Living With A Class A Tube Amp

This is not a class A amp. It is a push pull.

@carlsbad2 Push pull amps can be class A no worries. The Dynaco SCA35 using a pair of EL84s was a class A PP integrated amp. We’ve been making class A triode PP OTLs for decades.

If you were not aware that amps other than SETs can be class A, now you are. The trick is just the same as in an SET- the power tubes do not go into cutoff during any portion of the output waveform right up to full power. So you can also have class A solid state PP amps too.

@atmasphere  , thanks for clarifying that.

@jrcotner  , my old Cary V-12 is switchable between 100 wpc ultralinear and  triode, and in triode Cary says it is 50 wpc class A.  Yes, it does run hot, but I have not had to do anything special with it that I didn't do with my two previous tube amps.  I bought a set of 12 EL34s (reissued Russian Mullards) near the end of 17 and after a bit two years of being pushed pretty hard and a couple of mishaps they were sounding tired and the bias was doing funny things.  Sometime in early '20 I replaced them with a set of the reissued Russiian Tung Sols and they have held up beautifully (however, I don't run them as hard and no mishaps involved).  

As long as it doesn't get way too close to the curtains, I think you will be okay.

Sometime in early '20 I replaced them with a set of the reissued Russiian Tung Sols and they have held up beautifully (however, I don't run them as hard and no mishaps involved).  

@immatthewj If the amp really is class A, you do run them as hard. How loud you play the system has no bearing on the heat or tube life.

If the amp is class A1, if you were to put an Ammeter in series with the AC line, you'd find the current draw unchanged regardless if the amp is at idle or full power.

For your consideration

https://www.jadis-electronics.com/en/i70-57.php

@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.