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Re: 6N11 vs 6922, E88CC, and 6DJ8 tubes [message #98423 is a reply to message #98322]

Mon, 07 April 2025 19:04

positron
Messages: 138
Registered: May 2020

Master

Hi Kasper,

Just a thought, I have been performing some longevity testing
of the JJ E88cc tube for longevity by reducing the filament
voltage. I wanted to determine what causes deterioration of
this particular tube.

One can typically assume a major player might be gas, some to
poisoning/impurities of the cathode/sleeve materials, some due
to cathode temperature, or a combo of the above.

I found with the JJ brand, it is Mainly due to cathode temperature.
After nearly a 1,000 hrs, at 5.8 volts, approximately 9 ma, there
has only been a 1-1.5% lowering of cathode current.

(My audio buddy's sp-3 preamp has filament voltage so low that it is
difficult to see a red cathode.)

Just a thought, you may already be doing this already.

------------

A little tidbit for newbies about my decades research in the lab.
I hope this will help.

I exclusively use the JJ E88cc small signal tube in all my components
due to its incredibly low HD, some 19db less than any other tube
(2 volts rms output, -79db without negative feedback) and
incredibly accurate/natural sound. This assumes accurate and proper
size parts are used.

I once designed a PP circuit achieving 200 volts P-P signal output
at 0,05% measured harmonic distortion. (It depends upon the circuit
and cathode current used.)

I only wished the JJ would last longer; now it does with 5.8 filament
volts.

I have tried many many NOS tube types and this tube was sonically
superior across the entire audio band. I have many NOS tubes, but
never use them, which are now in the parts box.

Anyway, just some thoughts that might someone out there.

cheers
pos

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[Message index]

		6N11 vs 6922, E88CC, and 6DJ8 tubes By: kasperbergholt on Fri, 24 January 2025 05:21
		Re: 6N11 vs 6922, E88CC, and 6DJ8 tubes By: gofar99 on Tue, 04 February 2025 19:55
		Re: 6N11 vs 6922, E88CC, and 6DJ8 tubes By: kasperbergholt on Sat, 08 February 2025 10:05
		Re: 6N11 vs 6922, E88CC, and 6DJ8 tubes By: gofar99 on Sat, 08 February 2025 20:01
		Re: 6N11 vs 6922, E88CC, and 6DJ8 tubes By: kasperbergholt on Fri, 14 February 2025 06:03
		Re: 6N11 vs 6922, E88CC, and 6DJ8 tubes By: positron on Mon, 07 April 2025 19:04

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