do matched pair (or maybe a quad) output tubes "aged" at the same rate?

jarthel · 8th June 2007, 11:42 PM

like a design I saw in Andrea Cuffuli requires a quad of EL34 per channel.

an example:

I bought a matched quad of EL34 with a reading of 100 for all 4. After 500 hours, will the tubes still have the same reading?

Thank you.

kevinkr · 9th June 2007, 12:15 AM

These days probably not, but as long as the bias is adjustable on a per tube basis it should be ok.

jarthel · 9th June 2007, 12:30 AM

Quote:

Originally posted by kevinkr
These days probably not,

Care to explain that statement?

thank you.

nhuwar · 9th June 2007, 01:05 AM

I think it may mean that the quality control in the construction of new tubes are not as precisely put together as they used to be.

But Kevin will know for sure.

Nick

8th June 2007, 11:42 PM	#1
jarthel diyAudio Member Join Date: Jan 2002 Location: somewhere in Australia	do matched pair (or maybe a quad) output tubes "aged" at the same rate? like a design I saw in Andrea Cuffuli requires a quad of EL34 per channel. an example: I bought a matched quad of EL34 with a reading of 100 for all 4. After 500 hours, will the tubes still have the same reading? Thank you.

9th June 2007, 12:15 AM	#2
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	These days probably not, but as long as the bias is adjustable on a per tube basis it should be ok. __________________ "Extraordinary claims require extraordinary evidence." - Carl Sagan

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9th June 2007, 01:05 AM	#4
nhuwar diyAudio Member Join Date: Jan 2007 Location: Cypress Texas	I think it may mean that the quality control in the construction of new tubes are not as precisely put together as they used to be. But Kevin will know for sure. Nick