Anyone have experience with the Tung Sol 7581a vs. EL34, KT66, KT88, 6L6

I broke down and added another power tube (Tung Sol 7581a) to my collection.  That can get expensive as my Primaluna Dialogue HP Premium integrated has 8 power tubes.   

Why has this tube escaped me thus far?  Why is it not more popular?   Many folks don't sell this reissue tube.  

I think this is a great deal.  I was torn between the lush, thick midrange of the EL34 and the more evenly spread out sound of the KT88.  But the KT88, for all its more correct behavior didn't romance me like an EL34.  

The 7581a from Tung Sol can be had cheap and I really like them.  [I'll spare you all the audiophile terms].  They check the boxes that I was looking for. 

Does anyone have experience, information or knowledge about this splendid tube?  

PS  The next experiment is KT150s but I can't see doing it if I'm gonna lose any of that great EL34 midrange. 
Genalex Gold Lion KT77 is the best sounding EL34 variant I've heard I highly recommend it. I've been using them in my PP stereo amp for several years now. Pretty affordable ranging from $4-50 per tube I would highly recommend spending a bit more from a reliable vendor for better reliability.
I've tried Tung-Sol EL34's but not the 7581a. Not that familiar with that tube.

I noticed that tube awhile back and was always curious, since I too have the PL HP.
Nice to see they are ridiculously priced.

El34,KT77 & KT88 sound great. The compromise between those two for me have been the RCA 6L6G(the big bottles) they just fit under the cage.
Not terribly expensive as a killer NOS 34 or a new KT150

When I'm looking for a little audio excitement, I will keep the 7581 in mind.


JB you might want to add a Winged C EL34 to your list. I have never heard of the 7581. Is it a hybrid of EL34 and KT series maybe? 
I bought a pair of new JJ KT77s and they didn't sound as full and clear as the supplied Gold Lion KT88s or the Sovtek KT88s currently in use in my Dennis Had "Fire Bottle" SEP amp.. Are the Gold Lion KT77s simply better tubes? If so, I'd be willing to check em out…I tried the JJs with various rectifiers to see if there was some synergy issue, but went back to the 88s. Still, curious.
@wolf_garcia I can't comment on JJ KT-77s but in my system the Gold Lion KT-77s crushed JJ 6ca7 fat bottles, Psvane Phillips replica EL34's, Svetlana, EH EL34's as well as Tung-Sol reproduction EL34's. I can say they are great tubes and worth trying out.
jbhiller - Where did you buy your  Tung Sol tubes?  I've got a PrimaLuna integrated (older model with 4 output tubes) and might just try the Tung Sols.  I've tried the stock EL-34's and some Russian KT120's - but currently I'm running Gold Lion KT88's which, so far, are my favorites.

I use old stock 7581A tubes in my 6L6 amps acct their output in a push-pull design is closer to 35 watts per side. ( most other 6L6 subs get 25). I need that acct. the speaks are low 80’s dB. They also sound great. I have no input on the newer reissues.
I bought my 7581a's from a guy in Ohio--cleveland area-on Ebay.  He tests them and does a 48 hour burn in.  They were so cheap compared to others I have bought.  I'm not rolling these out since rolling them in. 

Also, as my 6 year old likes to point out--they have a blue glow in addition to the traditional incandescent glow.  Very cool. 

Noromance, I'm curious to see if you like them.  I'm going to call upscale and ask Kevin why he doesn't stock these tubes.  
Thanks, jbhiller.  I found the listings based on your earlier post that the (eBay) seller was in Ohio.  He does seem to stock a lot of interesting, reasonably priced tubes and has excellent feedback.

I may take the plunge and buy the 7581A's, and I may also pick up some 12au7's and 12ax7's for spares.

Thanks again
I tried them last night. Impressions:
Out of the box a little dry but extended in the treble. Very good bass. Clean and powerful sounding making my 1960s 6L6 Ratheon black plates sound a little tired. They did lack the sweet midband of the older tubes but they only have a few hours on them. Overall pretty impressed.

