• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Modern Tung-Sol 7581a Tubes

Got about 200hr on a set in my Rocket 88 and think they are the best sounding of the small power tube genre that I've tried (T-S EL34, GL KT77, etc.). A delightful tube. :thumbsup:
 
dcgillespie said:
I purchased a matched quad of JJ 6L6GCs over ten years ago, for a sound support amplifier that gets rather regular use. When I first bought them, I measured their performance in my power output tube tester, very much expecting them to act like every other Russian copy (of that day) of original American pieces I'd had the opportunity to test: Power output would typically only be 80% of the original American device, and quite often would either slowly rise (with heating), or droop (from a less than capable cathode) under extended power output testing (normally, the test only lasts about 3 seconds max). Whether it was copies of the 6550, EL34, the Sovtek 6L6, or carbonized 6V6s, it didn't matter. None of the Russian tubes could hold a candle to the original American pieces, and the JJ tubes were the bottom of the barrel. The best any of the Russian tubes could ever do was to hold a steady power output over time, but never at the levels that the American pieces could produce. But not these tubes. These JJs were just as capable as any RCA black plate tube I've ever tested in terms of maximum power output, and sustained, stable power output. They all held a steady power output level over extended test time, and even showed a near identical biasing characteristic to the fabled RCA device. Frankly, I was stunned. In my MC 240, they allow both channels combined to developed a sustained 100+ watts RMS, while meeting Mac distortion specifications -- something that only good American pieces are usually capable of doing.

I had occasion to yank the tubes a year or so ago to give them a quick test. All were still producing at least 98% of their original when new power output level. All continued to demonstrate a steady power output level under an extended test time. I continue to be very impressed by the tubes.

Everyone will always have their preferences sound wise, but to me, there was nothing objectionable about the sound of these tubes at all, with their performance proving to be all that the original American pieces were. These tubes had nearly 700 hours on them at the time they were retested. Tube life is this only parameter I'm watching (and waiting) to see in comparison the the American pieces. Time will tell.

The only other tube I have been as equally impressed with is the (relatively) new Gold Lion KT88 reissue. Same comments: Power output is every bit as much as that of the original British pieces, it is stable with extended testing, and has a biasing characteristic that is very much like that of the original tube.

Dave
Click to expand...

A very useful comment, thanks Dave.
 
Salectric said:
Has anyone compared the several T-S 6L6 variants? I have read favorable comments about each of them but nothing comparing them. The versions that spring to mind are 6L6GC, 6L6G, 6L6GC-STR, and now 7581a.

I recently bought a quad of T-S 6L6GC-STR on the recommendation of Jim McShane, and I am really impressed with them. They hold their own against my vintage quads of RCA, GE and SED Winged C. But now I am wondering whether the coke bottle 6L6G or 7581a might be even better.
Click to expand...

The Tung-Sol reissue 5881s are very nice. I actually prefer them to the originals I have, a bit more open and relaxed. Just be aware that they are NOT a substitute for the 6L6GC, but work very nicely in vintage Heathkit amps.
 
I ordered a quad of TS 7581a's a while back and never got around to listening to them. I just tried them in my modified Heathkits and indeed, they are impressive. A big rich sound, very clean.
 
JonL said:
Any reviews of these TS 7581a in Fender guitar amps?
Click to expand...

I'm sure there are if you google it. The extra headroom is particularly popular with guitar amp owners.

ETA: If you go to The Tube Store, for example, and read their reviews, there are lots of great comments from guitar players.
 
tube-a-lou said:
So guy's you mean I could put quad of KT66's instead of a quad of 6L6GC tubes
Click to expand...

I don't know what sort of demand the Bogen puts on the output tubes. The KT66 has 27 watts dissipation, as opposed to 30 for the 6L6GC. Assuming the Bogens don't runt the tubes too hard, you probably could. The Gold Lion KT66 is a lovely tube.
 
Salectric said:
Has anyone compared the several T-S 6L6 variants? I have read favorable comments about each of them but nothing comparing them. The versions that spring to mind are 6L6GC, 6L6G, 6L6GC-STR, and now 7581a.

I recently bought a quad of T-S 6L6GC-STR on the recommendation of Jim McShane, and I am really impressed with them. They hold their own against my vintage quads of RCA, GE and SED Winged C. But now I am wondering whether the coke bottle 6L6G or 7581a might be even better.
Click to expand...

