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12AT7 tubes

Hi audiogoners,
I need to replace one tube in my VTL phono stage, it marks 12AT7/ECC81. Is it safe to use tubes brands other than JJ tubes VTL recommends, like mullard or telefunken one.It looks like there are different version of 12AT7 in Mullard.Can someone tell the difference for each version.and your recommendations.Thanks for any information.KB
easytune
mechans
3,048 posts
 
The gain factor is constant for a 12AT7. The age of the tube can be a factor in dissipation but it's only noticible if you have a brand new or near dead tube. Is that what you meant about matching it to the 12AX7s. Go to the Tubestore.com and use their gain factor chart. Or did you mean matching channels in that case both should be very closely matched and the same tubes. I don't get it? You don't need to match the the 12AX7s.
tod914
16 posts
 
How does the EI fall into this group? They came stock with my stingray. Another member has a set of teles Im interesting in.

Thanks
atmasphere's avatar
atmasphere
12,100 posts
 
EIs are not bad sounding tubes. No-one seems to have mentioned the Electro Harmonix tube either, although if pcied for low microphonics, is a very nice sounding tube, even if it is a newly manufactered tube.

Often the Chinese 12AT7 gets denigrated in discussions like this, but I thought it important to point some things out about them: They are very quiet- the most consistant that we have tested. In a phono section this can be a big deal. If also hand-picked for low microphonics, they can rival the sonics of NOS tubes quite easily. One time Albert shipped us his amplifiers, which had Telefunken 12AT7s in it, and we replaced them with the Chinese tube. To our surprise, the Chinese sounded a lot better! We then tested the Telefunken tubes and found that they were testing in the '?' range of the tube tester. Since then we have seen quite a few good-testing Mullards, Siemans and Amperex that got dusted by the lowly Chinese tube...

One thing is for sure- its to your best interest to make sure you are installing a good tube! Make sure that whatever you get can be returned if you are not satisfied!
undertow
1,033 posts
 
Mullards are the best I have heard... Can change systems from nice to incredible.. Most of the time the gear is beyond the quality of the tube used in it and you would never need a 15 k piece of gear, just some real good and silent musical tubes out of the norm.
tonyptony
627 posts
 
"Mullards are the best I have heard... Can change systems from nice to incredible"

Undertow, what's your definition of incredible? I ask because tube rolling seems to be a way for people to get the sound they "want". I have an AVA FetValve 550, which also uses the 12AT7. Frank van Alstine ships these amps with JJs and is quite insistent on using these tubes. I tried Ei and also borrowed a pair of Mullards, and found that (to my ears) Frank was right. Of course, all that may mean is that Frank and I agree on what the "right" sound is for that amp. I found the JJ 12AT7 to have the least "tube like" characteristics of the ones I tried. My goal is to not hear anything that would tell me that I'm listening to either tubes or SS (FetValve is a hybrid).
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