What's the greatest bargain in SET these days?

I read those also and was intrigued. I should have it by next Friday.

I also like tube amps that don't go all out to maximize dissipation. Just backing off a little will increase tube life by a LOT. With my curren pushpull amps, it really is a very big deal that the amp runs the tubes conservatively. It utilizes four input/driver tubes that cost about $1,000 each and four output tubes that cost about the same. I am counting on the tubes lasting a very long time.

Larry,
At those prices I don't blame you. Israel Blume the builder of my amplifier believes in running tubes conservatively. He runs the 300b at 25 watt dissipation, max for this tube is about 40 watts. He says tube lifespan increases and tubes run conservatively sound better. Larry I suspect you'll get many years of use/pleasure from your tubes.
Charles,

Charles1dad,

I certainly hope the tubes will last much longer. I would expect that running tubes conservatively will lower distortion and should sound better. However, I know of a number of people who deliberately run certain tubes quite "hot" and like it that way. For example, a friend runs 45 tubes in an Audionote Kageki (parallel 2a3 amp) and likes the sound, although the tubes don't last very long. I don't know if he just likes the sound of the 45 more than 2a3 (I prefer 45s too) and would actually be better off changing the operating parameters of the Kageki to match the 45 (primarily lowering the plate voltage). I own a pair of Kageki amps too, and would never run anyting but the recommended tubes for fear of damaging a VERY expensive amp.

As for the benefits to longevity of running stuff conservatively, there are plenty of examples of people who have old tabletop radios that are still being used daily that have never had tubes replaced since the radio first went into use in the 1940s and even earlier.

The lifetime of a tube is determined by the lifetime of its cathode emission. And the life of the of a cathode is dependent on the cathode temperature, which means that it is dependent on filament or heater operating voltage.

Operate the heater/filament too hot, and the tube will give a shortened life. Operate it too cool and life may be shortened. This is especially true for thoriated filaments, which depend on replenishment of thorium by diffusion from within the filament wire.

For best, long lasting tube life it is recommended that you operate your tube within the tube manufactures specifications.