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Filament voltage ?
Filament voltage ?
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Old 28th August 2004, 09:14 PM   #11
fdegrove is offline fdegrove  Europe
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Hi,

Quote:
I learned this from an old master who engineered tubes at Mullard. Better stick to their wisdom.
Ir. van Mossevelde?

I suppose we have the same source of wisdom, Guido: Audio Discussions as published by A&T...
IIRC you were present when this was discussed among other related topic.

My documents from Belgian Philips licensee MBLE confirm this BTW.

Quote:
Tube life decreases drastically once below 6.0V (in the case of E type tubes).
When nominal heater voltage is 6.3V going below 6V doesn't allow for the cathode to reach operational temperature and causes cathode poisoning.

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Old 28th August 2004, 09:23 PM   #12
Guido Tent is offline Guido Tent  Netherlands
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Hi Frank

All correct, I initiated that talk

Pitty it is noty available in English. Lot of work to transalate.........

cheers
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Old 28th August 2004, 09:32 PM   #13
fdegrove is offline fdegrove  Europe
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Hi,

Guido,

Quote:
Pitty it is noty available in English. Lot of work to transalate.........
I wouldn't mind doing the translation of the document or at least a decent summary of it.
Knowing you have been an actual witness would be a great plus as some of the taped stuff is rather err....funny.

Either way, if you're interested just let me know and I'll schedule it for one of our long winterdays...

Cheers,
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Old 29th August 2004, 10:18 AM   #14
Guido Tent is offline Guido Tent  Netherlands
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Quote:
Originally posted by fdegrove
Hi,

Guido,



I wouldn't mind doing the translation of the document or at least a decent summary of it.
Knowing you have been an actual witness would be a great plus as some of the taped stuff is rather err....funny.

Either way, if you're interested just let me know and I'll schedule it for one of our long winterdays...

Cheers,

Hi Frank

That would be great, however the copyright is at Audio en Techniek so we have to discvuss with them

cheers

Guido
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Old 16th July 2017, 05:53 PM   #15
mr2racer is offline mr2racer  United States
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I know this is an old thread but I have a question. I'm building a line preamp using 6N6P triodes. I used Schottky diodes and a pi filter. Originally I had 7.4 volts with a .1 ohm resistor in the filter. So I added a 1 ohm resistor after the filter and now have 5.96 volts @ 1.54 amps for two tubes. Spec is 6.3 volts and 1.5 amps (for two tubes). Is that close enough? Its only .27 watts different from ideal.
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Old 16th July 2017, 06:15 PM   #16
fdegrove is offline fdegrove  Europe
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Hi,

That should work just fine.

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Old 16th July 2017, 06:16 PM   #17
mr2racer is offline mr2racer  United States
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Thanks!
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Old 17th July 2017, 12:55 AM   #18
Wavebourn is offline Wavebourn  United States
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Filament voltage ?
Here is interesting graph (right), dependence of anode current, transconductance, and G2 current, on filament voltage for 6P15P video pentode. I would assume 5.5V regulated is fine.


Click the image to open in full size.
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Old 17th July 2017, 02:07 AM   #19
kevinkr is offline kevinkr  United States
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Filament voltage ?
Since it's not a regulated filament supply I would trim for close to 6.3V at your nominal line voltage. We are probably talking something around 10 ohms parallel with the 1 ohm.

The 6N6 will tolerate 5.7V - 6.9V in normal operation according to the data sheet, so in theory this is fine. (I would be inclined to tweak a bit..)
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Old 17th July 2017, 10:42 AM   #20
DF96 is offline DF96  England
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Did the Mullard document ever get translated? My interest is not so much audio as running a 6AT6/EBC90 at reduced heater voltage to get better AM results from the diodes. Will this shorten valve life?
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