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    ST 70 Power Tube Shootout

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    kevco

    Posts : 70
    Join date : 2009-07-16
    Location : Aldan, PA, USA

    ST 70 Power Tube Shootout

    Post by kevco on Mon Apr 25, 2011 9:30 pm

    After much debate and curiosity, my tube amp amigo, Dan and I decided spend an afternoon rolling power tubes though my ST70 to make a modest attempt to subjectively determine what the differences, if any, may be between a pretty diverse blend of modern tubes that we have accumulated between us. I am posting the results of that shootout here. I realize that this undoubtedly will spark some debate about both our methods and results. Neither of us is a qualified reviewer of audio equipment, and we did this purely for fun and to satisfy our own curiosity. I am fully aware that other people's equipment will vary from my own, as will their taste in sound quality. Again, purely for fun.

    The equipment:
    Amplifier: Dynaco ST70, original power and output transformers, DiyTube driver board modified to use 6 volt 6CG7 driver tubes, Chong power supply cap board. G.E. gray plate triple mica 5751 as voltage amplifier, RCA "cleartop" 6CG7 drivers.

    Preamplifier: Eico HF-85, fully recapped. Telefunken "smoothplate" 12AX7's in line stage, connected to amp via "Tape Out" outlets to bypass tone control, allowing purer signal.

    Source: JVC XL-V161 compact disc player (nothing fancy here, but it's always sounded good to me.)

    Speakers: Klipsch Forte II's, Bob Crites crossovers. 99db/meter efficiency.

    Interconnects, Speaker Wire: All by Blue Jeans Cable.

    The Power Tubes: Genelex Gold Lion KT-66, Sino EL-34B, Electro Harmonix 6CA7, Electro Harmonix EL-34 (cryogenically treated by Cryoset), SED "Winged C" EL-34's and NOS Russian military 6p3S-e.

    Each set of tubes was biased at 45mA per tube and allowed to warm up for 15 minutes after biasing was complete. Four cds were used for testing each quad of tubes: Elliott Smith's "Figure 8", Radiohead's "OK Computer", Norah Jones' "Not Too Late" and The Rolling Stones "Sticky Fingers" (2009 remaster). Our impressions were very similar on each of the quads.

    Genelex Gold Lion KT-66: Probably the best overall performer here. Well rounded from bass to mids to highs. Nice wide sound stage. Had no trouble keeping up with the harder, faster music, yet delicate recreation of female vocals and piano or acoustic guitar. Nicely manufactured, you can see/feel the quality. Costly tubes but you're gonna notice the upgrade from just about anything! I would call their sound "accurate".

    Sino EL-34B: These were matched and tested by Ruby Tubes. I'd have to call these my least favorite tubes here while Dan preferred them to the 6p3S-e. I found them to have a flat mid-range and a lack of high end air. Sounded compressed and rolled off. Bass was decent. Sound stage was narrow. Ping like a cheap toaster on warm up. I would call their sound "compressed".

    Electro Harmonix 6CA7: Definitely sound more like 6L6 types than an EL-34. Great bottom end slam. This is the tube for rock music. Fast, balanced, wide sound stage. If the Gold Lions are out of your price range, try these. Some mechanical noise on start up. I would call their sound "accurate to bassie".

    Electro Harmonix EL-34 (Cryoset): These are a good bargain EL-34. Sweet pentode highs and mids, yeah I'd call 'em warm. Bass was lacking compared to the 6CA7. Sound stage pretty wide. I'd have no problem using these daily...If all I listened to was jazz/acoustic...but I don't. I would call their sound "warm, yet pretty accurate".

    SED "Winged C" EL-34: The warmest of the bunch. Construction definitely better than all of the above tubes except maybe the Gold Lions. Better bass than the EH EL-34's. These babies do some holographic high and mid range stuff that none of the others could match. We were both really impressed with the sound stage. I was sad to see my friend take 'em home...I would say that they sound "very warm".

    Russian Military 6p3S-e: These are the ones manufactured by Reflektor with the coin base. Bass is lacking on these little guys for sure..but the high end sizzle these things throw out is really fun. Mid range is sweet too. They are a bargain though, and very well made. Worth the low cost of entry even if all you do is keep them as spares. I'd call their tone "bright and accurate".

