I am mostly kidding, since I'm not exactly sure where I'd scrounge up a 11V 15.5 A supply for the heaters and keeping 2 kV sitting around the house for the plate isn't the greatest of ideas...
...but I recently found a (NOS as far as I know) JAN GE 851 triode in my attic, and the rated 600W (for AF class A) plate dissipation screams "mono amp so powerful my speakers would never forgive me."
Anyone done anything remotely similar?
...but I recently found a (NOS as far as I know) JAN GE 851 triode in my attic, and the rated 600W (for AF class A) plate dissipation screams "mono amp so powerful my speakers would never forgive me."
Anyone done anything remotely similar?
The A Number One challenge to a project like that is going to be the OPT. SE OPTs require a core gap to avoid DC core saturation, and for anything over a couple dozen watts becomes a formidable challenge to get it right and to get it sounding good. (I once had a design for a SET that used the 812, but Jack at Electraprint couldn't guarantee that the OPT would function as a HiFi OPT, so I ditched that idea.)
Not that it can't be done, and there have been some pretty insane SETs built with such high powered triodes. You might want to search for 833 SETs. (Tubelab did some experimentation with these.)
Not that it can't be done, and there have been some pretty insane SETs built with such high powered triodes. You might want to search for 833 SETs. (Tubelab did some experimentation with these.)
Hi, Electra-print used to sell (maybe still does) a SE transformer for the Eimac 304TL triode. Rated at 5K primary at 300ma. I don't know if it's rated for the 2-2.5KV B+ that the 851 needs to sing.
I thought about using this tube back in the late 80's when I was young and dumb and full of ..... You get the picture.
It's a VERY impractical project but can be done. Filament hum will be a major problem because of the 11 volt 15.5 amp rating of the filament, but the 851 tube is relatively easy to drive for a class A1 triode because of the mu of 20; easier to drive than the 845.
Anyway, I collected the tubes for the project, wound a filament transformer out of a torroid core that I had, but never saved up for the output transformers; I had other habits that needed supporting at the time...
If you decide to build, good luck, but you can build something that will sound better for way cheaper.
Daniel
I thought about using this tube back in the late 80's when I was young and dumb and full of ..... You get the picture.
It's a VERY impractical project but can be done. Filament hum will be a major problem because of the 11 volt 15.5 amp rating of the filament, but the 851 tube is relatively easy to drive for a class A1 triode because of the mu of 20; easier to drive than the 845.
Anyway, I collected the tubes for the project, wound a filament transformer out of a torroid core that I had, but never saved up for the output transformers; I had other habits that needed supporting at the time...
If you decide to build, good luck, but you can build something that will sound better for way cheaper.
Daniel
I do not need the power, and I am not planning on building anything with it in the near term, (since sourcing iron for it would be both difficult and expensive) I was just curious as to any experiences others might have had. When my grandfather gave it to me (years ago) he said it was a rectifier so I haven't looked at it until now. My original plan was to mount it in the chassis of a SE 6L6 stereo amp I'm building (unconnected) just for aesthetics, but I couldn't help digging up a schematic.
I figure that having an unconnected tube "just for show" is acceptable in an amp that doesn't contain any sand.
I figure that having an unconnected tube "just for show" is acceptable in an amp that doesn't contain any sand.
851 project
I'm currently working on a 851 100W SE amplifier project
Mainly the Power supply will be 2000V
The filament supply will be AC or regulated I will test both
The first stage of the amplifier will be done with a E80L pentode
The amplifier (mono block) will have four distinct parts
1 - for the main power supply (4U 19", housing a Variac for soft start)
1 - for the filament 11V 15 Supply (3U - 19")
1 - for the "auxilliary" supplies (First stage, négative, filaments.., 2U 19")
1 - for the tubes and the ouput transformers (2U 19")
The output transformer will be a Plitron 20 cm diameter 5 kohms "Special design" series
The supply transformers has been done by Heacom (French company) under specifications
.....
Funny project (but heavy)
André
I'm currently working on a 851 100W SE amplifier project
Mainly the Power supply will be 2000V
The filament supply will be AC or regulated I will test both
The first stage of the amplifier will be done with a E80L pentode
The amplifier (mono block) will have four distinct parts
1 - for the main power supply (4U 19", housing a Variac for soft start)
1 - for the filament 11V 15 Supply (3U - 19")
1 - for the "auxilliary" supplies (First stage, négative, filaments.., 2U 19")
1 - for the tubes and the ouput transformers (2U 19")
The output transformer will be a Plitron 20 cm diameter 5 kohms "Special design" series
The supply transformers has been done by Heacom (French company) under specifications
.....
Funny project (but heavy)
André
An externally hosted image should be here but it was not working when we last tested it.
a 851 on my right hand, a 211 on the left one...
Andre
OK, my tube is smaller than yours.....
Simple math. Maximum plate current = 1 amp. With an 8 ohm load the output power would be a whopping 8 watts. No not going to be a SE OTL.
