New tube test out

[Stevem]

I just had the time to test thru 10 new 12AX7 tubes, 10 from Mesa and 10 from electro harmonics.

The Mesa's are a STR-12-AX7-A type which is a short plate version.

The EH tubes are a mid size plate version labeled as a 12AX7EH.

Here is the Mesa results broken down by the tubes A side and B side .

Note here that to me any new tube that test out at 84% or less I will not buy / use as I find them to go weak very fast!

A side, 4 out of 10 tested above 90%.
A side, 4 out of 10 tested out between 92 and 96%.
A side, 3 out of 10 tested below 76%
B side , 2 out of 10 tested at 100%
B side, 6 out of 10 tested above 90%.
B side 4 out of 10 tested between 90 and 94.
B side, 4 out of 10 tested at 88% or less.
B side, 2 out of 10 test 82% or less.

Here is the EH results .

A side. 6 out of 10 test above 90%.
A side, 2 out of 10 test at 100%.
A side, 4 out of 10 test 88% or less.
A side, 2 out of 10 test at 76% or less.
B side, 1 out of 10 tested at 100%.
B side 4 out of 10 tested above 90%.
B side, 6 out of 10 test 88% or less.
B side, 4 out of 10 test 84% or less.
B side, 1 out of 10 tested 72% or less.

As you can see there are 4 out of 10 tubes from each supplier that I would not want to use or buy, and 2 out of 10 tubes are fairly well matched if you have a need for such .

In short, the crap shoot continues when you buy new ungraded tubes!!!

[67plexi]

No doubt I have had good luck with Tube Depot for new production.
But the music store I do repairs for made a large order from Ruby Tubes
I tested all of them and sent every one back. The next batch tested 100%
That said I'm sold on the JJ/Telefunken for new production.

[Leo_Gnardo]

No doubt I have had good luck with Tube Depot for new production.
But the music store I do repairs for made a large order from Ruby Tubes
I tested all of them and sent every one back. The next batch tested 100%
That said I'm sold on the JJ/Telefunken for new production.

Ruby, being a test/rebrand outfit sells tubes from Shuguang, JJ, Sovtek EH and maybe others. So.... who was the manufacturer of the tubes you rejected, and when did this happen?

FWIW I tried 12AX7 JJ's sold thru Ruby in the early 2000's. I didn't run them thru a tube tester, but most of them made ticking noises and weren't much good, unless you wanted your amp to sound like a Geiger counter. I tried another batch in 2007 and they were much better. No tick noises, good sounding tubes that didn't add hiss, or ring like a tiny bell the way Shuggies often do. JJ's have been a favorite ever since.

"Telefunken", JJ tubes presumably cryo treated by a company in Connecticut then painted with the Telefunken logo. A bit expensive, no? I would think in Alaska you could leave some tubes outdoors in the winter for a month or two, save yourself a small fortune.

[Matt D]

What tube testers are you guys using and what parameters are they measuring?

[Stevem]

Mine is a 1950s era Hickok 600 that does test for GM and I recal it every 6 months, or atleast check if it's drifted .

These things where built like a Tank , God bless them !

Just note that in a high gain 4 stage or more metal amp you can get into trouble at times with having preamp tubes in them that all test out over 88% on a GM test as they can start screaming with osccilation issues above a certain volume level due to crappy layout within the build!

Some of these can be addressed cost wise within reason and some can't .