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In the Forum: Audio For Dummies ™
In the Thread: Get, or made up a tube tester, it’s necessary
Post Subject: The more you know about tube testing,Posted by Paul S on: 1/11/2007
the less you know about...

So, how do we go about screening tubes for audio, particularly audio signal tubes?  The only person I can think of who claims to have found a specific testing paramerer for this is Roger Modjeski, of Music Reference and RAM (tube) fame, who says his tests for the "RAM Factor" weed out the bad/yield the good in terms of sonics.  I have used lots of his tubes, and they have always been good-sounding versions of whatever (generally-inexpensive) brand they started life as, but I cannot say that RAM tubes I tried sounded better than or even as good as various (expensive) NOS tubes I compared them to, in the same application.  Although I ass-u-me the NOS tubes in question were "tested" and "matched" by the seller, none claimed Ram Factor-like screening, which means that in my experience the particular brand and vintage of a tube may trump RAM screening of "lesser" tubes; ie, good bloodlines will out.

But this still does not solve the problem of what we should test for and how do we do it for a given tube.  Since this thread started I have been looking at testers, trying to land on one that appears to be worth the trouble, for my applications, which are strictly limited to audio.  What a maze!  In addition to the link I posted back up the thread I ran across this one:   Still, so far, all of them look like variants of the same testers that most of the decent vendors are already using.

With respect to the "decent vendors", I have for many years now averaged about 25% bad tubes from all sources, and I only buy from sources who at least claim they test and match, etc.  Does this mean that somehow the testers are dropping the ball on 25% of the tubes they test (if you can accept that they really do test them)?  

Germane to this thread,  how is any testing I do going to improve on this situation?

Is there any agreement on what is relevant?  Does anyone really know?

How many test and which tests does it take to adequately screen one's hi-fi tubes, and how many testers are required to run these tests?

I am more confused about this now than was when I started reading more about it.

Best regards,
Paul S

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