Yes, I have tried 3 of the TS variants you mention. The 6L6G, 6L6GC-STR, and obviously the 7581a I started this thread about.

All three are remarkable tubes. For decades I’ve been a “Vintage NOS Only” guy when it came to tubes. Current production TS has changed that for me.

While I still love my Vintage tubes, TS are a great substitute.

The TS "6L6GC-STR" are very good tubes. I own a few quads of Sylvania/Phillips STR 387/415’s which this tube is “based off of”. Are they as good as the vintage? Well that is subjective, I wouldn’t be to upset with the Modern TS version though. Sound wise, very similar. In my setups anyway. They seem very well built and hold up when run hard. Tbh though I’ve only got about 100 hours on them.

Now the 6L6G “Coke Bottle” tubes are KILLER. I love them. Built like tanks and look amazing. From everything Ive read, the TS 6L6G "Coke Bottle" share the same innards as the TS "6L6GC STR". HOWEVER....the "Coke Bottle" have thicker glass and a much are much bigger, aiding in cooling and microphonics, and overall build quality. Be sure you have enough room for them if your amp has a tube cage or they are inside a cabinet like a Guitar Amp. Nearly twice as tall as normal 6L6GC variants. They are GC spec's, despite the "G" name. I run them in my McShane modded HK Citation V. I couldn’t be happier. Put it this way. I’ve run quads of the following in that amp and ended up going back to the Coke Bottle 6L6G’s. RCA Blackplate 6L6GC, Sylvania 6L6GC-STR 415’s(Dual getter),Winged "C"'s(great tubes) and a nice crispy NOS/NIB set of GE 7581A “beige bottom” tubes I paid an arm and a leg for. All 3 sound great, especially the GE 7581a’s, which are what HK used from the factory. The build quality on them is superb and they are highly sought after and very well built(mil-spec). Yet the TS 6L6G “Coke Bottles” sound better in the Citation V, imo. I wanted to like the GE 7581a’s more, I really did, but alas....reality is the TS sound amazing. The Citation V are known for running the Output tubes right on the ragged edge. These TS Coke Bottles run with ease in it. I purchased one of my Quads from Jim.

Now, the McShane mods helped calm the V down a bit, but they also sound great in the original/unrestored Citation V I have as well(waiting on McShane Mods/Resto when I have the time). No issues yet in there either. My MC240's love the TS 6L6G tube as well....though I find Mc Tube amps to be less sensitive to output tube changes, they sound great with just about any tube that measures good.

Tbh, you’d be well served to follow ANY advice from Jim. He is about the best person I’ve ever dealt with in HiFi. Guy knows his tubes, if he said use them for your amp. You’ll be happy. The price is steadily rising as well on these TS's as word gets out. Steer clear of that "auction site" as MANY are Factory seconds. Not all, but you have to be careful. Jim's tubes are ALWAYS good....all his parts/kits/tubes always are. I have NO affiliation with Jim. Just a VERY satisfied customer. As nearly all his customers are. Guy is a Gem in todays HiFi market.

Bottom line....If I could only keep one set of the TS 6L6GC variants Ive tried....it would be the 6L6G's. A wonderful sounding tube, built like a tank, and look really nice. I hadn't yet tried them when I started this thread about the 7581a's, which would be a close second. Then the STR's....haven't tried the standard 6L6GC yet....no need.

Its a great time to be into Valve Amps, as there is now a modern alternative to the ever increasing Vintage tubes. Again, Im not saying that I wont use/buy vintage tubes anymore....I will. Its just that Ive built quite a collection of Vintage Tubes and its nice to have a modern alternative so I dont eat the life up on those


tube-a-lou said:
So guy's you mean I could put quad of KT66's instead of a quad of 6L6GC tubes
Click to expand...

I didn't notice if this was advised in this thread or not.....but NO. Don't do that. Not without first checking the spec's of your amp. KT66's pull about .3 amps more PER TUBE than 6l6GC's. That can add up quick, and pull another 1.2amps in a PP Stereo amp. Which your PT may not(probably) be able to handle. No fun to smoke one of those. Now, that isn't to say you cant, but they ARE NOT a direct sub for 6L6GC. What is the amp you're considering doing this on? I am leaving for vaca in the morning, but Ill try to check back and advise....otherwise I'm sure someone can. As a rule of thumb, dont ever sub tubes without 110% certainty that youre amp can handle it. You can try 7581a's and possibly 7027a's......depending on how your amp is wired.....KT66's are iffy though. Proceed with caution.
 
