Are there high voltage triodes in addition to the 845?
Plate current and wattage are not important - I'd rather have a smaller tube than an 845, as a matter of fact.
What matters is I need to swing 1,000 volts on the plate.
I understand I can triode-strap the 813, for example, but what I butt-headedly want is a true triode that can handle at least 1,000 volts plate voltage.
The 845 is a great choice, I just wanted to check to see if any of you experts on triodes would happen to know of any other choices.
(And yes, I have one of those triodes that can handle 30 KV...I forget the special type it is or the tube number...but that's not what I want, either, LOL - I want a true triode with a plate voltage between 1,000 and 1,500 volts)
Very Best, Synchro27
Plate current and wattage are not important - I'd rather have a smaller tube than an 845, as a matter of fact.
What matters is I need to swing 1,000 volts on the plate.
I understand I can triode-strap the 813, for example, but what I butt-headedly want is a true triode that can handle at least 1,000 volts plate voltage.
The 845 is a great choice, I just wanted to check to see if any of you experts on triodes would happen to know of any other choices.
(And yes, I have one of those triodes that can handle 30 KV...I forget the special type it is or the tube number...but that's not what I want, either, LOL - I want a true triode with a plate voltage between 1,000 and 1,500 volts)
Very Best, Synchro27
211 (VT-4C), 242A/C (same as 211), 212, 284 (same as 845) 8005, 805, 833A, 100TH, 100TL, 250TH, 250TL, 254W, 311CH, 810, 203A & 383 (zero bias types), 811A, 812A, 572B, HF100, HF200, 5867, 5868, 6569. And there are others but they are bigger and harder to work with or next to impossible to find.
Rereading your post the 212, 833A, 5868, 250TH/L & HF200 are all larger then you really want. The 8005 and 805 is probably your best bet.
Rereading your post the 212, 833A, 5868, 250TH/L & HF200 are all larger then you really want. The 8005 and 805 is probably your best bet.
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Thanks very much. Yeah, I had forgotten about the 833A and monsters like LOL.
I see now I should have specified negative bias triodes only; the positive bias transmitting types are of no use to me.
If you happen to know off the top of your head, could you shorten the list to only the negative biased ones?
I don't want to seem ungrateful; I'm happy to look them up on TDSL.
Very Best, Synchro27
I see now I should have specified negative bias triodes only; the positive bias transmitting types are of no use to me.
If you happen to know off the top of your head, could you shorten the list to only the negative biased ones?
I don't want to seem ungrateful; I'm happy to look them up on TDSL.
Very Best, Synchro27
thanks again, HollowState. I went through the whole list (I think).
The 100TL looks quite good. Up to 3KV, good for 100 watts. Negative bias. DHT. Nice. Really cool tube, would look great (under glass LOL). Ditto 100TH.
Not really what I'm looking for, but such a cool tube. $100 but hey, it's worth it. And it's a lot cheaper than an 845 unless you go Chinese...which is OK, but I really like going with an old original; I think I'll use it instead of the 845, because....
....I don't think what I'm looking for exists: a very low power small triode good for at least 1200 Vmax. I am not using it for power; I just want the plate swing.
Can't find the 284....if it ain't here, I doubt it exists (anymore): 30 to 698
Did I miss anything?
Thanks for the list - that 100TL is a FIND!!!!!!!! WOOOO HOOOOO!!!!
Very Best, Synchro27
The 100TL looks quite good. Up to 3KV, good for 100 watts. Negative bias. DHT. Nice. Really cool tube, would look great (under glass LOL). Ditto 100TH.
Not really what I'm looking for, but such a cool tube. $100 but hey, it's worth it. And it's a lot cheaper than an 845 unless you go Chinese...which is OK, but I really like going with an old original; I think I'll use it instead of the 845, because....
....I don't think what I'm looking for exists: a very low power small triode good for at least 1200 Vmax. I am not using it for power; I just want the plate swing.
Can't find the 284....if it ain't here, I doubt it exists (anymore): 30 to 698
Did I miss anything?
Thanks for the list - that 100TL is a FIND!!!!!!!! WOOOO HOOOOO!!!!
Very Best, Synchro27
Magz I am a great fan of yours, and your website. Your grid driver is brilliant; I plan to use it.
