The 6934A Triode Tube

thetubeguy1954 · 24th October 2011, 09:58 PM

Please check out this 6394A Triode Tube's | tube data If you'll go to page 4, in the second paragraph it states "A 30 second cathode time is recommended before the plate voltage is applied." What I'd like to know from those who are more knowledgeable than I am. Does that mean just when the 6394A tube is being used as a passing tube as described in that same paragraph or does that statement apply to the 6394A tube at all times and in all circumstances? The reason I'm asking is I think this would make a very interesting preamp tube. Might also make for an interesting SET tube as well...

TIA for any and all replies...

Thetubeguy1954 (Tom Scata)

SY · 24th October 2011, 10:02 PM

You want to do that for any use at all. I don't know that particular tube, but generally when you see that on a datasheet, it means that the plate has some scavenging metals which need to be hot before current flows in order to prevent poisoning. This is especially common for tubes with graphite plates.

edit: Pulled up the datasheet and confirmed. This tube looks very similar to 6336. Not terrific for linearity, but would work well in a push-pull circuit.

HollowState · 24th October 2011, 10:30 PM

The 6394 is the 26 volt filament version of a 6336A. Otherwise it's the same. I have a couple of dozen.

pieter t · 24th October 2011, 10:42 PM

This might be a great build:

Un ampli chargecathodique de 30 W (G.Marec)

30 watts cathode output ...

fdegrove · 24th October 2011, 10:54 PM

Hi,

That's one of those high altitude aviation regulator tube. Forget about it, it's too rare to be of any use.
Similar to its smaller brother the 6082.

Cheers,

kevinkr · 24th October 2011, 11:06 PM

Quote:

Originally Posted by fdegrove

Hi,

That's one of those high altitude aviation regulator tube. Forget about it, it's too rare to be of any use.
Similar to its smaller brother the 6082.

Cheers,

Unless of course you happen to have a bunch of them..

Otherwise as Frank says they are relatively rare..

pieter t · 24th October 2011, 11:06 PM

Quote:

Originally Posted by fdegrove

Hi,

That's one of those high altitude aviation regulator tube. Forget about it, it's too rare to be of any use.
Similar to its smaller brother the 6082.

Cheers,

Forget about it?
If I had "a couple dozens" of these like Hollowstate I would not mind use them for an amplifier.
I have heard excellent amplifiers with this kind of tubes (6AS7, 6336, 6C33C) especially when used cathode output.

fdegrove · 25th October 2011, 12:06 AM

Hi,

Any half decent amp (power and Zout-wise) amp will take up about four of those already.
With a OPT you could do with a pair per channel but then matching pairs are going to come from your small stash.
From experience I can tell you that matching anything like a 6080 and up in power is going to take more than just a few dozen of those bottles...

All in all not that great an idea not even to mention the mere ecological footprint of these babies....

Ciao,

kevinkr · 25th October 2011, 12:22 AM

I had very similar problems with the 6C33, I had to purchase dozens to get just 6 well matched ones per channel. That OTL amplifier was ill-fated for a lot of other reasons including my need to design a needlessly complex amp which as designed was never going to work, and then I discovered low power SE..

fdegrove · 25th October 2011, 12:36 AM

Hi,

The difference between chasing mere numbers and musical bliss, I reckon?

Cheers,

24th October 2011, 09:58 PM	#1
thetubeguy1954 diyAudio Member Join Date: Apr 2004 Location: Orlando, Florida. USA	The 6934A Triode Tube Please check out this 6394A Triode Tube's \| tube data If you'll go to page 4, in the second paragraph it states "A 30 second cathode time is recommended before the plate voltage is applied." What I'd like to know from those who are more knowledgeable than I am. Does that mean just when the 6394A tube is being used as a passing tube as described in that same paragraph or does that statement apply to the 6394A tube at all times and in all circumstances? The reason I'm asking is I think this would make a very interesting preamp tube. Might also make for an interesting SET tube as well... TIA for any and all replies... Thetubeguy1954 (Tom Scata) __________________ Central Florida Audio Society--SETriodes Group--Space Coast Audio Society---Full-range/Wide-range Drivers---Front & Back-Loaded Horns.

24th October 2011, 10:02 PM	#2
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	You want to do that for any use at all. I don't know that particular tube, but generally when you see that on a datasheet, it means that the plate has some scavenging metals which need to be hot before current flows in order to prevent poisoning. This is especially common for tubes with graphite plates. edit: Pulled up the datasheet and confirmed. This tube looks very similar to 6336. Not terrific for linearity, but would work well in a push-pull circuit. __________________ “Listening to records is like ****ing a picture of Brigitte Bardot.” - Sergiu Celibidache

24th October 2011, 10:30 PM	#3
HollowState diyAudio Member Join Date: Aug 2006 Location: Taxland, New Jersey	The 6394 is the 26 volt filament version of a 6336A. Otherwise it's the same. I have a couple of dozen. __________________ "The supercomputer is technologically impossible. It would take all of the water that flows over Niagara Falls to cool the heat generated by the number of vacuum tubes required." ~ Professor of Electrical Engineering, New York University

24th October 2011, 10:54 PM	#5
fdegrove diyAudio Senior Member Join Date: Aug 2002 Location: Belgium	Hi, That's one of those high altitude aviation regulator tube. Forget about it, it's too rare to be of any use. Similar to its smaller brother the 6082. Cheers, __________________ Frank

25th October 2011, 12:06 AM	#8
fdegrove diyAudio Senior Member Join Date: Aug 2002 Location: Belgium	Hi, Any half decent amp (power and Zout-wise) amp will take up about four of those already. With a OPT you could do with a pair per channel but then matching pairs are going to come from your small stash. From experience I can tell you that matching anything like a 6080 and up in power is going to take more than just a few dozen of those bottles... All in all not that great an idea not even to mention the mere ecological footprint of these babies.... Ciao, __________________ Frank

24th October 2011, 10:42 PM	#4
pieter t diyAudio Member Join Date: Apr 2009	This might be a great build: Un ampli chargecathodique de 30 W (G.Marec) 30 watts cathode output ...

25th October 2011, 12:22 AM	#9
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	I had very similar problems with the 6C33, I had to purchase dozens to get just 6 well matched ones per channel. That OTL amplifier was ill-fated for a lot of other reasons including my need to design a needlessly complex amp which as designed was never going to work, and then I discovered low power SE.. __________________ www.kta-hifi.net

25th October 2011, 12:36 AM	#10
fdegrove diyAudio Senior Member Join Date: Aug 2002 Location: Belgium	Hi, The difference between chasing mere numbers and musical bliss, I reckon? Cheers, __________________ Frank

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Power triode bias by tube rectifier	MrCurwen	Tubes / Valves	37	23rd September 2010 08:29 PM
24A tube in triode mode, help !!!	aldovan	Tubes / Valves	6	18th May 2010 10:36 AM
UXCV11 Triode Tube	tubeman	Tubes / Valves	4	5th May 2010 04:45 PM
Tube amp with Dual Triode	designermx2	Tubes / Valves	1	4th May 2010 04:56 AM
Help on 311-CH triode tube	georgehifi	Tubes / Valves	1	30th April 2004 12:55 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read