Review and Measurements of Hypex NC400 DIY Amp

[JimB]

The start of this thread, or maybe other threads I've read, raised some doubt about the quality or long term viability of the SMPS600. Other posts I've come across suggest that either, or both, the SMPS600 or 1200 may have been upgraded recently. So is one "better" than the other in terms of long term viability? Also, is there a post or thread on just how to bridge the NC400's?

Then again, maybe I should just take audioBliss's advice and stop sweating it and just build the mono's from hypex (although I prefer the stereo kits from Ghent as it would work better with my system and would only require one power cord).

I have built and used the two variants of NC400 stereo amps that Ghent supports, the Ncore-SE(200W) and the Ncore-SE(300W), where the difference is only the width. Both go together fine. The 300 mm wide case costs a bit more, but is less cramped inside, and obviously, has better cooling. In both cases (pun intended), I used a single SMPS1200, as I prefer it for heat sinking and total dissipation*. I used a bit of thermal compound under all three modules to get a bit lower device temperatures. I don't feel like I'm missing something relative to two mono cases with SMPS600s (done that too!).

* Others have noted that there is a shortcoming of the SMPS1200 for driving the NC400. The NC400 has its own Vdr regulator in case there is inadequate voltage from the power supply. The Vdr value from the SMPS1200 is about 1V short of meeting that requirement, so the NC400 provides it, and then each one dissipates about 5W more (about doubling its idle dissipation). Presumably, the SMPS1200 then dissipates a little less than it would, otherwise.

FWIW, I was deep into the case and assembly specs for a 3-channel build with a single SMPS1200 (more than adequate for a center speaker plus two surrounds, with the matching two channel case for FL and FR), but I've stopped that while I sort out my goals with Purifi module amps.

 

[BobPM]

I'm sold. The amp in the Ncore-SE(300W) case looks perfect. If I really think more power is required in the future, I can just build another one and bridge the NC400 modules.

 

[JimB]

I'm sold. The amp in the Ncore-SE(300W) case looks perfect. If I really think more power is required in the future, I can just build another one and bridge the NC400 modules.

Right. And you can use two SMPS600s in that case if you prefer, as their website shows.

 

[DDF]

I have built and used the two variants of NC400 stereo amps ... I used a single SMPS1200

That break out board is brilliant. I hand soldered a SMPS1200<->2xNC400 interconnect cable (board wasn't available yet), which doubled the work. You can see the diode kludge they attempted, to pull Vdr up to the level needed by the NC400, but it didn't work and they subsequently populated it with a jumper.

 

[HeavyMantra]

I don't see where the IEC is grounded, be very careful, I'd take it to a guy who knows what he's doing and make very sure it's safe--unless, of course, you own a home defibrilator and have a loved one who's trained in how to use it.

Thanks, I should probably open them up and have look. They work fine though

 

[Xyrium]

So, is the net of this giant thread such that Hypex modules produce only about 25% of their "rated" output as "continuous"? Sorry, I got to page 28 and that's where I began to shrug my shoulders.

I have an NAD C368, which NAD claims does 80W "continuous", of course, into 1kHz, but "continuous" nonetheless. Inside, it appears to be a puny amp module and equally puny power supply, which leads me to believe that they either read the Hypex specs wrong, or never measured the output for the "continuous" rating. It would seem that they would need 2x400W modules with that single power supply, to produce just 75W "continuously".

These two sites seem to support the NAD specs, but:

https://audio.com.pl/testy/stereo/wzmacniacze-stereo/2790-c368 (Actually seems to test maximum output compared to continuous)
https://stereo-magazine.com/review/nad-c368-review

 

[rodtor]

So, is the net of this giant thread such that Hypex modules produce only about 25% of their "rated" output as "continuous"? Sorry, I got to page 28 and that's where I began to shrug my shoulders.

I have an NAD C368, which NAD claims does 80W "continuous", of course, into 1kHz, but "continuous" nonetheless. Inside, it appears to be a puny amp module and equally puny power supply, which leads me to believe that they either read the Hypex specs wrong, or never measured the output for the "continuous" rating. It would seem that they would need 2x400W modules with that single power supply, to produce just 75W "continuously".

