For a detailed (read exhaustive) description of the various 12AT7s, try Joes Tube Lore over at the Asylum.
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
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