Really...My favorite power tube is reissue that's not widely popular

If you run 6l6/EL34 variants, I HIGHLY recommend trying this tube out.  The Tung Sol 7581A reissue.  I've had these for a good bit of time and compared them against KT150s, EL34s (several brands), KT88s, and maybe another that I'm forgetting.  They are a mere $30 a pop and they are the best tube I have heard. I know that's a brave bold statement to make as there is so much competition out there and the tube is very much under the radar from what I can tell.  

After having these around for a long time (and in and out of the amp), I had them in and was nearly spellbound one night by how great they sounded upon reentry into my amp.  I did a search and could only find one review, which I agree wholeheartedly with.  You can find it here:

I am nearly incredulous there isn't hype out there about this tube.  Simply my favorite tube.  I thought I'd pass this along as it may be much cheaper to give them a whirl then fuss with a much more expensive power cord, cable, or other tweak.  
Thanks for the heads up on this. What’s your opinion of the TS 7581A over a typical EL34? In other words what’s the 34 not doing as well as the 7581A? Thanks!
how would you compare to the Gold Lion KT77, another EL34 variant. I'm running those right now.
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invictus005...did you just get upset at your computer and forget you were typing? Your phone just burst into flames? Noticed your own shirt? The dumpster from the Chinese restaurant next door? 
In contrast, the EL34 can be a touch droopy and slow. It also lacks a bit of the whole spectrum while focusing on midrange. The 7581a gives a broader view like a KT88 but with charm and romance in the midrange. 
But I should note I like tubes like I like women. All are beautiful in their own right. Some just do it for me more than others. :) 

I will compare my notes and make an update with more details. 

I sgoujd akso note note the Gold Lion kt77 is the only one I really need to try so I can’t comment. I hear from others it’s super.  I don’t think you can go wrong with anything gold lion.  I love my GL 300bs and others. 
Gold Lion KT77s are fabulous tubes. I'll have a pair of 7581As in a day or two (coming from Viva/Only Glass in Easthampton MA about an hour from my house) and will pop them into my little Dennis Had SE amp (only takes 2 power tubes) to see if they can compete with the GL KT77s that I currently prefer. I've used KT150s, KT120s, a couple of KT88 variations, JJ KT77s which sucked (surprisingly), and have stuck with the GL 77s only because they sound astonishingly good relative to all those I just mentioned. If the 7581s don't cut it, jbhiller will be held personally responsible and I will require a  heart felt sincere apology from him. It's only fair.
I have heard great things about these tubes, looking forward to your feedback
In my Rogue audio m180 darks I (overall) like the kt120 best, I own GL kt77s and they sound awesome in the mids, but in my Amps are not as big and open as the kt120, Maybe I need the extra power. 
After reading the review you posted I might have to try them. A marriage of the kt120 and a 5881 sounds awesome.
Wolf, if you do not like them I could buy them off you.  But seeing as they are $30 a pop not a huge loss, which is why folks should try them out.  I love KT150s but at over $100 a pop they are a bigger risk for folks.  

And Wolf you are making me want to try the Gold Lion KT77. I need an octet though so it's going to be a bit of dough.
Thanks for the review!I'm definitely trying the 7581s.+1 on the Gold Lion tubes.Even their small signal tubes have that golden "house sound".

I have an octet of lightly used (less than 100 hours) Gold Lion KT77's from Tube Audio Store that I paid $600 for.   Will sell for $265 delivered if anyone is interested. 
I've played with pretty much every new/reissue tube and own all NOS EL34s available. There is only one king: Amperex EL34. Nothing even comes close. Old Mullards are nice, but the Amperex EL34s are simply the best, kind of like the original Genalex KT88s (still own two NOS matched quads). Then of course there are the new KT150s, which in the right amp, I feel just give the best of what NOS tubes had, plus total grip of woofers that no EL34 or KT88 can give. I'm keeping my collection for when I get back into two way bookshelf speakers again. 
New KT77s at VIVA are 287 bucks for an octet...matched, free shipping, 90 day guarantee return policy, and that’s where my recent pair came from.
I put my GL kt77s back in my Rogue m180 darks and while they sounded good the kt120s are still a better match, bigger, more open with better bass control. Still open to try the 6L6 tung sol though. 

The new 5581As arrived and they sound pretty damn good already. Giving the 77s some competition around here. Nice friggin' tube....the sound seems slightly Spanish with a hint of "Jet Age" Old European potato farmer. They imply but don't overstate an extended 2nd harmonic enhancement with flamboyantly reticent outer detail that could possibly inhibit mold growth.
Wolf, downright beautiful post.  You should be a reviewer. Way better than the drivel we see in the hifi porn magazines. :)
@jbhiller you sure do like them.
I'm still running them in 2 sets of monoblocs since your first recommendation in 2017!
@noromance ,

Yes, I do really like these tubes.  Many times I'm not so sure or as passionate because there are many fine tubes that don't stand out in any meaningful way for me.  These stand out.  

I've isolated my findings to the power tubes.  Even when I roll preamp tubes of different ilk, it is these power tubes that stand out across preamp tubes that I've used with other power tubes. 

I also like them because they are such a good value in the crazy tube market.  With NOS power tubes so scarce and expensive, these are solid value.  

One thing of big note. One power tube I haven't tried is the GL KT77, which is a shame.  I hope to do that soon.

I meant 7581As in my last post, lest anyone be reading this stuff. The Gold Lion KT77s really are a great tube and until now have been my reference (meaning I left them in my amp as they sounded better than other options) for a year or so...beautiful looking tube, and I recently bought a new set as one tube stopped that the 7581As are breaking-in (as far as that goes with tubes), they’re already a seriously great sounding tube...wide ranging effortless tone monsters with a cool looking blue glow at the plates...I like that...they’re gonna be around for a while as I bask in the damn things, and at 50 bucks a pair new and tested, there’s simply nothing not to like.