These two sites seem to support the NAD specs, but:

https://audio.com.pl/testy/stereo/wzmacniacze-stereo/2790-c368 (Actually seems to test maximum output compared to continuous)
https://stereo-magazine.com/review/nad-c368-review

I have the NAD C368 as well. I think that the 80 watt continuous rating might be accurate enough, into 8 ohms. As you say, it is confirmed by the two sources you cite. I also don't find it noticeably less powerful than an old Sony amp I own, and that is rated at 100 watts per channel. But, yes, there are times when I wish it had a bit more.

Regarding the NC 400: There has been some discussion in various threads about how Hypex reports its power ratings. Amir's test here found it falling short of the 'advertised' 400 watts into 4 ohms, but remember 2 things : The power supply in this particular assembly was less than that recommended by Hypex, and Amir's power rating, based on the 'hockey stick curve' is more conservative than some others. Based on his estimates and discussion, and the Hypex documentation, I would guess that the NC400 would produce around 270 watts continuous into 4 ohms, using his method, and about half that into 8.

 

[Xyrium]

I have the NAD C368 as well. I think that the 80 watt continuous rating might be accurate enough, into 8 ohms. As you say, it is confirmed by the two sources you cite. I also don't find it noticeably less powerful than an old Sony amp I own, and that is rated at 100 watts per channel. But, yes, there are times when I wish it had a bit more.

Regarding the NC 400: There has been some discussion in various threads about how Hypex reports its power ratings. Amir's test here found it falling short of the 'advertised' 400 watts into 4 ohms, but remember 2 things : The power supply in this particular assembly was less than that recommended by Hypex, and Amir's power rating, based on the 'hockey stick curve' is more conservative than some others. Based on his estimates and discussion, and the Hypex documentation, I would guess that the NC400 would produce around 270 watts continuous into 4 ohms, using his method, and about half that into 8.

Hi Rodtor, thanks for your reply. I also find myself turning the volume up far more than on previous "75W" amps, and definitely more than my previous setup into the baby of the Parasound Halo lineup, the A23. THis is the reason why this thread leads me to question the validity of the NAD specs. When I crank this little guy so I can play drums or guitar along with the music, it seems to run out of steam, even as I near the 0dB point on the volume. The tiny Dynaudio m10s I have attached aren't struggling to keep up either. So, the sound seems clear, timbre is still reasonably intact, but the amplitude is lacking.

Speaking of Amir's test, the power supply and amp module in the C368 are tiny. If Hypex only specs 75W continuous out of their "400W" module, then I'm quite certain that the module in the C368, which is only spec'd at 100W, is probably more like 25W continuous: https://www.hypex.nl/product/ucd102-oem/52
Spec sheet (direct link): https://www.hypex.nl/documenten/download/838

 

[rodtor]

Hi Rodtor, thanks for your reply. I also find myself turning the volume up far more than on previous "75W" amps, and definitely more than my previous setup into the baby of the Parasound Halo lineup, the A23. THis is the reason why this thread leads me to question the validity of the NAD specs. When I crank this little guy so I can play drums or guitar along with the music, it seems to run out of steam, even as I near the 0dB point on the volume. The tiny Dynaudio m10s I have attached aren't struggling to keep up either. So, the sound seems clear, timbre is still reasonably intact, but the amplitude is lacking.

Speaking of Amir's test, the power supply and amp module in the C368 are tiny. If Hypex only specs 75W continuous out of their "400W" module, then I'm quite certain that the module in the C368, which is only spec'd at 100W, is probably more like 25W continuous: https://www.hypex.nl/product/ucd102-oem/52
Spec sheet (direct link): https://www.hypex.nl/documenten/download/838

Yes, I'm not sure quite what to make of what Hypex means by 'continuous ' in its data sheets. My guess is that @March Audio and others here who are very familiar with these amps would say that the rating quoted above that one in the data sheets represents what most manufacturers call 'continuous ', though these would still be inflated compared to Amir's.

I don't know your speakers, but I wonder whether they might represent part of your problem; you mention that they are small. I use PSB X2Ts (floor standers) and recently added a sub. Most of the time I find this quite adequate, with enough power for my needs. Might adding a sub help your situation?

