Questions about tubes and gear that glows. FAQ
Do yourself a favor, and if you can, wire up your sockets to use the Russian 6n2p-ev Voskhod triple micas. The 6n2p is the Russian equivalent of the 12AX7 with only 6.3V heaters. Pin 9 is not the heater center tap, but a shield between the two triode sections (wire to ground). Pins 4 and 5 are for the 6.3V heaters. All the rest of the pin out is the same. The EV suffix is for the better long life special construction tubes the Voskhod is IMO the best factory, and the 60's early 70's triple micas are the best from that factory.
I bought a bunch years ago when they were really cheap. The words getting out, they are getting harder to find, and the price has been going up. Get them while you can. I've given some to folks who have built the Little Bear phono stage and they love them. I've heard posts from folks who claim they will trounce any 12AX7. I can't say for sure as I have no use for a 12AX7, but did put some in a guitar amp for a guy and he loved them. A simple 2 wire rewire if you have 6.3V available for filaments. Worth a try and only takes a minimal DIY capability.
Search ebay for 6n2p-ev and look for the ones titled Voskhod triple mica versions. Sometimes the seller doesn't know what he has and you can spot them by the photo. Just contact the seller before buying to make sure the photos are actually of the tubes for sale. Sometimes they will just put up a stock photo. Get them while you can. The Voskhod factory has the rocket logo, look carefully for the three micas (double mica on top), and the date codes are roman numerals for the month followed by a 2 digit year. For example IX-68 is Sept. 1968. Here's a link to the Russian bilingual data sheet.
Edits: 04/02/17This post is made possible by the generous support of people like you and our sponsors:
Topic - For all you 12AX7 users - twystd 23:51:51 04/01/17 (6)
- Nah, I'll stay with Sovteks in my phono stage. - Timbo in Oz 03:17:14 04/06/17 (0)
- RE: For all you 12AX7 users - Mechans 10:31:52 04/03/17 (4)