    I'll note that all of the tubes tested were burned in at least 150 hours, with 300 to 500 being average. Only the EH EL-34's had seen less than 150 hours, but not by much. I hope that somebody finds this interesting and please don't blast us on our testing methods too badly. It was fun!

    j beede

    Posts : 328
    Join date : 2011-02-07
    Location : California

    Re: ST 70 Power Tube Shootout

    Post by j beede on Mon Apr 25, 2011 9:43 pm

    Sounds like you guys had some fun... must have been left "home alone" I suppose. My only comment is that my EL-34 amp (not ST-70) needs more than 15 minutes to warm up. I imagine that you were swapping tubes at a pace that precluded the amp's thermal masses from cooling. Too bad the 6p3s-e didn't come out on top! What about the 6p3s that have the clear tops... they look so nice--anyone ever listen to these?
    ...j

    bigmm79

    Posts : 23
    Join date : 2010-09-15

    Re: ST 70 Power Tube Shootout

    Post by bigmm79 on Mon Apr 25, 2011 11:26 pm

    Great post, thanks for sharing your thoughts on these various tubes.
    I'd agree that of all the tubes I've tried, the Sino EL-34Bs were my least favorite.
    I'd also agree that the Gold Lion KT-66s are the best I've heard, though the Tung-Sol 6L6g are a very very close second, plus they are way cool looking.

    I've really been wanting to try the EL 6ca7. From your comments, I think I need to try them - Also want to try the Winged C now.
    The $$$ are gonna flow like diarrhea from the buffalo. No

    I use a low gain Latino ST-70, btw.

    wolverine

    Posts : 60
    Join date : 2010-02-20

    The Shootout and the Winged C's

    Post by wolverine on Tue Apr 26, 2011 8:52 am

    I agree Kevco.....the Gold Lions are the best sounding in my unit also, but the Winged C's are my second favorite of any tube I have ever used. I actually think I get a wider soundstage from the C's then I do the Gold Lions, just not quite as much detail. I highly recommend a matched quad of the C's for anyone.
    wolverine

    kevco

    Posts : 70
    Join date : 2009-07-16
    Location : Aldan, PA, USA

    Re: ST 70 Power Tube Shootout

    Post by kevco on Tue Apr 26, 2011 12:21 pm

    j beede wrote:Sounds like you guys had some fun... must have been left "home alone" I suppose. My only comment is that my EL-34 amp (not ST-70) needs more than 15 minutes to warm up. I imagine that you were swapping tubes at a pace that precluded the amp's thermal masses from cooling. Too bad the 6p3s-e didn't come out on top! What about the 6p3s that have the clear tops... they look so nice--anyone ever listen to these?
    ...j
    I'm gonna mention here that all the power tubes had been used in this amp a various points for runs of up to 12 hours. We allowed the tubes to warm up for 15 minutes before starting but in most cases the tubes remained in the amp for upwards of an hour during the "testing". The amp was as about as hot as it gets for the entire afternoon, especially the original power transformer...

    Tube Nube

    Posts : 643
    Join date : 2008-12-06
    Age : 53
    Location : Calgary, AB

    Re: ST 70 Power Tube Shootout

    Post by Tube Nube on Tue Apr 26, 2011 2:54 pm

    If you get a chance to try Gold Lion KT88s, I found them substantially, even dramatically better than the GL KT 66s.

    This was on JunkyJan's recommendation -- he had the same experience.

    FWIW.

    And good thread, BTW

    wolverine

    Posts : 60
    Join date : 2010-02-20

    Re: ST 70 Power Tube Shootout

    Post by wolverine on Tue Apr 26, 2011 5:10 pm

    I do intend to try a set of KT-88's in the future myself. I think the KT-66's should last me a good long time though first. I also have some sets of Winged C's to go through, some Mullard reissues, and some Svetlana's. I have three sets of 7199's left, so I should be good to go there.

    I checked on prices of Winged C's and I couldn't believe how much they go for these days. I must have bought mine longer ago then I remember because I paid a lot less then what I see advertised out there. They are selling for the about the same as the Gold Lions these days. At my age, I probably have all the tubes I need to get me by LOL, but sooner or later I will likely get the bug to try out a set of those KT-88's.
    wolverine

    Captain Coconut

    Posts : 216
    Join date : 2009-10-13
    Age : 64
    Location : Great White North

    Re: ST 70 Power Tube Shootout

    Post by Captain Coconut on Tue Apr 26, 2011 6:53 pm

    kevco wrote: Neither of us is a qualified reviewer of audio equipment, and we did this purely for fun and to satisfy our own curiosity.

