Tung Sol 12AX7 hum.....

Empty Uranus · Nov 14, 2007

Just did some tube work on my '83 Mk IIC.

Firstly - I'm no tube guru at all. They light up. They make heat. They make your amp work. This could be my problem.

I'd done a little research and got some new tubes. I'd been using some Svetlana (is that how you spell it?) 6L6's and was okay with them, though they (nor anything else) sounded like what I got when I bought the amp back in '83. I got some new Ruby 6L6's and can't describe how much better they sound than the Svetlanas. The distortion sound is so much smoother it was simply scary. THAT's how the thing sounded when I got it!

Anyway - to the 12AX7. I had Sovteks in all preamp spots. Thought I'd replace the main distortion 12AX7 with the Tung Sol, as I'd read so much good stuff on it (from Musician's Friend who had to backorder it).

It hums. The hum stays the same volume no matter what the volume, but it sucks when you, say - let a note ring out - it will cancel some of the sustain. The sound it gets is great and all, though not really that much better (at all) than the Sovtek.

Question - should I have replaced all of the preamp tubes with the same thing? Is this the result of a bizarre mismatch? It was sort of my understanding that the 12AX7's didn't need to be matched like the 6L6's need to be.

Do I need to replace the rest of them, or is this just a bad tube? I sure as hell won't be able to record with it....

Thanks for any help!

Mick · Nov 15, 2007

JMO.Buy some NOS tubes while they're still available. I don't use 'em in the rverb or effects loop but do use them in the pre amp slots and PI and power tubes. Saves alot of jerking around in my experience.

Have had good experiences with Mike at http://www.kcanostubes.com/content/, but there are others too.

Empty Uranus · Nov 15, 2007

Mick said:
JMO.Buy some NOS tubes while they're still available. I don't use 'em in the rverb or effects loop but do use them in the pre amp slots and PI and power tubes. Saves alot of jerking around in my experience.

Have had good experiences with Mike at http://www.kcanostubes.com/content/, but there are others too.

Thanks, man. Probably just got corned out of $12, but at least it wasn't $1200!

212Mavguy · Nov 15, 2007

JMO.Buy some NOS tubes while they're still available.

+1

If your amp is a head, try the real deal, get a few vintage old stock Tungsol 12ax7's, the sound is is special, sweet, balanced and harmonically detailed, and overdriven tone is nice. They tend to be a bit microphonic, so not the best choice for a high powered combo amp. I have gotten some killler deals on NOS/VOS tubes on ebay, one out of three aren't up to snuff microphonically but still come out OK bang for the buck compared to tube dealer prices for the same types. Microphonics are not as serious a problem if you run a head style amp. The more VOS varieties you collect the more you will enjoy them, fun to voice your amp for a certain axe or speaker setup. There are some real sweethearts floating around still. Some are rather inexpensive still.

IMHO believe that before shelling out money for a reissue tube that one ought to own and use the original first. Sure, there is a chance that not all of them will be wonderful, but the majority of my VOS tube purchases have turned ou fine, some have been absolutely screaming deals! That is what 200+ auction wins experience has taught me, FWIW.

All the best to you!

Mick · Nov 15, 2007

"just got corned....." I just about blew a snot rocket on my screen when I read that.!!! sick, I love it.

Should've mentioned that I bought 3 Tung Sol 12ax7's a few months ago and had to can 2 of them for being micrphonic in my reverb circuit. Stuck an old JJ in there and its been holding up. Next time I'm just gonna get some lower end NOS for the loop and'verb and be done with it.

Note>> Me and Mav were posting at the same time. The Tung Sol's I was referring to are new mfg. not NOS. I've also heard very good things about the NOS Tung Sol tubes.

Empty Uranus · Nov 15, 2007

Mick said:
"just got corned....." I just about blew a snot rocket on my screen when I read that.!!! sick, I love it.

Should've mentioned that I bought 3 Tung Sol 12ax7's a few months ago and had to can 2 of them for being micrphonic in my reverb circuit. Stuck an old JJ in there and its been holding up. Next time I'm just gonna get some lower end NOS for the loop and'verb and be done with it.

Note>> Me and Mav were posting at the same time. The Tung Sol's I was referring to are new mfg. not NOS. I've also heard very good things about the NOS Tung Sol tubes.

Thanks guys. Also have a feeling that it's probably worth an extra couple of dollars to pay somebody to actually check them out a little better before they ship them, too.

212 - I've actually got the 100/60 watt head with the original Boogie 4x12, so microphics aren't quite as much an issue.

The Tung Sol definitely has a nice tone to it, but I'm going to have to stick my Sovtek (12ax7lps) back in for playing out this weekend. That thing is 5 years old, but it honestly still gets a very nice sound. Believe it or not (in my case), the Ruby 6L6's did more to improve my dirty sound than the 12AX7's did in this case. Not only that, but I had some pretty bad microphonics with this last batch of Sovtek 12AX7's and Svet's. I automatically assumed that it was probably the Sovtek, but it was actually ALL coming from the 6L6's. Think I'll pass on the Svets from now on!