mercury rectifier for electrostatic bias

oublie · 11th July 2009, 11:23 AM

hi folk,

i'm in the process of starting a diy electrostatic speaker build and have just picked up a pair of c core 230v to 1240v transformers.

the specs are

6.3v @1.3a
24 - 0 - 24 @ 40ma
1240v @ 15ma

i was going to use these initially in reverse as step up transformers on my amps output into order to provide the necessary voltage for the stators but though they may be put to better use providing the dc bias for the speakers.

Now i'm completely new to tubes but have build a number of ss voltage multipliers and full wave rectifers for use with electrostatic headphones.

What i'd like to know is what mercury rectifer would be suitable for use with this kind of voltage and would the 6.3v 1.3a be enough for the heater?

I've done some homework and I'm aware of the fact the mercury tubes normally need to be pre heated prior to turn on so i would include either dual switches allowing for pre heat or some type of timer for a delayed start.

The reason why i'd like to do this is purely costmetic I could easily just use a lower voltage transformer with a solid state bridge followed by a suitable cockcroft walton voltage multiplier but i like the idea of incorporating big blue tubes into the base of the speakers.

Thanks for you help on this i hope you can help out a tube noob.

btw i has a look at the possibility of using these with tt21's or 75tl's (see told you i did some reading

) and actually build a couple of amplifiers but i dont think the tranformers could supply enough current for something like this.

oublie · 11th July 2009, 12:07 PM

btw forgot to mention that these will be used after a primary step up transfomers so output from the transfomers will be in the region of 3000v prior to being rectified - insulation is rated to 5000v

thanks

Gluca · 12th July 2009, 03:32 AM

Mercury vapor rectifiers do need many ampers to heat the filament and they usually have 2.5 or 5V filament not 6.3V

75TLs are really rare and finding an output transformer for these puppies is even harder. Mine are biased at 900V and 40/50mA . Next project I have on the bench is a preamp/headphone amp with 75TLs and/or 75THs ... it happens those are my preferred tubes.

Ciao
Gianluca

oublie · 13th July 2009, 10:56 AM

thanks for the info gluca,

so i would need a separate 2.5 or 5v high amperage source. i suppose i could use a smps 5v supply the heater element will run on dc right ? any ideas of specific tubes i could look into.

Gluca · 13th July 2009, 12:57 PM

Quote:

Originally posted by oublie
thanks for the info gluca,

so i would need a separate 2.5 or 5v high amperage source. i suppose i could use a smps 5v supply the heater element will run on dc right ? any ideas of specific tubes i could look into.

NOOOOOWAY! Filament is floating at high voltage. There are many MV rectifiers out there.

Gianluca

oublie · 14th July 2009, 02:10 PM

ok so what would you suggest?

nhuwar · 14th July 2009, 10:30 PM

Just get a simple filament transformer for them. Just make sure the secondary insulation is rated higher then the plate voltage,,,,,, OR ELSE,,,,,,,,BOOM.
All you need is ac too, don't know if anyone already told you that.

Nick

moray james · 14th July 2009, 10:43 PM

has anybody checked to see just what the UV radiation of these tubes are?

nhuwar · 14th July 2009, 10:51 PM

I seriously doubt it's enough to worry about.

Nick

11th July 2009, 11:23 AM	#1
oublie diyAudio Member Join Date: May 2009 Location: Northern Ireland	mercury rectifier for electrostatic bias hi folk, i'm in the process of starting a diy electrostatic speaker build and have just picked up a pair of c core 230v to 1240v transformers. the specs are 6.3v @1.3a 24 - 0 - 24 @ 40ma 1240v @ 15ma i was going to use these initially in reverse as step up transformers on my amps output into order to provide the necessary voltage for the stators but though they may be put to better use providing the dc bias for the speakers. Now i'm completely new to tubes but have build a number of ss voltage multipliers and full wave rectifers for use with electrostatic headphones. What i'd like to know is what mercury rectifer would be suitable for use with this kind of voltage and would the 6.3v 1.3a be enough for the heater? I've done some homework and I'm aware of the fact the mercury tubes normally need to be pre heated prior to turn on so i would include either dual switches allowing for pre heat or some type of timer for a delayed start. The reason why i'd like to do this is purely costmetic I could easily just use a lower voltage transformer with a solid state bridge followed by a suitable cockcroft walton voltage multiplier but i like the idea of incorporating big blue tubes into the base of the speakers. Thanks for you help on this i hope you can help out a tube noob. btw i has a look at the possibility of using these with tt21's or 75tl's (see told you i did some reading ) and actually build a couple of amplifiers but i dont think the tranformers could supply enough current for something like this.

14th July 2009, 10:43 PM	#8
moray james diyAudio Member Join Date: Aug 2003 Location: Calgary on the Bow	UV radiation... has anybody checked to see just what the UV radiation of these tubes are? __________________ moray james

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11th July 2009, 12:07 PM	#2
oublie diyAudio Member Join Date: May 2009 Location: Northern Ireland	btw forgot to mention that these will be used after a primary step up transfomers so output from the transfomers will be in the region of 3000v prior to being rectified - insulation is rated to 5000v thanks

12th July 2009, 03:32 AM	#3
Gluca tarmac ripper diyAudio Member Join Date: Nov 2004 Location: Back to Italy	Mercury vapor rectifiers do need many ampers to heat the filament and they usually have 2.5 or 5V filament not 6.3V 75TLs are really rare and finding an output transformer for these puppies is even harder. Mine are biased at 900V and 40/50mA . Next project I have on the bench is a preamp/headphone amp with 75TLs and/or 75THs ... it happens those are my preferred tubes. Ciao Gianluca

13th July 2009, 10:56 AM	#4
oublie diyAudio Member Join Date: May 2009 Location: Northern Ireland	thanks for the info gluca, so i would need a separate 2.5 or 5v high amperage source. i suppose i could use a smps 5v supply the heater element will run on dc right ? any ideas of specific tubes i could look into.

14th July 2009, 02:10 PM	#6
oublie diyAudio Member Join Date: May 2009 Location: Northern Ireland	ok so what would you suggest?

14th July 2009, 10:30 PM	#7
nhuwar diyAudio Member Join Date: Jan 2007 Location: Tomball Texas	Just get a simple filament transformer for them. Just make sure the secondary insulation is rated higher then the plate voltage,,,,,, OR ELSE,,,,,,,,BOOM. All you need is ac too, don't know if anyone already told you that. Nick

14th July 2009, 10:51 PM	#9
nhuwar diyAudio Member Join Date: Jan 2007 Location: Tomball Texas	I seriously doubt it's enough to worry about. Nick

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