I have a Will Vincent rebuilt st 70. It is able to use 6L6, kt66, EL34, or KT77 tubes.
The amp came from Will with jj kt77 tubes and it sounds incredible with those. I have since tried gold lion kt66( they sound very good but with slightly less 3d midrange), sed "winged c" new matched quad which has good bass but do not have the "magical" midrange and are so rolled off on top that it sounds like I threw a quilt over my speakers!
I have also tried a new matched quad of Electro harmonix el34's and they had a "thin" sound with little bass compared to the other tubes and had a "grainy" top end extension that was not pleasing in my amp.
All tubes were run in for at least 25-30 hrs.
The output tubes make the only major difference in sound quality or character in my amp. I am currently running a vintage 1961 blackburn mullard gz34, I have used an nos telefunken gz34 and chinese 5ar4. None of these had any effect on sound quality.
I have also changed from ge 7199's to nos rca blackplate 7199's with no audible change in sound from the amp.
I think that the speaker, amp, preamp synergy plays a major role in how different tubes will sound in your amp.
I would rather listen to my old marantz 2220b ss reciever than my dynaco with sed winged c's or electro harmonix el 34's in it. But if I switch to jj kt77's or gold lion kt66's, there is no contest. The dynaco is warm, magical,and lifelike sounding so the marantz is back collecting dust again.
My system consists of classe audio dr6 preamp, will vincent st70, quad 11L monitors. I have dialed in the sound I like and am very happy with my system now.
Good Luck and enjoy your tube rolling.
The amp came from Will with jj kt77 tubes and it sounds incredible with those. I have since tried gold lion kt66( they sound very good but with slightly less 3d midrange), sed "winged c" new matched quad which has good bass but do not have the "magical" midrange and are so rolled off on top that it sounds like I threw a quilt over my speakers!
I have also tried a new matched quad of Electro harmonix el34's and they had a "thin" sound with little bass compared to the other tubes and had a "grainy" top end extension that was not pleasing in my amp.
All tubes were run in for at least 25-30 hrs.
The output tubes make the only major difference in sound quality or character in my amp. I am currently running a vintage 1961 blackburn mullard gz34, I have used an nos telefunken gz34 and chinese 5ar4. None of these had any effect on sound quality.
I have also changed from ge 7199's to nos rca blackplate 7199's with no audible change in sound from the amp.
I think that the speaker, amp, preamp synergy plays a major role in how different tubes will sound in your amp.
I would rather listen to my old marantz 2220b ss reciever than my dynaco with sed winged c's or electro harmonix el 34's in it. But if I switch to jj kt77's or gold lion kt66's, there is no contest. The dynaco is warm, magical,and lifelike sounding so the marantz is back collecting dust again.
My system consists of classe audio dr6 preamp, will vincent st70, quad 11L monitors. I have dialed in the sound I like and am very happy with my system now.
Good Luck and enjoy your tube rolling.