HollowState, I was thinking the 100TL is seriously over the top for wattage I don't need, but....then I noticed the grid to plate capacitance and the amplification factor.
Waaaaay better than the 845!!!! Only 2+ uuF for the 100TL, whereas the 845 is much harder to drive with a grid to plate capacitance of 13.5, six times the capacitance of the 100TL!!! And, to boot, the 100TL has an amplification factor of 14...whoooo hoooo!!!! me like!!!!
My amp just transmogrified from an 845-based mu-stage to a 100TL-based mu stage heh heh heh heh. With that bulb shape and the white hot thoriated tungsten filament, it should look verrrrry cooooollll.
Now, if I could only find signal DHT's with amplification factors approaching at least 35...I need to get from standard line to a 75 volt swing to swing that 100TL grid....I hate to use 6922's cascoded, or 12AX7's CCS'd, but I guess I'll have to....sigh.
There wouldn't be any small signal DHT's with amplification factors of at least 35????? Hmmmm????????????/
Very Best, Synchro27
HollowState, I was thinking the 100TL is seriously over the top for wattage I don't need, but....then I noticed the grid to plate capacitance and the amplification factor.
Waaaaay better than the 845!!!! Only 2+ uuF for the 100TL, whereas the 845 is much harder to drive with a grid to plate capacitance of 13.5, six times the capacitance of the 100TL!!! And, to boot, the 100TL has an amplification factor of 14...whoooo hoooo!!!! me like!!!!
My amp just transmogrified from an 845-based mu-stage to a 100TL-based mu stage heh heh heh heh. With that bulb shape and the white hot thoriated tungsten filament, it should look verrrrry cooooollll.
Now, if I could only find signal DHT's with amplification factors approaching at least 35...I need to get from standard line to a 75 volt swing to swing that 100TL grid....I hate to use 6922's cascoded, or 12AX7's CCS'd, but I guess I'll have to....sigh.
There wouldn't be any small signal DHT's with amplification factors of at least 35????? Hmmmm????????????/
Very Best, Synchro27
Maybe the 1J6G? It is a dual triode tube, where the halves share a common cathode. But, the mu is pretty high, I think.
What about the russian GM70: http://www.mif.pg.gda.pl/homepages/frank/sheets/018/g/GM70.pdf
Regards,
Hilmar
Regards,
Hilmar
Not a DHT, in fact a tetrode (gasp!), but I can't say enough about the sound of the Russian 6E5P triode-strapped. Mu of 30-35, so you can run a two-stage, direct coupled design. The sound is excellent - clear, detailed, with depth and without harshness. Cheap, too! I bought 50 of them for $100.00!!
The 6BK4 was a high voltage shunt regulator designed to operate on the secondary side of the flyback transformer in a color TV set. Normal operating voltage is 25 to 27 KV. These were responsible for the "TV sets emit X-rays" scare in the late 60's. The tube was redesigned a dozen or so times to reduce X-ray emission before being discontinued when someone figured out how to put the shunt regulator on the primary side of the flyback.
The 6HV5 and it's lower cost relatives are beam triodes designed for color TV regulator service. These were the tubes that were used on the primary side of the flyback. They are effectively a sweep tube with the screen grid removed. Normal plate operating voltage is about 1500 volts with spikes to about 6000 volts. These can be used in audio amps that operate at high voltages and are usually seen in OTL amps for electrostatic speakers. Mu is high, about 300. There are two sizes 30 watt, and 35 watt. It is common to find one type number on both size tubes, so specify that you want them both the same when you order them. The only tube numbers that I can remember are 6HD5 and 6HS5, but there are others. Other than size, they are pretty interchangeable.
They are designed for negative grid voltage use, but you will need a plate voltage in the 800+ volt range to get sufficient plate current with negative bias. Plate resistance is pretty high too, but not a big issue with electrostatics.
A smaller tube?
Maybe this 572B
http://www.mif.pg.gda.pl/homepages/frank/sheets/164/5/572B.pdf
Or sv572-10 (Or 572-30 or sv572-160)
http://www.mif.pg.gda.pl/homepages/frank/sheets/164/5/572B.pdf
Maybe this 572B
http://www.mif.pg.gda.pl/homepages/frank/sheets/164/5/572B.pdf
Or sv572-10 (Or 572-30 or sv572-160)
http://www.mif.pg.gda.pl/homepages/frank/sheets/164/5/572B.pdf
I need to apologize in advance for two things:
1. I didn't properly specify precisely what I'm looking for, so unfortunately I accidentally misled a bunch of you in the wrong directions. Sorry!!! See bottom part of this post for what I'm ACTUALLY up to LOL.
