Metropoulos Forum

Although I've already had some bad experiences a while ago with the Tung Sol Reissue 12AX7 (and also the Sovtek 12AX7LPS), when putting it in CF stages, I recently buyed some again - hoping, that they became better meanwhile. But unfortunately I was mistaken

This week I got a VOX AC 15 for service and supplied all preamp stages with Tung Sol's. Only after 10 seconds (in Words: AFTER TEN SECONDS) playing the amp the CF tube died.

Ok, pulled it out and stuck another TungSol in this spot - this 2-nd one died immediately WITHIN THE FIRST SECOND of operation

Ok, tubes in the CF stage of a VOX are under higher stress than in a Marshall CF stage, because due to the 56K cathode R there's more current through the tube, than in a Marshall with a 100K cathode R - but...

... the previous (Chinese 12AX7) tube in this spot was working flawlessly there 12 years

Larry

novosibir wrote:Although I've already had some bad experiences a while ago with the Tung Sol Reissue 12AX7 (and also the Sovtek 12AX7LPS), when putting it in CF stages, I recently buyed some again - hoping, that they became better meanwhile. But unfortunately I was mistaken

This week I got a VOX AC 15 for service and supplied all preamp stages with Tung Sol's. Only after 10 seconds (in Words: AFTER TEN SECONDS) playing the amp the CF tube died.

Ok, pulled it out and stuck another TungSol in this spot - this 2-nd one died immediately WITHIN THE FIRST SECOND of operation

Ok, tubes in the CF stage of a VOX are under higher stress than in a Marshall CF stage, because due to the 56K cathode R there's more current through the tube, than in a Marshall with a 100K cathode R - but...

... the previous (Chinese 12AX7) tube in this spot was working flawlessly there 12 years

Larry

What is a CF stage?

It's top secret code for cathode follower stage Josh. How's that amp coming?

thousandshirts wrote:It's top secret code for cathode follower stage Josh. How's that amp coming?

From reading other threads, I'm guessing that is V2?

joshwilson3 wrote: From reading other threads, I'm guessing that is V2?

The V2 cathode follower driving the tone stack hit it big and got popular with the '5F6' Tweed Bassman. This was copied by Marshall to the JTM 45, where it survived through to the Plexi and Metal Panel amps, and JCM 800, as well. But not all guitar amps have cathode follower stages, and not all of them that do are V2.

For classic Marshalls though, don't put these tubes in V2.

what is the prefered current manufacture 12ax7 for v2 in a classic marshall ??


jimmy

I have a Tungsol RI in my JTM45 V2. It's been there since April and has seen a few gigs and many practices...

I must have got ahold of a good batch of the Tung Sol re-issues. Ive been using them for a couple of years. Have used them in both of my '80 2203's, my 79 superbass, my hacked up 1959 reissue, and my metro 68 12xxx. No problems at all with them.

Hey guys, bringin gback this thread.. I wonder if you guys can help me diagnose an issue i am having with my 1987x clone. I have the tung sols in V1 nd V2 and have swapped them out one at a time for a no name chinese with no difference. balnced JJ in phase inverter. What i've got is ugly distortion when i bend notes in unison.. if i play a D chord for example and strum heavier, a raspy thin distorion comes through almost like it is out of phase. Is this a preamp issue? Do you guys need some soundclips to help diagnose? Its brutal..

I've had TungSol reissues in my Metro JTM45 for a year and in my Metro JMP50 for about six months without problems. I buy from Lord Valve, who reportedly test hits them pretty hard to weed out the chaff. (Just don't talk politics with him. )

good experience here also----------

used at least a dozen......no prob.

any mass production item is prone to the occassional "f"-up !

BTW- Lord Valve......is he "right" or "left" in the political sprectrum??

just curious!

lifer wrote:good experience here also----------

used at least a dozen......no prob.

any mass production item is prone to the occassional "f"-up !

BTW- Lord Valve......is he "right" or "left" in the political sprectrum??

just curious!

I'm not sure I can see that far to the right.

I have one I've been rotating in amps for about a year, no problem. sounds good, maybe a little compressed but very fat and juicy, more than almost any tube i have, even NOS mullard. This Tung Sol reissue really sounds good in the pi slot, and gives the amp a great feel.