Review and Measurements of Nord One NC500 Amp

[willham]

This guy just get used to listen music in mist , with bad recordings etc...
Now when everything is cleared he blames the amp instead of trying to get a better recording.
It's a real shame.

Setting aside the reviewer himself, the region he complains about, or the 'glare' seems to coincide with the sharp rise in distortion in the treble past 2k.

Compared to the the Hypex NC400, which was mostly flat.

Is this a coincidence? Is 0.3% thd+n audible?

 

[BrokenEnglishGuy]

OK, here it is:

View attachment 27098

Ignore the initial glitch which was me turning off the generator by accident. I say from thermal point of view, the Nord One passes with flying colors. The top of the enclosure did not change temps at all. Bottom of the unit below the amps was slightly warmer than room temp. It can output this level of power forever.

the 100w is continous at 2 ohm too, right?

 

[Pritaudio]

the hypex nc502 is supposed to have sinad 96db according to the data sheet.
it is off the shelf with no buffer board.
but we need third party measurements.
this nc500 module only got 96db from nord When it’s data sheet suggests higher.
cant accurately trust hypex.

 

[Sam1879]

Hi there
Just wanna share my experiences with this amp, made short.
Had this amp for maybe a year now, and i can recommend it almost in every aspect.
Subjective review:
Sounds great on: power demanding Infinity Kappa 6.2i, Kappa 8.1i and Kappa 8
Sounds not so good on: less power demanding Dali Opticon 6 (with ribbon type super high freq. driver, crossed over at 14k)

No problems or downsides of any form.

I love the hypex amps. Small, cool and powerfull. These measurements are great too if not as good as the NC400's.

Off topic-ish; I bought the NC400 monoblock kit halfway through last year. I remember hooking them up and being very impressed. They did everything right from top to bottom, I heard none of the "class D" cliches I had psyched myself up about. But, something with drums was just not right. Snares and hi-hats especially. I told myself it was just the ultimate clarity and transparency of the amplifier. I used them until last week to get used to the sound.

Switching back to the class AB amp was a real "Ahhhh" moment. There were the snares, hats. Bass guitars even had a bit more flesh and crunch. If living with the hypex was like sleeping in a 5 star hotel It was like coming back home to my own bed. It seems theres no place like ...class AB amps. For me anyway. Call it me enjoying distortion or whatever but the AB amp just sounds more right, if not as transparent and powerful.

I can join McFly on this quote, but on the Dali Speakers only. Not on the Kappas. Everything fine on the Kappas.
Maybe to be more exact there was audible hiss in some higher frequency areas, i would say in the top female voice area.
And for the Dalis it was an absolutely oversized amp, of course.

But still, is there a measureable explanation for this?

Could it be the super high freq. driver reveal any switching noise in audible spectrum?
Is amp-speaker synergy 100% proven and "scientifically" accepted?
Maybe i just had a bad day and was hearing a ghost ? Did AB-Switching but not ABX blind.

 

[audioBliss]

Hi there
Just wanna share my experiences with this amp, made short.
Had this amp for maybe a year now, and i can recommend it almost in every aspect.
Subjective review:
Sounds great on: power demanding Infinity Kappa 6.2i, Kappa 8.1i and Kappa 8
Sounds not so good on: less power demanding Dali Opticon 6 (with ribbon type super high freq. driver, crossed over at 14k)

No problems or downsides of any form.



I can join McFly on this quote, but on the Dali Speakers only. Not on the Kappas. Everything fine on the Kappas.
Maybe to be more exact there was audible hiss in some higher frequency areas, i would say in the top female voice area.
And for the Dalis it was an absolutely oversized amp, of course.

But still, is there a measureable explanation for this?

Could it be the super high freq. driver reveal any switching noise in audible spectrum?
Is amp-speaker synergy 100% proven and "scientifically" accepted?
Maybe i just had a bad day and was hearing a ghost ? Did AB-Switching but not ABX blind.