2. what a ridiculously long post. sorry. I'm just trying to acknowledge everyone's kind help.
Needtubes: 1J6G (1J6GT) cool tube. Love that shared cathode…in a DHT. If I had a differential app where the cathodes could be tied directly to ground, this would be a FAB tube. But it’s in the same category as most of the other power DHT’s: designed to be run in positive bias with grid current, and the plate curves do not look good for low distortion in negative bias territory LOL. But I’m super glad to know about this tube, it has neat potential, thanks.
Hilmar53, kevinkr: GM70. Yeah, very cool tube, power DHT the way the Russians know how to do it, which is fabulous. It looks to me like it’s in the same ballpark as the 100TL. You know, I’m gonna be irrational here….it’s a great tube, but I just don’t want to use a Russian tube. I know, it’s not rational. I know. I dunno why…it’s not that it’s Russian, really, a lot of amazing tube designers and amp designers in Russia, I guess those long winter days snowed ten feet under must make for a lot of interest in indoor hobbies, but I just can’t get into them. Maybe someday I’ll do a totally Russky amp – that would be a great idea!!!
Stevenrotterdam: 6HV5. Thanks, great, great high voltage beam tube that, triode strapped, would make a fabulous high voltage power triode...not unlike the 813 in some ways. But, SORRY, I forgot to mention I am wanting only DHT’s. But, for an amp where one isn’t sticking solely to DHT’s, this is a great choice and economical too, which cannot be a bad thing.
Magz: thanks. SORRY, I completely neglected to mention I’m looking for DHT’s that can handle high voltage. The 6E5P is a tre’ cool tube, but it’s indirectly heated; sorry I accidentally misled you. I wish to make this amp completely DHT and/or DHP. I know that’s illogical, but hey, it’s gonna be mine, so I get to be as irrational as I please. However, for the purpose I have in mind, the 6E5P triode-strapped is one of the best choices, cost-wise and use-wise, for an indirectly heated triode-strapped tetrode there is. I think in triode-strapped mode it would have a very high mu, although I didn’t take the time to calculate it, kinda in a rush here. I’ll keep it in mind for the next irrational beastie… especially next Russky Irrational Beastie LOL….
Pmillett: 2C53 - thanks. Yeah, I can't find a datasheet either; however, they are $40 at VacuumTubes.net, so I'm hesitant to buy a pair just to find out what they are LOL...it's $23 at tubedepot, but they don't actually have it in stock ROTFL. Finding a cheaper price for a tube not in stock (and not bloody likely to be in stock anytime before the universe cools down to absolute zero) reminds me of the Monty Python skit "The Cheese Shop", in my opinion the funniest audio skit ever.
BTW, I did put in a phone call to vacuumtubes.net asking them if they know what it is. I'm awaiting a call back from someone there who "might know" LOL.
Esltransformer: 572B, sv572-10: thanks. Wow, great tubes, great POWER triodes…and thoriated tungsten filaments, too. I have to apologize; I did not correctly specify what I’m looking for; these, again, are tubes designed to be operated with grid current.
So, let me get more specific here, so that I’m not continuing to confuse people. I’m really sorry about this; I HATE IT when I assume people can just…read my mind LOL….
This amp is DHT throughout: tungsten or thoriated tungsten. All the triodes in the amp must be designed to work with negative grid bias – which automatically rules out most of the transmitting triodes. I am planning to use pentodes also, but they must be directly heated filament types as well. The 813 and the 1609 are examples; I have both, so I’ll probably use ‘em.
BTW, if anyone wishes to enlighten me on why transmitting triodes tend to be designed for positive grid bias, with grid current, I would love to know. I’m sure it has to do with efficiency and various bad effects be damned, given that we’re talking commercial radio here, and AM at that for the most part, but – not being an electronics genius type – I would never have guessed it would make any sense to operate a triode in such a fashion, once I got the notion of how a negatively biased grid works stuck in my head.
