I am considering using a couple of 866A rectifiers in my next project (probably a transmitting tube amp.). These monsters use mercury vapour, and are rated up to 5000V. I will probably run them at ~800V and 200mA, not too huge. The main reason I want to use them is because I have access to a large store of dirt cheap NOS ones, and I like the blue glow! (check this pic: 866A in operation )
Has anyone had any experience using them? From what I understand, in normal use they need to be preheated for about 1 minute before B+ is applied, and if they have not been used for a while, they should be heated for several hours.
I am not too worried about mercury getting loose, or the small amount of UV that might be generated. I live in New Zealand, so the Springtime ozone hole that covers us means lots of UV anyway!!
What I would like to know is: do they generate a lot of heat, do they create a lot of switching noise, and has anyone successfully used them with a CLC filter? I was thinking around 2uF for the first cap. I could use LCLC if necessary, but it lowers the B+.
Thanx
~ShiFtY~
Has anyone had any experience using them? From what I understand, in normal use they need to be preheated for about 1 minute before B+ is applied, and if they have not been used for a while, they should be heated for several hours.
I am not too worried about mercury getting loose, or the small amount of UV that might be generated. I live in New Zealand, so the Springtime ozone hole that covers us means lots of UV anyway!!
What I would like to know is: do they generate a lot of heat, do they create a lot of switching noise, and has anyone successfully used them with a CLC filter? I was thinking around 2uF for the first cap. I could use LCLC if necessary, but it lowers the B+.
Thanx
~ShiFtY~
theyre rated for 10kV actually!
they look much cooler in real life
but there are problems:
overkill, suck up alot of heater current.
CLC isnt much of an option.. they like choke input. ( i think if you do do it CLC, the first cap has to be <1µF ).
I'm not sure how much of the UV the glass filters out, but it can't be too good for your eyes.
ill attatch a pic if i can find it..
OK! heres a picture of a british 866AX on my hickok... (pardon the crappy digicam)
they look much cooler in real life
but there are problems:
overkill, suck up alot of heater current.
CLC isnt much of an option.. they like choke input. ( i think if you do do it CLC, the first cap has to be <1µF ).
I'm not sure how much of the UV the glass filters out, but it can't be too good for your eyes.
ill attatch a pic if i can find it..
OK! heres a picture of a british 866AX on my hickok... (pardon the crappy digicam)
An externally hosted image should be here but it was not working when we last tested it.
Don't know much about them. Have a couple dead ones. The mercury scares me. Josh Stippich uses them in his amp and they do look cool.
Some pictures
dave
Some pictures
An externally hosted image should be here but it was not working when we last tested it.
dave
Freddy Mercury Valves
Hello,
IMHO this series of rectifiers are very noisy devices.
They were designed for industrial usage and I wouldn't use them in any audio application.
Moreover,and this goes for any rectifier valve when used way below their intended design use, they tend to be even more noisy and unpredictable in behaviour in such apps.
I hear a lot of people using TV damper tubes as common HT rectifiers in cicuits using 300 to 500 B+ and noticing funny noises and tubes turning belly up.
This is to be expected.
So unless you use these at their intended voltages and adhere to their ratings I would advise against them.
If you must use these go for a LC filter,not CLC and use a big choke to isolate the rectifiers from the rest of the circuit.
Just my 2 Eurocents worth,
Hello,
IMHO this series of rectifiers are very noisy devices.
They were designed for industrial usage and I wouldn't use them in any audio application.
Moreover,and this goes for any rectifier valve when used way below their intended design use, they tend to be even more noisy and unpredictable in behaviour in such apps.
I hear a lot of people using TV damper tubes as common HT rectifiers in cicuits using 300 to 500 B+ and noticing funny noises and tubes turning belly up.
This is to be expected.
So unless you use these at their intended voltages and adhere to their ratings I would advise against them.
If you must use these go for a LC filter,not CLC and use a big choke to isolate the rectifiers from the rest of the circuit.
Just my 2 Eurocents worth,
Re: Freddy Mercury Valves
TTFN
PS: Try a 5C8S for rectifier with transmitting triode amps. Easier.
