Can I hurt my tube preamp with replacement tubes?

[Mittech]

I have a Mystere CA21 tube preamp that cam with Mystere 6SN7 output tubes. I changed them with PAVANE 6SN7C (CV181) tubes. When playing loud and for long tomes my center transformer heats up (pretty hot) and the two side ones stay cool. Is this normal or is it the tubes? Also does anyone know what the C at the end of the 6SN7C means? I know the tube label faces rear instead of front? Other wise it sound great.
Any help is truly appreciated.

 

[Mendel]

Real (NOS) CV181 tubes have a heater current draw of .96ma compared to 6SN7 heater current draw of .6ma. Problem is no one really knows what the specs are for the many ”premium” Chinese CV181 out there. If your power transformer runs hotter with these tubes than with the ones that came with the amp, you may have a problem.
I do not recommend any of these high priced new production 6SN7 types. Why bother when there are so many awesome NOS or used test new vintage 6SN7s available for the same or lower prices?

 

[Mittech]

Real (NOS) CV181 tubes have a heater current draw of .96ma compared to 6SN7 heater current draw of .6ma. Problem is no one really knows what the specs are for the many ”premium” Chinese CV181 out there. If your power transformer runs hotter with these tubes than with the ones that came with the amp, you may have a problem.
I do not recommend any of these high priced new production 6SN7 types. Why bother when there are so many awesome NOS or used test new vintage 6SN7s available for the same or lower.

Real (NOS) CV181 tubes have a heater current draw of .96ma compared to 6SN7 heater current draw of .6ma. Problem is no one really knows what the specs are for the many ”premium” Chinese CV181 out there. If your power transformer runs hotter with these tubes than with the ones that came with the amp, you may have a problem.
I do not recommend any of these high priced new production 6SN7 types. Why bother when there are so many awesome NOS or used test new vintage 6SN7s available for the same or lower prices?

Thank you for the information. I am new to Tube amps and learning,

 

[Mittech]

Thank you I am new to tubes and learning.

 

[Walter66]

CV181 is not the same tube as a 6SN7. I tried to swap some decades ago and the 6SN7 was louder, means it had more amplification. If that happens, the tube had different data, curves and working points. Thats what I recall.

 

[Sablon Audio]

Afaik Shuguang and Psvane use the CV181 designation in a marketing capacity and the tubes are regular 6sn7 spec. I owned an early pair about a decade ago and they sounded better than a number of revered nos options.