This tube is becoming wildly popular. How ironic. And I agree they sound great right out of the box...in the box, not so much. |
Take them out of the box? This explains why I’ve been getting cardboard build up in my tube sockets...thanks for the tip Wolf! |
Yeah...that can ruin what is a nicely made cardboard box. |
Just got my quad of these today and listened to them for about two hours. very impressed thus far. Is there any break in time associated with these and any audible difference over time. Associated gear is are Modified Eico HF20 JWN amps |
@metman Not a huge change as they burn in but they do loosen up becoming less dry and more open. |
The blue glow actually got a little bluer after a few days, so there's that, and after however many weeks I've had 'em I've become even fonder (is that a word?) of these things. A classy tube. |
Metman, Can you share some details on your “Eico HF-20 JWN” amps? Are these Eicos rebuilt by Jim Nichols using his input/driver circuitry?
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@salectric
I bought these second hand And actually traded an .EL34 based amp purchased through Jim (which was also stellar) and some cash for these which was modified with Jim’s circuit. I forgot how good these sound particularly with these tubes as they’ve been on the shelf for a couple of years. Jim did comment to me that these were one of his best amps. It’s a shame he’s no longer in the business |
@metman
I suspect the amps I am using right now look and sound similar to yours. I used HF-22 chassis (monoblocks), stripped them of all parts, and then rebuilt them using Jim Nichols’ circuit. I kept the Eico output transformers (same as in HF-20) but everything else is new. They sound great!
Right now I am using RCA blackplate 6L6GC from the 1960s but I also have some SED Winged C output tubes that sound really good too. |
@jbhillerHaving both KT150 and 7581A, how would you compare the two sets? I have a Primaluna HP integrated, and you have peaked my interest. Would you give up the KT150s for the 7581As? |
I think the output xformer was replaced with a Chicago brand of I’m not mistaken and seems quite robust. I also used some winged Sed el34 with my last speakers and they did sound quite nice. It’s hard to do a comparison as I just got some new speakers and was a little concerned they wouldn’t be a good match but they sound fabulous
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@metman @salectric
I have two sets of EICO HF35s one of which is a Stu Remmington rebuild with chokes, fixed bias and revised input circuitry. I believe they’re based on the venerable Mullard 5-20 push-pull circuit. I use a Psvane 6SN7 Globe with the TS 7851A tubes and it’s a stunning amplifier. |
followup to my earlier post. I've had the 7581a in my PL Dialogue Premium integrated well over 100 hours. I didn't listen to the tubes out of the box and let them run 10 hours or so after installation. I didn't really detect any "break in" sound changes. The tubes are dead silent and I like the blue glow too. So compared to the original EL34's that came with the amp, no contest to me. Much more detail, especially bottom end definition and extension with a more dynamic and "faster" sound. Compared to the Gold Lion KT77, the detail and dynamics were about the same but the bottom end somewhat more developed and pronounced but still balanced. All three tubes I've used are very good, just a matter of your taste. I like a strong dose of tone without being over the top, that's the 7581a to me.
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@tuberist
For midrange, which one do you like out of the three? |
In addition to the overall tone and detail I’m very impressed with the bass definition as well. Tempted to order another quad - just because |
@noromance
The stock Eico amplifiers are based on the Mullard 5-20 design. It is a tried and true performer.
The Jim Nichols circuit referred to above is a different design that uses a floating paraphase inverter instead of the Mullard long tailed pair inverter. They are both capable of great sound. So much depends on the execution. |
Working around the Eico sidebar....good question re midrange. Let’s face it we are all looking for the “Goldilocks” tube, the mid warmth and tone of the EL34 and the highs and lows of the KTs. Have the 7581a’s now, trying to find time to plug them in.
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There are at least 3 Tung Sol reissue tubes that can be used in an amp designed for 6L6 outputs—the 7581a, 6L6G and 6L6GC-STR. I recently bought two pairs of the STR version and have just started breaking them in. So far I am very impressed. They have a strong bass with excellent detail and weight, and the entire spectrum is fast and detailed. I still prefer the midrange refinement and coherency of my vintage RCA blackplates, but the T-S is a bonafide contender.
