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Nord Three SE 1ET400A Dual Mono Stereo Amp Review

amirm

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#1
This is a review and detailed measurements of the Nord Three SE 1ET400A Dual Mono Stereo Amp with the optional Sonic Imagery 990Enh gain stage. With that option, the cost is £1,979.00 excluding VAT. This translates into US $2,554. The unit was purchased new and drop shipped to me by a kind member. I had previously measured the reference design from Purifi so will be good to see how this version rates with a different input stage.

The Nord dual monoblock comes in a very attractive enclosure (most of which is not visible in this image):

Nord Three SE 1ET400A Dual Mono Stereo Amp With  Sonic Imagery 990Enh Audio Review.jpg

Efficiency of class D amplifiers and switchmode power supply enables such slim case to be used. There are two rows of heatsinks on the sides but they are decorative for the most part. I will do a teardown separately. For now, the amplifiers dissipate heat into the bottom of the chassis and dual power supplies have their own heatsinks inside the box.

The back panel shows seriously beefy and nice feeling speaker connectors:

Nord Three SE 1ET400A Dual Mono Stereo Amp With  Sonic Imagery 990Enh Back Panel Audio Review.jpg

When I received the unit, it immediately shut down. The reason was a blown fuse. I replaced it with a spare that comes in the IEC holder. That worked for all but my last test which is the strenuous power vs frequency. I have let Colin know that I think the fuse amperage needs to be increased given our low operating voltage in US. Note that with music you are not going to hit this easily so it is more of an issue of lab/stress testing. I don't have a higher amp fuse to try with it until a batch arrives on Monday. The fuse is the smaller 5x25mm which I only have a few of in low amperage (usually are used in multimeters and such).

Other than this, the amplifier was solid in its performance never shutting down or complaining. The enclosure didn't even get warmer than room temperature. Inclusion of two power supplies here relieves my worry of a the power supply being the weak link, not the amplifier.

Amplifier Audio Measurements
As usual we start with our dashboard of 5 watts into 4 Ohm at 1 kHz:

Nord Three SE 1ET400A Dual Mono Stereo Amp With  Sonic Imagery 990Enh Audio Measurements.png


This is right on the money as far as THD+N and hence SINAD:
Best Stereo Audio Amplifier Reviewed.png


Which is great news of course.

Noise performance also matched the Purifi reference design:

Nord Three SE 1ET400A Dual Mono Stereo Amp SNR Audio Measurements.png


We have a very low distortion and very low noise floor. This is all that you would want to ask an amplifier. That, and power so let's see how it does there:

Nord Three SE 1ET400A Dual Mono Stereo Amp With  Sonic Imagery 990Enh Power into 4 Ohm Audio M...png


Dual power supplies don't give you more power as we are essentially matching the reference design with one power supply.

I was surprised to see a rise in distortion with one channel worse than the other. Is this the Sonic Imagery 990Enh gain stage in play or were we given better evaluation samples at announcement? We won't know until we test another amp that uses Purifi gain stage.

Same issue exists at 8 ohm although not as exaggerated:

Nord Three SE 1ET400A Dual Mono Stereo Amp With  Sonic Imagery 990Enh Power into 8 Ohm Audio M...png


This makes me think the issue may be in the amplifier.

Note that this is not an audible concern so don't jump off the cliff please. :)

We see an exaggerated version of the same in intermodulation distortion relative to input level:

Nord Three SE 1ET400A Dual Mono Stereo Amp With  Sonic Imagery 990Enh IMD Audio Measurements.png


Frequency response is flat and similar to reference design:
Nord Three SE 1ET400A Dual Mono Stereo Amp With  Sonic Imagery 990Enh Frequency Response Audio...png


Sweeps of power versus frequency gives us varying curves (ideal = all curves on top of each other):

Nord Three SE 1ET400A Dual Mono Stereo Amp With  Sonic Imagery 990Enh Power vs Frequency vs Le...png


We see that at 20 Hz where we need most power, we have least amount of it. This is typical of amplifiers since 20 Hz tone changes slowly not giving a chance for power supply capacitors to recharge between cycles.

Finally here is the 19+20 kHz at the same 5 watt power of Purifi reference design:

Nord Three SE 1ET400A Dual Mono Stereo Amp With  Sonic Imagery 990Enh 19+20 kHz Audio Measurem...png


The pair around the main tone are identical to reference design. Noise floor is a hair higher but that is probably run to run variation.

Conclusions
The Nord Three SE 1ET400A Dual Mono Stereo Amp is an attractive build of the Purifi class D amplifier technology. The dual mono configuration raises the price fair but but my belief is that it will last a lot longer than the single power supply version. Measured performance is just a bit worse than Purifi reference design as power increases beyond 25 watts or so. Not an audible difference but would be good to figure out where this is coming from. I can't detect any improvement from Sonic Imagery discrete 990enh opamps. So personally I would go with the stock gain stage and save enough money for a night out alone.

