Hypex NCx500 Class D Amplifier Review

[Tom22]

„headroom for peace of mind“ (quote @Sokel ) is the keyword here and the ultimate goal for any audiophile

The R3 seems not really difficult to drive and while an NC252MP would for sure be sufficient, I perfectly understand your thoughts…sometimes you just want to go for the ultimate solution, overkill or not.

I had the same thought with the Monos as impedance sinks to 1 Ohm > 10 kHz, but with an overall impedance of 3.5 Ohms it is probably not really necessary. But heck, it‘s not always about pure necessities, as you can see with cars…

 

[Sokel]

„headroom for peace of mind“ (quote @Sokel ) is the keyword here and the ultimate goal for any audiophile

The R3 seems not really difficult to drive and while an NC252MP would for sure be sufficient, I perfectly understand your thoughts…sometimes you just want to go for the ultimate solution, overkill or not.

I had the same thought with the Monos as impedance sinks to 1 Ohm > 10 kHz, but with an overall impedance of 3.5 Ohms it is probably not really necessary. But heck, it‘s not always about pure necessities, as you can see with cars…

Yep.
I mean it's not even a price consideration if it fits,price difference between smps3ka700 and smps1200A700 is about 80 euros (240 vs 320 euros VAT included)??
Totally worth it.

 

[Tom22]

145 x 200 mm vs. 105 x 165 mm, so it is bigger and would require a different case design…I cannot evaluate the choice of PSU but boXem, Apollon and colleagues will have their reasons to go for the 1200A700…

 

[Sokel]

By eye only,it seems to fit with the Apollon dual PSU case some posts ago (it should be also cheaper! ) right in the middle between modules and with IEC filter on it's side.
But I'm maybe wrong.

 

[boXem]

The SMPS3k is in theory not adapted to "single ended" modules like the NCx500; 1ET400A, 1ET7040SA, ... With some tricks it can be used for stereo designs using such modules.

 

[peng]

28 A is the short circuit detection thresholds. You have to compare it to peak values, not RMS. 14.14 A RMS is 20 A peak.
Doesn't change the fact that 28 A is plenty, as is the 25 A limit from the 1ET400A.

I would like to compare peak values too. In this case, I used RMS current, because I thought the 800 W referenced to, is average power output, so to calculate current using the power formula will result in rms current, not peak current. If we were to compare the peak current draw by the OP's reference 3 meta's maximum peak current, we would have to know the value.

 

[peng]

Is the KEF R3 really survives around 1 kW input power for the claimed 113,5 dB peak SPL with it's twin 6,5" woofers and a regular 1" dome?

If the duration is short enough for the peak, I would say probably yes, and if you are talking about "survives", regardless of sound quality.

KEF website says the following about their maximum output spec:

Maximum Output

UTS – Maximum Output

us.kef.com

Maximum Output is the highest SPL (Sound Pressure Level) a loudspeaker can produce over an extended period. Burst, or transient volume is not measured as that number can ne quite high but is misleading. Proper measurement of Maximum Output is on the form of an average.

Based on that, is the 113.5 dB really peak SPL? The specs just say maximum, did not say peak. We should ask KEF for clarification.

 

[peng]

I'm now considering two Apollon mono blocks. This is the configuration that Hypex recommends and also reviewed by Amir.

These are the reasons supporting my decision (please correct me if I'm wrong):
- Less (but not zero) limitation of the amps by the PSU. The recommended SMPS for a single NCx500 is 1200A700 (1200W in a constrained set of conditions, 325W continuous), but apparently it's still not sufficient to realize the full potential of these amps. At 4 Ohms it limits the output power from 700W to 420-440W according to Amir's power vs distortion curve.
- Shorter speaker cable length: around 1m instead of 2.5-3m in my case, not sure how much improvement it'd mean though.
- Zero crosstalk: even if it's not audible, I can find mentions here and there on this forum that soundstage can be impacted and I probably don't want to risk it with these Kefs.
- Better thermal properties? (having a single case as heat sink for each PSU)

I think it is a good idea to go for the two mono blocks, each powered by its own SMPS1200A700 regardless (that is, the stereo version would do fine). Too bad they don't have a larger one, seriously. In this case, more/higher is better, its only money.

 

[boXem]

I would like to compare peak values too. In this case, I used RMS current, because I thought the 800 W referenced to, is average power output, so to calculate current using the power formula will result in rms current, not peak current. If we were to compare the peak current draw by the OP's reference 3 meta's maximum peak current, we would have to know the value.

peak = RMS * 2^(0.5)

 

[peng]

peak = RMS * 2^(0.5)

Sorry I wasnt clear, I meant to say the power formula I used would result in rms current, not peak.

For peak, of course one would multiply it by sqrt2, for sine wave anyway.

 

[bobopich]

I'm now considering two Apollon mono blocks. This is the configuration that Hypex recommends and also reviewed by Amir.

These are the reasons supporting my decision (please correct me if I'm wrong):
- Less (but not zero) limitation of the amps by the PSU. The recommended SMPS for a single NCx500 is 1200A700 (1200W in a constrained set of conditions, 325W continuous), but apparently it's still not sufficient to realize the full potential of these amps. At 4 Ohms it limits the output power from 700W to 420-440W according to Amir's power vs distortion curve.
- Shorter speaker cable length: around 1m instead of 2.5-3m in my case, not sure how much improvement it'd mean though.
- Zero crosstalk: even if it's not audible, I can find mentions here and there on this forum that soundstage can be impacted and I probably don't want to risk it with these Kefs.
- Better thermal properties? (having a single case as heat sink for each PSU)

Nord have 3 channel NCx500 version which is basically 3 mono blocks with 3 separate PSUs in one case and I think the price is cheaper than everything else.