The output stage is going to be a differential mu-stage, DHPentodes above DHT’s, with an output voltage swing max of at least 1,000 volts. Or, I might cascode DHT’s above DHT’s…still ruminating on that idea. The load is a special 2,000 ohm speaker I will build myself. I’ve done it before, I know it works. Thus, no output transformer, which is kinda the whole point of this rig. For various and sundry reasons, cost and weight included to get a really, really good one, I hate output transformers. I will go to great lengths to get around having to use them, which I know is irrational, but, like I said, behind the door of my den, I get to be as irrational as I please, and I do.
Finally, to get enough gain from one driver stage, I’m probably going to use a DHP. I have the 1609, which is a really sweet directly heated pentode, but I’m not sure it will give enough gain…with a 100K load, it works out to about 58 amplification factor. Perhaps I can get away with a 200K load, since it will be driving Tubelab.com’s Power Drive…that gives an amplification factor of 96. Now…that’s more like it.
Or I could cascode two DHT’s for the single amp/driver stage, for essentially the same effect. The 1H4G looks like a nice little DHT, with an amplification factor of 9.3 and a gm of 900, and they’re only $10 on vacuumtubes.net. Nice! In cascode, two 1H4G’s should give a gain of approximately 86, no? So, that would save a bunch of 1609’s….any problem with using a cascoded 1H4G stage for my gain/driver single stage, into tubelab.com’s Power Drive circuit?
Finally, I know the idea of inserting mosfet’s into the signal path of an amp dedicated to DHT’s and DHP’s seems absurd (tubelab.com Power Drive), so I think I’ll try using the 1609 there, as well, (DHP CF), but now this amp is getting seriously pricey and I only have two dozen 1609’s, so the question is will I use up all my 1609’s before I die? Probably not, I have maybe ten years left, so what the heck, let’s do it.
OTOH….I could do the cascode trick again, and instead of using up a 1609 for the DHP CF, I could again use cascoded 1H4G’s as the CF….
And this could work well in terms of distortion cancellation….1H4G cascodes, in series, gain stage to CF stage, the 2nd in counter-phase to the first. I like it!!!!
All in all, I still like the 100TL idea the best for my DHT with 1,000 volts swing on the plate. I will get one, CCS the plate at a moderate current, and take a transfer curve around a reasonable negative bias – minus 100 volts, I think, since the amplification factor is 14 - and see what it looks like.
Schematic coming soon. Wot phun.
Very Best, Synchro27
1. I didn't properly specify precisely what I'm looking for, so unfortunately I accidentally misled a bunch of you in the wrong directions. Sorry!!! See bottom part of this post for what I'm ACTUALLY up to LOL.
2. what a ridiculously long post. sorry. I'm just trying to acknowledge everyone's kind help.
Needtubes: 1J6G (1J6GT) cool tube. Love that shared cathode…in a DHT. If I had a differential app where the cathodes could be tied directly to ground, this would be a FAB tube. But it’s in the same category as most of the other power DHT’s: designed to be run in positive bias with grid current, and the plate curves do not look good for low distortion in negative bias territory LOL. But I’m super glad to know about this tube, it has neat potential, thanks.
Hilmar53, kevinkr: GM70. Yeah, very cool tube, power DHT the way the Russians know how to do it, which is fabulous. It looks to me like it’s in the same ballpark as the 100TL. You know, I’m gonna be irrational here….it’s a great tube, but I just don’t want to use a Russian tube. I know, it’s not rational. I know. I dunno why…it’s not that it’s Russian, really, a lot of amazing tube designers and amp designers in Russia, I guess those long winter days snowed ten feet under must make for a lot of interest in indoor hobbies, but I just can’t get into them. Maybe someday I’ll do a totally Russky amp – that would be a great idea!!!
Stevenrotterdam: 6HV5. Thanks, great, great high voltage beam tube that, triode strapped, would make a fabulous high voltage power triode...not unlike the 813 in some ways. But, SORRY, I forgot to mention I am wanting only DHT’s. But, for an amp where one isn’t sticking solely to DHT’s, this is a great choice and economical too, which cannot be a bad thing.