Treyphan said:
Yes, I have tried 3 of the TS variants you mention. The 6L6G, 6L6GC-STR, and obviously the 7581a I started this thread about.

All three are remarkable tubes. For decades I’ve been a “Vintage NOS Only” guy when it came to tubes. Current production TS has changed that for me.

While I still love my Vintage tubes, TS are a great substitute.

The TS "6L6GC-STR" are very good tubes. I own a few quads of Sylvania/Phillips STR 387/415’s which this tube is “based off of”. Are they as good as the vintage? Well that is subjective, I wouldn’t be to upset with the Modern TS version though. Sound wise, very similar. In my setups anyway. They seem very well built and hold up when run hard. Tbh though I’ve only got about 100 hours on them.

Now the 6L6G “Coke Bottle” tubes are KILLER. I love them. Built like tanks and look amazing. From everything Ive read, the TS 6L6G "Coke Bottle" share the same innards as the TS "6L6GC STR". HOWEVER....the "Coke Bottle" have thicker glass and a much are much bigger, aiding in cooling and microphonics, and overall build quality. Be sure you have enough room for them if your amp has a tube cage or they are inside a cabinet like a Guitar Amp. Nearly twice as tall as normal 6L6GC variants. They are GC spec's, despite the "G" name. I run them in my McShane modded HK Citation V. I couldn’t be happier. Put it this way. I’ve run quads of the following in that amp and ended up going back to the Coke Bottle 6L6G’s. RCA Blackplate 6L6GC, Sylvania 6L6GC-STR 415’s(Dual getter),Winged "C"'s(great tubes) and a nice crispy NOS/NIB set of GE 7581A “beige bottom” tubes I paid an arm and a leg for. All 3 sound great, especially the GE 7581a’s, which are what HK used from the factory. The build quality on them is superb and they are highly sought after and very well built(mil-spec). Yet the TS 6L6G “Coke Bottles” sound better in the Citation V, imo. I wanted to like the GE 7581a’s more, I really did, but alas....reality is the TS sound amazing. The Citation V are known for running the Output tubes right on the ragged edge. These TS Coke Bottles run with ease in it. I purchased one of my Quads from Jim.

Now, the McShane mods helped calm the V down a bit, but they also sound great in the original/unrestored Citation V I have as well(waiting on McShane Mods/Resto when I have the time). No issues yet in there either. My MC240's love the TS 6L6G tube as well....though I find Mc Tube amps to be less sensitive to output tube changes, they sound great with just about any tube that measures good.

Tbh, you’d be well served to follow ANY advice from Jim. He is about the best person I’ve ever dealt with in HiFi. Guy knows his tubes, if he said use them for your amp. You’ll be happy. The price is steadily rising as well on these TS's as word gets out. Steer clear of that "auction site" as MANY are Factory seconds. Not all, but you have to be careful. Jim's tubes are ALWAYS good....all his parts/kits/tubes always are. I have NO affiliation with Jim. Just a VERY satisfied customer. As nearly all his customers are. Guy is a Gem in todays HiFi market.

Bottom line....If I could only keep one set of the TS 6L6GC variants Ive tried....it would be the 6L6G's. A wonderful sounding tube, built like a tank, and look really nice. I hadn't yet tried them when I started this thread about the 7581a's, which would be a close second. Then the STR's....haven't tried the standard 6L6GC yet....no need.

Its a great time to be into Valve Amps, as there is now a modern alternative to the ever increasing Vintage tubes. Again, Im not saying that I wont use/buy vintage tubes anymore....I will. Its just that Ive built quite a collection of Vintage Tubes and its nice to have a modern alternative so I dont eat the life up on those




I didn't notice if this was advised in this thread or not.....but NO. Don't do that. Not without first checking the spec's of your amp. KT66's pull about .3 amps more PER TUBE than 6l6GC's. That can add up quick, and pull another 1.2amps in a PP Stereo amp. Which your PT may not(probably) be able to handle. No fun to smoke one of those. Now, that isn't to say you cant, but they ARE NOT a direct sub for 6L6GC. What is the amp you're considering doing this on? I am leaving for vaca in the morning, but Ill try to check back and advise....otherwise I'm sure someone can. As a rule of thumb, dont ever sub tubes without 110% certainty that youre amp can handle it. You can try 7581a's and possibly 7027a's......depending on how your amp is wired.....KT66's are iffy though. Proceed with caution.
Click to expand...