I wonder how the other T-S reissues compare. Have any of you with 7581a tubes compared them to either the 6L6G or 6L6GC-STR? |
My Dennis Had "Inspire Fire Bottle HO" single ended amp (12wpc supposedly) will accommodate everything from KT150s, 120s, 88s, 77s to 6l6s and their ilk, and, other than 6L6s, I've tried all of the above. Swapping out the rectifier tube can help things, but I generally keep a 274B in there...before the 7581As the Gold Lion KT77s sounded best by far, and I raved about them like an unhinged maniac. Now I'm so impressed by the 7581A's tone palette and seemingly effortless tight power grip from top to bottom, they're staying put. Besides, the blue phosphorescence is so appealing, and clearly I need to get out more. |
Keep these comparisons coming.. interesting to read above subjective opinion on 7581a and GL KT77. Also quite curious why some prefer the JJ KT77 over the GL version. Thinking the JJ KT77 may be similar in some ways to the 7581a. |
I like the 6L6 family of tubes. Anyone made a comparison with a 350B? I like that tube. |
@larryi
I have never had 350B tubes to try, but I do have 4 sets of 6L6GC tubes that I have been trying in my new 6L6 amps. These are RCA blackplates, GE gray plates, SED Winged C and new Tung Sol STR. The RCA and GE are from the 1960s, the SED is from the late 1990s, and the T-S is a new reissue. So far my favorite is the GE.
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JJ KT77s are so inexpensive that I bought a pair a while back, and they sounded (surprisingly) so much worse in my Had SE amp that I simply shrugged and considered it a lesson learned. Maybe some amp synergy with the JJs was off, and I even tried different rectifier tubes to no avail...When I looked at Gold Lion KT77s and noted obvious build differences I finally got over my KT77 issues and was pleasantly surprised by how good they were, and kept them in the amp until the 7581As bumped them from the top spot.
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Has anyone tried the 7581A's in the Music Reference RM9 MK2?
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Based on all your feedback I ended up getting a set of 4 for my PL Dialogue integrated and have about 25 hrs on them so far. I'll give some feedback once I get more time with them. To date I've used the original PL EL34s (still going strong) and KT150's. I love the huge sound and authority of the KT150's but use a pair of Mullards in the pre to warm things up and bring some texture to the mids. I still love the EL34s overall, though it's fun to swap back and forth and do so once a month whether it needs it or not :-)
@arch2 and @tuberist What bias setting are you using for the 7581A's? Do you have it switched to KT88/120 or EL34? |
I’ve been bopping around through my systems this summer. I just got back to horns fed by these tubes. Soooo good. Time has shown me these are just so special new production tubes. |
The review of 6L6s linked to further up in the thread lists the SED 'Winged C' 6L6 NOS as even better. Anyone heard those?
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Best current production power tubes available hands down! I have a Dennis Had Fire Bottle wired triode and a PL Prologue Classic and both amps Sonics greatly improved with the 7581a. I have spent thousands of dollars on tubes over the years trying to find the holy grail to my ears and my favorites were TS NOS 6550, the GL KT77, Sophia EL34, and Winged C 6l6. The TS 7581a bested them all!
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Completely agree. JB turned me onto these 6 months ago and I’ve never taken them out. Superb performance bass and mids, with a top end that i can only describe as effortless. And at $100 a quad!
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I wasn’t even aware there was a vintage Tung-Sol 7581A to "reissue". Obviously New Sensor / EH doesn’t have rights to the Philips / Sylvania, RCA, or GE names, so perhaps they just pick their "Tung-Sol" label as the go-to for reissues of power tubes mostly associated with American makes.
