Thank you ZM. Yes, I'm fiddling with the fan speed. Not sure why it's running that hot. During my initial tests (way back when) it ran cooler. Nothing changed but the power supply voltage, which is now lower (of course I biased the amp for the lower voltage).
well, besides fan airflow itself, never underestimate importance of intake and out-take paths
usually when these two are organized properly, job can be done with smaller fan speed than you expected
usually when these two are organized properly, job can be done with smaller fan speed than you expected
The fans a mounted directly to the sinks, which are oriented to the back of the enclosure (see earlier photos). The bottom of the enclosure is open, and the top and back are perforated steel which should allow plenty of airflow.
Unfortunately, the 10k trimpot that controls fan speed is oriented in such a way that the adjuster is inaccessible without disconnecting the power and i/o wires and removing the amp subassembly (dumb oversight). Tomorrow I'll pick up a trimpot with a side-mounted adjuster, which will make it accessible from the bottom of the amp without taking it apart...
Unfortunately, the 10k trimpot that controls fan speed is oriented in such a way that the adjuster is inaccessible without disconnecting the power and i/o wires and removing the amp subassembly (dumb oversight). Tomorrow I'll pick up a trimpot with a side-mounted adjuster, which will make it accessible from the bottom of the amp without taking it apart...
OK, so the really hot spots seen in the IR pic are actually the four power resistors... reaching 90+ C. I think they're 3W resistors, but TBH I'm not sure. Just for a wider safety margin I might replace them with 5W, though I assume they'll still get toasty. Also, to manage the heat of those resistors and the boards, I added 2 more fans (6 total 😵):
The heat sinks are bloody hot, but I think I can live with that:
And with that, I think I'm done with ACA Concept II, except for the PSU enclosure. I'll post one more pic when that's done, whenever that is. In the meantime, I'll just enjoy the music... it really does sound nice...
Oh, and then on to ACA Concept III
The heat sinks are bloody hot, but I think I can live with that:
And with that, I think I'm done with ACA Concept II, except for the PSU enclosure. I'll post one more pic when that's done, whenever that is. In the meantime, I'll just enjoy the music... it really does sound nice...
Oh, and then on to ACA Concept III