Thank you all for your comments and questions. I will try to answer them all. You also found some gaps in my report.
Apologies for that. I will try to address them.
Active cooling lowers temperatures, who could have expected that?
Yes, we already knew it worked. It was about getting measurements of the effect of active and convective cooling. Based on my experience with PC cooling I expected a stronger effect from the convective cooling.
So two things, is there anything indicating real temperature problems, besides usual - temperature bad, look at my 70'C class A amp from the 80s, its a beast
And second: what speeds was those coolers from the test and why there's no cooler on the bottom - the most logical for me - option tested?
The benefit of cooling would not be seen for years. If the unit is well designed it would probably be decades. So, why bother...Why not? It's likely my personal inclination.
In this setup the fan (Arctic P12 PWM) is running at 12V. Unregulated this fan is supposed to run at 1800 RPM. It was somewhat audible at that speed. My PWM controller is on its way from AliExpress. At slower speeds it will be inaudible.
The cooler on the bottom option wasn't tested because it would have required a more elaborate Lego rig than I was able to assemble before the end of the day. The other approaches got down to 27.3ºC so there are diminishing returns as to how cool I could get. Ambient room temperature was 21.8ºC, so I wouldn't be able to go any lower than that.
Cooling the bottom surface will yield best result. The single test you avoided to do. It's practically the equivalent of a CPU lid of of the unit, cool that, and the rest will largely follow. Your own ~2c internal/external observation supports this.
I did try having the fan blowing at the "bottom" unit on the right of the "stack" when they were sideways. I felt this was a poor approach. The V3 Mono is a little brick and blocks all air flow to the "top" unit on the left. One objective was to understand the effect of what I thought was an ineffective approach (blowing air across the two stacked units). Another objective was to test the effect of convection. I wasn't setting out to come out with the optimal cooling design, but as I mention above there is diminishing return. To cool both units in that fashion would have required another fan (which I have) but more significantly, a more elaborate Lego setup and it was getting to dinner time.
I will note that Fosi appears to be designing a desktop component rack that will accommodate four fans blowing up from the bottom. On the one hand, that's cool
, but on the other hand I think it's overkill.
Well that was above and beyond the call of duty. But I certainly appreciate the effort.
Thank you for your feedback. I have become a little paranoid about heat and cooling. I had a NAD 7020e sitting in a shelving unit a couple of years ago. It was working fine until I left it running on for a couple of days. It now has a hum and is waiting patiently for me to recap it. I replaced it with a 7220e and I have a pair of fans venting the air. It runs cool as long as I have the fans on. Yes, I know, the NAD is 40+ years old and there are all kinds of age related factors. It's just me.
Dust. Now there's an interesting consequence. I will have to keep an eye on that. I suppose active airflow is going to be worse than what falls into most of the units over years. I appreciate the warning.
Yes, the amps were under load. I was listening to music at a comfortable level the whole time. I was aiming to mimic a daily usage scenario.
Finally, I think we got off on the wrong foot on this topic. In the end I learned a few things about cooling. Thanks for that.
