Nord Three SE 1ET400A Dual Mono Stereo Amp Review

[amirm]

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?

Yes, a Denon is waiting for review.

 

[amirm]

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

Audio Precision doesn't make such measurements easy as strange as that is. I can measure them but it requires work and I don't see a lot of value in them.

 

[maty]

https://www.audiosciencereview.com/...ements-of-nord-one-nc500-amp.7704/post-230766

Nord NC500 mono

I guess it is one of the first implementations.

Hopefully the implementation has improved since then. And not only with the new PURIFI 1ET400A stereo also with NC500 stereo.

 

[boXem]

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.

The supply you measured is the SMPS600N400. It's a Diy only supply and I would be surprised that it's the one used here.
About using 2 supplies in parallel, well, your point is valid even if I personally call this overengineering . I am just wondering if this is not the reason for the THD+N hump at low frequencies in your new test. Concerning your new distortion vs power vs frequency, do you still have the reference design from Purifi for comparison?

Edit: never try to anayse measurements curves on a phone...

 

[Audiocrusader]

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.

Nobody on this forum seems to understand that the NC400's in that review used 600w supplies, and this amp uses 1200w supplies. And these 1200w supplies are capable of 1500w peak. 2 Purifi modules clip at 900w. So there won't be under any circumstances, any performance gains by using dual supplies. We already have 600w more peak power capability than the amp modules will ever draw with a single supply. And since a single 1200w supply will barely be working, under real world conditions there will actually be more heat with dual supplies as now we have 2 devices generating heat in the case rather than 1. So in reality with dual supplies we just end up with 1 more part to wear out and replace, possible channel to channel mismatches like seen in this review, increased idle energy consumption, and increased heat. And with all these disadvantages, absolutely no gains in performance. The 2nd supply is merely there to cater to the audiophile myth the Amir has subscribed to that 1 is good, 2 must be better. So in summary, we need to stop the misinformation on this forum. We need to stop lying to the membership and tell them that "When I performed a teardown of the DIY Hypex NC400 with the same power supply as used here".

 

[JimB]

... the NC400's in that review used 600w supplies, and this amp uses 1200w supplies. ....

Yes, their website specifies TWO SMPS1200's. That is 4X the nominal power supply rating in the box of the first NC400 unit Amir tested. But also, the SMPS1200 is much better on heatsinking , in that it has a large transfer plate that mounts to the case, transferring heat to the outer case, rather than to the air inside the case. I'd take a single SMPS1200 over two SMPS600s. In fact, I have. I've even worked out that I'll use a single SMPS1200 for three NC400s rather than three SMPS600s. Less total heat generated and better heat sinking. As for the benefits of an SMPS1200 for each 1ET400A, it does seem like overkill unless maybe one expected to run consistently at very high power outputs and wanted to maximize PSU life.

 

[maty]

As for the benefits of an SMPS1200 for each 1ET400A, it does seem like overkill unless maybe one expected to run consistently at very high power outputs and wanted to maximize PSU life.

More cheap: silent (Noctua) cooling forced.

https://www.audiosciencereview.com/...ds/vera-audio-class-d-amp-build-quality.9895/

-> https://www.audiosciencereview.com/...io-class-d-amp-build-quality.9895/post-267521

We are using the SMPS3kA700 PSU. We started with two SMPS1200 PSU's but we were not happy with the heat generated in the transformers. When driven hard the temperature reached 120 degrees! The SMPS3kA is surprisingly much better and the hottest spot on the transformer reaches only 88 degrees under same conditions. In fact the SMPS3K is about 50% more powerful than two SMPS1200s.

 

[Audiocrusader]

You will not increase reliability even at high output because even if you were running the 2 Purifi modules to the clipping point all day long every day, the single 1200w supply is not working hard at all. This supply was designed to power the 3 times more powerful NC1200. And be able to do it continuously under high load. So if anything the 2nd supply will reduce reliability by raising the ambient case temp, as well as the heatsink temp. Not to mention 2 supplies to replace when they eventually fail. These supplies run almost as hot at idle as when under load.

