Who makes great 6L6 tube amps ? ....
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GaryProtein
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Do people buy amplifiers because they use specific tubes????????????
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I would say so Gary. People buy 300b amps specifically to bask in the glory of the 300b magic. Conversely, people don't buy certain amps because of the tubes (just ask Kev from Australia). For me, I would generally tend to shy away from KT120/150 amps.
Now, if I could just find a sweet 45 tube amp....
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yes gary, some people i know die for el34's. and i dont think they are all that. but a friend of mine buys them and also builds them, he is el34 4 life.
i only search and read about 300b's because im lookin for the perfect 300b amp for me.
some people are sold on 2a3's and 845's
and i still havent figured out the difference between 211's and 845's.
it seems every power tube has its own fan base. if you like one there is no going to another or you feel like you are missing something. at least i do.
i agree with mike kt120s and 150s just arent that good i dont think. just my opinion of course. and kt88's aside from a few amps ive heard i can live without also.
dlb2
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If I recall correctly the 6L6 tube was the American answer to the English EL34. It sounds bigger and bolder and has a more distinct bottom end. Like Steve I always liked these in guitar amps. I don't think I've ever heard a 6L6 audio amp before. The only amp I can think of off hand that can use them is the Leben CS600. It can use either 6L6 or EL34 tubes in it.
also thinking on it the granite audio amps are el34 or 6l6 as well.
ive tried that leben amp doug its a pretty sweet setup!!!
mep
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The 6L6 was comparable to the KT-66, but the KT-66 made by Genelex was a much better tube. I don't know of anyone who is building 6L6 tube amps for audio. There is nothing special about the 6L6 tube that would make me want to seek out a 6L6 amp for home stereo.
mep
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I don't know why you would say that unless you are just hung up on flea watt triode amps or big daddy triode amps. I will take the KT-120 and KT-150 tubes any day over modern KT-88s.
dlb2
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mep
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If memory serves me correctly, the 6L6 was known to have a kink in its frequency response. The KT-66 cured that kink and in fact, the "KT" stands for Kinkless Tetrode.
In fact, if you want a kick-ass amp and you can get buy with 15 Class A watts of power, buy a pair of the original Quad II amps and make sure they have been gone through by a competent tech. Buy 4 NOS Genelex KT-66 brown base clear glass output tubes and a pair of the Mullard GZ-32 rectifiers and a quad of Phillips EF-86 tubes and you have one mighty sweet sounding amp.
In fact, if you want a kick-ass amp and you can get buy with 15 Class A watts of power, buy a pair of the original Quad II amps and make sure they have been gone through by a competent tech. Buy 4 NOS Genelex KT-66 brown base clear glass output tubes and a pair of the Mullard GZ-32 rectifiers and a quad of Phillips EF-86 tubes and you have one mighty sweet sounding amp.
i agree with mikes statement about the kt120/150 amps. but ive only heard a few and none really impressed me, they have a sound that seems ....not to my liking. although someone is trying to change my mind with the allnic t2000 integrated. im sure like any type of amp there are good ones out there.im also not that impessed with many kt88 amps. there are good ones ive heard, but for the most part i think im just bored of them, since ive had a bunch over the years. i jumped ship to el34's too and wasnt all that impressed with those either.
funny i heard the cat jl2's several times and always thought there were 16 kt88s in there, never thought to look closer, and i love those amps but i found out later that they were 6550c's. dont think ive heard that tube in any other amps before.
to me flea watt triodes rule.lmao!!! now i gotta find speakers for them.
KeithR
Active member
wasn't McIntosh the one known for a great 6L6 amp back in the day?
I had the Shindo Haut Brion which uses the tube. It listed for 9k a couple years back and comes with Shindo blessed NOS tubes. It needs a high efficiency speaker though with even impedance. I didn't find its 20 watts particularly powerful.
I had the Shindo Haut Brion which uses the tube. It listed for 9k a couple years back and comes with Shindo blessed NOS tubes. It needs a high efficiency speaker though with even impedance. I didn't find its 20 watts particularly powerful.
mep
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I should have known if anyone would have made a recent 6L6 amp it would be a Shindo (insert weird sounding French model name).
Roger A Modjeski
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The 6L6 is a favorite tube of mine but sadly has not captured the attention of the audio community. It appears to be a bit of a black sheep in the flock of popular output tubes. What I like about it is never mentioned so I will. It has the lowest filament consumption vs. plate dissipation of all the power tubes. It was also the first "beam" tube and the original sketch of the internals has become the most often pictured of the internals and electron path of any tube on this planet.
With that introduction lets set a few things straight that I have read here.
1. It is nothing like an EL-34 which is a traditional pentode with a loosely wound screen grid. Its little brother is the EL-84 which is of the same construction.
2. The KT series does indeed stand for Kinkless Tetrode but the 6L6 never had kinks. The tubes that had kinks were the early tetrodes with a screen and no supressor grid. They were awful and short lived in tube manufacture. The kinks refer to the verboden negative resistance region where the plate voltage swings below the screen.