I agree, but my information is anecdotal. I have a few but haven't used them yet (no need). Reports are that they can be noisy, and are a PITA to use, even though they look very cool. They are very low impedance though.fdegrove said:
Huh? The damper diodes I've used are <i>very,very</i> quiet and have given no greif so far. They're a heck of a lot tougher than things like 5AR4 etc, cheap too. However, I never load them less than 100mA or so.
Yep. But PSU's always sound better with a LC supply rather than a CLC.
TTFN
PS: Try a 5C8S for rectifier with transmitting triode amps. Easier.
TV dampers
Hi,
Ok Brett ,if you know what you're doing,then fine.
The info I shared is from sleeping whith the RCA secretaries.
You can call that anecdotal for sure.
The Freddy M. tubes' low internal impedance is something of little importance to me.Not necessarily a blessing.
I always try to depend on very good PSU regulation where called for so that I do not depend on the capabilties of transformer and rectifiers to respond immediately to current demands.
Seriously,I see a lot of people toying with tubes having read page one of the books and then complaining afterwards that things don't seem to turn out what they expected.
As a general rule of thumb a tube is designed for a certain job and logic has it that when it can do more it can do less,right?
Well,with tubes this just doesn't hold up:there are working points that need to be respected or results can be unpredictable.
Sometimes you can get away with it,other times you face Mr.Murphy.
Pretty soon you'll have someone using thyratrons to fire up their B+....
It was meant as a cautionary note.
See you,
Hi,
Ok Brett ,if you know what you're doing,then fine.
The info I shared is from sleeping whith the RCA secretaries.
You can call that anecdotal for sure.
The Freddy M. tubes' low internal impedance is something of little importance to me.Not necessarily a blessing.
I always try to depend on very good PSU regulation where called for so that I do not depend on the capabilties of transformer and rectifiers to respond immediately to current demands.
Seriously,I see a lot of people toying with tubes having read page one of the books and then complaining afterwards that things don't seem to turn out what they expected.
As a general rule of thumb a tube is designed for a certain job and logic has it that when it can do more it can do less,right?
Well,with tubes this just doesn't hold up:there are working points that need to be respected or results can be unpredictable.
Sometimes you can get away with it,other times you face Mr.Murphy.
Pretty soon you'll have someone using thyratrons to fire up their B+....
It was meant as a cautionary note.
See you,
salute guys
an opinion that can help !
recently in my audio preamp, i tried a lot of different rects.
normal/fast recovery/hexfreds & then i decided to use a tube
rectifier.
i pulled out an old 5u4 & wired up to my preamp and the improvment was so huge i could not believe.
i learned that solid states rects are very noisy specially hexfreds.
so guys i consider that tube rect is the best option for diy
(at least on preamps)
i have a question.
on this design i have a pi type ( cap+resistor+cap)
on one of the posts says that eliminating the first cap
sonds better or performs better, why??/
thanks
richt
an opinion that can help !
recently in my audio preamp, i tried a lot of different rects.
normal/fast recovery/hexfreds & then i decided to use a tube
rectifier.
i pulled out an old 5u4 & wired up to my preamp and the improvment was so huge i could not believe.
i learned that solid states rects are very noisy specially hexfreds.
so guys i consider that tube rect is the best option for diy
(at least on preamps)
i have a question.
on this design i have a pi type ( cap+resistor+cap)
on one of the posts says that eliminating the first cap
sonds better or performs better, why??/
thanks
richt
Recifiers
Ola hombre,
On this particular occasion I advised this type of filtering.
On any rectifier tube you will have the recommend value of input cap given by the manufacturer.
Generally,nothing against CLC filtering.
You should try a choke with your preamp for a sonic blast away experience.
Brett,
Send some "poulet roti" my way please!
Not polluted by mercury if possible?
Buenas noches,
Paco
Ola hombre,
On this particular occasion I advised this type of filtering.
On any rectifier tube you will have the recommend value of input cap given by the manufacturer.
Generally,nothing against CLC filtering.
You should try a choke with your preamp for a sonic blast away experience.
Brett,
Send some "poulet roti" my way please!
