Living With A Class A Tube Amp

@atmasphere  ,

quoting from my owner's manual:  "CIRCUIT TYPE:  Push-Pull Ultralinear Amplification in Pure Class A"  then "POWER OUTPUT 50 watts-Triode  100 watts - ultralinear."

As always, I defer to your knowledge on these subjects.  I had just assumed that when I was blasting away at ear bleed levels and the room was getting warmer the output tubes were taking a beating.  I also acknowledge that a lot of my preconceived notions are often wrong.  

I will say that this current set of EL34s is holding up better than the last set, but I am sure that there could be other reasons for that.

@immatthewj Class A, if we are talking about tubes, comes in three flavors, A1, A2 and A3 (recently patented).

If the amp really does get hotter when you push it and it really is class A, then its class A2. In class A2, grid current can exist during part of the audio waveform so the driver has to be a bit more robust in order to maintain linearity during that portion of the cycle. Our OTLs are class A2.

@atmasphere  , thank you for the explanation--that is interesting and makes me a better informed hobbyist.  

"Pure Class A" was a direct quote from the owner's manual, so that is all I know about it, as my ability to comprehend electrical theory is limited.

I always thought the room got warmer when I used to crank it way up, but that typed, these days I listen at low to moderate levels, and after a couple of hours, if I put the palm of my hand on one of the transformers, it is hot enough to make me remove it (my hand) fairly quickly.  And, after a few hours of listening at low to moderate levels the room still gets warm.  So I do not know for sure that  making it scream had it running hotter or not--I just felt that it must be; and I also do not know which category of Class A Cary was referring to by "Pure Class A"; until now, I was not aware of the different categories.

If it makes a difference as to how hot it gets, these days I always run it in triode.

@immatthewj FWIW, 'pure class A' is a marketing phrase. As far as engineering goes, a circuit is either class A or its not. None of this 'enriched class A' stuff you often see (such amps are class AB). In your case my guess is class A1.

@immatthewj FWIW, 'pure class A' is a marketing phrase. As far as engineering goes, a circuit is either class A or its not. None of this 'enriched class A' stuff you often see (such amps are class AB). In your case my guess is class A1.

I thought after I read your postings on the different categories of Class  A that "pure Class A" probably was the manufacturer romanticizing the owner's manual.  Thanks for the info.