Hi,
That's one of those high altitude aviation regulator tube. Forget about it, it's too rare to be of any use.
Similar to its smaller brother the 6082.
Cheers,
Hey Fdegrove!
I have 8 NOS Tung-Sol 6394a tubes I picked up fairly cheaply ---{$200 for the eight tubes}--- after hearing the 6394a tubes driving a pair of "coke-bottle" 6L6 tubes in a preamp, made by a local fellow.
I really liked what I heard from the preamp in the system it was placed in, but unfortunately the owner won't bring the 6394a-based preamp to my house so I can hear it in my system, nor is the builder appearing inclined to build another of these preamps that I can listen to in my system.
The reason the builder doesn't want to build another of these preamps is because he says the power-supply that's needed to power this preamp is extremely costly & difficult to build. As I know squat about building preamps or their power supplies, I don't know if the statement about the power supply being extremely costly & difficult to build, is true or not! Any input from the more knowledgeable here?
Thetubeguy1954 (Tom Scata)
Hello Hollow!
Those 6394a tubes are really beautiful looking tubes up close, don't you agree? Especially those all those thin gold wires running back & forth....
Thetubeguy1954 (Tom Scata)
Using a tube like a 6394, or it's variants, in a preamp is pretty bizarre. But I suppose I shouldn't be too surprised since I've seen and heard modern globe-shaped 2A3s in a preamp. Something from China, and it sounded very good. Incidentally, all the other 6394As, as well as all of his inventory (truckloads), went to a tube dealer in Florida. I don't remember which one it was, but I think it was someone relatively new and starting out at the time. This was the early, or mid, nineties.
Assuming you mean the grid wires, I don't think they're real gold. But they do look sorta gold colored on close inspection. If I knew it was real gold, I'd smash them all for recovery.
(just kidding)Victor
Hi Tubelab,
What other tubes are you using with your 6336a tubes?
Thetubeguy1954 (Tom Scata)
Using a tube like a 6394, or it's variants, in a preamp is pretty bizarre. But I suppose I shouldn't be too surprised since I've seen and heard modern globe-shaped 2A3s in a preamp. Something from China, and it sounded very good. Incidentally, all the other 6394As, as well as all of his inventory (truckloads), went to a tube dealer in Florida. I don't remember which one it was, but I think it was someone relatively new and starting out at the time. This was the early, or mid, nineties.
Assuming you mean the grid wires, I don't think they're real gold. But they do look sorta gold colored on close inspection. If I knew it was real gold, I'd smash them all for recovery.
Victor
Hi Victor, thanks for your quick reply back. It just so happens I purchased the last eight 6394a tubes from this guy in florida: VacuumTubes net It's possible he may have attained more since I purchased mine almost 1 year ago. I know he had some 6336a/6336b @ $48ea and 6528a @ $64 These are the specs for the 6528a tube: http://www.tubebbs.com/tubedata/sheets/115/6/6528.pdf
Between the...
6394 @ Vf 26.5 Volts / If: 1.2 Ampere / -: Direct, Double Triode
6528 @ Vf 6.3 Volts / If: 5 Ampere / -: Indirect / , Double Triode
6336 @ Vf 6.3 Volts / If: 4.75 Ampere / -: Indirect / , Double Triode
...you can find in enough of an abundance of one of these tube types to build the preamp, SET or OPT amp you'd like to make.
Thetubeguy1954 (Tom Scata)
Hi,
My point exactly. But using one of those to drive a penthode a la 6L6 certainly sounds desperate to me and no doubt others.
Those are regulator tubes meaning nobody cared about tolerance much for as long as they did what they were designed for.
Certainly not audio which does not mean they can't be used for that but then you need to take precautions so the tubes don't take the design into a current hogging imbalance, right?
As for preamp use?
Come on, there's an end to poshiling the digital turd isn't there?
Cheers,
My point exactly. But using one of those to drive a penthode a la 6L6 certainly sounds desperate to me and no doubt others.
Those are regulator tubes meaning nobody cared about tolerance much for as long as they did what they were designed for.
Certainly not audio which does not mean they can't be used for that but then you need to take precautions so the tubes don't take the design into a current hogging imbalance, right?
As for preamp use?
Come on, there's an end to poshiling the digital turd isn't there?
Cheers,
Yes, does not make sense.
6L6 driving a 6336/6C33 however is not bad at all.
I once heard a very good SE amp where the 807 drove the 6C33 through an interstage transformer.
Hi,
My point exactly. But using one of those to drive a penthode a la 6L6 certainly sounds desperate to me and no doubt others.
Those are regulator tubes meaning nobody cared about tolerance much for as long as they did what they were designed for.
Certainly not audio which does not mean they can't be used for that but then you need to take precautions so the tubes don't take the design into a current hogging imbalance, right?
As for preamp use?
Come on, there's an end to poshiling the digital turd isn't there?
Cheers,
Hi fdegrove!
Remember I am NOT diy-savy. All I can tell you is that I heard a preamp designed by a local diyer which consisted first of 6L6 tubes driving 6L6 tubes and it was the ONLY preamp tubed or solid-state that ever made my 135lb, Italian, Mastersound Reference 845, integrated SET amp ---{it can be turned into a power amp at a flick of a switch}--- actually sound better than when run as an integrated amp!
After hearing the level of improvement that preamp made, the designer, along with the owner of the new preamp, decided to add some triode sound to this preamp by using the 6394a tubes to drive the now paralleled 6L6 tubes. As I stated previously I've only heard this 6394a rendition of the preamp in the owner's system, but I'm familiar with the owner's system and I can honestly tell everyone here with this new 6394a-based preamp the system now sounds amazing!