 

[Buckeye Amps]

- Less (but not zero) limitation of the amps by the PSU. The recommended SMPS for a single NCx500 is 1200A700 (1200W in a constrained set of conditions, 325W continuous), but apparently it's still not sufficient to realize the full potential of these amps. At 4 Ohms it limits the output power from 700W to 420-440W according to Amir's power vs distortion curve.

Just a clarification. Amir’s power rating is at the knee of the distortion curve. The rated 700w is at 1% distortion. The SMPS1200A700 can drive the NCx to the specified 700w at 1% distortion.

 

[soerenssen]

Just a clarification. Amir’s power rating is at the knee of the distortion curve. The rated 700w is at 1% distortion. The SMPS1200A700 can drive the NCx to the specified 700w at 1% distortion.

Indeed, with dedicated PSUs they reach 1%THD a bit "later".

- Is this roll-off beyond 10K something that can be compendated (with EQ / Dirac)? Comparing with the Purifi, that has a completely flat FR.
- Is that -80dB "hump" in power vs 15KHz distortion (4 ohm) something to be concerned about about? I noticed the same in the Purifi and Nilai reviews too.
- Do we have any data about thermal properties? Wondering why Audiphonics uses a larger heat sink for the PSU, if it's not necessary. How hot could it get under continuous load?
- Are there any crosstalk measurements available for the stereo version? How much can this vary between the different implementations?

 

[soerenssen]

Nord have 3 channel NCx500 version which is basically 3 mono blocks with 3 separate PSUs in one case and I think the price is cheaper than everything else.

Nice value proposition, especially for those living in the UK (for me, here in Germany, not so much, especially after I add the same extras as the Apollon products already have), considering that ultimately I'll have a 3-channel (LCR) setup at the front. Although I'm not sure that it's possible to gain match an AVR (e.g. x4800h) that has 2V RCA outputs only, with a stereo DAC that has 4-5V (or even more, e.g. RME) balanced output. As opposed to the Audiphonics amp, at least the Apollon/Nord have the gain switcher/jumper on the back, not on the bottom. Something like an LA90D in dual mono setup with HT bypass would be the way to go?

 

[bobopich]

Nice value proposition, especially for those living in the UK (for me, here in Germany, not so much, especially after I add the same extras as the Apollon products already have), considering that ultimately I'll have a 3-channel (LCR) setup at the front. Although I'm not sure that it's possible to gain match an AVR (e.g. x4800h) that has 2V RCA outputs only, with a stereo DAC that has 4-5V (or even more, e.g. RME) balanced output. As opposed to the Audiphonics amp, at least the Apollon/Nord have the gain switcher/jumper on the back, not on the bottom. Something like an LA90D in dual mono setup with HT bypass would be the way to go?

Not sure the Apollon is cheaper than Nord as I also live in Europe, Nord price is without VAT you pay it in your country upon delivery, Apollon price is also without VAT and they add the VAT in the process of purchase which is the same. I am also considering 3 channel NCx500 amp purchase.

 

[soerenssen]

Not sure the Apollon is cheaper than Nord as I also live in Europe, Nord price is without VAT you pay it in your country upon delivery, Apollon price is also without VAT and they add the VAT in the process of purchase which is the same. I am also considering 3 channel NCx500 amp purchase.

I don't find the basic Nord 3-channel NCx500 on their website anymore, only the MKII with Sparkos.

 

[diddley]

Well this is excellent and nice to see the results. Also an interesting comparison to Purifi based amps. Thanks @Rick Sykora for building/sending in and @amirm.

Indeed and a lovely town to visit too, very picturesque.


JSmith

It's a universaty town with lots of students and a vivid nightlife.
I live now 60km from the town and miss it like crazy, i shure will return to Groningen
But 60km isnt far so i visit regulary.
Have you lived there?

 

[Matias]

I don't find the basic Nord 3-channel NCx500 on their website anymore, only the MKII with Sparkos.

Just e-mail Colin.

 

[Bach]

„headroom for peace of mind“ (quote @Sokel ) is the keyword here and the ultimate goal for any audiophile

The reasoable alternative being making sure your amp cannot be overdrived: the max. inputlevel is just a little under the need for the max. outputlevel of the ( main) amp. Adjust the outputlevel of the source accordingly. Also consider the max, level of speakers, be it electric or sonicly. If that means that some music cannot therfor not be played louder than you wish: let it be, let it be. Or upgrade the most limiting part of your installation.

 

[grobalt]

Becareful .. Nord prices are only valid after they accepted the order. They dont care what they show on the website. Currently you find 3 channel with 3 Power supplies for 1480 GBP and 4 channel with 2 power supplies for around 2700 .. does not make any sense. I reported strange numbers in the configuration tools months ago, they did not say anything, just that they dont care and calculation mistakes are shown after order and prices will be adjusted. After that point Nord was out for me...
The special tax package that you can order is nothing else than shipping undervalued to reduce tax which is higly illegal as well. I dont concider Nord as a professional vendor.