Hi everyone. Just received a couple of above lamps, new, NOS in boxes. Looks sort of cool and I would like to use them in some audio. Looking for line-headphones amp schematics with these, best would be simple, no gain OTL paralleled cathode follower.
Looks like 832 are similar to GU/FU32, a lot of schematics for amps wit these on web, but none for OTL.
Can someone suggest stable schematics and proper values for OTL cathode follower wit above lamps, I can sure come up with proper gain stage, PS and so on...
Regards, Davorin
Looks like 832 are similar to GU/FU32, a lot of schematics for amps wit these on web, but none for OTL.
Can someone suggest stable schematics and proper values for OTL cathode follower wit above lamps, I can sure come up with proper gain stage, PS and so on...
Regards, Davorin
Describe your Headphones, Please.
Impedance, Ohms
Sensitivity, dB / milliwatt
Without that, the Archer is blindfolded and trying to hit the target.
Impedance, Ohms
Sensitivity, dB / milliwatt
Without that, the Archer is blindfolded and trying to hit the target.
Hello,
well, I use a few of them, mostly Audio Technica ATH-AD900X, 38Ohms and 100dB, I guess.
But that is not so important, I would just like to make some "useful" from that lamps. Other than SE power amps at about 3W (That I don't need..) I found only schematics bellow..but two lamps like that looks like a big "waste of iron" for a line preamp in that configuration. Cathode follower should at least squeeze some mA out of these..?
Thanks, appreciated any more info.
well, I use a few of them, mostly Audio Technica ATH-AD900X, 38Ohms and 100dB, I guess.
But that is not so important, I would just like to make some "useful" from that lamps. Other than SE power amps at about 3W (That I don't need..) I found only schematics bellow..but two lamps like that looks like a big "waste of iron" for a line preamp in that configuration. Cathode follower should at least squeeze some mA out of these..?
Thanks, appreciated any more info.
deonaudio,
Where did you get that schematic?
The plates are starved for current (100k RL to 'run' two beam power plates?).
But there will be no plate current anyway, because the screen is at 0 Volts.
There will be no signal at the output.
This 'line amp' is at ground zero.
Perhaps we can think of a good way for you to use those beauties.
Later.
Where did you get that schematic?
The plates are starved for current (100k RL to 'run' two beam power plates?).
But there will be no plate current anyway, because the screen is at 0 Volts.
There will be no signal at the output.
This 'line amp' is at ground zero.
Perhaps we can think of a good way for you to use those beauties.
Later.
He-he, "schematics" is from some Japanese DIY site, some friend sent me a link. 🙂
http://bbs.hifidiy.net/thread-369173-1-1.html
Warning; If you scroll down this site, you will see how this guy realized a PCB for that preamp. IMHO, for some, that will not be easy to forget, you may need some therapy... 🙂 🙂 😉
Anyway, for me..the only way to use these lamps is OTL current buffer. One lamp in parallel for each channel. I did something like that with 6AS7 a years ago, worked OK but didn't finish it. Can't remember the schematics I used, tough..
Regards, Davorin
http://bbs.hifidiy.net/thread-369173-1-1.html
Warning; If you scroll down this site, you will see how this guy realized a PCB for that preamp. IMHO, for some, that will not be easy to forget, you may need some therapy... 🙂 🙂 😉
Anyway, for me..the only way to use these lamps is OTL current buffer. One lamp in parallel for each channel. I did something like that with 6AS7 a years ago, worked OK but didn't finish it. Can't remember the schematics I used, tough..
Regards, Davorin
Well, might not be a big deal... someone familiar with 832 lamps should punch in the red column values...for usable OTL buffer..
http://www.mh-audio.nl/Calculators/CF.html
Myself..could make a decent SS audio buffer from what lies in a workshop can..but sort of out of my depth with these RF valves... 🙂
Regards, Davorin
http://www.mh-audio.nl/Calculators/CF.html
Myself..could make a decent SS audio buffer from what lies in a workshop can..but sort of out of my depth with these RF valves... 🙂
Regards, Davorin
Attachments
@6A3sUMMER,
Had some time to "research" and yes, connection of pin 3, "screen" on above scheme is confusing. These 832A are tetrode, right. As I can see, these can be used as a triodes, with screen basically connected to anode voltage, or via some resistor divider to a portion of anode voltage. But, on the other hand; these are "beam" tetrode ..and apparently a lot of these have screen already internally connected to... cathode..? 😉Guess I would be better off with solid-state as usual. 🙂 But, funny, every 5 years or so I feel a need to do something with tubes, solid-state can be so ..predictable.
Anyway, already order sockets and anode clips for these, when they arrive..power supply and scope is here to see what is working.
In a meantime, if someone has some more insight, most appreciated.
Regards.
The cathode (your output) impedance is 1/Gm or 1/3500uMho or 286 Ohms per section, 143r for both in one bottle. Driving 38 Ohm load the gain can't be as high as 0.21. You will need near 7Vrms (10V peak) at the grid. THD will be quite high.
