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-   -   Mini review: Class-D Designs NX200 vs Hypex (http://www.diyaudio.com/forums/class-d/141588-mini-review-class-d-designs-nx200-vs-hypex.html)

cirrus18 1st April 2009 12:53 PM

Mini review: Class-D Designs NX200 vs Hypex
 
Recently I built a Hypex stereo amplifier and was really thrilled with the results and thought it was the best amplifier I had ever heard, posted here: http://www.diyaudio.com/forums/showt...39&highlight=.

In the discussions It was mentioned that the Class-D Designs NX200 amplifier was a match for the Hypex and in fact perhaps even better. http://www.classd.ltd.uk/product.php?productid=16269 This intrigued me as I thought it was nearly impossible to improve on the Hypex and wondered if other people had found the same http://www.diyaudio.com/forums/showt...498&highlight= but didn't get any satisfactory results as no one has seemed to have listened to one.

As they are so inexpensive compared with Hypex I decided to take the bull by the horns and try them out for myself. I bought the NX200s (which incidentally are not Class-D but Class AB amplifiers so would satisfy the purists) connected them up using the Hypex switch mode power supply and set back to listen to really superb sound.
All the clarity, dynamics and more was there compared to the Hypex and to my ears I thought the presence and soundstage was a little better.
All that I said about the Hypex in my review above can be applied to these NX200s so I'm not going to repeat myself here.

When you consider the price of the NX200s compared with the Hypex amplifiers, to my mind, the NX200s win hands down.
These amplifiers are crying out for someone to organise a Group Buy and depending on the quantities one could get them for as little as 26 each compared with 120 each for the Hypex. It's a no-brainer.

Incidentally, before someone starts jumping up and down I have no connection with any company and these views are my own personal ones.

mitch90 1st April 2009 02:04 PM

Mini review: Class-D Designs NX200 vs Hypex
 
Hello cirrus18.

Just to be fair and compare apples to apples cost wise,
NX200 modules will need bigger heatsinks than
Hypex modules for equal amount of output power
they produce.

So my conclusion is: the cost of heatsinks need to be added into total cost equation.


Regards,


MITCH.

cirrus18 1st April 2009 02:46 PM

Re: Mini review: Class-D Designs NX200 vs Hypex
 
Quote:

Originally posted by mitch90
Hello cirrus18.


So my conclusion is: the cost of heatsinks need to be added into total cost equation.


Regards,


MITCH.

Well, to my mind that seems quite a nit-picking comment. Must have a Hypex devotee here. Please, let's have unbiased comments. We are talking about well over $100 each amplifier cheaper than the Hypex. That buys a hell of a lot of heatsink if indeed extra heatsinks are required. The efficiency of these amplifiers is supposedly similar to Hypex.

Ouroboros 1st April 2009 03:17 PM

Why are we comparing the Hypex class-D design to a conventional (albeit lateral MOSFET) classAB design? They are totally different items!

mitch90 1st April 2009 03:26 PM

Hello cirrus18.

I am not a Hypex devotee, but I do think that
class-d topolgy is way to go, and that is my personal
opinion.


-"The efficiency of these amplifiers is supposedly similar to Hypex."-

Well from my experince with clas AB amps I find this hard
to belive, do you have any source to confirm this finding?

Price difference also can be attributed to the fact
that NX200 modules do not include overcurrent or overvoltage protection circuitry onboard.

What I am trying to say here is: fair comparison
between NX200 and UCD is something that can not be done very easy it is like comparing
apples to oranges.


Regards,


MITCH.

cirrus18 1st April 2009 03:58 PM

Quote:

Originally posted by Ouroboros
Why are we comparing the Hypex class-D design to a conventional (albeit lateral MOSFET) classAB design? They are totally different items!
Well, it's quite simple really. Because of the rather misleading name of this company "Class-D Designs" and to the fact that they look very similar to class-d amplifiers there was some confusion at the beginning to what they really were. They got included on this class-d forum. Because of the continuing interests here I've just continued it.
Anyway, as I am comparing it with the Hypex amplifiers, which are definitely class-d designs and do belong here, it's a moot point in which forum the posting should be in.

bwaslo 1st April 2009 04:03 PM

"The efficiency of these amplifiers is supposedly similar to Hypex."

If class AB, that's highly doubtful.

Watch out for specmanship games here. At full power out, they might approach comparable efficiency, but at less than full output power (where the class AB drops most of the supply voltage across its output transistors at the total current it has to feed to the load), a decent class D design can still have efficiency near its full power efficiency. Class AB efficiency tends to be quite poor in that situation. And when playing music, much less than full power is the normal situation, since absolute full power (i.e., just at clipping) should not be hit if you want things to sound good. That's why you can run things like Hypex or ICEpower with no, or almost no, heatsink, when it is used as a hifi amp. Don't try that with a class AB!

jkeny 1st April 2009 04:08 PM

Surely the real point is the sonics of the amp - this is what we are here for, I presume - slightly better than the tweaked out 180HG with HXR is a pretty good result, in my book.

I doubt that the efficiency is anything like the Hypex amps but you say they run cool at normal listening levels - what size heatsink have you mounted the modules on?

bwaslo 1st April 2009 04:46 PM

I have them (Hypex) mounted on the side of the sheet metal chassis (180HG) and no other heatsinks. Barely warm to the touch.

Sonics (a subjective matter, of course) are to me better than any Class AB amps I've run. My previous amp was a decked-out, cascoded, servoed, coupling-capless MOSFET AB amp. Subjective evaluation is also influenced by psychology -- whether a listener is more positively effected by being around heatsinks, by glowing tubes, or by amps that physically seem not to be there. Probably the last suits me better than glowing things and big metal, but nothing wrong with the others.

DcibeL 1st April 2009 04:55 PM

Hi Cirrus18,
It looks as though you have posted this same information several months ago here:
http://www.diyaudio.com/forums/showt...hreadid=134498

As it was shown in that thread, the Class-D company has poor business ethics, and better amplifier modules with accurate power rating can be purchased directly from the man that designed them, here. They are more expensive, but cost does reflect on quality in this case.

It has also been shown in This thread that the Class-D company has been very flaky to deal with, and some solder joints on their modules on the output transistors does not meet IPC specifications. If they are to offer free boards to people as a promotion for the company, these free boards should be the best performing boards of a production run, but they are sub-par at best.

I would not recommend an amp from the Class-D company to anyone.


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