 

[audioBliss]

Take all the power figures here and dubble them and you get what the mono blocks will give you. But the mono blocks will be even more quiet as suggested when he did the measurement for one channel. The 400W is correct it's just confusing since usually 8Ohm power is the figure being talked about but the 400W is what these deliver in 4Ohm. The NC1200 for instance does not give you 1200W in 8 Ohm since that is the 2Ohm power figure

The NC400 is 200W 8Ohm, 400W 4Ohm, 580W 2Ohm like it says on their own website.

The continuous power rating for NC400 is 100W if I remember correctly.

But then people want to save money and buy multiple nc400 modules separately and the power supply that's intended to power just one of the modules. That's the issue with these power figures that it's missing a power supply.

In my opinion the continuous power is not as interesting. 100W continuous into your speakers is pretty damn loud.

As for turning the volume up more than with previous amps says not about the power of the amp at all. The amount of gain you get depends on the amps gain in combination with the pre-amps gain. The THX standard is 29dB gain but a lot of PA amps for instance have like 34dB gain and the nc400 have 26dB. So every notch on the volume nob would do less on something that has 26dB gain.

 

[Xyrium]

Yes, I'm not sure quite what to make of what Hypex means by 'continuous ' in its data sheets. My guess is that @March Audio and others here who are very familiar with these amps would say that the rating quoted above that one in the data sheets represents what most manufacturers call 'continuous ', though these would still be inflated compared to Amir's.

I don't know your speakers, but I wonder whether they might represent part of your problem; you mention that they are small. I use PSB X2Ts (floor standers) and recently added a sub. Most of the time I find this quite adequate, with enough power for my needs. Might adding a sub help your situation?

Thanks guys. I do have a sub, but the Dyns just need to represent the above 100Hz spectrum for my needs. They are indeed rated at almost double the continuous output of the NAD, so they could easily take the power, they just aren't getting it from the NAD. I'll do some additional reading on the topic, because this interests me, and it appears that some serious implications were brought to bear in this thread.

@audioBliss: 100W is indeed very loud. I have a 90W Mesa Boogie Mark V amp, and it will blow the doors off of most homes into a 4x12 cab. That is what leads me to believe that the 1.5dB reduction or so down to the rated 80W of this amp, is not what it seems. You also mention input voltage, of which I recently ordered a Topping D10 just to see where this stands. More to come!

 

[JimB]

Yes, I'm not sure quite what to make of what Hypex means by 'continuous ' in its data sheets. My guess is that @March Audio and others here who are very familiar with these amps would say that the rating quoted above that one in the data sheets represents what most manufacturers call 'continuous ', though these would still be inflated compared to Amir's. ...

Let's be realistic about what continuous means for music. Unless you plan on high levels of distortion, continuously, you are not going to be able to play over about 1/3 of peak capability as the continuous average output of power, and that is somewhat extreme. Real music (not special tone tests) is not an absolutely steady level - you need room for peaks. This is addressed in the Hypex datasheet for the NC400 module. Two things outside the amp module itself are going to impact its output: heatsinking and power supply. With quite reasonable heatsinking, it is certainly able to output 133W (into 4 ohms), "continuously". In their "intensive use" example, you could play, continuously, with 400W peaks, and 133W average output. Put another way, it should be relatively easy to implement these modules to play music, up to full rated output on peaks, continuously. The Hypex mono case kit certainly can do this. But you can build an amp with these modules that will not achieve it. That is certainly true of the example tested for this review, where TWO modules were powered by a single power supply rated for ONE amp module. Even that is fine, as long as you are not trying to run at levels above what the power supply can support. For the tested amplifier, it is likely just fine for both channels, simultaneously, up to maximum output for 8 ohm loads. This is DIY - you can build what you want.

