But it seems to be made to go right against the bottom of an enclosure. Are their some examples of designs that heat sink this module in a way that you would call proper?
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Class D amp long term reliability
- Thread starter sophie smith
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@MakeMineVinyl and @pjug we have a ASR member here that designed his own amp case and vertically mounted the PCB's to vertical heatsinks inside a case. I can't remember who it is. Perhaps he will read this and provide pics of his excellent case design and assembly.
antennaguru
Senior Member
Possibly me, but I was just following the datasheet requirements for the IcePower 125ASX2 module that mounting it needed to be vertical so that convection cooling would be adequate for its output rating. Here is a picture of one example I assembled:
BO 125 inside by antennaguru uda, on FlickrIn this particular case I also used a Class A vacuum tube input stage that would allow the 125ASX2 module to be used with highish output impedance preamps (tube type) as the 125ASX2 module alone only has an input impedance of around 8K ohms. In the end I found that tonally the tube input stage made the whole amplifier a little too bright sounding, and so it could only be used with a preamp that also had tone controls - which is how it has been operating for over 5 years. The lid of the box has perforations to outlet warmed air and you can also see some air inlet holes at the bottom of the left side to to allow for better convection cooling for both the tube stage and the 125ASX2. I have also built these modules with Class A solid state input stages and found their tonal response flatter. Nevertheless I built one with an Op Amp based tone control input stage so it would be at home both tonally and impedance wise in any system.
The front panel is plain except for one LED, and the rear panel looks like this:
BO 125 rear by antennaguru uda, on Flickr
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Sokel
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I have temporarily put my 1200as2 into an old's amp heavy case,solid alu,the only thing I did was fine sanding the part witch I should place it with (the lot) of screws and drilled little holes for the leds witch show the various conditions (on the permanent case I'll replace them with 2 multicolors to avoid drilling 10 holes
). It goes warm evenly on all sides but never too hot.
To give a hint of the use,except the easy work on my active setup it has been tested with Virgos,802D,and Maggies 20.7 and never reached the thermal limits.
The new generation of the good class D amps (hypex,purifi,Ice edge) seems rock solid to me as far as I know.
). It goes warm evenly on all sides but never too hot.To give a hint of the use,except the easy work on my active setup it has been tested with Virgos,802D,and Maggies 20.7 and never reached the thermal limits.
The new generation of the good class D amps (hypex,purifi,Ice edge) seems rock solid to me as far as I know.
somebodyelse
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I think you mean this thread - the reasoning including links to relevant documentation, and the internals. For most hifi use it would be overkill. Vera Audio discuss their approach here, including monitoring and fans.
Close but not this one. The one I am thinking about has like 5 or 6 amp modules inside all vertically arranged.
I have an old Halcro MC70 that has been in service since 2005 in my home theater. They updated the internal amp modules back in 2007 since they said mine was an early version and should be updated. But I have had no issues with it and it works fine. It was rated at 200 watts per channel into 8 ohms with all channels driven. The amp still works fine but I'm tempted to update to an 8 channel NC502MP Buckeye just because it's been so many years. Does anyone know if the new class D designs would provide more power or sound a lot better?
JayGilb
Major Contributor
Only if you're looking for more reliability due to the age of your Halcro. The THD+N spec for your amp is: 0.007% which well past the point of audibility.
New Class D amps would only provide more power if they were designed to do so. Your Halcro is a powerhouse in it's own right.
I'm using vintage amps from the 80s and 90s, some of which have been recapped, not because they failed, just for prudence sake.
I'll just pipe in to say that my March Audio p252 (bought 2019) is doing fine. As it should...
Me too,tested here (NAD 2200 vintage test)
valerianf
Addicted to Fun and Learning
Has somebody already repaired a class D amp without changing the OEM module?
Pictures here of how Nad do it with the purify module. This is how I would want to do it if diy-ing.
NAD M28 7 Channel Purifi Amplifier Teardown
I recently reviewed the NAD M28 multichannel amplifier based on Purifi modules. As promised, this is a tear down of the unit with kind permission of the owner. The amp was a delight to open with beautiful screws holding the attractive top down. Once removed, we are greeted to a nice and...
www.audiosciencereview.com
Sokel
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That's what Ice Power describes:
Edit:
It is important someone to specify it's needs as inadequate cooling can greatly reduce power:
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somebodyelse
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Yes, and I'm an amateur. In this case it was in a guitar amp, but the manufacturer's implementation on their own board was close to IR's datasheet, and we've seen similar in active speaker teardowns. There was no OEM module.
What needed to be fixed?
somebodyelse
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A failed output transistor.
That's a sorry sight. (The mechanical construction, that is.) I was about to pull the trigger on one of these NC252MP's but now I don't know... that's just sloppy! They clearly didn't have reliability as an important consideration when designing these. Makes one feel even less at ease about the capacitor brands they use as well. (And yes, I've repaired several of my own electronic thingys where electrolytic capacitors were the cause of the failure - ATX power supply, inverter etc.)
Do you happen to have a picture of the entire bottom side of the PCB? I'm wondering if it's possible to DIY some better solution. Perhaps mounting the board upside-down and attaching heat spreaders or heat sinks with thermal adhesive? Or perhaps one could add some kind of clamp over the entire board to press down on the PCB to ease the strain...
That device was manufactured in 2019. They may well have improved the design since then. Probably worth contacting hypex to ask - I'd certainly be interested in the answer if you did.
restorer-john
Grand Contributor
Yes, I have a high resolution scan of the board. Probably too big to attached. PM me if you like.
It's just not worth bothering with to be honest. IMO, there's too much that is wrong for long term reliability. I don't think I've ever seen a commercial product with such poor heat producing device mounting practices.
Hypex have redesigned their new modules and appear to using better device to heatsinking design, superior capacitors and some other improvements. Whether that is enough for you to plunk down your cash, I dunno.
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