• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Review and Measurements of Nord One NC500 Amp

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
18,981
Likes
19,285
Location
Seattle Area
#1
This is a review and detailed measurements of the Nord One Hypex NC500 class-D module based power (speaker) amplifier. It is on kind loan from a member who recently purchased it. Nord is a British company so lists the cost of the Nord One as £ 979 or US $1,250 as of this writing. For that cost you get a pair of NC500 class-D modules from Hypex with dual PS1200 power supplies. I *think* this cost includes the stock input "buffer" (amplifier) from Hypex. You also have a choice of fancier, audiophile-type input buffer.

The Nord One comes in a very large enclosure (full 19 inch rack width):

Nord One NC500 Amplifier Class D Audio Reviews.jpg

A hard push button turns the unit on and off. Even with overdriving the unit, I could not get it to go into protection mode so not sure if such a feature is there or not.

The back panel has the bare minimum plus trigger sockets:
Nord One NC500 Amplifier Class D Back Panel Audio Reviews.jpg

The unit as it came had an issue. Can you spot it?

Nord One Speaker Miswire.jpg


Look at the right channel: the red cable is connected to black terminal instead of red. So the two channels were out of phase from each other. I can just imagine someone buying this and raving about soundstage and such, only to realize that it is a defect, not a feature. :) Anyway, I fixed it for the measurements you are about to see.

The speaker terminals are massive by the way.

While we are looking inside, here is what it looks like (pardon the mobile phone picture):
Nord One NC500 Amplifier Teardown.jpg


Not a whole lot in there as all the heavy lifting is done by Hypex in producing the switching power supplies, the NC500 amplifier modules and an "input buffer" board which seemingly does more. Main power is routed through it rather than directly to the amplifier modules. Speaker output also goes through it.

The large enclosure allows the components to be easily laid out. Wiring is generally neat and is better than most non-skilled people could do. It seems like good value to me for all the functionality that is in there and hand assembly of the unit.

Power Amplifier Audio Measurements
As usual, we start with our 5 watt output into 4 ohm load for the dashboard:
Nord One NC500 Amplifier Audio Measurements.png


I was a bit unhappy about the channel in blue which seemed to dance around with those extra spikes. The levels are low but not nice engineering.

Overall THD+N as expressed with SINAD is in very good category:

Best Audio Amplifiers Reviewed 2019.png


At 96, it is well above our geometric mean of all the amplifiers tested so far (80). It does lose by a big margin compared to the NC400 though which ironically was a DIY build with a single power supply.

Let's see what the power output looks like relative to distortion:
Nord One NC500 Amplifier Power at 4 Ohm Audio Measurements.png


I worked hard to get the distortion as low as I could as Hypex data is slightly better than this. I realized that when the unit is dead cold, it performs a bit better. I suspect Hypex has tested the amp some other way than with that eval input buffer board as distortion seems to set it very early in my testing at around 2 watts whereas Hypex doesn't show this effect:

1559330632746.png


Overall power versus distortion curve though does match what they show with that increasing distortion from 5 to 30 watts and then settling down to a lower number. It is unfortunately to see some non-linearity in that range where a lot of listening will be done.

Anyway, the good news is that the dual power supplies do their job, helping the NC500 amplifiers to produce copious amount of power to the tune of 445 watts. Combine this with excellent signal to noise ratio and you have a lot of clean power:

Nord One NC500 Amplifier SNR Audio Measurements.png


Frequency Response is uneventful:
Nord One NC500 Amplifier Frequency Response Audio Measurements.png


By the way the above measurements were made without any AES-17 filter. I was asked to evaluate this amp with and without it so I thought I show that in the power measurements at 8 ohm:

Nord One NC500 Amplifier Power at 8 Ohm Audio Measurements.png


The graphs with and without AES-17 filters are essentially the same. Below 1 watt, the output level is low enough that the analyzer gets a bit confused with the ultrasonic noise and glitches up and down a bit. So no, AES-17 filter (with 40 kHz flat response) that I use do not give any advantage to class-D amps.

Speaking of ultrasonics, here is the output without an AES-17 filter:
Nord One NC500 Amplifier 1 kHz Spectrum Audio Measurements.png


The switching noise is very high at just -12 dB below signal level. Would have liked to see this lower. The Nord One has no CE mark so would be interesting to see if additional filtering would have been necessary to pass certification. Of course it is not audible so it is OK in that regard.