Thanks for the prelim review, noromance.  Please post a follow-up after you've lived with the tubes for a while.
I'm shy of 2 weeks into these tubes.  I have a good time running them in and with the holiday I was able to really let them run.  I'd say they have 40 hours on them now.  

To be honest, I think they changed a little but not too much from out of the box.  They "feel" like they settled in--yet that could be me getting used to them.  

I think these are more intimate in their presentation than the GL KT88, but not as bombastic or powerful.  They are not as shiny on top as the KT88 or as liquid as the EL34 in the midrange.  So what's to like? Much. 

These have an honest tweedy warm sound.  While the EL34 is--to my ears--sugary and heavy in a good chunk of the spectrum, this one is not but more so than the GL KT88.  What is odd and pleasing is that this one sounds better than the KT88 with percussion.  Snare drums really vibrate with the skin against the spring/rod or whatever they are made of.  Cymbal and strikes to percussion pieces of kit stand out--just a bit.  I liked that. 

The tube is not forward sounding to my ears.  There's a good chunk of energy pushing detail through.  

I'm going to get used to them more and then start rolling preamp/driver tubes through them to see what stands out, despite the swaps.  That should help me isolate their core characteristics. 

This is a fine tube and I am very pleased with it.  I'm still trying to figure out its fingerprint.  

A week or so later. Bass has got really good. Razor sharp. Depth and air have opened up. Highs fine. Midband fine if lacking a little sweetness (color; coloration?) Overall, very neutral, fast and clean. I will swap back my old reference 6L6 black plates to compare and report back.


I agree!  I wish the 7581a could mate with an EL34 and have offspring.  The 7581a is near perfect for me--I just want a touch more of the EL34 midrange syrup. 

I’m with you on the TS7581A’s. I use them in my Dennis Had Inspire Fire Bottle PSE amp with excellent results. All the attributes you already mentioned apply in my system as well. I’ve also swapped in the GLKT66’s which sound good as well. The KT66’s offer up a bit more air and a touch wider soundstage but in turn the bass is looser and the highs are a touch less defined.

I like the sparkle and bass that the 7581A’s have!
Follow up on this. I tried putting the old Raytheons back in and it was no contest. Existing attributes have consolidated initial impressions and any tiny lack of midband sweetness now seems like a more neutral clarity, if you know what I mean. Tung Sol 7581a are keepers for the moment. 

I did not have good life on a matched quad of Tung Sol 6L6 G big bottle tubes.   They sounded really good and looked cool , but they started to drift and one died after only a few months.   Gold Lion KT66 is a rugged sweet sounding 6l6 variennt
I'm wondering if the GL KT66 hits that sweet spot everyone is wanting. Can't seem to find much feedback tho.
Update...I now consider KT120s my fave for my Dennis Had Inspire "Firebottle" HO (it's a HO...says it right there on the amp) single ended pentode amp. So there.
I recently built a Fender Tweed Pro 5E5-A.  I put Tungsol 7581A tubes in it.  The tone is rich, chiming, well balanced - everything one could want from a Fender amp IF you like clean tones (I do, at least for this amp).  I can turn it up as loud as I dare and it is still clean and rich.   