Good advice on the filament current of the KT66's. I forgot about that.
 
Treyphan said:
Yes, I have tried 3 of the TS variants you mention. The 6L6G, 6L6GC-STR, and obviously the 7581a I started this thread about.

All three are remarkable tubes. For decades I’ve been a “Vintage NOS Only” guy when it came to tubes. Current production TS has changed that for me.

While I still love my Vintage tubes, TS are a great substitute.

The TS "6L6GC-STR" are very good tubes. I own a few quads of Sylvania/Phillips STR 387/415’s which this tube is “based off of”. Are they as good as the vintage? Well that is subjective, I wouldn’t be to upset with the Modern TS version though. Sound wise, very similar. In my setups anyway. They seem very well built and hold up when run hard. Tbh though I’ve only got about 100 hours on them.

Now the 6L6G “Coke Bottle” tubes are KILLER. I love them. Built like tanks and look amazing. From everything Ive read, the TS 6L6G "Coke Bottle" share the same innards as the TS "6L6GC STR". HOWEVER....the "Coke Bottle" have thicker glass and a much are much bigger, aiding in cooling and microphonics, and overall build quality. Be sure you have enough room for them if your amp has a tube cage or they are inside a cabinet like a Guitar Amp. Nearly twice as tall as normal 6L6GC variants. They are GC spec's, despite the "G" name. I run them in my McShane modded HK Citation V. I couldn’t be happier. Put it this way. I’ve run quads of the following in that amp and ended up going back to the Coke Bottle 6L6G’s. RCA Blackplate 6L6GC, Sylvania 6L6GC-STR 415’s(Dual getter),Winged "C"'s(great tubes) and a nice crispy NOS/NIB set of GE 7581A “beige bottom” tubes I paid an arm and a leg for. All 3 sound great, especially the GE 7581a’s, which are what HK used from the factory. The build quality on them is superb and they are highly sought after and very well built(mil-spec). Yet the TS 6L6G “Coke Bottles” sound better in the Citation V, imo. I wanted to like the GE 7581a’s more, I really did, but alas....reality is the TS sound amazing. The Citation V are known for running the Output tubes right on the ragged edge. These TS Coke Bottles run with ease in it. I purchased one of my Quads from Jim.

Now, the McShane mods helped calm the V down a bit, but they also sound great in the original/unrestored Citation V I have as well(waiting on McShane Mods/Resto when I have the time). No issues yet in there either. My MC240's love the TS 6L6G tube as well....though I find Mc Tube amps to be less sensitive to output tube changes, they sound great with just about any tube that measures good.

Tbh, you’d be well served to follow ANY advice from Jim. He is about the best person I’ve ever dealt with in HiFi. Guy knows his tubes, if he said use them for your amp. You’ll be happy. The price is steadily rising as well on these TS's as word gets out. Steer clear of that "auction site" as MANY are Factory seconds. Not all, but you have to be careful. Jim's tubes are ALWAYS good....all his parts/kits/tubes always are. I have NO affiliation with Jim. Just a VERY satisfied customer. As nearly all his customers are. Guy is a Gem in todays HiFi market.

Bottom line....If I could only keep one set of the TS 6L6GC variants Ive tried....it would be the 6L6G's. A wonderful sounding tube, built like a tank, and look really nice. I hadn't yet tried them when I started this thread about the 7581a's, which would be a close second. Then the STR's....haven't tried the standard 6L6GC yet....no need.

Its a great time to be into Valve Amps, as there is now a modern alternative to the ever increasing Vintage tubes. Again, Im not saying that I wont use/buy vintage tubes anymore....I will. Its just that Ive built quite a collection of Vintage Tubes and its nice to have a modern alternative so I dont eat the life up on those




I didn't notice if this was advised in this thread or not.....but NO. Don't do that. Not without first checking the spec's of your amp. KT66's pull about .3 amps more PER TUBE than 6l6GC's. That can add up quick, and pull another 1.2amps in a PP Stereo amp. Which your PT may not(probably) be able to handle. No fun to smoke one of those. Now, that isn't to say you cant, but they ARE NOT a direct sub for 6L6GC. What is the amp you're considering doing this on? I am leaving for vaca in the morning, but Ill try to check back and advise....otherwise I'm sure someone can. As a rule of thumb, dont ever sub tubes without 110% certainty that youre amp can handle it. You can try 7581a's and possibly 7027a's......depending on how your amp is wired.....KT66's are iffy though. Proceed with caution.
Click to expand...