Not polluted by mercury if possible?
Buenas noches,
Paco
Re: TV dampers
I also have a lot of jokes about, special tube handling proceedures, red hot anodes and appropriate mountings, but I won't mention them here or the fuddy-duddy's will have apoplexy.
Ciao
I seldom know what I'm doing. The more I learn the less I know, and the more I accept.fdegrove said:
Whatever you want to call it, it sounds like a lot more fun than reading the manuals.The info I shared is from sleeping whith the RCA secretaries.
You can call that anecdotal for sure.
I also have a lot of jokes about, special tube handling proceedures, red hot anodes and appropriate mountings, but I won't mention them here or the fuddy-duddy's will have apoplexy.
Agree, adding a good shunt reg is always beneficial
What, you mean I have to read a <i>whole</i> page of the manual?
Yes generally, but I was referring to the 6D22S, 6CJ3/6CH3, EY/PY500A type tubes, which for a typical tube pre or power are fine.
Always wise.It was meant as a cautionary note.
Ciao
Hi Brett,
And you wonder why Grey is complaining about USA levels of education?
I could go on about that problem ad infinitum.Frustaaating!
Actually,I may surprise you here:I found the manuals far more interesting than these secretaries although we were all interested in tubes.
Now I should really hit the sack,5.49 AM here...
Ciao too,
And you wonder why Grey is complaining about USA levels of education?
I could go on about that problem ad infinitum.Frustaaating!
Actually,I may surprise you here:I found the manuals far more interesting than these secretaries although we were all interested in tubes.
Now I should really hit the sack,5.49 AM here...
Ciao too,
HG vapor rects and my Hallicrafters HT45 mk II
With mercury vapor rectifiers you should wait a minimum of 4 minutes warmup time before applying the high voltage. Hallicrafters actually says in the HT45 manual that 15 minutes is preferable (this is a solid kilowatt linear amp from the 1960's.)
The ARRL handbooks of the 1950s and 1960s often discussed the noise with mercury rectifieres.
With mercury vapor rectifiers you should wait a minimum of 4 minutes warmup time before applying the high voltage. Hallicrafters actually says in the HT45 manual that 15 minutes is preferable (this is a solid kilowatt linear amp from the 1960's.)
The ARRL handbooks of the 1950s and 1960s often discussed the noise with mercury rectifieres.
866A usage
I have used 866A with good results.
Let the tubes stand upright for a week or so before applying filament power.
And KEEP them upright or start over!
Run the tubes on filaments only for a couple days before applying B+ for the first time.
Check the filament voltage and adjust as needed before applying B+.
Noise? I got no stinking noise
L-C-L-C filters work well.
Happy Ears!
Al
I have used 866A with good results.
Let the tubes stand upright for a week or so before applying filament power.
And KEEP them upright or start over!
Run the tubes on filaments only for a couple days before applying B+ for the first time.
Check the filament voltage and adjust as needed before applying B+.
Noise? I got no stinking noise
L-C-L-C filters work well.
Happy Ears!
Al
I had always assumed that designers put mercury rectifiers in farady cages to limit the effects of the rf noise they produced, but if the following is true then maybe it was the other way round:
(RCA data sheet for 872 rectifier)
"Shields and rf filter circuits shuld be provided for the 872-A if it is subjected to extraneous high-frequency fields during operation. These fields tend to produce breakdown effects in mercury vapour and are detrimental to tube life and performance"
"Rf filters are employed to prevent damage caused by rf currents which might otherwise be fed back into the rectifier tubes"
(RCA data sheet for 872 rectifier)
"Shields and rf filter circuits shuld be provided for the 872-A if it is subjected to extraneous high-frequency fields during operation. These fields tend to produce breakdown effects in mercury vapour and are detrimental to tube life and performance"
"Rf filters are employed to prevent damage caused by rf currents which might otherwise be fed back into the rectifier tubes"
Thanks for the tip on the RCA 827-A data sheet, very informative. My understanding is that mercury vapour rectifiers have a negative resistance at part of their IV characteristic and that this can combine with the leakage inductance and stray capacitance of the mains transformer to produce a circuit that can oscillate if excited. Since the system is excited at a 50Hz (or 60Hz) rate, this can lead to squegging at a 50Hz rate. Ferrite beads are usually touted as the cure. The RSGB and ARRL manuals are good places to look for information on using these rectifiers.