If, on the other hand, you like grind and compression from the power tubes, go for 5881.  6L6GC split the difference. 
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Another update...after being smitten (smote?) by Gold Lion KT77s and much preferring them to anything else in my little SE amp, I've switched to 7581As and now prefer them over the various power tubes I've stuck in this amp...including KT120s, 150s, KT88s from GL and Sovtek, and JJ (worse of the lot) and Gold Lion 77s. My tube drawer is gettin' kinda full.
My $,02 worth here. I have a pair of Quicksilver Mid Monos that allow for me to run almost any tube that is octal based. I have used JJ KT77, TungSol KT66, TungSol 7581A, JJ and EH 6CA7, and Gold Lion KT66. To me, and this is me and my gear, the TungSol KT66 is better all around than the GL KT66 as the TungSol sounds a little less "congested" as the GL tube can to me. But the big winner here is the TungSol 7581A. As much as I love my TungSol KT66 (huge soundstage, wonderfully full and warm mids, with deep bass and tantilizing highs without the hard sound) the 7581A does all of that time 10! This is an amazing tube! I have also tried the TungSol KT120 and I keep going back to the 7581A! The Mid Monos are supposed to be about 40wpc with the 6L6 tube and its variants. Well, you sure could fool me as I feel I have a lot more power than that and my speakers are not all that efficient (87db). If you can get away with the 7581A, I would do it. Viva Tubes has matched quads for about $90, a bargain. I like the 7581 a lot more than my NOS Sylvania 6L6GC, a whole lot more, and the TungSol is not nearly as hard to get.
Okay, so that was like $.50....Sorry...
The new RUSSIAN production power tube to beat in my system (LTA ZOTL40 AMP) is the Tung Sol 7581a (6L6 type). Less than $100 a quad, bettered the KT77 GL, El34 Mullard and Tung Sol 34b. The KT66 is a very linear, clear, smooth sounding tube. I felt the Mullards were a bit grainy on top, I do like the GL KT77, but the 7581a are more refined overall. The issue is the 7581a need at least 150hrs of burn in for them to open up. I still need more hours on the TS EL34b to proper evaluate them. The TS EL34b are definitely smoother on top compared to the Mullards so far. I bought the 7581a from Viva Tubes. Highly recommended.

I buy my 7581a tubes from Viva also, and only recently noticed the break-in phenomena...I haven't used any actual EL34s since my Had amp can run pretty much anything from 150s to 77s, and I have plenty of those, but yeah...I had recently bought another pair of 7581a tubes for my second Had amp, a Hot Rod version of the version I already own, and liked the sound of my original amp just a little more...until the tubes aged a little, resulting in a pretty much identical sound between the two amps...I'll likely sell one of these amps in the near future so keep your eye out for that in the A'gon tube amp sales area if anyone wants one of these things.
Zkidd, thanks for posting.... I have a pair of Mid Monos and love them, they are awesome amps. I have had several tubes and my favorites have been KT66 and KT88 Gold Lion but I have not really had long life with them.... I had a pair of KT66 that one shorted , big fire in the bottle and it took out my midrange on my speaker..... honestly would rather that happen than amp damage..... easy fix on a Klipsch.

So in a pinch I bought a quad of Apex matched JJ EL34 locally and they actually sound quite good but I like everything I have been hearing about 7581a tubes and think I am going to order a quad.
Speaking the modern EL34 Mullards , i only got 6 months before one died.....pretty disappointing.   I think the green label EH 34s sound better and are tough....  anyway hope the 7581a possess the goodness of EL34 and 6L6 types in one bottle!!!
7581a tubes show more internal "blue glow" than any tube I've tried...I like it...and it illustrates my seemingly low threshold of entertainment.
Almost 2 years on with 2 x quad sets of Tung Sol 7581A in four monoblocs and they still sound superb. They've held the initial bias settings which indicates good stability and look great.  
Hey guys,  I've read your thread on the 7581a and really want to try it but I'm wondering if I can use them in my amp?  It's a Sonic Frontiers SFC-1.  The manual says it can use EL34's,6CA7's or 6550/655OA/KT88/KT90/KT99a types.  Does anyone know if I can use them and if so, what should I bias them at?  The manual says to bias EL34 at 40.  It says I can bias the others at 50.  Thanks
No clue about the bias requirements as that seems to be amp specific, but if you can use all the tubes you noted I bet the 7581a would work fine.
Thanks Guys. Think I’ll give the 7581a in my Latino ST-70. I’m thinking about also trying a inexpensive EL-34 (EH) so I can experience the supposed magic. I’ve kinda shied away from them because I am a classic rock, blues and some jazz fan and tend to like a good bass line. (I’m a drummer). So I really like a full spectrum sound which doesn’t emphasize any particular frequency range
Drummer? Then you'll appreciate the new Tung Sol 7581A. Great, clean, snappy bass. Give it about 10-20 hours to sound its best.
I finally tried the Gold Lion KT77s. Great tube. I think they are as good as the 7581. The GL KT88 was not as good in my setup. 
"The GL KT88 was not as good in my setup." Interesting.
I remember the 88's as dynamic in PL systems, but everyone  has different situations.

