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Hypex NCx500 Class D Amplifier Review

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 3 0.7%
  • 2. Not terrible (postman panther)

    Votes: 6 1.3%
  • 3. Fine (happy panther)

    Votes: 55 12.0%
  • 4. Great (golfing panther)

    Votes: 394 86.0%

  • Total voters
    458

Triliza

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We are seeing the same arguments for some potential issues with class D amps, isn't there some way to test them and be done once and for all with them, whatever the outcome we'll be the wiser. Has anyone having those concern tried contacting Hypex? Most likely they have data to refute or confirm whatever those issues may be.
 

SuicideSquid

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both impressive, but due to topping previous reliability issue on the amp, and that both SINAD is beyond audiable, while power headroom is better than without, I would take the HypeX any time of the day
Not sure I've heard anyone complain of reliability issues with the LA90.

This is just a weird comparison generally. They're totally different products targeting different market segments. LA90 is a class AB stereo amp for under $1,000 targeted at desktop or smaller room uses. When this Hypex amp module actually ends up in commercial designs, they'll likely start at double the LA90's price and be more appropriate for larger speakers in larger rooms.

If I was building a living room system with floorstanding speakers I'd reach for the Hypex (and have, I have a Buckeye power amp based on the previous generation of hypex amps) but for an office or bedroom system powering bookshelf speakers the LA90 makes a lot more sense.
 

pseudoid

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I have been puzzled since the release (thank you @amirm) of this review, why this Hypex NCx500 was built as a mono-block to begin with.
Was it originally conceived to be paired with some subwoofer?
 

Matias

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I have been puzzled since the release (thank you @amirm) of this review, why this Hypex NCx500 was built as a mono-block to begin with.
Was it originally conceived to be paired with some subwoofer?
Because the amp module is mono and can be assembled by manufacturers single or in multiples inside a chassis, so that the end product can be mono, stereo ou multichannel using the same module. Higher parts reuse = lower costs.
 

pseudoid

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Because the amp module is mono and can be assembled by manufacturers single or in multiples inside a chassis, so that the end product can be mono, stereo ou multichannel using the same module. Higher parts reuse = lower costs.
:confused: /\ the obvious still leaves me \/
...puzzled...
without an answer to my question.
"Higher parts reuse = lower costs"? If the majority of use cases would be for a minimum of stereo; then, would the re-use of the same smps for both channels be more relevant and lower costs? Less parts usage also includes the enclosure, and other common piece parts to be shared between L/R.
 

Rick Sykora

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@BR52 and anyone else wanting to know how Hypex modified the NC500 eval board for use with the NCx500, please see my update to post #86.

I posted the information there to ensure it the official instructions are easy to find.
 
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pma

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@pseudoid : It is a high power module. It is difficult to get high current from small size SMPS supply. It is easier to supply current to one channel than into two.
 

pseudoid

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@pseudoid : It is a high power module. It is difficult to get high current from small size SMPS supply. It is easier to supply current to one channel than into two.
When I first saw the internals in the original @amirm review; I thought how it would perform with a single outboard smps (higher current) and feeding 2 of these modules
in a single (but separate) chassis.
Doesn't appear that this mono-block would get much performance improvements (noise, etc) but imo it would provide for a more acceptable/appealing usage case.

EDIT: @pma, your NC252MP-based power amp seems to be a performer.
 
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AdamG

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@BR52 and anyone else wanting to know how Hypex modified the NC500 eval board for use with the NCx500, please see my update to post #86.

I posted the information there to ensure it preempts @Classdampman's more questionable mods.
Let us know if there are other post that are misleading and or incorrect configuration and we will remove them. Thanks for building this and your generosity of time and effort to have this delivered to Amir for testing. ;)
 

Sokel

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I'm still puzzled by the rise of distortion after the first 10 watts,for the same rise (almost exactly) we made a huge argument in the Buckeye amp thread forcing him to redesign it.
If we want to be fair this must be pointed,this one doesn't seem normal too.

I would not point that out if it was 100-200-500 watts,that's a mere 10 watts,how can it struggle right after that?
 