3. The KT series was the European answer to the beam tube (6L6) and some say RCA worked with the Brits developing it but get RCA to admit that! News of it was released in the first volume of RCA news in 1936 which I have studied in great detail. There is a good article on Wikipedia which I find to be accurate and the first time I have read that the Brits licensed it to RCA. In RCA news they claim to have invented it. Of course with David Sarnoff at the helm what else could one expect from the man who financially ruined Major Armstrong, the inventor of most every early radio circuit including FM and Philo Farnsworth, the father of Television. Search 6L6 on Wikipedia for more.
4. The 6L6 internals, known as the "mount" were used, with a bit larger plate, in the 807, 1625 and the first horizontal sweep tube the 6BG6. These are all essentially 6L6s.
5. The smaller brother of the 6L6 is the 6V6 beam tube and the 7 pin 6AQ5.
6. The beam tube is the output tube in the All American Five, the most popular table radio made by everyone.
7. The KT-66 is close but not quite a 6L6 as it has higher dissipation and heater current.
8. The KT-88 is the Brits answer to the Tungsol 6550
9. The KT-77 is a distant cousin to the EL-34 and was created to be a drop in replacement by Genelex. However the EL-34 is a true pentode and the KT-77 is a beam tube. The curves are quite different. The American version of the KT-77 is the 6CA7. To my knowledge no American company every made EL-34s as a true pentode. This is a rare example of making a entirely different tube as a drop-in replacement. At this time I cannot think of another.
10. The KT-90 was the creation of David Manley and Electron Industria (EI) in Nis Yugoslavia. It was a bastardization of a EL-509 and has some rather bad characteristics. When I visited the factory I chastised them for that but they said "David made us do it" What David wanted was a tube he could run at 550 Volts in an Ultralinear amp. The early Genelex tubes could do that but the modern ones couldn't.
11. The KT-120 and KT-150 are not drop in replacement for KT-88s but close enough for most amps that can handle the heater current and somewhat different bias. They are a creation of New Sensor/Electroharmonix/Sovtek headed by Mike Matthews. I have no complaints about them and time will tell. I see here pro and con reports of its sound.
12. I fully believe that the sound of a tube cannot be expressly stated as it varies with how it interacts with the amplifier. We do however see more use of the EL-34 in ultralinear circuits and the KT-88/6550 in pentode circuits. I have found this to be true in my own designs also for purely technical reasons.
With that introduction lets set a few things straight that I have read here.
1. It is nothing like an EL-34 which is a traditional pentode with a loosely wound screen grid. Its little brother is the EL-84 which is of the same construction.
2. The KT series does indeed stand for Kinkless Tetrode but the 6L6 never had kinks. The tubes that had kinks were the early tetrodes with a screen and no supressor grid. They were awful and short lived in tube manufacture. The kinks refer to the verboden negative resistance region where the plate voltage swings below the screen.
3. The KT series was the European answer to the beam tube (6L6) and some say RCA worked with the Brits developing it but get RCA to admit that! News of it was released in the first volume of RCA news in 1936 which I have studied in great detail. There is a good article on Wikipedia which I find to be accurate and the first time I have read that the Brits licensed it to RCA. In RCA news they claim to have invented it. Of course with David Sarnoff at the helm what else could one expect from the man who financially ruined Major Armstrong, the inventor of most every early radio circuit including FM and Philo Farnsworth, the father of Television. Search 6L6 on Wikipedia for more.
4. The 6L6 internals, known as the "mount" were used, with a bit larger plate, in the 807, 1625 and the first horizontal sweep tube the 6BG6. These are all essentially 6L6s.
5. The smaller brother of the 6L6 is the 6V6 beam tube and the 7 pin 6AQ5.
6. The beam tube is the output tube in the All American Five, the most popular table radio made by everyone.
7. The KT-66 is close but not quite a 6L6 as it has higher dissipation and heater current.
8. The KT-88 is the Brits answer to the Tungsol 6550
9. The KT-77 is a distant cousin to the EL-34 and was created to be a drop in replacement by Genelex. However the EL-34 is a true pentode and the KT-77 is a beam tube. The curves are quite different. The American version of the KT-77 is the 6CA7. To my knowledge no American company every made EL-34s as a true pentode. This is a rare example of making a entirely different tube as a drop-in replacement. At this time I cannot think of another.
10. The KT-90 was the creation of David Manley and Electron Industria (EI) in Nis Yugoslavia. It was a bastardization of a EL-509 and has some rather bad characteristics. When I visited the factory I chastised them for that but they said "David made us do it" What David wanted was a tube he could run at 550 Volts in an Ultralinear amp. The early Genelex tubes could do that but the modern ones couldn't.
11. The KT-120 and KT-150 are not drop in replacement for KT-88s but close enough for most amps that can handle the heater current and somewhat different bias. They are a creation of New Sensor/Electroharmonix/Sovtek headed by Mike Matthews. I have no complaints about them and time will tell. I see here pro and con reports of its sound.
12. I fully believe that the sound of a tube cannot be expressly stated as it varies with how it interacts with the amplifier. We do however see more use of the EL-34 in ultralinear circuits and the KT-88/6550 in pentode circuits. I have found this to be true in my own designs also for purely technical reasons.
dlb2
New member
Great post Roger. Thanks for clearing up a few things.
Welcome Roger! It was nice chatting with you yesterday. I hope you can fill in some of the details on your new OTL amps.
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