Magz: thanks. SORRY, I completely neglected to mention I’m looking for DHT’s that can handle high voltage. The 6E5P is a tre’ cool tube, but it’s indirectly heated; sorry I accidentally misled you. I wish to make this amp completely DHT and/or DHP. I know that’s illogical, but hey, it’s gonna be mine, so I get to be as irrational as I please. However, for the purpose I have in mind, the 6E5P triode-strapped is one of the best choices, cost-wise and use-wise, for an indirectly heated triode-strapped tetrode there is. I think in triode-strapped mode it would have a very high mu, although I didn’t take the time to calculate it, kinda in a rush here. I’ll keep it in mind for the next irrational beastie… especially next Russky Irrational Beastie LOL….
Pmillett: 2C53 - thanks. Yeah, I can't find a datasheet either; however, they are $40 at VacuumTubes.net, so I'm hesitant to buy a pair just to find out what they are LOL...it's $23 at tubedepot, but they don't actually have it in stock ROTFL. Finding a cheaper price for a tube not in stock (and not bloody likely to be in stock anytime before the universe cools down to absolute zero) reminds me of the Monty Python skit "The Cheese Shop", in my opinion the funniest audio skit ever.
BTW, I did put in a phone call to vacuumtubes.net asking them if they know what it is. I'm awaiting a call back from someone there who "might know" LOL.
Esltransformer: 572B, sv572-10: thanks. Wow, great tubes, great POWER triodes…and thoriated tungsten filaments, too. I have to apologize; I did not correctly specify what I’m looking for; these, again, are tubes designed to be operated with grid current.
So, let me get more specific here, so that I’m not continuing to confuse people. I’m really sorry about this; I HATE IT when I assume people can just…read my mind LOL….
This amp is DHT throughout: tungsten or thoriated tungsten. All the triodes in the amp must be designed to work with negative grid bias – which automatically rules out most of the transmitting triodes. I am planning to use pentodes also, but they must be directly heated filament types as well. The 813 and the 1609 are examples; I have both, so I’ll probably use ‘em.
BTW, if anyone wishes to enlighten me on why transmitting triodes tend to be designed for positive grid bias, with grid current, I would love to know. I’m sure it has to do with efficiency and various bad effects be damned, given that we’re talking commercial radio here, and AM at that for the most part, but – not being an electronics genius type – I would never have guessed it would make any sense to operate a triode in such a fashion, once I got the notion of how a negatively biased grid works stuck in my head.
The output stage is going to be a differential mu-stage, DHPentodes above DHT’s, with an output voltage swing max of at least 1,000 volts. Or, I might cascode DHT’s above DHT’s…still ruminating on that idea. The load is a special 2,000 ohm speaker I will build myself. I’ve done it before, I know it works. Thus, no output transformer, which is kinda the whole point of this rig. For various and sundry reasons, cost and weight included to get a really, really good one, I hate output transformers. I will go to great lengths to get around having to use them, which I know is irrational, but, like I said, behind the door of my den, I get to be as irrational as I please, and I do.
Finally, to get enough gain from one driver stage, I’m probably going to use a DHP. I have the 1609, which is a really sweet directly heated pentode, but I’m not sure it will give enough gain…with a 100K load, it works out to about 58 amplification factor. Perhaps I can get away with a 200K load, since it will be driving Tubelab.com’s Power Drive…that gives an amplification factor of 96. Now…that’s more like it.
Or I could cascode two DHT’s for the single amp/driver stage, for essentially the same effect. The 1H4G looks like a nice little DHT, with an amplification factor of 9.3 and a gm of 900, and they’re only $10 on vacuumtubes.net. Nice! In cascode, two 1H4G’s should give a gain of approximately 86, no? So, that would save a bunch of 1609’s….any problem with using a cascoded 1H4G stage for my gain/driver single stage, into tubelab.com’s Power Drive circuit?
Finally, I know the idea of inserting mosfet’s into the signal path of an amp dedicated to DHT’s and DHP’s seems absurd (tubelab.com Power Drive), so I think I’ll try using the 1609 there, as well, (DHP CF), but now this amp is getting seriously pricey and I only have two dozen 1609’s, so the question is will I use up all my 1609’s before I die? Probably not, I have maybe ten years left, so what the heck, let’s do it.
OTOH….I could do the cascode trick again, and instead of using up a 1609 for the DHP CF, I could again use cascoded 1H4G’s as the CF….