AdamG

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Guys let’s try as hard as we can to keep the conversation rooted in the Equipment tested. Otherwise we end up with a Review thread filled with off topic conversations and ultimately reduced utility of creating separate Review threads in the first place. You all know this, I am simply and kindly reminding you.

Please and thank you for your cooperation.
 

SuicideSquid

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You are confusing high sampling rate with high dynamic range.
Given that this amplifier has among the widest dynamic range tested, what's your issue, exactly?

The initial SINAD measurement at 1khz, 5W lulz us into a false sense of security. Not only do we see distortion rise dramatically after 10W, by the time we reach 25W the NCx500 loses any advantage it had over modules like the 1ET400A, the latter maintaining distortion levels well below -110dB from 20w onward to 200w. Further, moving onward to the distortion/power sweep across various frequencies, we see that there is audible distortion across all power levels. Lastly, I question linearity under real-world load given the strange distortion behavior of this module. This is not what I would expect from a well-engineered class D amplifier, particular not in the face of what Purifi has given us in the form of Eigentakt. L

At the very least, the data gathered here indicates that there is something fundamentally flawed in this amplifier's design.

Assuming your use of "lulz" isn't a Freudian slip and you're engaging in good faith - the rise in distortion needs to be kept in context. Into 8 ohms, THD+N doesn't cross -100dB until 200watts output. At 4ohms, it crosses -100dB at 120 watts. If you're driving typical-sensitivity speakers in a normal environment, you're only ever going to be asking for that level of power output for milliseconds at a time, unless you want to destroy your speakers, damage your ears, and get yourself fined for noise bylaw violations. Across the range where you'll actually be asking for continuous power from the amplifier - 20mW-10W - THD+N is around 10dB on average lower than the Purifi design.

The rise in THD+N when driving the amplifier hard indicates an area for potential future improvement. It absolutely doesn't "indicate there is something fundamentally flawed in this amplifier's design".
 

Matias

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:confused: /\ the obvious still leaves me \/

without an answer to my question.
"Higher parts reuse = lower costs"? If the majority of use cases would be for a minimum of stereo; then, would the re-use of the same smps for both channels be more relevant and lower costs? Less parts usage also includes the enclosure, and other common piece parts to be shared between L/R.
Minimum of stereo and a shared SMPS is their MP line, which should eventually refresh to NCoreX tech too.

Also some users prefer mono amps so they offer the mono module for these users. Having mono amps close to the speakers using longer XLR interconnected cables and shorter speaker cables is a best practice, and highest channel separation too (no crosstalk).
 

SuicideSquid

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It was auto-correct, actually.

Also the rest of what you're saying is incorrect. With buffer, this graph shows distortion dropping below -100dB only at 500mw. Without buffer, the level is much lower at 20mw.

index.php


However this is at a single frequency (probably 1khz). If you take a peak at these two graphs, you get a much different story.

index.php


index.php


If you review these, we see a much different story, to the extent that it almost proves the first graph entirely wrong, given that this graph shows no tested tone dropping below -100dB SINAD until 3w w/buffer, 500mw w/o buffer. We also see that certain frequencies /never/ drop below ~-97dB SINAD. To make matters worse, these impact primarily higher frequencies. The human "ear" is more sensitive to distortion at higher frequencies than lower ones, and the two primary distortion culprits here (10khz and 15khz) directly impact air/stage. Distortion at these frequencies tend to lead to poor imaging, stage, and a sense of clutter.

Given this distortion, I have grave concerns about the linearity of the amplifier under load real-world. At current, Amir doesn't run any linearity tests at real-world power levels (5w is abysmal for speakers) or against loads that mimic real-world load impedances.
You're comparing apples to oranges here, since we don't have a comparable graph for the Purifi module you're comparing to, except from the Buckeye amp which has a buffer issue (and which this Hypex module significantly outperforms). As it is, I stand by my previous statement - this is an area for future improvement but not one that indicates any kind of fundamental flaw. The Buckeye buffer Amir flagged as problematic was producing 2-4 times the noise and distortion across the audible spectrum at 20 watts than this Hypex module is.