Mercury Vapor Rectifiers in SE Power Amplifiers??
Hi,
This is my first post to this forum.
I have been designing and building ultra-fi audio gear for the last 25 years, but I am looking for some guidance on a power supply modification I would like to make to my power amplifiers.
I very much like the sound the type 83 mercury vapor (MV) rectifier imparts to my homebrew phono preamp. As such, I'd like to change the rectification for my homebrew power amplifiers to the type 83 MV rectifier as well.
My amplifiers use a transformer-coupled driver stage to a SE WE-300B output. The 300B uses DC heating by way of the superb Rod Coleman Regulator, and the 300B is pre-heated before the application of the plate voltage. Plate supply rectification is presently via a 5U4G, with L-C-L-C filtering.
As we all know, MV rectifiers require pre-heating of 30 seconds or so before the application of AC to the rectifier plates. I can turn the 83 filament supply on prior to the application of the HV AC, and my question is as follows; when the 83 rectifier is fully warmed up and ready to conduct, will there be a very loud turn-on transient thump in the loudspeaker? Very loud is of course highly subjective, but my loudspeakers are around 103 dB sensitivity.
Subjectively, it seems to me that the turn-on transient is going to be significant, and could possibly cause damage to the Altec 416-8A woofers in my Altec A5 horn-loaded system.
Many well-known ultra-fi amplifier designers, such as Sakuma-San and Josh Stippich of Electron-Luv use MV rectification in their power amplifiers, and their amplifiers are certainly used with very high sensitivity loudspeaker systems. They pre-heat the MV rectifier, and then the HV AC is applied to the rectifier by closing a switch to connect the plate transformer center-tap to ground.
Can anyone with any actual experience with MV rectifiers in a power amplifier comment on this issue I can see with the turn-on transient? If the transient is of minimal amplitude (whatever that means), then of course there is nothing to worry about, but before I start changing things in my current amplifier topology, I would like to get some guidance from the group.
Thanks & Regards,
Bruce
Hi,
This is my first post to this forum.
I have been designing and building ultra-fi audio gear for the last 25 years, but I am looking for some guidance on a power supply modification I would like to make to my power amplifiers.
I very much like the sound the type 83 mercury vapor (MV) rectifier imparts to my homebrew phono preamp. As such, I'd like to change the rectification for my homebrew power amplifiers to the type 83 MV rectifier as well.
My amplifiers use a transformer-coupled driver stage to a SE WE-300B output. The 300B uses DC heating by way of the superb Rod Coleman Regulator, and the 300B is pre-heated before the application of the plate voltage. Plate supply rectification is presently via a 5U4G, with L-C-L-C filtering.
As we all know, MV rectifiers require pre-heating of 30 seconds or so before the application of AC to the rectifier plates. I can turn the 83 filament supply on prior to the application of the HV AC, and my question is as follows; when the 83 rectifier is fully warmed up and ready to conduct, will there be a very loud turn-on transient thump in the loudspeaker? Very loud is of course highly subjective, but my loudspeakers are around 103 dB sensitivity.
Subjectively, it seems to me that the turn-on transient is going to be significant, and could possibly cause damage to the Altec 416-8A woofers in my Altec A5 horn-loaded system.
Many well-known ultra-fi amplifier designers, such as Sakuma-San and Josh Stippich of Electron-Luv use MV rectification in their power amplifiers, and their amplifiers are certainly used with very high sensitivity loudspeaker systems. They pre-heat the MV rectifier, and then the HV AC is applied to the rectifier by closing a switch to connect the plate transformer center-tap to ground.
Can anyone with any actual experience with MV rectifiers in a power amplifier comment on this issue I can see with the turn-on transient? If the transient is of minimal amplitude (whatever that means), then of course there is nothing to worry about, but before I start changing things in my current amplifier topology, I would like to get some guidance from the group.
Thanks & Regards,
Bruce
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