I had the 77's in my HP for a bit. Great tube. I'v kept the old RCA 6L6G's   cookin in mine for a few years now. 

I may step up and try the might 150's this year, just for audio kicks.
8@$100 each, is kind of a downer though. I've been expense free with audio nonsense for awhile.

Opening the wallet, I hear the old Foreigner song-"Feels like the first time!"

I play drums and love the Russian Tung Sol 7851a,,.however I recently installed a quad of JJ EL34L and prefer them. They have that great midrange magic, tight punchy bass and smooth highs. The JJ's are my favorite new production power tube. They are even cheaper than the 7851a. They beat the Russian GL KT77, Mullard EL34 and Tungsol EL34B in my amp. The JJ's are a very underrated tube.
Hi Just saw your post rel the 7581A. I bought a pair for my Dennis Had HO Inspire "Hot Rod" amp and really love them. I bought the amp used, it came with KT66s.

I bought the 7581 from Tung Sol and really love them, great sound - much warmer than the KT66 IMO. I also bought NOS RCA 6F6G Power Pentodes and have landed here. 

I tried the KT66, 7581, KT120 but really love the 6F6G and haven't gone back. They don't put out as much power (it seems that way) but I have high efficiency speakers and they play plenty loud for me i.e. the preamp volume control is always at 9:00 position, so the 6F6G has plenty of power for me your results may vary but I really do like the 7581A tubes - can't go wrong with them, just my 2 cents

485 posts

Latino ST-70. I’m thinking about also trying a inexpensive EL-34 (EH) so I can experience the supposed magic.

I've heard EL34 that brought magic to the room, I've heard EL34 that made me leave the room. Don't get too cheap. You'll hear some of the worst bass and highs you ever heard. On the other hand, 6L6 like the RCAs, GOOD vintage GE are the benchmark of quality BASS and mids,
little lacking on the top, but what a GEM. Before I ever Roll power tubes, I  always check them.. I prefer to change the signature, with the signal tubes. FIRST. RCAs, Telies, Amprex or Volvos, Solvex then Mullards, everything after that may sound good, but be aware. Cheap valves can really tear up a great amp or speakers..

KT 90s are a great sounding valves, (very close to a 6550 / kt88 hybrid sound) Very clinical. I like them MUCH better than the 120 or 150s. Second they hold up forever.. Almost.

@oldhvymec Just checking that you know the thread is about replacing EL34 et al with new Tung Sol 7581A for a big improvement. 
Ran GL KT88s in my Cary Rocket 88 but missed the wonderful mid's of  EL34s. Rolled in a set of the Tung-Sol reissue EL34s and the magic is back. However, I purchased as my 'back-up' tube set and they are 'on-the-shelf' as I've rolled in a quad of GL KT77s, which, as stated above, are the creme-de-la-creme of EL34s. They were the 'keepers' in my previous CJ amp and same in the Cary. But, based on the theory (never disproven) that one cannot have too many tubes, I want to try a set of the reissue Tung-Sol 7581As. Failing that, I'll go with their 6L6GC-STR.
Don't know how much of tube listening preferences are simply about differences, but being a 7581a fan I was surprised at the "difference" when I swapped in my GL KT77s this little amp sort of came to life. Perhaps the 7581s are getting older or something...I'm starting a log regarding tube life to avoid such issues.

@wolf_garcia ,  I'm sure folks could charge me with ignorance or blasphemy here--  I think the 7581as sound better with less than 1000 hours on them.  I think they fade off just a touch in my system after that.