Around 10 years ago I ran a restored pair of Heathkit W5 monoblocks with 1960’s GE 7581A side-getters & "flesh" colored bases (into Tannoy Kensington SE), and there was definitely some magic there. Wonderful tone, holographic 3D image. I later had the amps re-fitted to Gold Lion reissue KT66, which sounded more powerful and dynamic, but lost some of the "magic" tone and 3D imaging. The GE tubes looked to be exceptionally well made - the Russian "re-issues" look ugly but I realize that may have no bearing on sound quality. I think I still have some of them, but my fancy new amps only take KT88 and up, 8 at a time (or my old amps which can take the 7581A, but freakin’ TWELVE at a time) :( |
I'd love to hear the GE and TS side by side. I run the TS in EICO HF35. |
@noromance
Eicos are awesome too! I had an HF-87 with the most incredible vintage tube amp tone (it was even a good tone with cheapo EH EL34, but better with Mullard XF2/3/4 and a bright-ish 12AX7 to balance, e.g. Japanese). Small sound stage though - but I know they have mono amps that can do much much better. Heard a pair of HF-22 once, and loved them! |
@mulveling I have 2 pairs of HF35s. One pair is a full rebuild with fixed bias and 3 chokes, PIO caps, Mullard GZ34, Psvane Globe 6SN7 ($375 a pair but amazingly detailed), TS 7581A and it sounds better than many amps costing a LOT more.
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@jbhiller Thanks for sharing info about the 7581a. I ordered a set and just rolled them into my PL HP. So far, they sound really nice, and I think I like the tone better than the KT150s.
But, question for you... where do you put the tube switch on the HP? I moved it to the EL34 setting. Is that right? |
I’m not even sure what I originally searched for to eventually stumble onto this old thread, but I‘ve now ordered a new set of tubes tonight.
I blame all of you. |
@soundermn
A vintage 7581A should be closest to a 6L6GC, and then to KT66. It's not really "that" close to an EL34, but according to Prima Luna's manual the EL34 setting is your best choice available and should work fine though it will somewhat reduce the power output available from the amp. I wouldn't expect the power reduction to be TOO much; maybe say 30%? |
@mulveling Thank you for the follow up! I actually stopped playing in this forum, because I got tired of so many jack asses who have to pontificate and condescend in every darn thread. I'm sure you know who I mean. But, this one thread sent me an email because I'm subscribed, and I wanted to update on my progress.
To update, I did use the 7581A for a while, and I really liked them. After I got new speakers, Revel F228Be, I did a bit of a shoot-out with KT150, EL34 and the 7581A. The winner by a small margin was the stock Primaluna EL34, then 7581A and last KT150. I sold the KT150s, and still have the 7581 octet, but would sell them if anyone is interested (Under 500 hours, fair price, PM me). I don't see going back at this point. And, to your point, I did run them on the EL switch setting. They were very nice, the price is right, and I can see that with a different room or speaker it could go the other way.
So, what I ended up doing is I got better EL34. I ordered TungSol EL34b, and they were definitely an improvement over the PL EL34. Like the 7581 they are priced right, and the sound is clearly the best of all I have tested. While the 7581 sounded better than the KT150, the EL34b was another step in the right direction. I was surprised, because I thought the KT150 would "grip" the large speakers the best, but it didn't work out that way.
I don't expect much change in the system for a long time... I've reached the nirvana I wanted. And, I'm intending to stick with what I have, rather than try to improve every month or two... and I'm just enjoying it all!
PL HP Integrated
Vintage JVC VL8 with AT ART9 cart
Manley Chinook
Revel F228Be
Pair REL T9/i subs
EL34b power tubes
Cifte Input tubes
PL rectifier tubes. |
What improvement did you hear? Can you describe? I have 4 pairs of 7581As. Thanks. |
@soundermn
Awesome, glad you found out your favorite tube and personal nirvana, even if it was with the original EL34! Funny, I tried KT150 in my own amps (VAC 200iQ) earlier this year, and like your case they came in dead LAST of 3 sets - versus Tung-Sol KT120 and Gold Lion KT88 reissue, in my case. The bottom end was VERY powerful, dynamic, and punchy, but in the end it just swamped the music and sounded unbalanced. Sounds like my amps were really designed for KT88, but the KT120 are similar enough and actually eek into the #1 spot for my tastes. The KT150 just sound like a different species compared to those two, but I realize they might be amazing in amps designed specifically for them. |
@noromance My experience was similar to @mulveling . But, it's definitely speaker-dependent. Before the new speakers, I had B&W 803N and then Revel F208. For both of those, the KT150 was better than EL34 overall, although I'd say that the EL34 did have a sweeter midrange (or it seemed that way because the bass was less punchy). KT150 retained a lot of the flavor of the EL34, but had more punch in the bass, well balanced across all frequencies, and IMO better control of the speakers. When I moved up to the F228Be, the KT150 sounded good until I started to compare. The 7581a are really nice (better than KT150 overall), and really close to the EL34, especially in midrange. But, somehow the EL34 seemed to have cleaner, deeper bass, and clearer, crisper highs. All of that was definitely improved further when I got the TungSol EL34b. And, on top of tha, they have that liquid midrange wonderful sound that EL34 gives you. It's just better all around.
