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Do vacuum tube test values reflect sound quality?

I recently ordered a pair of output tubes to try in my LTA MicroZOTL preamp. Two Sylvania 6SN7WGT tubes, Gold Brand. I’ve had good luck with Sylvania 12sn7gt bad boy tubes, so I thought I’d give them a try.

After I bought them, I saw a similar pair for more money that had slightly higher test values. Does that mean they might sound better or that they just have more life left? What properties do you look for in tubes?

Below are the values of the tubes that I bought.

 

Tubes are matched for dynamic gain and structure, testing at 3000-2750 and 3000-2750 where pass/fail is 1625 micromho. They have the same structure inside and out, having matching date codes of "922", the 22nd week of 1959

sls883

Showing 1 response by intactaudio

intactaudio
303 posts
 

Tubes like the 12AX7, used by many companies as a cathode follower, are not a good choice. They do it because there are billions of 12AX7s in the world

Many did it because the high µ was needed and the other half of the tube was right there without a good use so it was turned into a CF to buffer the high Rp that comes part and parcel with the high µ.

The marantz 7C uses three AX7s per channel.  4 sections are used for gain and two are cathode followers.  It would be a mess if a more suitable tube were used for the CFs

dave

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