I am happy to recommend the Nord Three SE 1ET400A Dual Mono Stereo Amplifier. It builds on state-of-the-art Purifi amplifier modules and delivers it in nice packaging.

--------
As always, questions, comments, corrections, etc. are welcome.

The Pink Panthers are making up their Christmas list and I can tell you it is going to be a long, long list. The have become sophisticated enough to create their lists on Amazon! One has been daring enough ot put in Caviar for heaven's sake! I am going to need money and lots of it. So please donate generously using : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 
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VintageFlanker

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#5
Dual power supplies don't give you more power as we are essentially
Hum. To be honest, I was expecting a significant increase in power, thinking the reference design was limited with only one SMPS.:confused:

The Purifi specs still claim 450W/4ohms and 225/8ohms at maximum. So, no way to reach these numbers? We're still far.

In the same league, I would be curious to see NC400 mono amps, see if the power goes up with two SMPS or not.
 
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amirm

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#6
The Purifi specs still claim 450W/4ohms and 225/8ohms at maximum. So, no way to reach these numbers?
Their criteria is different than mine. I stop when at the knee of the curve. Others pick some distortion number and then see how much power there is. They use a much higher level than what I show. And that translates to larger numbers.
 

VintageFlanker

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#7
Their criteria is different than mine. I stop when at the knee of the curve. Others pick some distortion number and then see how much power there is. They use a much higher level than what I show. And that translates to larger numbers.
Alright. In your review of IOM NC252MP, you published Peak Power that basically matched the Hypex specs:
Peak power is sadly not much more than steady state due likely to regulated power supplies:


Would you please do the same for the Nord?:)
 

amirm

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#8
Would you please do the same for the Nord?:)
I can't. As I reported, the fuse blew when I tried to push it that way. I have some coming in on Monday so I can continue then.

It uses these miniature fuses which are not common. I only have a few values of that and are too low.
 

restorer-john

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#9
The Purifi specs still claim 450W/4ohms and 225/8ohms at maximum. So, no way to reach these numbers? We're still far.
Alright. In your review of IOM NC252MP, you published Peak Power that basically matched the Hypex specs:
The Hypex and Purifi specs are in my opinion, blatantly misleading, cherry picked, and full of superlatives they cannot backup. You get statements like this absolute pearler:

"1ET400A is a single-channel, ultra-high performance, analog-input Class D Amplifier module capable of over 400W of power at an audio quality level that sets the standard for power amplifiers of any operating class."

Their own datasheets and Amir's testing show that at [email protected], the amplifier's THD at 1KHz is nearly 1%. Wow, that's really setting the audio quality level standard isn't it? Not. There are hundreds if not thousands of amplifiers that can deliver [email protected] with THD well under 1%.

But Purifi will protest and say, Oh, wait a minute, that magic 400W (rated [email protected]%) is achieved at 2ohms, but:

1573975080252.png


So, here we go again. It's not continuous, and the only standard it will set is for the shortest operation time before it shuts down at that "audio quality level" from overheating because nobody can get rid of the heat quick enough before the thermal protection kicks in to 'protect' itself...
European specifications are rubber- they make them up, stretch them a bit for the marketing message and then massage them a bit more. In short, they are bullsh#t specs.


Here's their "product brief". Negligible (0.00017%)THD at rated power? No way. Maybe at less than a quarter of rated power. What a joke.
1573973371324.png


You know me, I want truth in advertising, truth in specifications and perhaps a return to honesty in a field which has been wrecked by charlatans and scammers. Purifi can do a whole lot better and rate their chit according to the gold standard, the FTC amplifier rule. Anything else is a waste of time and not worth the paper it is written on, be it white or PDF.
 
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#10
@amirm. Thank you for yet another interesting review.

You write that the dual mono probably will last a lot longer than the stereo version.
Could you elaborate a bit on this please?
what lifespan do you think we can expect from these amps?
 

Thomas savage

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#11
The Hypex and Purifi specs are in my opinion, blatantly misleading, cherry picked, and full of superlatives they cannot backup. You get statements like this absolute pearler:

"1ET400A is a single-channel, ultra-high performance, analog-input Class D Amplifier module capable of over 400W of power at an audio quality level that sets the standard for power amplifiers of any operating class."

Their own datasheets and Amir's testing show that at [email protected], the amplifier's THD at 1KHz is nearly 1%. Wow, that's really setting the audio quality level standard isn't it? Not. There are hundreds if not thousands of amplifiers that can deliver [email protected] with THD well under 1%.