Unfortunately, although the designer originally promised me that if I liked the sound of the preamp with the 6934a triodes, better than the sound of the all 6L6 tubed preamp, he'd make me one of these new preamps, for some reason he now acts as if that isn't what was never said and he won't build a 6394a-based preamp for me. This is why I'm now asking questions here.
Now as far as whether the 6L6 tubes are regulator tubes and nobody cared about their tolerances, all I can say is they sound glorious in whatever circuit topology the designer used. As for me, I'd personally love to hear a preamp consisting of Bendix 6900 tubes driving the 6394a tubes to see what that would sound like, but placing my fantasies aside, to date the preamp using the 6394a tubes to drive paralleled 6L6 tubes, smokes my Audio Research SP9preamp and every other preamp I've heard!
Thetubeguy1954 (Tom Scata)
Hi Pieter!
The designer also initially felt that the correct way to design the preamp would be to have 6L6 driving a 6394a, but being a fanatic he tried it both ways and he prefered the sound of the 6394a driving the 6L6 tubes sounded better ---{unless of course he's lying about that too! Afterall he lied when he said he'd build me the preamp I prefered (all 6L6 or 6394a/6L6) so what's one more lie}---- at this point in time, I no longer communicate with the designer, but get all my info through the preamp's present owner. Thus everything I hear these days is second hand...
Thetubeguy1954 (Tom Scata)
Hi Tom,
I don't doubt that good sounding preamps can be made this way; however it is not the first what comes into mind when designing a preamp.
Microphony can be a problem with the big bottles handling line levels.
Look at this one, also a preamp with one of the familiy of pass tubes:
Zeus SE Triode Preamp PP MOSFET Power Amp Tests
I don't doubt that good sounding preamps can be made this way; however it is not the first what comes into mind when designing a preamp.
Microphony can be a problem with the big bottles handling line levels.
Look at this one, also a preamp with one of the familiy of pass tubes:
Zeus SE Triode Preamp PP MOSFET Power Amp Tests
Hello again Pieter!
I wasn't trying to imply you didn't think the preamp sounded good. Fact is when these two preamps: the all 6L6 version and the 6394a driving the 6L6 version, were finally made. I think the designer was as surprised as anyone else with just how nice they sounded. I know the owner of the preamp with the 6394a tubes driving the 6L6 tubes and from what he tells me, both the designer and himself believe the reason that these two preamps sound so nice is because of the large plate area of the two 6394a & four 6L6 tubes!
Whether that's the reason or not I don't know. What I do know is this; most every 2A3 or 300B based preamp I've heard in the past and these newer 2A3, 300B based preamps from Ming Da, not to forget Mick from Supratek's newest 25th Anniversary Cabernet Dual preamp ---{yes you get 2 preamps on one chassis}--- one's with a 6SN7 driving a 101D DHT and the other uses a 6SN7 driving a 6H30 tube in White Follower configuration, are all using fairly large plate tubes and these imho are some of the nicest sounding preamps I've ever heard! ---no I haven't heard Mick's latest preamp using the 101D, but I heard an earlier version that used 101D tubes and the Ming Da's need to be modded some to come up to this higher level of musical reproduction!
So perhaps there is something to this large-plate = better sound, design philosophy afterall? In any event, it's always nice discussing audio rationally. Thanks for your input Pieter and I hope you're enjoying your audio system as much as I'm enjoying mine! As for me, just as soon as I post this I'll be putting Sophie Milman's ---{Sophie's the best fairly new & mostly unknown female jazz singer around}--- 2nd recording called "Make Someone Happy" which you can hear samples from by clicking on the name, into my Goldenote Stibbert CDP and I'll be enjoying the music. Pieter I hope you'll be doing the same with the music of your choice, enjoy...
Thetubeguy1954 (Tom Scata)
Hi,
I think you're confusing a few things here. It was not about an 6L6 as a regulator but a 6394 as such.
That said I'm having a hard time imagining what I coinsider a preamp with all those powertubes in it...
I think older octal tubes for preamp use often sound beter than they're noval socket counterparts though. Not sure plate area has anything to do with it though.
Less distortion more likely.
Ciao,
I think you're confusing a few things here. It was not about an 6L6 as a regulator but a 6394 as such.
That said I'm having a hard time imagining what I coinsider a preamp with all those powertubes in it...
I think older octal tubes for preamp use often sound beter than they're noval socket counterparts though. Not sure plate area has anything to do with it though.
Less distortion more likely.
Ciao,
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The amp in question was just an experiment to see how a circuit designed in the 1950's for use as an oscilloscope preamp could be used as a power amp. The circuit uses a 6EM7 wired as a 2 watt SE amp just to develop enough drive voltage for the cathode follower output section. The Augmented Cathode Follower uses a 12AX7 as the error amp and any of the octal dual triodes for output. 6336A, 6080, 6AS7, 5998 and even the 6SN7.
The entire thread is here:
http://www.diyaudio.com/forums/tube...wer.html?highlight=augmented+cathode+follower
A picture with 6336A's is in post # 76. I got an email from the original inventor of the circuit. He is still alive and still inventing stuff, but no more tube circuits.
The schematic is in post # 11 of this thread:
http://www.diyaudio.com/forums/tubes-valves/118289-6336-rectifier.html
It's been 3 1/2 years since I fired the board up, but it is still sitting on the shelf waiting for my attention to return.
hi,
can you give more info like operating points, psu, and topology if you can please? thanks....i am also protyping a 1624 preamp.....
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