    You are as qualified as any reviewer out there. Check the credentials of reviewers and you'll find that none of them have any knowledge of electrical theory, physics and so on. What they all share in common is a lifetime interest in music. Wow! Who doesn't?

    Recently, TNT was looking for a reviewer and you guessed it, no experience required. All you needed to do was write well. The only thing you forgot to do Kevco, was describe what you heard in a more restaurant reviewing style like " the midrange was sumptuous with a just the right amount of bloom combined with a subtle yet delicious lower treble that suggested a wonderful combination of detail and depth." Cool

    Luddite

    Posts : 235
    Join date : 2009-02-04
    Age : 66
    Location : Texas

    Re: ST 70 Power Tube Shootout

    Post by Luddite on Tue Apr 26, 2011 7:13 pm

    [quote="Captain Coconut"]
    kevco wrote:
    Recently, TNT was looking for a reviewer and you guessed it, no experience required. All you needed to do was write well. The only thing you forgot to do Kevco, was describe what you heard in a more restaurant reviewing style like " the midrange was sumptuous with a just the right amount of bloom combined with a subtle yet delicious lower treble that suggested a wonderful combination of detail and depth." Cool

    Cap'n

    I think you nailed that one. Very well said! lol!

    Best Regards,
    Charlie

    fswideck
    Guest

    Re: ST 70 Power Tube Shootout

    Post by fswideck on Tue Apr 26, 2011 8:16 pm

    bigmm79 wrote:Great post, thanks for sharing your thoughts on these various tubes.I'd agree that of all the tubes I've tried, the Sino EL-34Bs were my least favorite.I'd also agree that the Gold Lion KT-66s are the best I've heard, though the Tung-Sol 6L6g are a very very close second, plus they are way cool looking.I've really been wanting to try the EL 6ca7. From your comments, I think I need to try them - Also want to try the Winged C now.The $$$ are gonna flow like diarrhea from the buffalo. :no:I use a low gain Latino ST-70, btw.

    j beede

    Posts : 328
    Join date : 2011-02-07
    Location : California

    Re: ST 70 Power Tube Shootout

    Post by j beede on Tue Apr 26, 2011 10:10 pm

    Were the EH 6CA7 thr large diameter envelope style?

    GP49

    Posts : 735
    Join date : 2009-04-30
    Location : East of the sun and west of the moon

    Re: ST 70 Power Tube Shootout

    Post by GP49 on Wed Apr 27, 2011 11:48 am

    "...Each set of tubes was biased at 45mA per tube..."

    At the risk of throwing another variable into the test, did anyone consider that the different tubes may have functioned to their ideal, with different idling currents and not the same 45mA on all of them?


    Last edited by GP49 on Wed Apr 27, 2011 4:01 pm; edited 1 time in total

    mantha3

    Posts : 298
    Join date : 2010-11-10

    Re: ST 70 Power Tube Shootout

    Post by mantha3 on Wed Apr 27, 2011 2:17 pm

    I agree with Captain Coconut.. You should buy an issue of Wine Spectator or something.. Then just sub in the work "music" or "Tube" in place of "wine"

    For example "The lush inky tannins of the Gold Lion KT-66s really came forward in the Song #####"

    Seriously, thanks for taking the time to report on a fun day of tube rolling. Sounds like it was fun and I'll have to do it some time.

    I'd like to do it with the center spot on my VTA board (hi gain)

    Some rainy day

    frank

    Posts : 95
    Join date : 2011-02-14
    Location : Pacific Northwest

    Re: ST 70 Power Tube Shootout

    Post by frank on Wed Apr 27, 2011 3:59 pm

    bigmm79 wrote:
    I'd also agree that the Gold Lion KT-66s are the best I've heard, though the Tung-Sol 6L6g are a very very close second, plus they are way cool looking.

    How close are they? Are they really, really close? I think they are cool looking too.
    I am looking for a slightly warm sound with great gobs of "spaciousness". The closest to what I want I've found so far are the Shuguang EL34s. After 80 hrs or so they are still too rough or unrefined sounding.

    My favorite tubes so far are the Russian 6P3s-E; just not much of that lush, sumptuous, bloomy spaciousness I want.