This tube really wants to be push-pull transformer coupled. The iron from a Fender Deluxe/Deville with 833 and a hot driver can make over 10 Watts at low THD, or 0.1W (headphone level) at very low THD.
Thanks. You are right, AT with 32 Ohms will be hard to drive. I also have Bayerdynamic DT770 PRO, with 250 Ohms..these would be much more suitable.
Still, as wrote before, using this lamps as a pure headphone amp is not my target. I would just like to use them in some preamp, as a voltage gain stage or as a buffer ( cathode follower..)..whatever the driving capability will be. I'm perfectly willing to use them even as a gain stage ..with mosfet follower. Problem is; other than push-pull or SE power amplifier..I have no dependable schematics neither for gain stage or buffer...
Regards
Still, as wrote before, using this lamps as a pure headphone amp is not my target. I would just like to use them in some preamp, as a voltage gain stage or as a buffer ( cathode follower..)..whatever the driving capability will be. I'm perfectly willing to use them even as a gain stage ..with mosfet follower. Problem is; other than push-pull or SE power amplifier..I have no dependable schematics neither for gain stage or buffer...
Regards
Post # 8 says: 833. That is a big power triode, just the filament alone takes 100Watts.
I have a dud 833 triode, 1/2 of the filament is open, the other half is 10V @ 5 Amps.
I use it as a decorative Christmas Light.
I am sure what was meant was the 832, a much lower power tube.
It is not a tetrode.
It is a beam power tube, with grid g1, screen grid g2, and Beam Formers that are connected internally to the cathode.
I have a dud 833 triode, 1/2 of the filament is open, the other half is 10V @ 5 Amps.
I use it as a decorative Christmas Light.
I am sure what was meant was the 832, a much lower power tube.
It is not a tetrode.
It is a beam power tube, with grid g1, screen grid g2, and Beam Formers that are connected internally to the cathode.
Yes, the topic is about RCA 832A. Or equivalent; Russian GU32 or Chinese FU32.
https://frank.pocnet.net/sheets/049/8/832A.pdf
https://frank.pocnet.net/sheets/049/8/832A.pdf
Funny, Chinese are selling this thing as a headphone amp, with one FU32 tube. "Compatible with wide impedance range(12-200Ω)"
https://www.aliexpress.com/item/33012784010.html
Since this tube has joined cathode there is no way it could drive any kind of stereo headphones in cathode follower configuration with only one tube. So, FU-32 for voltage gain and "NE5532" with some MOS...as a buffer..? 🙂
https://www.aliexpress.com/item/33012784010.html
Since this tube has joined cathode there is no way it could drive any kind of stereo headphones in cathode follower configuration with only one tube. So, FU-32 for voltage gain and "NE5532" with some MOS...as a buffer..? 🙂
832 tube
Cathodes are joined
Screens are joined
But Plates are separate, and each plate has its own individual grid, g1.
Stereo headphones might be possible, I see at least one 8 pin DIP Integrated Circuit.
832 Plates drive something like an LM386, or something similar?
Cathodes are joined
Screens are joined
But Plates are separate, and each plate has its own individual grid, g1.
Stereo headphones might be possible, I see at least one 8 pin DIP Integrated Circuit.
832 Plates drive something like an LM386, or something similar?
From the description, they probably use anodes ( plates) to drive NE5532. Maybe some additional bipolar or mosfet to buff up the NE5532 output current. No problem with that, If I get schematics ( and values ) for 832A as a voltage amplifier... would do for a start..
Or to put it simple, how do you connect "joined screens", Grid nr.2, pin 3 on 832A ..?
832A:
Section 1 and section 2 common elements
Pin 3 is both g2 grids in parallel
Pin 4 is both cathodes, and both beam formers, all in parallel.
Pin 5, filament mid point
Section 1:
Pin 6, g1 #1, and top pin Plate #1 'work together'
Pin 7 filament
Section 2:
Pin 2, g1 #2, and top pin Plate #2 'work together'
Pin 1 filament
Use an 832A in any of the following modes:
Push Pull Beam Power tube
Parallel Beam Power tube
Parallel Triode wired tube
Parallel Cathode Follower
It is just as simple or just as complex as that.
Have fun!
Section 1 and section 2 common elements
Pin 3 is both g2 grids in parallel
Pin 4 is both cathodes, and both beam formers, all in parallel.
Pin 5, filament mid point
Section 1:
Pin 6, g1 #1, and top pin Plate #1 'work together'
Pin 7 filament
Section 2:
Pin 2, g1 #2, and top pin Plate #2 'work together'
Pin 1 filament
Use an 832A in any of the following modes:
Push Pull Beam Power tube
Parallel Beam Power tube
Parallel Triode wired tube
Parallel Cathode Follower
It is just as simple or just as complex as that.
Have fun!
Socket arrived, tried and measured parallel cathode and anode voltage gain amp configuration, tubes are doing their "job" without any issue. Guess only remaining ongoing challenge will be preventing our "Resident Evil" cat from chewing 250V anode wires/clips. 🙂 🙂
