best method for measuring noise level of a 6AU6?

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outoftune

Well-known member
Joined
Jul 14, 2007
Messages
757
Location
canada
i have some 6au6's that i'd like to screen for noise...will be using them in a sony c800g. what do you folks recommend for a testing method? thanks.
 
What I did was to build burn in circuits.   I wired 4 sockets with 100K plate resistors and 1K cathode resistors and 1meg or what ever you have grid to ground.  B+ might have been 140VDC not critical.  I ran the heaters at 6.3VDC and let the tubes burn in for many hours I then switched to 5.7VDC for hours.  I then tested them in circuit.  Steve Benches site had a good write up on cycling tube heater voltages and tube noise.  This seemed to help.  

I tried Mullards GEs and other brand tubes.
 

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