And this could work well in terms of distortion cancellation….1H4G cascodes, in series, gain stage to CF stage, the 2nd in counter-phase to the first. I like it!!!!
All in all, I still like the 100TL idea the best for my DHT with 1,000 volts swing on the plate. I will get one, CCS the plate at a moderate current, and take a transfer curve around a reasonable negative bias – minus 100 volts, I think, since the amplification factor is 14 - and see what it looks like.
Schematic coming soon. Wot phun.
Very Best, Synchro27
Iko, thanks.
That 3C24 is a MUCH better choice than the 100TL for my purposes:
amplification factor higher at 24 (vs 14), lower wattage at 25 W, plenty of Vmax at 2K, grid/plate capacitance even lower than the 100TL at 1.6 uuf, and the cost is a TON cheaper: $17 at vacuumtubes.net rather than $100 for the 100TL.
And the 35T is even better: even lower wattage at 15, still capable of 2KV on the plate, low grid/plate capacitance at 1.6 uuf also, but an amplification factor of average 39. The only drawback is the price at $40, a little steep compared to the 3C24.
It remains to be seen what the transfer function looks like in negative bias territory for the 35T and 3C24, as well as the 100TL, but I'm fairly confident it will be fine.
Very Best, Synchro27
later, when I have some time, I'll do a detailed comparison of the GM70 vs the 35T and 3C24, for the purposes of this design.
That 3C24 is a MUCH better choice than the 100TL for my purposes:
amplification factor higher at 24 (vs 14), lower wattage at 25 W, plenty of Vmax at 2K, grid/plate capacitance even lower than the 100TL at 1.6 uuf, and the cost is a TON cheaper: $17 at vacuumtubes.net rather than $100 for the 100TL.
And the 35T is even better: even lower wattage at 15, still capable of 2KV on the plate, low grid/plate capacitance at 1.6 uuf also, but an amplification factor of average 39. The only drawback is the price at $40, a little steep compared to the 3C24.
It remains to be seen what the transfer function looks like in negative bias territory for the 35T and 3C24, as well as the 100TL, but I'm fairly confident it will be fine.
Very Best, Synchro27
later, when I have some time, I'll do a detailed comparison of the GM70 vs the 35T and 3C24, for the purposes of this design.
The type 40 tube is a DHT with amplification factor of 30 which you can use as the preamp, although it has a veeery high rp (150k)
Another high mu DHT for use as preamp with mu 30 and rp 40k, but it is very rare (~5 on ebay per year)
40:
http://www.mif.pg.gda.pl/homepages/frank/sheets/021/4/40.pdf
841:
http://www.mif.pg.gda.pl/homepages/frank/sheets/081/8/841.pdf
Another high mu DHT for use as preamp with mu 30 and rp 40k, but it is very rare (~5 on ebay per year)
40:
http://www.mif.pg.gda.pl/homepages/frank/sheets/021/4/40.pdf
841:
http://www.mif.pg.gda.pl/homepages/frank/sheets/081/8/841.pdf
thanks, marcelop. the 40 is only $18 at vacuumtubes.net, so that's a good sign.
in cascode, it would give a really high gain...900 gain seems a bit unlikely, though, to be realizable, LOL, especially given the high rp.
OTOH...it just occurred to me... if I use the 35T with an amplification factor of 39, the amplification factor of the 40...being 30...would be enough.
So, the 40 with a DHP CCS on the plate, and then a 40 CF with a DHP CCS on the cathode, and the distortions should mostly cancel, and there's enough current drive for the grid of the 35T (I think....) - although the high rp might be a problem with that idea....
Might need to double up in parallel the CF 40's.
This is getting better and better
Very Best, Synchro27
in cascode, it would give a really high gain...900 gain seems a bit unlikely, though, to be realizable, LOL, especially given the high rp.
OTOH...it just occurred to me... if I use the 35T with an amplification factor of 39, the amplification factor of the 40...being 30...would be enough.
So, the 40 with a DHP CCS on the plate, and then a 40 CF with a DHP CCS on the cathode, and the distortions should mostly cancel, and there's enough current drive for the grid of the 35T (I think....) - although the high rp might be a problem with that idea....
Might need to double up in parallel the CF 40's.
This is getting better and better
Very Best, Synchro27
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