I was surprised that there was less intermodulation distortion at high frequencies than our best measured yet Benchmark AHB2:

Nord One NC500 Amplifier 19 and 20 kHz IMD Audio Measurements.png


I will have to double check to make sure the Benchmark was also tested at 5 watts. There is however harmonic distortion that is much higher than the Benchmark starting at 35 kHz.

We can see that in this graph of THD+N versus Frequency at a few different power levels:
Nord One NC500 Amplifier THD vs Level vs Frequency Audio Measurements.png


The red graph is at lowest power (probably less than 1 watt) and the pink is at max (440 watts). The rise in distortion above 1 kHz is too steep in my liking. In that regard, the 1 kHz measurements we usually perform are the best case scenario.

Conclusions
I went into this review expecting better results than I achieved. Despite higher designation, the NC500 seems to be a lower performing module than NC400. How much the input buffer board adds to this, is unknown until we test other variations.

That aside, you are getting huge amount of clean power here that outdoes all of the bargain amplifiers we have tested so far (switching or not). At nearly 500 watts into 4 ohm, you should have ample power to drive anything from subwoofers to main speakers. The extremely high signal to noise ratio should be silent in use. Price is reasonable assuming shipping is not too expensive and it includes the input buffer.

In other words, we have found another power amplifier that I can recommend.

----------------------
Questions, comments, critique, etc. are welcome.

My late grandfather-in-law used to say, "it is hell getting old." To wit, I don't remember if I asked you all to send me money so I can buy a boat and enjoy the beautiful weather we are having. Regardless, send me the money anyway using:

Patreon: https://www.patreon.com/audiosciencereview), or
upgrading your membership here though Paypal (https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054).
 
Joined
Jan 1, 2019
Messages
50
Likes
39
Location
São Paulo - Brazil
#3
Left channel might be noisier because it is the channel with the SMPS with the heatsink facing out, while the right channel has the SMPS heatsink facing in. Maybe this blocks interference? Just speculation on my part.

In that sense the Apollon NC800SL amplifier is symmetrical.
Apollon-Audio-Hypex-Nc500-based-Amplifier-front.jpg


A pity it is not the special buffer rev D option and the Sonic Imagery and Sparkos opamps. Would have liked very much to see how they measure.
https://www.nordacoustics.co.uk/product-page/nord-one-se-up-nc500dm-stereo-black
 
Last edited:

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
18,981
Likes
19,285
Location
Seattle Area
#5
Here is the info on the cost from the owner:

"It was 979 GBP base; 50 GBP extra for the trigger circuit; and 75 GBP for shipping. The standard (Hypex eval) input buffer is included at that price; their in-house “boutique” input buffers are extra. "
 

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
18,981
Likes
19,285
Location
Seattle Area
#6
For a UK product that seems very odd.
So much audio gear goes under the radar this way. Fortunately the modules themselves are designed to at least be safe so it is not as bad as someone cooking up their own power supply and such.
 

RayDunzl

Major Contributor
Central Scrutinizer
Joined
Mar 9, 2016
Messages
6,829
Likes
2,953
Location
Riverview, FL
#7
Look at the right channel: the red cable is connected to black terminal instead of red. So the two channels were out of phase from each other. I can just imagine someone buying this and raving about soundstage and such, only to realize that it is a defect, not a feature.
I can imagine it too.

A few weeks ago Audio Buddy brought over his new DAC to compare to the Benchmark (he had an original DAC1 before).

I set his up direct source to DAC, and flattened all the settings in the chain to mine.

His sounded exceptionally glorious (stereo-wise) on some material compared to the Benchmark, less so on other pieces.

We decided "well, the new one is intersesting, but you get used to the other after listening for a minute".

After a while, the Wow!! turned into What??

Eventually found the Benchmark was being fed the right channel data going to both channels with some crossover setting between them.

Not expecting not to hear something wrong, we didn't interpret it as "wrong", just different. It wasn't quite mono. Hard-panned material lost whatever was only in the left channel. That was the key to the realization something was wrong...

Finally figured out the problem. Found them audibly equivalent afterwards.
 
Last edited:

Michael Kelly

Member
Manufacturer
Patreon Donor
Joined
Aug 22, 2018
Messages
32
Likes
37
#8
Based on the specifications from HYPEX, the NC400 is indeed a lower THD product. It is however significantly more expensive per module than the NC500 series. You would have to ask them what the reasons are for the distinctions between them.
 