 

[rodtor]

Let's be realistic about what continuous means for music. Unless you plan on high levels of distortion, continuously, you are not going to be able to play over about 1/3 of peak capability as the continuous average output of power, and that is somewhat extreme. Real music (not special tone tests) is not an absolutely steady level - you need room for peaks. This is addressed in the Hypex datasheet for the NC400 module. Two things outside the amp module itself are going to impact its output: heatsinkng and power supply. With quite reasonable heatsinking, it is certainly able to output 133W (into 4 ohms), "continuously". In their "intensive use" example, you could play, continuously, with 400W peaks, and 133W average output. Put another way, it should be relatively easy to implement these modules to play music, with 400W peaks (into 4 ohms), continuously. The Hypex mono case kit certainly can do this. But you can build an amp with these modules that will not do that achieve it. That is certainly the case with the example tested for this review, where TWO modules were powered by a power supply rated for ONE amp module. Even that is fine, as long as you are not trying to run at levels above what the power supply can support. For the tested amplifier, it is likely just fine for both channels, simultaneously, up to maximum output for 8 ohm loads. This is DIY - you can build what you want.
View attachment 47388

Thank you for this informative discussion, @JimB; very helpful. I have been thinking of building, or purchasing from Audiophonics, a pair of NC400 monoblocks. From all I've seen here, including your input, I doubt that I would need more power. And the measurements for THD&N and so forth are impressive.

 

[JimB]

Thank you for this informative discussion, @JimB; very helpful. I have been thinking of building, or purchasing from Audiophonics, a pair of NC400 monoblocks. From all I've seen here, including your input, I doubt that I would need more power. And the measurements for THD&N and so forth are impressive.

Their MPA-M400NC looks well assembled and a good value. Their stereo version, HPA-S400NC, also looks well made, but for that fancier case, you'll pay more than double the price of the mono version. It depends what you value.

 

[Xyrium]

Pretty common for two channels to cost twice the price of one.

You save with the stereo version because you'd only have to buy one fancy, audiophile approved, esoteric power cable for $5M for the stereo version, vs two for monoblocks.

 

[rodtor]

Their MPA-M400NC looks well assembled and a good value. Their stereo version, HPA-S400NC, also looks well made, but for that fancier case, you'll pay more than double the price of the mono version. It depends what you value.

Yes, I noticed that the stereo version costs more than two monoblocks, which seemed odd. I don’t think I need the fancier case.

 

[Julf]

Yes, I'm not sure quite what to make of what Hypex means by 'continuous ' in its data sheets.

The continuous power is limited by heat and power supply.

Here is the worst case, two NC400s fed by one shared SMPS600, no extra cooling:

 

[rodtor]

The continuous power is limited by heat and power supply.

Here is the worst case, two NC400s fed by one shared SMPS600, no extra cooling:

View attachment 47408

Thanks, @Julf. That looks like the power supply that Amir tested here. Are you aware of similar data for the presumably more typical scenerio of one SMPS 600 power supply for each amp?

 

[Julf]

Thanks, @Julf. That looks like the power supply that Amir tested here. Are you aware of similar data for the presumably more typical scenerio of one SMPS 600 power supply for each amp?

Unfortunately not.

 

[March Audio]

Yes, I'm not sure quite what to make of what Hypex means by 'continuous ' in its data sheets. My guess is that @March Audio and others here who are very familiar with these amps would say that the rating quoted above that one in the data sheets represents what most manufacturers call 'continuous ', though these would still be inflated compared to Amir's.

I don't know your speakers, but I wonder whether they might represent part of your problem; you mention that they are small. I use PSB X2Ts (floor standers) and recently added a sub. Most of the time I find this quite adequate, with enough power for my needs. Might adding a sub help your situation?

I'm not sure under what conditions they derive the "continuous" rating, its not stated in the spec sheets, but its not representative of any testing I have performed. It will be limited by the power supply and heat as Julf says above. In Julfs data it states there is no further cooling which I assume to mean no heatsink. They wouldn't be run like that in a real product.

In my testing they do what they say on the tin. In fact Amir's test of our P502 it exceeded the rating. Rated at 500 watts it achieved 553 watts and burst testing showed 630 watts.

As has been already been mentioned don't forget that music does not have a high rms level. It might only be 1/5th of the peak so in the example above it might only be around 100 watts.

Just for interest here is our P252 running an FTC type of power test. It's conditioned at 1/3rd power for an hour followed by full rated power (250 watts per channel) for 5 minutes.

In Amir's test the NC400 power output was limited by the power supply. Too small for two nc400s