Class D Amps with good thermal control / heat sinks

[ebrandon]

I'm going to buy a Hypex or Purifi amp, a fairly powerful stereo amp (Hypex NC500 or NC502MP, 1ET400A or 1ET704SA)

I've done a lot of research and am looking at many of the usual suspects for manufacturers:
- March Audio
- Deer Creed Audio
- Buckeye
- NAD
- Apollon
- KJFAudio
- Boxem
- Audiophonics.fr

It seems to me that one of the few things that really distinguish one amp from the other is the size and quality of the heat sinks. I've heard these amps can be thermally limited if you push them a bit, and that good heat sinks really help.

But this is one of the hardest things to figure out in my research - which of these amps have good heat sinks?

Any advice?

 

[ebrandon]

Follow up question -- the other difference between these amps are the input boards. I don't know if it actually makes any difference in the sound, but I do know that I'd like the option to swap in different input modules and see if it makes any difference for myself.

Are any of these brands' amps more appropriate/easier for someone to switch out input modules?

 

[DVDdoug]

I don't know the answer but class-D efficiency can vary so you can't just compare the heatsinks in two different amplifiers. You have to trust the manufacturer to provide enough cooling. If you are in an unusually warm environment you might want to check with the manufacturer. Or, if you intend to stress the amplifier with constant high-power test-tones.

And of course, efficiency and relatively-cool running MOSFETs is the main feature of class-D.

 

[MakeMineVinyl]

Monoprice Monolith class D. Has extremely effective heat sinks and 5 year warranty.

8x200 Watts

8x100 Watts

ATI also makes a full line of class D amplifiers as well as class A/B in several configurations from monoblocks to 16 channels and powers up to 500 Watts.

 

[groovybassist]

You might want to add @tomchr build to your consideration. He posted a vid of how he builds them using his Neurochrome products in the build.

 

[NTK]

The Vera Audio Hypex NC500 based P400/1000 is also worth considering. It has a very well thought out thermal design.

Vera Audio P400/1000 Review (Amplifier)

This is a review and detailed measurements of the Vera Audio P400/1000 Hypex NC500 based amplifier. It was sent to me by the company and costs 26 000 NOK ex VAT (US $2934). The case is milled from solid aluminum and has a nice quality and look to it. It is also quite heavy for a class D amp...

www.audiosciencereview.com

 

[pma]

It seems to me that one of the few things that really distinguish one amp from the other is the size and quality of the heat sinks. I've heard these amps can be thermally limited if you push them a bit, and that good heat sinks really help.

You may check the size of heatsinks in my NC252MP implementation:

PMA NC252MP power amplifier

Manufacturers do not use large enough heatsinks for 2 reasons:
- cost
- case size

With the heatsinks that I use you may run the amplifier at any power within 0 - 250W at any time duration. No heat limited power here.

 

[KMO]

It seems to me that one of the few things that really distinguish one amp from the other is the size and quality of the heat sinks.

That's basically the nature of class D. They're so efficient that the power dissipation difference between "idle" and "full power" is much bigger than class A/B, or other amps.

Which means that the amount of cooling is very load-dependent, and hence there's a wide potential space of design choice, and trade-offs with mass/cost/size.

If you choose to get a class D with maximal cooling, in a way, you're not really taking advantage of one of class D's key features - that normal audio loads do not remotely resemble "full power continuous 250W", so don't need that sort of cooling solution.

If you fit a continuous 250W-capable heatsink to a class D amp, it's kind of a contradiction. Dumb over-engineered cooling on a smart optimised-for-low-average-load amp. (Although there will certainly be some high-power users, and class D still makes sense for them, so it makes sense that at least some exist, but are you such a user?)

Now, the Vera Audio one's interesting because it retains the class D "low average power" logic, but adds fans - it knows it would need those fans running to keep going full power, but it also knows that in practice they won't run, so you can largely ignore them. But on the day you do decide to run max power continuously, they might start whizzing.

Anyway, don't just buy the amp with the biggest heatsinks - and don't assume big heatsinks necessary means "quality" - buy an amp with cooling capability that make sense for you.

Personally, I've got Apollon's 1ET400A Pure 5 - 5 Purifi modules in a flat aluminium box - top and bottom air holes, no fins. Very pretty, and seems thermally perfectly adequate.

 

[tomtoo]

Vera Audio P400/1000 Review (Amplifier)

This is a review and detailed measurements of the Vera Audio P400/1000 Hypex NC500 based amplifier. It was sent to me by the company and costs 26 000 NOK ex VAT (US $2934). The case is milled from solid aluminum and has a nice quality and look to it. It is also quite heavy for a class D amp...

www.audiosciencereview.com

They take a lot attention to thermal stability.

 

[ebrandon]

That's basically the nature of class D. They're so efficient that the power dissipation difference between "idle" and "full power" is much bigger than class A/B, or other amps.

Which means that the amount of cooling is very load-dependent, and hence there's a wide potential space of design choice, and trade-offs with mass/cost/size.

If you choose to get a class D with maximal cooling, in a way, you're not really taking advantage of one of class D's key features - that normal audio loads do not remotely resemble "full power continuous 250W", so don't need that sort of cooling solution.

If you fit a continuous 250W-capable heatsink to a class D amp, it's kind of a contradiction. Dumb over-engineered cooling on a smart optimised-for-low-average-load amp. (Although there will certainly be some high-power users, and class D still makes sense for them, so it makes sense that at least some exist, but are you such a user?)

Now, the Vera Audio one's interesting because it retains the class D "low average power" logic, but adds fans - it knows it would need those fans running to keep going full power, but it also knows that in practice they won't run, so you can largely ignore them. But on the day you do decide to run max power continuously, they might start whizzing.

Anyway, don't just buy the amp with the biggest heatsinks - and don't assume big heatsinks necessary means "quality" - buy an amp with cooling capability that make sense for you.

Personally, I've got Apollon's 1ET400A Pure 5 - 5 Purifi modules in a flat aluminium box - top and bottom air holes, no fins. Very pretty, and seems thermally perfectly adequate.

Thank you. Very interesting take. It's difficult to let go of my possibly out of date audiophile mentality - heat sinks important, dual power supplies good, monoblocks better than stereo amps, etc.