There are very few true Class A transistor amps. Most so-called Class A amps switch over to Class B after a few watts. A true Class A amp of considerable power will always run extremely hot under zero load and then progressively cooler as output level increases!
How hot is hot when moving from class a/b to to a or tubes?
I am considering moving from a class a/b Luxman L509x to a class a or tube amp.
I have never owned a class a or tube amp, so have no experience of living with one. My kids are hopefully old enough and wise enough not to burn themselves, but I do live in an already warm house with bifold doors leading to a south facing garden. There is no escaping the sun, despite having uv treated glass.
My room is roughly 9 meters by 12 open planed living space. Equipment is, Luxman L-509x integrated, Zu union 6 supreme, 99db sensitivity (this is why I am considering a lower powered tube I can barely turn the Luxman up) music is played roughly 6 hours a day, more on weekends
who here has moved from class a/b and d to class a with or without tubes. What were the differences of things like:
warming up time
additional heat to the home
Running in summer time
additional cost to run
any considerations I should make before purchasing something. I will try in my home, but will need to free up funds
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All amplifiers can reach their normal operating temperature, but class A amps in general may become warmer internally as if you are driving speakers for up to an hour. If speaker impedance dips, the amplifier will be tasked at supporting them with more current. Just make sure you use a Class A amplifier in a dry environment and leave vents unobstructed; so heat loss can occur normally. Otherwise, nothing to worry about... |
Regardless of what tube amp you get, I highly recommend if you have kids and/ or pets to get one that has some type of cage around all the tubes! Better safe than sorry for a bad burn or blown amp. I have a Rogers High Fidelity RHF 200 Mark II w/ two KT - 150 power tubes per side that generate 100+ watts / channel in full class A. Great amp & love it but it gets real hit. I bought the very well made vented lexan cover because I have two very curious cats who gravitate towards warm things. You can still see the beautiful amp & it’s outstanding workmanship but it’s safe! |
Define your description of what is "hot" to you?. I'm re-evaluating this myself again recently. May be helpful to compare w/others. SS: My full-on Class A 50w solid state amp is said to be operating normally when you can hold your hand on the side heat sinks for about a max of "ten seconds", reasonably. Confirmed by the original designer and recent tech who performed checks and upgrades. Special grease was added to the OPTs for maximum heat transfer to heat sinks, @47-50c temp max, and recently biased up and upgraded. TUBE: my two mono block tube amps run two KT150 or two KT120 output tubes per amp. Can hold a hand on the transformers for ~30-45 seconds no issue. Toasty warm but not what others might consider "hot". Will recheck actual temp with infrared laser next wk after re-biasing tubes to their max to see what max heat is. I'd expect higher power 211, 845 triode amps to run a bit hotter in full Class-A. |
i kept the hot question vague for the reason you describe - want to get a gauge on how others articulate it. My main concerns were: potential burns to the kids (probably their friends. Thanks @jonwolfpell for the cage comment), how much it will heat my already hot home, anyone speaking about shutdown modes from over heating (there are few Texas folks running them in the summer, the UK won’t be hitting those temperatures), hopefully getting some insight on what experienced owners would do if they were starting out again. |
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