Nord Three SE 1ET400A Dual Mono Stereo Amp Review

[boggit10]

I used to own a NordOne hypex amp and it was largely excellent, 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?

That was an expensive £30 Swiss Schurter switch, we replaced them about 2 years ago and have had no issues with the new one.

 

[Feargal]

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?

Yep, the front button is sticky on my 3 year old Nord One SE too. It also has a rear switch which I use instead. Good to hear from Colin the issue was fixed some time ago.

 

[maty]

Schurter are my favourite (ALL my DC Blockers used them, only the Schurter IEC C14 power inlet with two little fuses) and connectors to. I LOVE the Schurter IEC C13 connector too. But with RF/EMI mains input filters only I trust in Schaffner.

 

[Tks]

Feels odd being indifferent seeing a device rank in the top three of the class.

Maybe due to uninspiring movement in the performance metrics over such a long time. Also the nagging voice in my head that keeps asking.. What are manufacturers waiting for? Either implement the THX modules (or your own feedforward feedback system) into power amps, or do some serious legwork in the same fashion that JDS Labs did with the headphone amp market if you want to flex on others in the most showboating/MSRP justifying way possible.

The products and assembly issues/complaints lately with anything but the Benchmark amp simply leave people off put about these products that even perform relatively well.

Is this the best that can be mustered out of power amps? Makes me want to petition the E1DA creator to put his mark on the power amp market. He seems no-nonsense enough to get this done so we really can get a gauge of this lag in high performers with respect to power amps.

 

[peng]

Good morning Amir, thank you for another great review with measurements. By the way, any chance to see you measure a highly popular mid range AV receiver from Denon and/or Marantz, such as the AVR-X3500H, SR6013 or higher models? Then we can compare theirs to Yamaha, Pioneer, Anthem, NAD and Sony's you have already reviewed/measured.

 

[MediumRare]

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

Could you please explain (or direct me to a resource) on phase accuracy? And, are shifts like this audible?

 

[Matias]

Different device under test, same people with the same arguments that were already answered many times before. It really gets old...

 

[MediumRare]

So, distortion at 5 watts is great, but once you push above 100, things go sideways pretty fast. At 175 watts you’re up by two orders of magnitude. I recall testing amps and 150 watts into 8 ohms just wasn’t quite enough with sensitivity around 90. Obviously a moving target depending on the speakers and room but isn’t clean 200 watts (not at 1% THD, more like .05%) necessary for modern music at club/live levels?

 

[DS23MAN]

Different device under test, same people with the same arguments that were already answered many times before. It really gets old...

Still waiting for the mains filter improvement...

 

[maty]

Could you please explain (or direct me to a resource) on phase accuracy? And, are shifts like this audible?

Not in this thread.

* https://www.diyaudio.com/forums/class-d/321578-phase-shift-class-amplifiers-affects-sound.html

* https://www.diyaudio.com/forums/aksa/294346-brand-super-aksa-saksa-85-a-post4878481.html

by Hugh Dean (AKSA)

6. Many musical qualities are not easily measured. I try to aim at phase shift of no higher than 3 degrees at 20KHz, and ensure that all devices are fast and working with optimal compensation. This forces you to rely on subjective listening, both with the designer and a sample of selected audiophiles who are willing to do the long time listening tests. You do need a lot of tests and measurements regardless; amps must be engineered so that at clip they behave, deliver a higher S/N ratio, that at low levels they sound clear, and with complex music they deliver clean sound with no 'smearing'.

In short, in class D we have a new variable in the equation, which complicates everything. Depending on the phase curve of the speakers, it will affect more or less in some frequency sections.

If the phase is constant, flat, until 20 kHz we forget that possible problem, as class A and class AB amps. All the components of an audio equipment meet that requirement, why should not class D meet it?

Today, with the old TDA 1541, 16-bit DAC chip, in this very good implementation:

https://www.audiosciencereview.com/...rum-anniversary-tda-1541-my-diy-replica.9939/

Only 0.4º at 20 kHz, no problema.

- End off topic -

 

[Killingbeans]

- End off topic -

Nope... You forget your own thread on the subject here at ASR.

And, are shifts like this audible?

