Charles1dad,
Here's something I pasted from AA. The author is Chris O. It could explain a lot.
"You really have to watch out when you start swapping 300b or other big filament power tubes. The current draw on the heater for one tube brand or type or batch may be very different. Plugging several different brands of tubes (EH, TJ, KR) into a given amp showed each had very different voltage on the heater and bias points for the voltage and current supplied by the amp. In particular, the TJs sounded bad with 5.7 volts on the heater, much better at 5 volts exactly. Also, at the higher voltage they would have had a short life. The EH with the same supply were 5.2 volts.
Don't slam tubes (or anything else) if you don't know how you are using them. Most of the time, using the tube within the manufacturers specifications and optimizing a tubes operational points based on listening makes them a lot better."
Here's something I pasted from AA. The author is Chris O. It could explain a lot.
"You really have to watch out when you start swapping 300b or other big filament power tubes. The current draw on the heater for one tube brand or type or batch may be very different. Plugging several different brands of tubes (EH, TJ, KR) into a given amp showed each had very different voltage on the heater and bias points for the voltage and current supplied by the amp. In particular, the TJs sounded bad with 5.7 volts on the heater, much better at 5 volts exactly. Also, at the higher voltage they would have had a short life. The EH with the same supply were 5.2 volts.
Don't slam tubes (or anything else) if you don't know how you are using them. Most of the time, using the tube within the manufacturers specifications and optimizing a tubes operational points based on listening makes them a lot better."