I hadn’t used the Mullard reissue valves before but it’s my understanding they are Sovtek made valves. I thought they might be good for this 1980 2203 amp. I got the valves from Amplified Parts (as I can’t purchase from CE Distribution.) I have arranged to get TAD 12AX7 to replace it, and contacted Amplified Parts about a replacement. I have yet to hear from them.
The 12AX7 worked well for about three weeks till yesterday it became microphonic. I can’t see me using these valves again somehow. Pleasing ringing tone though.
Thoughts on the valve and best valves for Amps such as the 2203?
jabguit wrote: ↑Tue May 28, 2024 10:41 am
I believe they are New Sensor/EH made in Russia. Much like the Tung-Sol reissues.
cheers,
Thanks for your reply.
Wow, the Tung-Sol reissues have a good reputation. I wonder how this one failed the QC?
I had a JJ 12AX7s go microphonic on me a few days ago as well. This was after a couple weeks too. Its really hit and miss with new preamp tubes these days. But I have also had over 170 JJ12AX7s work perfectly for me before that. I have gone through about 9 of those new Mullards and they have all worked great. Its the luck of the draw.
I've broadly had really positive experiences with JJ's, though I know the sound isn't for everyone in terms of the treble roll-off. Pretty rugged tubes that have put up with some butter-fingered moments and have stood up to abuse in high voltage DCCF applications. I have heard the long plate 12AX7 JJ makes (ECC803) has better treble response than other JJ's, but I don't have firsthand experience. My understanding is that you're correct; the Mullards are made in the same factory as EH, Sovtek, Genalex, and Tung Sol. I haven't been able to determine what, if any, is their process for differentiating tubes of the same type. They do make short and long plate 12AX7's, so obviously there's some difference there, but I'm not sure what differentiates the tubes when comparing long plates to long plates and short plates to short plates, e.g. what makes a Mullard long plate 12AX7 different from the Sovtek LPS or the Genalex (other than the latter having gold pins).
jabguit wrote: ↑Tue May 28, 2024 10:41 am
I believe they are New Sensor/EH made in Russia. Much like the Tung-Sol reissues.
cheers,
Sovtek...
"From visual inspection it can be seen that the Reissue is not manufactured with Mullard tooling. Its internal construction appears to be identical to the ‘Sovtek’ 12AX7LPS. This isn’t surprising, since both tubes originate from New Sensor’s “Экспопул”( “Expopul”) factory (formerly Reflector) in Saratov, Russia."
I found out today that Amplified Parts are going to stiff me for the 12AX7 as they don’t accept returns on microphonic valves. I was a bit annoyed as I don’t recall asking to purchase a microphonic 12AX7.
usually tube is microphonic in stage where is maximum gain..and input signal very low... V1 position.. tube rolling can help.. also adding grid stopper too.. microphonic tube shift to PI position, and some short plate 12AX7 to V1..
Mark wrote: ↑Fri May 31, 2024 5:21 am
I found out today that Amplified Parts are going to stiff me for the 12AX7 as they don’t accept returns on microphonic valves. I was a bit annoyed as I don’t recall asking to purchase a microphonic 12AX7.
Yeah, I think I won’t be buying Mullard again.
I don't buy ANY tubes from Amplified Parts any more, although I do buy many, many other amp parts from them.
I get my tubes from Tube Depot and pay for testing on the pre-amp tubes and burn-in for power tubes. I consider it insurance. They've always worked with me on any tube issue I've had with a tube from them.