But Purifi will protest and say, Oh, wait a minute, that magic 400W (rated [email protected]%) is achieved at 2ohms, but:

View attachment 39091

So, here we go again. It's not continuous, and the only standard it will set is for the shortest operation time before it shuts down at that "audio quality level" from overheating because nobody can get rid of the heat quick enough before the thermal protection kicks in to 'protect' itself...
European specifications are rubber- they make them up, stretch them a bit for the marketing message and then massage them a bit more. In short, they are bullsh#t specs.


Here's their "product brief". Negligible (0.00017%)THD at rated power? No way. Maybe at less than a quarter of rated power. What a joke.
View attachment 39082

You know me, I want truth in advertising, truth in specifications and perhaps a return to honesty in a field which has been wrecked by charlatans and scammers. Purifi can do a whole lot better and rate their chit according to the gold standard, the FTC amplifier rule. Anything else is a waste of time and not worth the paper it is written on, be it white or PDF.
pussy_galore_james_bond_films_redonline.co.jpg
 

VintageFlanker

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#12
You know me, I want truth in advertising, truth in specifications and perhaps a return to honesty in a field which has been wrecked by charlatans and scammers.
Sure thing. At least, the datasheet of my ICEpower 1200AS2 is quite clear about this, under which conditions power specs are given. For example, max peak power: "one channel driven", stereo peak power: "90 seconds before the module shut down" etc, etc.
 

Thomas savage

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#14
I still have a soft spot for Pussy and her entire Flying Circus. Even now I'd still want a Piper Cherokee.
Well Shaun here is clearly thinking " she is serious, this looks dangerous but ..., I like it".
 

Fred Jacquot

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#15
The Hypex and Purifi specs are in my opinion, blatantly misleading, cherry picked, and full of superlatives they cannot backup. You get statements like this absolute pearler:

"1ET400A is a single-channel, ultra-high performance, analog-input Class D Amplifier module capable of over 400W of power at an audio quality level that sets the standard for power amplifiers of any operating class."

Their own datasheets and Amir's testing show that at [email protected], the amplifier's THD at 1KHz is nearly 1%. Wow, that's really setting the audio quality level standard isn't it? Not. There are hundreds if not thousands of amplifiers that can deliver [email protected] with THD well under 1%.

But Purifi will protest and say, Oh, wait a minute, that magic 400W (rated [email protected]%) is achieved at 2ohms, but:

View attachment 39091

So, here we go again. It's not continuous, and the only standard it will set is for the shortest operation time before it shuts down at that "audio quality level" from overheating because nobody can get rid of the heat quick enough before the thermal protection kicks in to 'protect' itself...
European specifications are rubber- they make them up, stretch them a bit for the marketing message and then massage them a bit more. In short, they are bullsh#t specs.


Here's their "product brief". Negligible (0.00017%)THD at rated power? No way. Maybe at less than a quarter of rated power. What a joke.
View attachment 39082

You know me, I want truth in advertising, truth in specifications and perhaps a return to honesty in a field which has been wrecked by charlatans and scammers. Purifi can do a whole lot better and rate their chit according to the gold standard, the FTC amplifier rule. Anything else is a waste of time and not worth the paper it is written on, be it white or PDF.
Fighting marketing bull is a noble cause, but I am wondering if you have chosen the right target. Purifi and Hypex are not OEM, they supply to OEMs. Why don't you shoot at AKM, ESS, TI,... because no DAC ever measured here has reached the components specification? BTW, ever looked at a product brief from ESS?
In example, we both know very well that amplifier power is deeply linked to the power supply. Purifi says 450W at 65V. The Nord and reference modules use an SMPS1200A400 which is rated typical 63VDC at 230VAC. Delivered power is lower than component spec. Not really a surprise.
 

Ceburaska

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#18
I used to own a NordOne hypex amp and it was largely excellent, with two caveats.
Firstly, it got rather hot. So it’s good to see this doesn’t. Secondly, the on/off button kept getting stuck in the off position, and I had to open the top and jiggle round inside a bit to get it to pop out. This happened at least five times in a year of owning it.
So when you do the tear down, can you have a look at the on/off button please?
 

maty

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#19
Another request, when it is possible, can you measure the phase? To compare with that of the Hypex NC400.

Bruno Putzeys said it is only at 20 kHz in the PURIFI 1ET400A, an excellent data.

https://www.audiosciencereview.com/...ments-of-hypex-nc400-diy-amp.5907/post-132771

Here is the corrected results:



Before it was about 16º at 20 kHz. The corrected result is much worse: 41º at 20 kHz.


BOSC 150W HiFi Monoblock GaN Audio Amplifier

https://orchardaudio.com/bosc at 30 kHz

Bosc-150W-GaN-Amplifier-gain-phase-shift.png


To me is a very important data if I decide to buy the future PURIFI kit module. And other SMPS with much better components and cheaper than Hypex SMS1200, a new Cresnet SMPS probably.
 
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