. I found that the members there seem to be very hostile, and there is a lot of in fighting. Jeez. Like I need to be pissed off when I'm surfing. Anyway, welcome aboard, all, hope you'll find MP forums rewarding.

 

Jack

You are correct about the HC forums... there seems to be a lot of adolescent behavior there. I don't think it's too much to expect decent, courteous interaction on these types of boards, but I guess it's all up to the individual users, and what the moderators (or lack of in HC forums case) will allow.

 

Hey Myles... Nice to see that you are still accessible!!! Another great post, Sir. I look forward to reading many more of yours, as well as everyone elses here.

duderanimous ...

 

Yes, I will be here. You can also always ask me anything via my email address if you want an individual reply to some issue that you might feel is specific to you and not as applicable to a forum issue, especially if you think we would be having an ongoing dialogue on the subject for a while.

 

Regards

[dave123]

hi myles,

 

i've been thinking about getting my marshall dsl 100 head retubed and the shop that works on my amps recommends groove tubes. does the gt el-34 ls give your amp more "crunch and shimmer" than the oem svet's? yes i know it depends on the preamp tube you're using and the quality of the phase inverter tube.. but i'm talking about the power tube characteristics when the tube is driven to saturation.

 

thanks,

dave123

[6AM]

Originally posted by myles111:

Originally posted by 6AM:

I only wish I knew what all those test results mean!

6AM ....

 

I will try to keep it a little more simple in the future. Sorry for too much techo mumbo jumbo ...

 

What I will try to do on future reports is have an overall area where I will list the strong points and weak points of tubes maybe ... or perhaps the best picks for particular amps or applications. I'll have to think this through.

 

If anybody here has ideas as to a format you'd like to see, I am open to any suggestions.

 

Regards,

I just wish I knew how the curves translated to bass, mids, and highs and over all tone.

[steve f]

Bogner claims 80 watts from a pair of Svetlana EL34s in their Shiva amp. Is this realistic? Seems awfully high. They acknowledge the plate voltage is very high. If it is a realistic figure I'm wondering what the lifespan of a pair of tubes is?

[signal1000]

I've been using GT E34Ls in my Marshall Jubilee for about four years now. They increased the output and gain dramatically. I had Svets in there to begin with and some RCAs that are made in W. Germany (not sure what they are). The Groove Tubes beat them and the mesas I've tried in that amp for tone and power.

 

Also a HC guy who's followed Myles over here. I've learned a lot from his posts and his site.

[peel]

hi!

 

hey, yet another HC escapee here. yes Im tired of the nonsense so here I be. :~)

 

"I've been using GT E34Ls in my Marshall Jubilee for about four years now. They increased the output and gain dramatically. I had Svets in there to begin with and some RCAs that are made in W. Germany (not sure what they are). The Groove Tubes beat them and the mesas I've tried in that amp for tone and power." (hi signal-nice to see you again-you in Montreal??? me - toronto))

 

I also own the 2550 jubilee which currently has svetlana el-34s, not sure about the 12ax7. Ive switched cabs from the matching 4 x 12 2551 down to a nice 2 x 12 and it has made the sound much better, less harsh. Now im wondering about the tube factor... any recommendations regarding this type of marshall.. that is, is it unique or will the jj's be an improvement over the svetlanas (as mentioned about other marshalls.)

 

I usually run it on the clean setting w/o the rhythm clip and use pedals to boost the signal for leads, although lately i have been using the r-clip and also using the lead setting for solos.

 

thanks in advance. peel

[myles_rose]

Originally posted by dave123:

hi myles,

 

i've been thinking about getting my marshall dsl 100 head retubed and the shop that works on my amps recommends groove tubes. does the gt el-34 ls give your amp more "crunch and shimmer" than the oem svet's? yes i know it depends on the preamp tube you're using and the quality of the phase inverter tube.. but i'm talking about the power tube characteristics when the tube is driven to saturation.

 

thanks,

dave123

Dave,

 

The LS's are more powerful, have more headroom,but are stronger in the mids. The Svetlana's are a more balanced and softer tube. If you use your amp for a wide variety of music styles, and play sometimes in a clean way, or rhythm guitar, the Svetlanas may be the way to go. If you are more of a full out person that does a lot of harmonics, hammer-ons, and has the amp close to max a lot, then the LS's may be the way to go.

 

Its a tough call, as it is really personal preference, and either tube can overlap the other depending on how the amp is set up in other ways.

 

One way of reducing the brighness of that amp is to use a Chinese 12AX7C in V1. If you want more brightness ... too much for some folks, then in V1 use a 7025.

 

Hope this helped.

[signal1000]

Originally posted by peel:

(hi signal-nice to see you again-you in Montreal??? me - toronto))

hey peel - good to see you again too. : ) glad that the Jubilee is back in your repertoire. I'm actually in Calgary, but good to see other Canadians on the boards.

Originally posted by peel:

I also own the 2550 jubilee which currently has svetlana el-34s, not sure about the 12ax7. Ive switched cabs from the matching 4 x 12 2551 down to a nice 2 x 12 and it has made the sound much better, less harsh. Now im wondering about the tube factor... any recommendations regarding this type of marshall.. that is, is it unique or will the jj's be an improvement over the svetlanas (as mentioned about other marshalls.)

