Re: 12SX7's

OTL Asylum

OTL, Output Transformerless Amplifier User Group.

In Reply to: 12SX7's posted by Dan on October 25, 1999 at 08:07:40:

At the risk of boring Mark to death, because he has heard from me directly on this, I will tell you what I found as a result of ordering 12SX7s from two different vendors: From one vendor, I received obviously pristine NOS RCA 12SX7s, in their original perfect boxes with factory cushioning. These tubes did not have any JAN notations on them anywhere. Nor was there any indication of previous burn-in. From the other vendor, I received (1) several "JAN"-labeled RCA-branded 12SX7s. All of these had silvering on the glass indicating previous turn-on; a few were in the classic gray military boxes with the JAN designation on the outside. (2) A few used-looking GEs that were labeled "12SN7" on the glass envelope and "12SX7" on the tube base. These I returned as possibly bogus. (3) A few GE-branded, JAN-labeled 12SX7s. These are most interesting. The glass envelope is a lot taller than that for any of the others or for any 6SN7. Previous use or burn-in is evident. The internal elements are similar in size to that seen inside the RCA versions, so there is a lot of empty space in these tubes.
When I queried the first vendor regarding the provenance of his tubes, he was critical of the second vendor, implying that the tubes with silvering were simply used ones. When I asked the second vendor about the provenance of HIS tubes, he said that the silvering I see often occurs as tubes age on the shelf and don't necessarily indicate previous use or that the tubes are "used" (a sin of which I did not accuse him). If I ever get to install any of these babies, I will let you know if the physical differences correlate with any sonic differences. My thesis is that the pristine NOS non-JAN RCA 12SX7s are simply production tubes that were not screened for mil use, but I wonder whether the unusual looking GE versions are something special.

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Follow Ups Full Thread

Topic - MESSAGE FOR MARK GILMORE: RE HOOKUP WIRE & RECTIFING THE AC DRIVER FILAMENTS - P. BERNARD 14:20:32 10/24/99 (7)

Re: MESSAGE FOR MARK GILMORE: RE HOOKUP WIRE & RECTIFING THE AC DRIVER FILAMENTS - mark 18:16:41 10/24/99 (6)

12SX7's - Dan 08:07:40 10/25/99 (5)

Re: 12SX7's - Lew Markoff 08:37:58 10/25/99 (4)

Re: 12SX7's - mark 10:20:40 10/25/99 (3)

Re: 12SX7's - P. BERNARD 16:20:14 10/25/99 (2)

Re: 12SX7's - Lew 08:08:34 10/26/99 (0)

Re: 12SX7's - P. BERNARD 13:33:51 10/26/99 (1)

Re: 12SX7's - P. BERNARD 18:58:16 10/25/99 (0)

Follow Ups

Re: 12SX7's - Lew Markoff 08:37:58 10/25/99 (4)

Re: 12SX7's - mark 10:20:40 10/25/99 (3)

Re: 12SX7's - P. BERNARD 16:20:14 10/25/99 (2)

Re: 12SX7's - Lew 08:08:34 10/26/99 (0)

Re: 12SX7's - P. BERNARD 13:33:51 10/26/99 (1)

Re: 12SX7's - P. BERNARD 18:58:16 10/25/99 (0)