Nos cv4004?

[digitalscream]

Found somebody on eBay selling a load of Teonex-branded CV4004 "NOS" valves at fairly low prices (JJ 12AX7 prices, in fact).

To my knowledge, the CV4004 is the UK government's code for a "special quality" 12AX7. Is this true? Anybody tried them? Is it worth taking a punt?

[Cirrusband]

I have a Brimar one, hasn't given up on my after a couple of years but then, neither have some non cv4004 ecc83s I use.

[ICBM]

If they're Teonex branded they may well be RFTs, which are excellent East German valves from the 1970s. They were used by a lot of importers under many different labels.

It's a little bit ironic (dontcha think) [/Alanis] that the British military was fighting the Cold War with valves made by the enemy .

If they're JJ prices, buy them.

[ESchap]

If its these .... http://www.ebay.co.uk/itm/TEONEX-Bra...item3a7c2f865d .... though it's hard to tell from the photos, I'd say they are not RFT which have a distinctive "star" pattern to the Mica spacers and usually have a half box plate inside that looks like an aerofoil. Going by the shape of the spacers .. smooth and oval, I'd say these are most likely Russian in origin. I'd be particularly careful about the ones he described as having a silver box section .. those sound like Chinese. He has other tubes up for sale and seems to know what they are and what they are worth. If he thought these were a premium European make, I think he'd be saying so and charging accordingly. Having said all that, they could be good valves, even if they are Russian! May buy a couple myself to find out.

[parker_knoll]

a NOS mullard one went yesterday for about £16. was gonna get it but couldn't be bothered in the end as i;m about to get a new amp

EDIT: someone should tell him it's spelled "striped" though

[digitalscream]

OK, I bought five of them for my JCA22H - I guess we'll find out whether they're any good I'll hazard a guess that they're not going to be significantly worse quality than the JJs I've got in my JCA50H, and I'm pretty damn certain they'll be better (or at least longer-lasting) than the Chinese valves that came with it.

[Gagaryn]

OK, I bought five of them for my JCA22H - I guess we'll find out whether they're any good I'll hazard a guess that they're not going to be significantly worse quality than the JJs I've got in my JCA50H, and I'm pretty damn certain they'll be better (or at least longer-lasting) than the Chinese valves that came with it.

Okay, you can be the official Musicradar tester. If they are any good let me know. :-)

[digitalscream]

Hmmm. They just arrived...I'm wondering if "NOS" really describes them, because the markings on the glass are pretty well-worn. If they really were new old stock, and still boxed, I'd have expected all the markings to be intact.

For what it's worth, a cursory comparison with a cheap Chinese 12AX7 shows identical plate structure.

[ICBM]

Hmmm. Yes, the twin bright chrome strips are distinctive (and only a characteristic) of Chinese preamp valves.

Some people think that "NOS" means "old". It doesn't, it means NEW old stock, ie unused.

Some other people think that NOS means any old unused valve - technically it might do, but the real meaning of NOS in valve terms is original US or European production, from before about the mid-80s. A Chinese or Russian valve from the 90s, even if it's truly unused, is not really "NOS". In fact, some of these early new-production valves (the power valves especially) are some of the very worst and are what started the whole NOS ball rolling in the first place.

So it sounds like these fail the description on both counts.

[ESchap]

Can you post a photo?

The way he described them on eBay may give you recourse for a refund as he said he was going to ship the grey box anode ones first. If he's sent you the "silver ones then he's been a bit liberal with his statements. Incidentally there are loads of those Chinese "CV4004's" around.