 

I usually run it on the clean setting w/o the rhythm clip and use pedals to boost the signal for leads, although lately i have been using the r-clip and also using the lead setting for solos.

 

thanks in advance. peel

good question. I'm curious too since I've been using JJs in the preamp, but perhaps there is something a bit better.

 

I use my Jubilee with the GT E34Ls for a classic rock Marshall roar. They seem to have more grind and output than the Svets did. I do bluesy things up to a Marshall crunch and they suit my style just fine.

[myles_rose]

Originally posted by 6AM:

Originally posted by myles111:

Originally posted by 6AM:

I only wish I knew what all those test results mean!

6AM ....

 

I will try to keep it a little more simple in the future. Sorry for too much techo mumbo jumbo ...

 

What I will try to do on future reports is have an overall area where I will list the strong points and weak points of tubes maybe ... or perhaps the best picks for particular amps or applications. I'll have to think this through.

 

If anybody here has ideas as to a format you'd like to see, I am open to any suggestions.

 

Regards,

I just wish I knew how the curves translated to bass, mids, and highs and over all tone.

6AM ....

 

Don't feel bad.... the curves do not translate to those bass, mid, etc., parameters. The curves are just linearity and amplification. If the volume raises smoothly, etc.

 

Those other issues have more to do with the construction, vacuum, cathode coatings, and other factors.

 

The best test of the things you mention, is to listen to the tube in your amp, or a friends amp of the same basic type.

 

If you want the "listening" reviews, there are a number of places those can be found. There are some great ones at Watford Valves, The Tube Store, KCA, Tubeworld, etc. I have some of the Watford Valves reviews on my website.

 

Regards,

[myles_rose]

Originally posted by steve f:

Bogner claims 80 watts from a pair of Svetlana EL34s in their Shiva amp. Is this realistic? Seems awfully high. They acknowledge the plate voltage is very high. If it is a realistic figure I'm wondering what the lifespan of a pair of tubes is?

steve f ...

 

I have measured a few Shiva heads and combos, and they typically put out a lot more power than they are advertised. If you are in the Los Angeles area, there are a few Shivas at Westwood Music, and I would be more than happy to meet with you one day over there and we can throw one of them on the scope.

 

Bogner might use high plate voltages, but I can say that in the amps I have measured, it is nowhere close to the 800 volts than an EL-34 can be driven at. It is also nowhere close to some of the old plexi Marshalls that had as much as 600 volts.

 

When I measure for power, I do so at 40HZ, 400Hz, 1000Hz, and 10000Hz .... just to see how things fall off and where. Even though some of those ranges are outside of the amps design specs, it tells me things about the transformers, power supply in general, and capacitors.

 

I also measure for maximum wattage clean, and then maximum flat out.

 

Getting 80 watts out of a duet of EL-34's can be done, but each amp has to be looked at individually to verify this, as it would be rare. In any case, tube life would be reduced at this rating, possibly as much as 1/2.

 

If you are going for max output, the JJ/Tesla EL-34L would be the tube to use. It is a lot stronger than the Svetlana (which is the supplied tube I have seen in Bogner amps). The JJ does have some of its own unique sound qualities though, so this would also be a consideration.

 

Hope this helped.

 

Myles

[peel]

]

hey peel - good to see you again too. : ) glad that the Jubilee is back in your repertoire. I'm actually in Calgary, but good to see other Canadians on the boards.

 

calgary, ok, now i remember...hey the jubilee never left, though i have flirted with my mesa 50/50 and the VooDu.

 

Im more happy now than ever with this amp and my FX, especially with the new cab. I know dickall about matching output tubes, phase inverters, swapping tubes etc, so im hoping to pickup some info here and maybe some specifically about this head. there isnt nearly as much out there on the 2550...Is it as unique as many claim.? I like it, it doesnt sound like a typical JCM. im not sure if that is due to a number of factors, or if it is indeed the amp. One thing I noticed compared to a JCM 900, the Jube doesnt have that crunch - its softer -could be the svets too.

Im not that concerned because in fact I need a fairly versatile amp for my band, as we cover all types of music and the jube is a bit more versatile sounding VS JCMs IMO.

 

I dont have a lot of gain at my disposal using the amp distortion - its more of a 70s sounding gain, so it would be nice to have a more saturated sustained gain for modern rock, though Im not expecting it to sound like a Soldano. Do you find this too or is yours modded?

 

peel

[myles_rose]

Originally posted by signal1000:

I've been using GT E34Ls in my Marshall Jubilee for about four years now. They increased the output and gain dramatically. I had Svets in there to begin with and some RCAs that are made in W. Germany (not sure what they are). The Groove Tubes beat them and the mesas I've tried in that amp for tone and power.

 

Also a HC guy who's followed Myles over here. I've learned a lot from his posts and his site.

signal1000

 

The Ls's in your amp are what is as close to a perfect match as possible. Marshall' run high gain structures and higher plate voltages, and it just brings those tubes to life even more than in many other amps.

 

Regards