I went down this road a few years ago. I got too far down the road before sanity crept back into my brain and put the brakes on the project. Hey I live in south Florida. We don't have cold winters, we might have a few days during the "absence of summer" where the temperature approaches freezing. The tube I was considering (the 833A) needs only 100 watts to light the filament. Another 300 to 500 watts on the plate. No I could never get the heat out of the house.
As others have stated the OPT is the missing link. I paid quite a few bucks to have the Transcendar guy make one. While it would make a killer guitar amp or subwoofer amp, the 3db point was 17KHz. Power at clipping was 212 watts though! I put the idea on infinite hold. I think that the tubes (I have about 15 of them) the transformer (black thing to right of glowing 833A) and most of the other "unlikely to ever get built" stuff will wind up on Ebay soon.
The test amp and some data is here:
The 833A SE Amp Prototype
Simple math. Maximum plate current = 1 amp. With an 8 ohm load the output power would be a whopping 8 watts. No not going to be a SE OTL.
I went down this road a few years ago. I got too far down the road before sanity crept back into my brain and put the brakes on the project. Hey I live in south Florida. We don't have cold winters, we might have a few days during the "absence of summer" where the temperature approaches freezing. The tube I was considering (the 833A) needs only 100 watts to light the filament. Another 300 to 500 watts on the plate. No I could never get the heat out of the house.
As others have stated the OPT is the missing link. I paid quite a few bucks to have the Transcendar guy make one. While it would make a killer guitar amp or subwoofer amp, the 3db point was 17KHz. Power at clipping was 212 watts though! I put the idea on infinite hold. I think that the tubes (I have about 15 of them) the transformer (black thing to right of glowing 833A) and most of the other "unlikely to ever get built" stuff will wind up on Ebay soon.
The test amp and some data is here:
The 833A SE Amp Prototype
Why oh why do the laws of thermodynamics mandate the presence of a cold reservoir
... Imagine the possibilities!
If you are interested on DHT SE Amplification, you have several cases concerning the use of this kind on amplification
1 - You choose a small power DHT SE (2A3, 300B, AD1....), you bi-amp your system, you plug the DHT on a medium-tweeter horn, and you choose something heavier for the amplification of the bass loudspeaker. In my present system it is the case, I use a WE VT52 to feed a TAD 2001 driver + horn and something like a clone of a Dynaco mk3 on the Altec 515C.
2 - You can try to use a bigger DHT to extend the range of the SE amplifier to a full range system, you can go to the 845, 211, MC1-60, the Russian GM70, the French TM100.... but you will need to go to a very high sensitivity system (VOTT, K-Horn, JBL "cube".....) This is one option; it is really working well if you know how to deal with this kind of stuff.... And the bass response will be limited by the size of the horn....
3 - You can try to find a solution to have more power with a DHT in order to drive, for example an Altec 515C in a bass-reflex cabinet.... then you go to the WE212, Russian GM100..., The 851 can be a solution, it is linear, very linear, but you will need to have 2000V on the main power supply, 11V 15A on the filament a SE transformer able to pass 300mA.... not easy. Is it working better than a bi-amped system, I don't know.... but I hope that I will now more.... In the next months...
Thanks
André
The curves network for the 851, like a 845.... but bigger...
1 - You choose a small power DHT SE (2A3, 300B, AD1....), you bi-amp your system, you plug the DHT on a medium-tweeter horn, and you choose something heavier for the amplification of the bass loudspeaker. In my present system it is the case, I use a WE VT52 to feed a TAD 2001 driver + horn and something like a clone of a Dynaco mk3 on the Altec 515C.
2 - You can try to use a bigger DHT to extend the range of the SE amplifier to a full range system, you can go to the 845, 211, MC1-60, the Russian GM70, the French TM100.... but you will need to go to a very high sensitivity system (VOTT, K-Horn, JBL "cube".....) This is one option; it is really working well if you know how to deal with this kind of stuff.... And the bass response will be limited by the size of the horn....
3 - You can try to find a solution to have more power with a DHT in order to drive, for example an Altec 515C in a bass-reflex cabinet.... then you go to the WE212, Russian GM100..., The 851 can be a solution, it is linear, very linear, but you will need to have 2000V on the main power supply, 11V 15A on the filament a SE transformer able to pass 300mA.... not easy. Is it working better than a bi-amped system, I don't know.... but I hope that I will now more.... In the next months...
Thanks
André
An externally hosted image should be here but it was not working when we last tested it.
The curves network for the 851, like a 845.... but bigger...
The elements for the power supplies, main transformer on the left, filament transformer on the right, the choke (front)
The KT88 is here to show the scale.....
The variac for the soft start of the high voltage....
And the main capacitor....
A plus
Andre
An externally hosted image should be here but it was not working when we last tested it.
The KT88 is here to show the scale.....
The variac for the soft start of the high voltage....
An externally hosted image should be here but it was not working when we last tested it.
And the main capacitor....
An externally hosted image should be here but it was not working when we last tested it.
A plus
Andre
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