Indeed, because that would require being correct.
So you're saying we should ignore the "e.g., an adequately design [sic] aluminum chassis" bit? Is that just decoration, do you think?
Neither said nor implied any such thing, but your cognitive ability seems to leave you swirling around that particular drain.
think that the fins/pins on a heat sink are "just decoration"? Is NAD attaching "finny things" because they had a bunch of them sitting around that they needed to surreptitiously dispose of?
Did you actually read (and understand) my original comment on this topic? Specifically the part where I wrote, "Purifi's own demonstrator units lacked dedicated heat sinks and (seemed) to rely on thermal conduction/dissipation via the lower chassis plate
Subsequent to that, I also wrote, "none of the reviews that I found mentioned anything about thermal or abrupt amplifier shutdowns occurring during the review process.
The clear implication being that thermal management did not seem to be an issue even though I would've expected the demo units to be treated more harshly than one that was actually owned by an individual. To spell it out for you, this is a positive.
Sure, more fins can't hurt, but I'm not seeing any reason to suppose they're necessary for something of this level of power.
You would need actual information such as the operating requirements (including duty cycle and environmental conditions) to make a meaningful supposition, but you do you.
And there are two, very straightforward, reasons to implement conservative thermal management:
- to paraphrase Purifi's datasheet - continuous output power is limited by thermal management
- capacitor service life roughly doubles with each 10C reduction in temperature. As these are the components that frequently fail age out/fail in amplifiers, cooler is better.
If you neither require much power for your listening, nor are concerned about the longevity of your gear, then this won't matter to you. I tend to keep my gear around for 10-20 years.
Where? The only reference I can see is attached to "e.g., an adequately design [sic] aluminum chassis". Nothing about fins.
Again, here's what they actually said, including the piece that you like to exclude, "It is recommended to mount the module on a heatsink, e.g., an adequately design aluminum chassis.
Engineers, good ones at least, tend to speak with precision (the rest design high-end speaker cable and interconnects.) While I have no doubts that Purifi's engineers are very, very good, their datasheet is lacking detail/clarity in some areas (such as an actual RMS rating [even if it's couched with temperature envelope data], along with the inclusion of some typos.) Perhaps they have/use slightly different terminology, or perhaps it may have originally been written in Danish and something didn't quite translate the same.
Yes, Purifi used "adequately design aluminum chassis"
as an example of a heat sink, but their datasheet doesn't provide any guidance regarding thermal dissipation requirements, so the example is not useful from an engineering perspective. Without that information, how does one know if the aluminum chassis in use is "adequately designed" aside from repeated prototyping & environmental testing?
It's really not uncommon to see Class D devices just using a plain case as the heatsink. (And yes, dedicated "heatsinks" in a catalogue are the finny things, but other things are also heatsinks).
One pair of examples that springs to mind - the KEF KF92 and KC62 subwoofers, both of which are sealed (so no ventilation) and have 2x500W amps in them.
The KF92 has one of the finny things you'd recognise as a heatsink on the back.
The KC62 simply uses the non-finny aluminium case you don't recognise as a heatsink as its heatsink.
Well, that explains why neither the 1.2KW class-D amp in my Velodyne sub (that I've owned since 2009) nor the 200W class-D woofer amplifiers in each my ML mains (~2010) have "finny" things.
But we're not talking about Kef, are we? Perhaps you'd like to go off on a tangent about the color red
while you're at it?
You just need sufficient area and airflow. Which may or may not involve fins.
I never said that, depending the specific circumstances, a properly spec'd heat spreader couldn't work to keep a device within its operating envelope.
What I did say is that I had not found may Purifi-based devices, aside from a limited few, any that had much in the way of actual heat sink
area. As I've said, heat sink
has a specific meaning in the electronics world, and my use of that specific term was not accidental.
Since you're having such a mental block about that, I'd suggest that you ask an engineer, one that has both the time and crayons, to explain the difference between a heat sink and a heat spreader to you (hint, it's the finny things), and why cooler operating temperatures are (generally) a good thing.
Based on the mechanical prints for that particular chassis, those fins have more than doubled the effective surface area of left & right sides of that particular chassis.
The fins on the side of the box in your picture really aren't adding that much area, proportionately.
Please tell us what your
statement is based on.
A 200%+ increase in effective surface area is not insignificant.
They're not decorative, but they're not radically changing the box's properties.