I've bought this one for my good old Marshall Valvestate VS100. As it's a hybrid amp, it only has one tube and uses the tube only for the pre-amp section. The power-amp section is solid state.
Valvestates are not tube amps so, if you're a purist, a traditional tube amp lover (and solid state amp hater) you're going to be offended now, because I've never been able to here the difference between tubes that well. A tube is a tube, they're mostly all made in the same factory, same tube, only different label (and price). The difference between an old and a new tube, yes, that's clear, but you're final sound depends on way more things than your tubes. First your guitar, than your speakers, your cables, your pedals and most of all: your fingers. So, to me, a tube doesn't need to be "top-of-the-pop". It just needs to work and this tube is quietly (as far as you can call a Marshall quiet) doing it's job perfectly. I don't use overdrive or distortion pedals, all the boost and distortion comes from the amp (read: the pre-amp = this little tube) itself and, man, it gets loud!
So, if your looking for a reasonable priced, solid tube as a replacement for your old 12AX7, this is the one. Pure solidity.