 

[JimB]

You will not increase reliability even at high output because even if you were running the 2 Purifi modules to the clipping point all day long every day, the single 1200w supply is not working hard at all. This supply was designed to power the 3 times more powerful NC1200. And be able to do it continuously under high load. So if anything the 2nd supply will reduce reliability by raising the ambient case temp, as well as the heatsink temp. Not to mention 2 supplies to replace when they eventually fail. These supplies run almost as hot at idle as when under load.

More stuff to go wrong, is, more stuff to go wrong, and I'm not advocating using extra, wasted PSUs, but, I'd be quite interested to see some thermal images of the SMPS1200 under some specified output conditions. Standby current is 7W? Their higher efficiencies at lower powers probably beats this. That is, the specs indicate that the total dissipation of a box with two SMPS1200s driving two 1ET400As should be marginally lower than with one SMPS1200, or at the very least, not significantly higher, at output powers of, say, 400W / chan. And, I'd expect the operating temperatures of key devices on those PSUs to be correspondingly lower.

Despite all that, for a compact three channel NC400 amp build (center and rear surrounds, with sub woofers), I determined that I'd be most happy with a single SMPS1200.

EDIT Jan 7, 2021. Two posts below, @Audiocrusader shows data that is different than what I suggested above. They are different from the curves I referenced. Here they are from the latest datasheet - Rev. 10, showing dropping efficiency at highest output. Total heat in the case will be a bit higher with two supplies than one, but component temps should be a bit lower. Either way, the differences are very small, and don't change conclusions on recommendations.

 

[LLL]

Thanks @amirm. Another thorough review.

 

[Audiocrusader]

More stuff to go wrong, is, more stuff to go wrong, and I'm not advocating using extra, wasted PSUs, but, I'd be quite interested to see some thermal images of the SMPS1200 under some specified output conditions. Standby current is 7W? Their higher efficiencies at lower powers probably beats this. That is, the specs indicate that the total dissipation of a box with two SMPS1200s driving two 1ET400As should be marginally lower than with one SMPS1200, or at the very least, not significantly higher, at output powers of, say, 400W / chan. And, I'd expect the operating temperatures of key devices on those PSUs to be correspondingly lower.

Despite all that, for a compact three channel NC400 amp build (center and rear surrounds, with sub woofers), I determined that I'd be most happy with a single SMPS1200.

In the real world people are not going to be running these amps right to clipping continuously. The efficiency of these supplies under 400w drops down to 85% from 90%. So for 98% of most peoples listening, using dual supplies will result in the supplies operating in the lowest region of efficiency. And since there's 2 supplies instead of 1, we're now pissing away 30% of the incoming energy to heat, rather than 10%.

However what these plots don't tell us, is now both supplies are not in an ambient case air temp or heatsink temp of room temperature like they would be without a 2nd supply providing each with an external heat source. And any heat over and above room temp, is going to add directly to the max temp of each of the supplies. Not that temps are going to be an issue in the least anyways. It's just that having this 2nd supply is only really there to fool audiophiles into thinking it's better. When in reality there's nothing but disadvantages. So now if a smart manufacturer who would rather offer an amp at a lower cost by running 1 supply, or putting more money into other areas which will yield higher gains instead, audiophiles will think it sucks because it only has 1 supply. This is what we call audiophile myths, and misinformation.

 

[Victoria]

Ohh finally! Thank you very much Amir for this review!

Kind of what I expected, especially given the previous review of the 1ET400A modules. This definitely makes me a lot more confident in maybe just going ahead and picking up a couple of Hypex NC400 DIY kits though! We'll see.

I also noticed though that Nord doesn't let you spec their 1ET400A amplifiers to just use the stock buffers? Seems a little weird given that they do give that options for some of their other amplifiers. Also, to anyone who has actually owned any Nord products before: how's the build quality in person? I seem to be getting mixed feelings based on their online photos; from some angles their products look super well machined but from other angles you do get the impression that there's quite a few rough edges here and there in their manufacturing.

 

[restorer-john]

but from other angles you do get the impression that there's quite a few rough edges here and there

I think that's pretty much par for the course with most good value things, people included.

 

[Tks]

These supplies run almost as hot at idle as when under load
.

I'm noticing this myself.