Shifts like these in amplifiers are essentially group delays, meaning that it's the amplitude and not the phase that shifts. It is NOT audible.

At least that's my limited understanding of it. I bet other users in here can explain it more clearly.

Obviously a moving target depending on the speakers and room but isn’t clean 200 watts (not at 1% THD, more like .05%) necessary for modern music at club/live levels?

If I pumped 200W into my speakers, it would probably kill me

I don't really care about power ratings. Give me a THD+N vs. W plotting, and I'm happy. That way I can calculate the THD+N for my preferred SPL.

 

[MediumRare]

If I pumped 200W into my speakers, it would probably kill me

I don't really care about power ratings. Give me a THD+N vs. W plotting, and I'm happy. That way I can calculate the THD+N for my preferred SPL.

200 w continuous is frighteningly loud, but 20 w continuous is plausible on occasion (I was there just last night). The headroom beyond 20 has to be there for transients, hence clean 200 as a requirement. My issue is that many amps’ power ratings allow up to 1% THD at peak power. That’s not clean.

I want to have @amirm test my amp but it’s too heavy to ship. The rated THD is 0.005% at all power levels up to 200 wpc into 8 ohms and I run into 4 ohms.

 

[Killingbeans]

My issue is that many amps’ power ratings allow up to 1% THD at peak power. That’s not clean.

Setting the power rating at the knee like Amir does is definitely the most honest way.

I guess it's just easier to write '1%' on a product description than it is to write 'the point where things go sour fast'

 

[BDWoody]

Feels odd being indifferent seeing a device rank in the top three of the class.

Maybe due to uninspiring movement in the performance metrics over such a long time. Also the nagging voice in my head that keeps asking.. What are manufacturers waiting for? Either implement the THX modules (or your own feedforward feedback system) into power amps, or do some serious legwork in the same fashion that JDS Labs did with the headphone amp market if you want to flex on others in the most showboating/MSRP justifying way possible.

The products and assembly issues/complaints lately with anything but the Benchmark amp simply leave people off put about these products that even perform relatively well.

Is this the best that can be mustered out of power amps? Makes me want to petition the E1DA creator to put his mark on the power amp market. He seems no-nonsense enough to get this done so we really can get a gauge of this lag in high performers with respect to power amps.

Why I still love my old amps...
I don't mind the heat...starting to get cold out anyway.

 

[oldsysop]

@amirm : ¿Se pueden incorporar amplificadores de velocidad de respuesta y factor de amortiguación en las mediciones?

 

[MediumRare]

Amir: Can Slew Rate and Damping Factor amplifiers be incorporated into measurements?

Curious what you're looking for? My understanding is all modern amps have solved both these issues.

 

[Deleted member 2944]

Nope... You forget your own thread on the subject here at ASR.



Shifts like these in amplifiers are essentially group delays, meaning that it's the amplitude and not the phase that shifts. It is NOT audible.
At least that's my limited understanding of it. I bet other users in here can explain it more clearly.

Your "limited understanding" is entirely correct. This is a frequency-independent effect in this context. Something maty still (after all this time) seems incapable of understanding.

Dave.

 

[amirm]

You write that the dual mono probably will last a lot longer than the stereo version.
Could you elaborate a bit on this please?

When I performed a teardown of the DIY Hypex NC400 with the same power supply as used here, I found that to have the hottest components: https://www.audiosciencereview.com/...-hypex-nc400-diy-amp.5907/page-19#post-134676

As you see, the bottom module which is the power supply is much hotter than either (round) amplifier modules. And if my memory is right, the power supply also uses second or third-tier capacitors which means they also should be kept cool for best life.

By using two power supplies in this Nord build, the load, and the heat is spread across both of them, resulting in cooler operation. And longer life.

Related, the amplifiers dissipate their heat through the case since their power transistors are mounted to the bottom plate. The power supply on the other hand is relying on that one bent piece of aluminum for cooling so much less efficient.

 

[maty]

Efficiency.

* PURIFI 1ET400A - > 94% How much?

* Hypex NC400 - 93%

* Hypex NC500 - 93%

* Hypex NC1200 - 93%

 

[amirm]

Can you ask permission from its owner to open it and take pictures of the inside?

A teardown will be coming later today.