    THx,
    Frank

    frank

    Posts : 95
    Join date : 2011-02-14
    Location : Pacific Northwest

    Re: ST 70 Power Tube Shootout

    Post by frank on Wed Apr 27, 2011 4:01 pm

    fswideck wrote:
    bigmm79 wrote:Great post...ST-70, btw.

    Won't try posting by cellphone again.

    kevco

    Posts : 70
    Join date : 2009-07-16
    Location : Aldan, PA, USA

    Re: ST 70 Power Tube Shootout

    Post by kevco on Thu Apr 28, 2011 8:51 am

    j beede wrote:Were the EH 6CA7 thr large diameter envelope style?
    Yep, the "big bottle" 6CA7's...These are a beam tetrode rather than a true suppressor grid pentode like the EL-34. My goal on writing this post was to not use any of the ludicrous language I see in hi-fi reviews. I figured that we can all make sense of "compressed" or "bassie", while gushing terms like sumptuous, velvety and sparkle are really meaningless.

    bigmm79

    Posts : 23
    Join date : 2010-09-15

    Re: ST 70 Power Tube Shootout

    Post by bigmm79 on Thu Apr 28, 2011 2:29 pm

    [quote="fswidecki"]
    bigmm79 wrote:

    How close are they? Are they really, really close? I think they are cool looking too.
    I am looking for a slightly warm sound with great gobs of "spaciousness". The closest to what I want I've found so far are the Shuguang EL34s. After 80 hrs or so they are still too rough or unrefined sounding.

    My favorite tubes so far are the Russian 6P3s-E; just not much of that lush, sumptuous, bloomy spaciousness I want.

    THx,
    Frank

    I have Shuguang EL34s and the Tung Sol 6l6g absolutely destroy them. There is a slight difference in sound between the TS 6l6 and the Gold Lion KT-66 - I'm not good at putting sound into words, but I would say that the GL are a bit more detailed and maybe have a little bit bigger sound stage. The TS are warmer and more liquid, I would say - only slightly less detailed. I greatly prefer the TS in the pentode setting. Not as big a preference between pentode and triode with the GLs - I maybe lien toward triode with those.

    On the whole - at $15 less or so per tube, I would go with the TS. One caveat - I don't think they will fit under the standard ST-70 cover. I don't use one, so I'm not sure.

    frank

    Posts : 95
    Join date : 2011-02-14
    Location : Pacific Northwest

    Re: ST 70 Power Tube Shootout

    Post by frank on Thu Apr 28, 2011 6:44 pm

    Thanks, bigmm79

    frank

    Posts : 95
    Join date : 2011-02-14
    Location : Pacific Northwest

    Re: ST 70 Power Tube Shootout

    Post by frank on Wed May 04, 2011 5:56 pm

    Hey bigmm79,

    Got my Tung-Sol 6L6-Gs. They are my new favorite tubes. Thanks for the tip!

    Frank

    bigmm79

    Posts : 23
    Join date : 2010-09-15

    Re: ST 70 Power Tube Shootout

    Post by bigmm79 on Thu May 19, 2011 12:08 pm

    fswidecki wrote:Hey bigmm79,

    Got my Tung-Sol 6L6-Gs. They are my new favorite tubes. Thanks for the tip!

    Frank

    Glad you like those!

    Recently tried some JJ KT-77s after seeing some positive comments around the net. I really liked them. Wide soundstage, a wonderfully warm and tubey sound without overly sacrificing detail. Best I've heard with the female voice. I tried a wide variety of music with them and they were good with most. Seemed to get bogged down with bass heavy rap and fast/loud metal. So I'd say a really enjoyable tube, but a specialist and not an all-rounder.

    j4570

    Posts : 141
    Join date : 2010-08-30

    Re: ST 70 Power Tube Shootout

    Post by j4570 on Thu May 19, 2011 9:33 pm

    I compared my Valve Art Matched EL34B's and the Russian 6n3cE from BSA_79 and the 6n3cE clearly are the winners in my opinion.

    I also put in the original RCA 6CA7 U.S.A. made tubes in the right channel (I only have two and who knows how many hours they have on them) and I was disappointed, the treble sounded lacking, though they gave the best bass response.

    For now, the 6n3cE's go back in. No question.

    For me, I only want tubes that will fit under the cage.

    So, I guess I'll look for tubes in the fall, as it's summertime when travel eats all the money......

    JW

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