Thanks for the detailed reply. Much appreciated! I need to get some of the T-S reissue 6L6G tubes.
 
Treyphan said:
So I recently purchased a Quad of Tung-Sol 7581a tubes.
After seeing a few glowing reviews, from “so-called” modern tube “haters”. I figured for the cheap price....why not?

I’m a Big 6L6 amp guy. So I had plenty of amps to try them in. I’m usually a Vintage NOS tube guy only, if I’m buying them. However, with Tube Prices getting out of this world, especially on 6L6GC tubes. I decided it was worth the, relatively small cost as a test.

I received them about 2 weeks ago, and have over 100 hours on them now. So they are certainly “broken in”, if you believe in that. Not looking to make this a thread about that.

Anyway. First amp I tried them in was a Stromberg Carlson ASR-444/Stereo 60. (Accepts 7027/6L6/etc)This is a wonderful 30 watt stereo amp, that I recently COMPLETELY restored. I love it. It originally ran a Quad of RCA 7027a’s, which are still measuring nearly NOS and that I love. Anyway, I couldn’t believe my ears once the TS 7581a’s were installed. Pure bliss. Nice across the entire Freq Range and just great. The bass seemed a bit tighter, with a very nice mid, not too scooped as is common with 6L6 variants...still supple and nice though.
Click to expand...

Hi, how are them TS 7581 sounding two years later? I ask because I too rebuilt an ASR-444. It has old 7027 tubes. I recently bought EH 7868 for my Sherwood S5000II and was amazed. So I'm thinking of taking your advice and trying a matched quad of TS 7581 in my ASR-444. So, I can use those because, like the 7027, they are a 6L6 variant, right? And they'd require no modification, right? Just install and enjoy?

Thank you.
 
Any 6L6GC equivalent will work in the ASR-444, including 7581s. The 7027 has extra pins (unused on 6L6) connected to elements inside, but Stromberg chose to wire only the pins that match up with the 6L6.
 
Thanks for reminding me about these. After ~1000hr on the GL KT88s its time to roll the 7581s back in........... So many tubes, so little time (and $$).
 
JonL said:
Any reviews of these TS 7581a in Fender guitar amps?
Click to expand...
I've installed several sets in Fender gear. They may be the best option out there. They sound great and they can handle the abuse of those late 70's Fenders with the UL transformers and extra high plate voltages. Money well spent.
 
JohnT123 said:
I've installed several sets in Fender gear. They may be the best option out there. They sound great and they can handle the abuse of those late 70's Fenders with the UL transformers and extra high plate voltages. Money well spent.
Click to expand...

Yep. 500V ain't no big thing to these tubes. They just roll with it, and go.


They have pretty much taken over where we used to use the 6L6GC-MSTR tubes. I was worried when those disappeared from the market (due to the Shuguang tube plant fire), but these TS 7581s have definitely filled the bill...

Regards,
Gordon.
 
I run KT88s & 6550s at 200mA bias, 7581s & KT66s at 160mA and EL34s at 150mA in the Rocket 88. All seem happy at these levels.
Would be interesting to see what the plate voltage is, but likely more effort then I'm will to expend.
 
I'm thinking your B+ must be pretty low. With those current levels the plate dissipation would likely be exceeded if the plate voltage was in the average to high range.
 
JohnT123 said:
I'm thinking your B+ must be pretty low. With those current levels the plate dissipation would likely be exceeded if the plate voltage was in the average to high range.
Click to expand...

I was wondering about that myself. 42 watts (KT88 absolute max dissipation) from 200ma, would only be 210V B+..

Now, if that is for a PAIR of tubes- then things make much more sense. 100ma per tube, at 350V B+, could be an entirely reasonable operating point.

Regards,
Gordon.
 
They are running at 20wpc Class A at the 200mA bias. I do not have the schematic so cannot divine the voltage divider, but will guess it is 200mA for the four tubes, so 50mA each. If memory serves, Dennis Had was generally noted for running the output tubes pretty 'hot' in his designs. So won't surprise me to find 450+ on the plates. Eventually I'll get around to pulling the bottom plate to measure and draw up the schematic. Maybe this fall.
 
You must log in or register to reply here.
Back
Top Bottom