The blue glow--even though it has nothing to do with anything sonic (or likely doesn't)--is pretty sweet indeed.  Super cool.  I thought I'd lay low on the blue glow because the sonics of the tube are enough of a sell for us.  The blue glow is sooooooooo kewel. 
I've used KT120s and like them...had a quad last for 2 years or so in another amp, and have a pair for this amp. Great tube, doesn't sound as good as the GL KT77s or the 7581s in this particular amp.
Hmmmm, the kt 120s sound better in my amp, I wonder if my kt77s are getting long in the tooth. The kt77s are smoother but the kt120 are more dynamic with a bigger more 3D soundstage, the kt77s sound smaller and more intimate. I still might try the 7581s if they also have dynamics.
The 120s sounded great in a Jolida 502p push-pull amp that I used them in primarily, and only swapped 'em out when they got weak....wound up using Gold Lion KT88s mostly. In the amp I now use (Dennis Had Inspire Firebottle HO 12wpc...4 tubes total in this thing) I can put pretty much any power tube in there (with a rectifier tube change when needed for "sag" avoidance or encouragement...or something) and the amp itself seems simply more revealing of tube differences. I might put the 120s back in sometime just for some tonal mischief, and because I feel bad for all of the lonely tubes that dwell in the darkness of my tube drawer.
Based on these postings, I have a quad of 7581A coming on Monday. I've been using the Gold Lion KT77 as my power tubes, they are truly outstanding and no complaints at all.....I'll post a comparison of the two tubes me, more tone is always good if not syrup.
Maybe some artistically applied gold meanderings on the 7581As whoud make them seem more welcome around the 77s.
I have some 7591a Tung sol. They’re by far the best new power tubes I’ve got in the last decade. They were 30$ each and I love them. 
They are as good as some nos GE or Westinghouse tubes but much cheaper. 
tuberist...have you had a chance to do some comparisons? I purchased 8 for Primaluna Dialogue Premium HP amp. Looking forward to the comparison with the stock EL34's.
arch2....I've been running the 7581a now for several days after replacing the Gold Lion KT77. In my PrimaLuna I like the 75s better.....much more tone, the sound staging and the detail is comparable to the Gold Lion....both tubes are wonderful, I prefer the Tung-Sol because the tone is stronger and the bass deeper and more fleshed out.
Great to hear. Thanks! I should have mine by the end of the week and I'll follow up with a comparison to the stock EL34's.
I misspelled "would" although otherwise my last comment is accurate...I still like the 7581As in my "Had HO" amp...just somehow more revealing of musical detail maybe...something...
Jbhiller....thanks for tip. I ordered a quad today, will report back. And I thought I was all done tube rolling :)
@glowworm, I hope they work out for you. Sorry to make you start “rolling” again. It’s cheaper than a therapist! 
jb...LOL so true!

willmacc....I have a set of TS EL34Bs so I’ll let you know how they compare. They do have the typical 34 shortcomings, in that they can be a tad bright on top and the bass is not well defined. But the mids are exceptional. Really lush and involving, trumpets are unreal. For like $22 each an amazing mid-range and a very nice tube.  

I’ve rolled a number of the popular reissues,  and I’m thinking I simply like the TS sound more than the GLs (though I do have GL KT77s arriving today). I am trying GL KT88s now, going to sell them. They have a nasty glare on top I just can’t rid of (on many different recordings), and after 100 hours I don’t think they will change nearly enough with more hours. 

I do like the TS KT120s (shy in the mids but vintage Mullards in the pre helped a lot).  They have a reputation for glare, but I don’t hear it. Might just be someone mentioning it in forums and it’s become folk lore. More of a SS sound, but a really good tube, esp. if KT150s aren’t an option for your amp.  

Hope me this is helpful, will get back about the 7581A compare.  

Just placed my order for a quad of the 7581S Tung Sols.For that price gotta try em:)They’re up against GL KT 88s in an Aric Audio Transcend Push Pull.In other applications I’ve found Tung Sols to be clean,clear but with an annoying glare(like Wolf with his GLs)
The OP made comparison of the TS 7581 tubes to, among other tubes, the KT88's in his first sentence.  So far as I know, few tube amps can swap between EL 34's and KT88's.  I am super happy with the pricey Shaguang KT-88-t tubes in my Don Sachs power amp.  They are much better than the Gold Lion KT88's, which are also very good.     
I put the 7581As in my elekit 8200 and they really took the sound up a notch (compared to NOS el34s I had in there prior) - love the punchy dynamism with no harshness. Thanks for the recommendation!

I’ve been listening to the TS 7581A’s this weekend in my Primaluna Dialogue Premium HP amp. I agree with a number of comments particularly in regards to being more revealing. I was quite surprised by that. So revealing in some instances it was like hearing a slightly different version of a song I may have heard a hundred times before. Bass is tight and extended in comparison to the stock EL34’s, but, I think I prefer the roundness of the bass and the midrange flow with the EL34’s. They seem bigger sounding and fuller in my setup. I only have 10 or 15 hours on the 7581A’s so I’ll give them a good baking before coming to any final conclusions. I consider myself a “jet age, old European potato farmer” kind of guy so I’m keeping my fingers crossed.
Just got the 7581A  tubes today.Very nice.Smooth but lively.Good bass too.This is right out of the box.Very impressive!Thanks jbhiller:)
Just just ordered a quad of these today from Viva $92.00 with shipping   Hoping to hear those intrinsic organic overtones and supple extended high frequencies associated with these tubes. All kidding around aside the  VIva website lists these as KT 66  Variants. Looking forward to hearing them as I haven’t listened to my tube amps for almost two years