5 watts into a typical (~88dB/watt@1metre) efficiency speaker at 1 metre will produce about 100dB output - more than twice as loud as is safe to listen to for any length of time. 5 watts is the top end of what normal users will demand from a power amplifier unless you've got exceptionally inefficient speakers, which is I believe why Amir uses this as a benchmark.
 

Sokel

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5 watts into a typical (~88dB/watt@1metre) efficiency speaker at 1 metre will produce about 100dB output - more than twice as loud as is safe to listen to for any length of time. 5 watts is the top end of what normal users will demand from a power amplifier unless you've got exceptionally inefficient speakers, which is I believe why Amir uses this as a benchmark.
I would be more than happy if that needed 5 watts.
But numbers don't lie.

(note,it's about 80 db average)


index.php
 

AdamG

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Guys let’s try as hard as we can to keep the conversation rooted in the Equipment tested. Otherwise we end up with a Review thread filled with off topic conversations and ultimately reduced utility of creating separate Review threads in the first place. You all know this, I am simply and kindly reminding you.

Please and thank you for your cooperation.
Thread cleaned up a little. If you had a post deleted consider that a warning about off topic posts in a Review thread. If we have to come back Warnings and Thread Bans are next.

Please and thank you.
 

sarumbear

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Thread cleaned up a little. If you had a post deleted consider that a warning about off topic posts in a Review thread. If we have to come back Warnings and Thread Bans are next.

Please and thank you.
Guilty as charged. Apologies. Got carried away.
 

zoidbb

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You're comparing apples to oranges here, since we don't have a comparable graph for the Purifi module you're comparing to, except from the Buckeye amp which has a buffer issue (and which this Hypex module significantly outperforms). As it is, I stand by my previous statement - this is an area for future improvement but not one that indicates any kind of fundamental flaw. The Buckeye buffer Amir flagged as problematic was producing 2-4 times the noise and distortion across the audible spectrum at 20 watts than this Hypex module is.

5 watts into a typical (~88dB/watt@1metre) efficiency speaker at 1 metre will produce about 100dB output - more than twice as loud as is safe to listen to for any length of time. 5 watts is the top end of what normal users will demand from a power amplifier unless you've got exceptionally inefficient speakers, which is I believe why Amir uses this as a benchmark.
Not really comparing that apples to oranges, this graph lets us get a reasonable approximation of what the data would look like if measured the same way.

index.php


As for only needing 5 watts, why would anyone who only needs 5 watts want a 250w amplifier? The answer seems obvious to me -- they need more than 5 watts. Firstly, sensitivity levels are not representative of how much power a speaker will actually use -- they're used primarily to roughly compare sensitivities between speakers whose sensitivities have also been measured in the same fashion. No transducer is perfect, and many will require dramatically more power at the extreme ends of frequency response. This is why we care about amp "headroom" -- to handle not just to handle amplitude peaks in the source music, but also power peaks in our transducers

Further, users of class D amps are often driving power-hungry speakers like large passive subwoofers, big planar speakers who have inherently low sensitivity, or are running speakers in large rooms where you need dramatically more power to maintain listenable levels.

Bottom line is, nobody buys a ridiculously high power amp for no reason, so a review of such amps should be testing them at the powers they're marketed for.
 

mdsimon2

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I'm still puzzled by the rise of distortion after the first 10 watts,for the same rise (almost exactly) we made a huge argument in the Buckeye amp thread forcing him to redesign it.
If we want to be fair this must be pointed,this one doesn't seem normal too.

I would not point that out if it was 100-200-500 watts,that's a mere 10 watts,how can it struggle right after that?

I agree, especially because it doesn't match the Hypex datasheet measurement which for a 4 ohm load shows less than -113 THD+N from 5 W to 200 W. This amp is nowhere near that level of performance.

Is it due to the power supply used? Grounding practices of this amp? I'd like to see this issue explored more so that we can understand what is actually going on and to understand if it is similar to what was seen on the Buckeye Purifi amp.

@Hypexsales any idea what might be causing the difference we are seeing with the ASR measurements compared to the datasheet?

Michael
 
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