Yes, it's just one that has been selected for operation at low voltages. But there's a mystique around it and people pay an arm and a leg for it.
Actually the salient difference between the 12SX7 and the 12SN7 is the the former has a twisted filament for lower hum like a 12AX7A or 7025A.
John
That's interesting - it doesn't mention that in the Milspec document.
Perhaps it was an expediant taken by the designers to help the tube meet the specification of running (quietly) at the 26.5v plate supply voltage.
John
The picture of your 12SX7 doesn't look like the ones I have. Mine have a large RCA logo on the tube and the box is a traditional RCA red,white, and black box of the fifties. There is no typewritten JAN or tube name on the box.
I know that I've tried a large number of Octal tubes in my Mu-Follower preamp. It originally ran with 6SN7s- the best of which was the WWII era Mil-spec Sylvania with the anchor symbol on the silver base. Sylvanias in general worked better than most other brands. They sounded cleaner with less distortion and muddy bass. The worst was a NOS RCA 6SN7 which had very muddy bass and midrange-like a poor 12AU7.
The 12SX7 easily sounded as good as the Mil-Spec Sylvania. It sounded cleaner and had less distortion than any other Octal tube I've run in my preamp. This may be because I'm running about 250V B+ in a totem pole design. I understand that the 12SX7 runs best with about a 90V plate voltage.
I know that I've tried a large number of Octal tubes in my Mu-Follower preamp. It originally ran with 6SN7s- the best of which was the WWII era Mil-spec Sylvania with the anchor symbol on the silver base. Sylvanias in general worked better than most other brands. They sounded cleaner with less distortion and muddy bass. The worst was a NOS RCA 6SN7 which had very muddy bass and midrange-like a poor 12AU7.
The 12SX7 easily sounded as good as the Mil-Spec Sylvania. It sounded cleaner and had less distortion than any other Octal tube I've run in my preamp. This may be because I'm running about 250V B+ in a totem pole design. I understand that the 12SX7 runs best with about a 90V plate voltage.
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