tube distortion and amp matching
for a number of years I had a CJ PV10A pre with SS amp and like anyone with tube gear I did some playing round, ended up with quite a few duds but overall the difference between a good tube and a bad tube stayed one of sound stage, dynamics and tonal fidelity . In the past year I bought a Prima Luna Integrated, wanting tube amplification and thinking that time must have bettered the PV10A (it had not). I did the same rolling with it and over time ended up with a configuration I was happy with using the PV10A into it's HT input.
Enter yesterday brand new KT-120's to replace the GL KT-88's. I decided to start with a default "safe" configuration of Mullard NOS CV4004/12AU7's to match PL's factory spec vs my 12AT7/12AU7 preferred combo. After the obligatory first few hours of break in awfulness the KT-120's opened up, were lovely and I started rolling pre/driver tubes for a few hours. As I did this the following dawned on me.
1) of the better 12AU7 tubes I had set aside in my original KT-88 configuration, all had been set aside because on some set of recordings I could hear distortion that another tube did not have
2) that the KT-120 tubes made that distortion more blatant
3) that in the CJ PV10A that distortion did not exist
Which leads me to 2 questions for those who have done this for a while with many different tube amps and the 12AU7/12AT7/12AX7 families
1) does paying for a better tube amp get you better stability with a wider range of tubes?
2) conversely of the NOS tube manufacturer's which is best behaved in the widest variety of tube amps?
Enter yesterday brand new KT-120's to replace the GL KT-88's. I decided to start with a default "safe" configuration of Mullard NOS CV4004/12AU7's to match PL's factory spec vs my 12AT7/12AU7 preferred combo. After the obligatory first few hours of break in awfulness the KT-120's opened up, were lovely and I started rolling pre/driver tubes for a few hours. As I did this the following dawned on me.
1) of the better 12AU7 tubes I had set aside in my original KT-88 configuration, all had been set aside because on some set of recordings I could hear distortion that another tube did not have
2) that the KT-120 tubes made that distortion more blatant
3) that in the CJ PV10A that distortion did not exist
Which leads me to 2 questions for those who have done this for a while with many different tube amps and the 12AU7/12AT7/12AX7 families
1) does paying for a better tube amp get you better stability with a wider range of tubes?
2) conversely of the NOS tube manufacturer's which is best behaved in the widest variety of tube amps?