For instance in my Vanatoo T1 Encore powered speakers.. Just having them active the back of the speaker is too hot to touch (not that I do this, I set them in place and forget that, but in the beginning I was wondering why so much heat when I am using them for basic TV viewing with others, and other tests I did, just leaving them idle for a few hours, they're simply hot no matter what). Then I noticed on my headphone setup (789 + RME) both are hardly what I would even call warm, but they're always the same temperature regardless of what I am listening to and at what volume. Oddly enough though, sometimes both units get actually decently warm, and sometimes cool. Completely random throughout the day.

I am pretty confused why audio devices function this way regardless of load. From a PC perspective, this is virtually unheard of behavior.

 

[Ceburaska]

Also, to anyone who has actually owned any Nord products before: how's the build quality in person? I seem to be getting mixed feelings based on their online photos; from some angles their products look super well machined but from other angles you do get the impression that there's quite a few rough edges here and there in their manufacturing.

I had an SE case Nord and I think it was fine. Not as nice as my current Sony ES, but on a par with Naim olive amps I’ve had.
I did have a minor issue with the On button, but that is now apparently solved (see comment #21).

 

[hapnermw]

In the real world people are not going to be running these amps right to clipping continuously. The efficiency of these supplies under 400w drops down to 85% from 90%. So for 98% of most peoples listening, using dual supplies will result in the supplies operating in the lowest region of efficiency. And since there's 2 supplies instead of 1, we're now pissing away 30% of the incoming energy to heat, rather than 10%.

View attachment 39195
However what these plots don't tell us, is now both supplies are not in an ambient case air temp or heatsink temp of room temperature like they would be without a 2nd supply providing each with an external heat source. And any heat over and above room temp, is going to add directly to the max temp of each of the supplies. Not that temps are going to be an issue in the least anyways. It's just that having this 2nd supply is only really there to fool audiophiles into thinking it's better. When in reality there's nothing but disadvantages. So now if a smart manufacturer who would rather offer an amp at a lower cost by running 1 supply, or putting more money into other areas which will yield higher gains instead, audiophiles will think it sucks because it only has 1 supply. This is what we call audiophile myths, and misinformation.

This analysis of the value of using dual Hypex SMPS 1200 power supplies to power Hypex/Purifi modules in a stereo amp isn’t quite as comprehensive as it appears. There are at least two data points that conflict with its conclusion.

First, the review of the Purifi single SMPS 1200 amp reports that it shut down during testing of its distortion at power at multiple frequencies. This did not happen with the Nord amp.

Second, the Hypex SMPS 1200 spec includes the following note:

The SMPS1200 is designed for music reproduction and is therefore not able to deliver its maximum output power long-term. The RMS value of any common music signal generally doesn’t exceed 1/8 th of the maximum peak power.

The spec goes on to list its continuous power spec as 325 watts at 230V 50Hz (it also lists some examples where max power at 120V is a bit lower than at 230V). The continuous power of two Purifi modules at 4 ohms in the Nord test is a conservative 514 watts. It’s true that few users will be running their amps at a continuous 160+ watts per channel into 4 ohm speakers. On the other hand, this does indicate that one SMPS 1200 does not support the full operational envelope of the Purifi modules. This may explain why the Purifi amp review sample shut down during power testing.

So, the question is, would you or would you not, prefer having an amp power supply that supports the full operation capability of the amp you are buying even if you never actually plan to use it?

 

[amirm]

FYI, the only two amplifiers that I have killed during measurements so far , have had their power supplies die.

 

[Audiocrusader]

Yes with this Nord amp, the inlet fuse blew before the current limiter in the amp modules, not the power supply, could trigger.

If we were to talk about the continuous output of the Purifi modules into 4 ohms using the same 325W continuous rating Hypex uses for the SMPS1200, the Purifi modules put out around 100w a piece. So combined we have 200w continuous. A long ways below the 325w continuous rating of the SMPS1200. So yes since we are talking about the Purifi 1ET400A modules which output around 100w continuous into 4 ohms, people certainly won't be running them at 160w continuous. So you have that part correct.

 

[boXem]

As far as I remember, the ABH2 was also shutting down during testing.
Did anybody complain about this while listening music?

 

[Audiocrusader]

Oh I may have been a bit high on my continuous power rating of the Purifi modules based on Hypex's standard for continuous. Which they share the exact standard for when rating their supplies. We can see here with their NC-500 modules which are rated for 700WPC into 4 ohms @ 1% THD, they rate them at 100W continuous.