MZKM

Active Member
Joined
Dec 1, 2018
Messages
261
Likes
158
Location
Land O’ Lakes, Florida
#9
I worked hard to get the distortion as low as I could as Hypex data is slightly better than this. I realized that when the unit is dead cold, it performs a bit better. I suspect Hypex has tested the amp some other way than with that eval input buffer board as distortion seems to set it very early in my testing at around 2 watts whereas Hypex doesn't show this effect:



Overall power versus distortion curve though does match what they show with that increasing distortion from 5 to 30 watts and then settling down to a lower number. It is unfortunately to see some non-linearity in that range where a lot of listening will be done
Their data also shows/measures 700W into 4ohm at 1% THD, whereas yours show 300% more distortion, luckily that means just 3%.

Using your “hockey stick” approach to wattage values, the NC400 should be capable of hitting 400+ watts into 4ohm, but as you noted the unit you got is using a single power supply for two modules, so its wattage is almost 1/2 of what it should be.

Two NC400 monoblock kits run you ~1210€ with cheapest shipping (<4€ extra for express), which is currently $1355 USD.

Don’t wanna seem like promoting, but currently the only way I see to get it built for you is by James Romeyn, he charges around $1940 shipped for a pair of the assembled monoblock kits (~$1530 for stereo model, ~$3000 for bridged monoblock pairs).

Unless you want the stereo or bridged mono, the regular monoblock pair looks like it can be assembled in no time, so unless you immensely value your time, I would just get the kit.
 
Last edited:

MZKM

Active Member
Joined
Dec 1, 2018
Messages
261
Likes
158
Location
Land O’ Lakes, Florida
#11
What I find incredible is how tiny the NC500 module is.
Any chance you can test continuous power? Because this is what the data sheet shows:
7FC8B7EA-9119-4DE2-A0E7-2C7084858D48.jpeg

Is “continuous” that much different than RMS?
Maybe do a wattage vs time measurement to see how long it takes to reach that (opposite of plateauing?).
Also, odd how there are no parameters in regards to bandwidth nor THD.
 
Last edited:

RayDunzl

Major Contributor
Central Scrutinizer
Joined
Mar 9, 2016
Messages
6,829
Likes
2,953
Location
Riverview, FL
#12
What I find incredible is how tiny the NC500 module is.
I was surprised how small the amplifier in the JBL 3 series is.

1559339227497.png
 

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
18,981
Likes
19,285
Location
Seattle Area
#13
Don’t wanna seem like promoting, but currently the only way I see to get it built for you is by James Romeyn, he charges around $1940 shipped for a pair of the assembled monoblock kits (~$1530 for stereo model, ~$3000 for bridged monoblock pairs).
So is his stereo one using two or one power supply?
 

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
18,981
Likes
19,285
Location
Seattle Area
#14
Is “continuous” that much different than RMS?
The unit is not made for continuous power at max wattage. I can try it but would need permission from the owner as there is always risk of damage. We tried this in NC400 thread.
 

Ron Texas

Major Contributor
Joined
Jun 10, 2018
Messages
1,215
Likes
710
Location
Equidistant From Everywhere
#16
SINAD of 96 DB is likely transparent. I believe the monoblock NC400 kits direct from Hypex are 575 euros each and the single power supply problem is avoided. I don't know the shipping, but they look easy enough for anyone who has ever done any kit to put together.
 
Last edited:

pos

Senior Member
Patreon Donor
Joined
Feb 13, 2018
Messages
317
Likes
271
#17
Thanks for the review @amirm!
Nice to see the long-lasting nc400 vs nc500 debate find its answers, at least with the default buffer (I cannot imagine any boutique buffer measure better than the default one though...)
 

MZKM

Active Member
Joined
Dec 1, 2018
Messages
261
Likes
158
Location
Land O’ Lakes, Florida
#18
So is his stereo one using two or one power supply?
He uses the SMPS1200A400, where as the stereo unit you measured previously used the SMPS600. It looks to be 60€ (<$70 USD) of a difference.

There are two other SMPS1200 models, whose only difference seems to be voltage (the A400 is 64Vdc whereas the A180 is 46Vdc and the A700 is 84Vdc), not sure what different that results in.
 
Last edited:

MZKM

Active Member
Joined
Dec 1, 2018
Messages
261
Likes
158
Location
Land O’ Lakes, Florida
#20
Top Bottom