[Pez]

I have been rolling tubes lately and am currently experiementing with KT66's. I usually use EL34's, but Tyson convinced be the try the 66's. I'm currently using Gold Lions reissues and they sound pretty darn good. I find them to have a more robust sound really filling out the mid-range.

I'm not sure if it's because I don't have tube dampers or if it's just a characteristic of 66s, but I'm finding a little bit of grittiness in the lower treble range, cymbals, tamborines, etc when compared directly to the EL34s. (EL 34's I'm using winged Cs)

Obviously without trying some dampers I'm not 100% sure if the issue is with lack of damping or if that's just a characteristc of the 66's. Any way I was wondering if anyone else has compared the 2 and what their impressions were.

[Niteshade]

The problem is- you can't compare them. You are hearing the circuit's interaction to different tube varieties. The circuit will play them differently because they're not electrically equivalent even if their pinout is the same.

I have had circuits that made EL34's sound like 6L6's and 6L6's sound like EL34's.  I have seen 6L6 amps that would not tolerate El34's- they would break up way too soon. On the flip side, some designs caused a 6L6 to break up sooner and the El34 sang with more clarity than I thought possible. (These things would happen without going past either tube's tolerances & with proper biasing.)

Major factors: Amount of B+ and output transformer primary impedance.

The phase splitter & voltage amp circuits control other tone qualities and will have varying effects on power tubes as well. In a nutshell- it's the circuit's response to different tubes and the tube is an innocent bystander.

[FullRangeMan]

Nice point of view.  Thanks

[Pez]

wow that's quite a brilliant explanation that in hindsight seems very obvious. That's the sign of an excellent answer. Thank you!