SummerTime and Amp Heat


My B&K has some massive heat sinks but I still place a fan on it to draw cooling air through it. It seems each summer I need to do this. Am sure some of you do as such?
barroter
No one seems to have mentioned the associated load on the amp and its output stage[s]. As a corollary, one sometimes sees ads that say "drove my Thiels/Apogees/'stats with aplomb". That's all good and well but it would seem that driving the amp to its upper limits might shorten its useful life and perhaps wear it out faster than one would with an easier load. Just wondering...
05-30-11: Tripper
No one seems to have mentioned the associated load on the amp and its output stage[s]. As a corollary, one sometimes sees ads that say "drove my Thiels/Apogees/'stats with aplomb". That's all good and well but it would seem that driving the amp to its upper limits might shorten its useful life and perhaps wear it out faster than one would with an easier load. Just wondering...
all (larger) power amps have output protection circuitry ( that kicks in if there is unusually high DC offset) + thermal shut-down circuitry that cuts off the output power stage if the heatsink temp goes too high (this is often monitored by transistors attached directly to the heatsink & the bias running thru these transistors is set to the upper limit of the heatsink temp that the designer thinks is safe) + the power transformer is also designed to provide lower current than the transistor's max so that the transistors always operate in their SOA. All these safety checks (idiot-proofing) ensure that (unless you short the speaker binding posts) the amp will operate safely & within its limits 99% of the time.
So, if the amp is driving somebody's Thiels/Apogees/'stats with aplomb then it is doing so within the SOA region of the output transistors (otherwise it'd be shutting down time & again & the owner would not make such a statement).
By "a matter of degree" I meant (along with a lame pun) the degree to which you're using the amp...running into a 4 ohm load to get 115db peaks for 5 hours might cause more heat than a day of light background music. I have a later MOSFET Forte' A/B that get toasty-ish only when I play something kinda loud for a while, but unless you have the amp in a VERY hot room I'd think excessive heat (risking shut down) is a design flaw, and the amp designer should have included fans. I'm amazed that some "all Class A" amps don't melt in "normal" use...but maybe I'm easily amazed.
When I received my Krell 300cx Steve at Krell said:
Don't leave it on 24/7
Yes it will run hotter than a lizards ass on a hot rock.
No don't worry about it as long as you have the required open air space as noted in the manual.
Now when I know it is getting hot I just smile and know she's just getting outa' 2nd gear.
Enjoy, John
OneMug,
I think blazing saddles got the idea from 'Treasure of theSiera Madre'....a terrific Bogart Movie. Alfonso Bedoya delivered the line which has been paraphrased in a bunch of movies, including some animal comedy where 'badges' was morphed into 'badgers'. fun for all.