Again, it was a completely different outcome with different speakers. So, you have to try for yourself. If you still have EL34 and 7581, do a comparison and see which you like.
Interestingly, @mulveling , I didn't like the KT120 nearly as much as the rest of these. I found them to have a certain "glare" in the midrange, especially around vocals. For example, Mark Knopfler's voice always sounded a little "fuzzy" around the edges. With all the others, that effect is completely gone. But, again, it is probably speaker dependent. I didn't have any KT120s to try with the F228Be speakers, so I can't validate. If it works for you, then spin some vinyl (or shiny discs) and enjoy the music! |
Also discussed earlier in this post is the GL KT77. Well worth a try as well, an excellent alternative to the 34. Great mids like the 34, but with extended top end and bass and very refined. I never have been able to decide between the 77 and the 7581a since JB brought them to my attention...I finally solved it by switching back and forth every few months. Both are excellent, you can’t go wrong with either. |
soundermn-
Your setup looks good.What PL integrated is tube integrated? I thought the preamp was the only model tube rectified.
"PL HP Integrated
Vintage JVC VL8 with AT ART9 cart
Manley Chinook
Revel F228Be
Pair REL T9/i subs
EL34b power tubes
Cifte Input tubes
PL rectifier tubes."
I use the old RCA 6L6G lower power, big bottles in my PL HP. |
Primaluna Dialogue HP Integrated
Maybe "rectified" is the wrong word? I only know enough to be dangerous sometimes...
@tablejockey |
Tung-Sol 7581 vs Tung-Sol 7591…. What’s the difference? |
7591 is a 19 watt tube with different pin layout from a 30watt 6L6/EL34/7581.
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Anyone try TS 7581A’s in a Music Reference RM9? RM9 accepts KT66, EL34 and KT88's... so not sure if the Tung Sol 7581 is compatible. |
As I stated here before, my favorite among popular tube types are 6L6 and KT66 for pentode/tetrode tubes. For single-ended triode amps, I like 45s and 2a3s. For less common types, I like the 349 (a tube I run in my pushpull amps) and 350 (similar to 6L6). For super rare tubes, I heard an amazing amplifier that ran the 252 meshplate tube. |
I've been running an octet of 7581A in a Primaluna Evo 400 power amp. I do like them more than the original EL34 in my system. Sacrifices just a smidge of midrange magic for better low end meat and upper end presence. Just a nice balance from top to bottom.
Enough to make me want me to keep the Primaluna.
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Would the 7581A be biased the same as a 6L6GC/KT-66? I am currently running KT-88s in my DeHavilland 50A mono blocks and would like to try the 7581As. The DeHavilland is designed to accept 6L6/KT-66 tubes and a bias setting for those is specified in the owners manual. Would it be safe to assume that the same bias setting be used for the 7581A?
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Would the 7581A be biased the same as a 6L6GC/KT-66? I am currently running KT-88s in my DeHavilland 50A mono blocks and would like to try the 7581As. The DeHavilland is designed to accept 6L6/KT-66 tubes and a bias setting for those is specified in the owners manual. Would it be safe to assume that the same bias setting be used for the 7581A?
I'm not a tech but NO I would not assume that. I was running Heathkit W5 monos originally with NOS GE 7581A. When I switched to reissue Gold Lion KT66, those ran a LOT hotter and my tech had to adjust the bias down so they wouldn't orange-plate.
Of course you're talking reissue Tung-Sol 7581A which I haven't quite tried yet, but I do have three quads on the way to try in my Rogue Apollo Dark monoblocks :)
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