12AX7 vs 6n2p-EV

[Phil_S]

I'm contemplating a build that needs some 12AX7's. I'm wanting to find a place to economize. Maybe I'm looking in the wrong place. I can buy 6n2p-EV for about $3 each shipped from somewhere in Europe [1]. The question is one of tonal compromise or not. Just how good or bad is the 6n2p-EV for something "Fenderish?" Are there certain positions where this tube is neutral or even an improvement? Are there some positions where it is decidedly a poor choice (like V1?)

[1]These would be eBait purchases -- I know -- let's assume I can live with the risk of bad product or no delivery. No need to sidetrack the tone question. I see vendors hawking them from GB and Georgia. I'm thinking nothing from Ukraine or Russia will get here until the flip flap over Crimea settles down.

Opinions will be appreciated. Thanks.

Phil

[tubeswell]

For $3 per tube plus postage, I think a little experimenting may be in order.

[Phil_S]

OK, thanks for holding up the mirror for me. I placed an eBait bid for a quantity of 16 tubes, $33 US shipped from Great Britain That's ~$2 each. I still have to be the high bidder, so we'll see. I may consider upping the ante if there is competition, but I am generally able to control myself. I regularly bid on eBait and let things go. I believe, "There is always another one of those." LOL, these are NOS from 1978. Maybe. If you can believe what people write.

[tubeswell]

FWIW I bought a whole box of about 30 NOS 'Sovtek' (coke bottle) 5U4G a wee while ago from some Siberian on e-bay and it worked out to something like $6 per tube. While the postage was a bit slow, all the packaging was top-notch and all the ones I've tried from the box seem to be working so far.

[rock_mumbles]

I used the 6N2P-EV tubes in my 10 watt Wreck like amp ... They work fine ...

Overall quality does depend on when they were manufactured

[Phil_S]

OK, so I'm in with both feet. I tried to be careful (given the state of affairs in Russia and Ukraine) and selected a seller that says the location is UK. Paid $38 including shipping for 16 tubes. I guess that makes $2.375 per tube. At that price...well...I agree it is worth trying. I'm thinking I can't get hurt at that price, even if the package never arrives. (No one WANTS to lose $38, but not exactly taking food off my table.) Thanks for the (faint) encouragement.

For anyone else, the seller, frau-olia seems to be very measured, not wanting to cannibalize the market, I noted that she listed another lot when mine was sold: http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0804335501

[tubeswell]

... Thanks for the (faint) encouragement.

You're welcome. I'm picking you are soon to become the TAG go-to expert on 6N2P-EV.

[Phil_S]

... Thanks for the (faint) encouragement.

You're welcome. I'm picking you are soon to become the TAG go-to expert on 6N2P-EV.

I'm not sure a guy in his 6th decade can hear well enough to say I'm thinking, sooner than we'd like to admit, all the old stock USA and Old Europe made tubes will be used up. We'll have to get used to it when all we have to choose from are the Eastern European varieties or the Chinese. These 6n2p may prove to be better than average in that crowd. <shrug> Here's hoping...with any luck a package will arrive in my mailbox in 10 days or so.

[David Root]

From what I've read many of the Soviet-era tubes are pretty good, tough and toneful.
I have tried Sovietski uber-EL84s (6**14-EV?) which are indeed very good. These were '82 IIRC. I have heard that the '60s and '70s are even better quality.

I shall have to try a few of these 6n2p-ev, the price is right.

Did some looking, there is a guy on Ebay selling these with an adapter, claims the pinout is different from 12AX7. Looks the same to me on the datasheet.

EDIT: Good thing I looked again, it's not the same pinout. Pin 9 is a screen, not a humbucking heater connection.

[Phil_S]

Yes, I saw that auction with the adapters. Pricing was actually decent, IMO.
Yes, heaters are wired differently. A while back, someone (Martin?) posted a schematic for switching the heaters (with a switch!), which might be good or better than adapters...not sure.

[David Root]

This one, from Aleksandr Niemand, uses an ON-OFF-ON DPDT mini-switch. It also grounds the 6p2n screen which is nice (redline).

I guess you could use a plain ON-ON DPDT too. If you switch a 12AX7 in the 6n2p position it won't light up so no harm done. Vice versa likewise.

Incidentally, the 6n2p pinout is the same as a 6DJ8/ECC88/6922 so if your tester can test a 6DJ8 it can also test the 6n2p-ev. My tester will handle a 6DJ8 so that makes me feel better about buying some 6N2P-EVs.

[David Root]

I ran the 6N2P-EV in TubeCad, with a typical Fender/Dumble low plate setup (100K/1K5). Attached are two results, compared with a standard 12AX7 in the same setup. The third 6N2P-EV result is 110K/1K8 and gets the current back down near 1.0mA.

In setting up the 6N2P-EV parameters I used mu=92 because many seem to say this tube is usually a tad lower mu than the 12AX7. I used 45K as the 6N2P-EV plate resistance as it has higher transconductance and therefore current than the 12AX7.

Comments welcome!

[talbany]

The first digit or digits is usually the heater voltage ratings, in a miniture.
Thought I would mention..
BTW..I have some Bugle Boy and some Amperex (orange Globe) ECC88's (reasonable price)if anyone is interested PM Me

Tony

[Phil_S]

OK, so just a minor follow-up. Delivery was fairly quick, purchased March 23, the shipping label and postmark indicates it was shipped on March 25, and it was delivered April 2. However, the seller was less than truthful about location. She said location was UK, but package was sent from Lithuania, not that it matters and somehow I wasn't surprised. I received 16 tubes (as expected) with mixed date codes from the 70's and 80's mostly. I think one was '90's. A couple of tubes look sloppy on the upper support structure, but I suspect it isn't a problem and if it is, so what? It will be a while until I get to the project, but when I do, I'll be sure to post something.

[rp]

FWIW I bought a whole box of about 30 NOS 'Sovtek' (coke bottle) 5U4G a wee while ago from some Siberian on e-bay and it worked out to something like $6 per tube.

Considering the free cryogenic treatment you got a bargain.