I had the annoying high frequency hiss on my Apollon amp using the NC502 modules until I switched to a balanced preamp. Then it was all silent from there. I tried 2 different RCA-XLR (one of them being the Nord silver one) but both had the hiss. At least on the NC-modules you basically need a real balanced connection. The NC400 monoblocks don't have this hiss even using unbalanced preamp. Not sure what pre-amp you are using but that's my experience with hiss using Hypex stuff.

In my opinion you can't really oversize an amp. I use NC502 even for speakers that can max handle 80W and it's awesome. For my speakers that can take thousands of watts it's also awesome

 

[Sam1879]

thanks for sharing your experiences. as far as i remember i had (and still have) it balanced directly on the smsl su8v2 dac, but is quite a while ago. maybe it was really connected with a rca-xlr cable on an unbalanced dac output. i‘m not 100% sure anymore.

 

[Sam1879]

but thinking back... i think it was really an unbalanced output when the hiss happend.

 

[watts]

When not in use it is better to turn them off. Another thing is to turn them on for a while before listening to music, class A and class AB amps.

About two years ago I had a power surge because of some old power company cables, 400 Vac (Spain: 230 Vac / 50 Hz). The stereo was saved thanks to a varistor that I decided should have the DC blocker x4 ME (from the first DCB protototype). It also burned one of the two fuses.

[IMG, link] http://maty.galeon.com/WP-imagenes/hum/ATL-Hi-Fi-DC-Blocker-x4-ME-open-front-side-3.jpg

Other option is a DIY SMPS with much better components. Pinnocchio using them for the new amplifier you are mounting. Made by Cresnet.

https://www.diyaudio.com/forums/solid-state/312866-global-loop-amplification-post5973161.html

[IMG, link] http://maty.galeon.com/WP-imagenes/hum/Simpelstark-with-Cresnet-smps-by-pinnocchio.jpg

After leaving these on for 4 years, and having the caps in the SMPS1200 go south, I think I will try to turn them off more often Maybe that will increase longevity, but maybe higher quality caps will as well.

Would be interested to hear some of your thoughts of the upgraded Nichicon caps in the power supply. I am aware I could have replaced the board for less.

(Still love the sound from these amps by the way)

 

[maty]

In a switched source I do not know what improvement they can bring except for a longer duration and reliability.

The problem is paying so much for one that uses mediocre capacitors. To understand us, can you imagine a sports car with sky seats instead of leather?

 

[TheBatsEar]

It is odd that a limited production hand assembled amp would leave the manufacturer with its channels out of phase.

A larger manufacturer would add a test to make sure it never happens again. This one could be electronic and fully automatic in nature. Write once, benefit forever and for any type of amp you build.

I guess it's harder to do it like that for a smaller manufacturer, he probably works with some kind of manual checklist to ensure quality. Which will fail every now and then, because: people do people errors.

On the other hand, perhaps the builders are objectivists, who have been scientifically proven to be unable to hear this difference.

More reason to let a computer do it.

 

[pras1011]

So just to confirm that this can do 270 watts 8ohms and 445 watts in 4 ohms? Is that over a 20hz to 20khz frequency range?

The specs on the Hypex website is 400 watts 8 ohms and 700 watts 4ohms and therefore are incorrect?

 

[kazsud]

I ordered one yesterday after reading the review but didn't get as far into the tread where the talk about the potential RF interferance is talked about Does anyone think they have made revisions to the design since then?

 

[kazsud]

I ordered one yesterday after reading the review but didn't get as far into the tread where the talk about the potential RF interferance is talked about Does anyone think they have made revisions to the design since then?

They gave me a freaking partial refund wtf. I ordered it less than 24 hours ago and they kept $108.59!!!

 

[Xaero]

The unit as it came had an issue. Can you spot it?

View attachment 27027

Look at the right channel: the red cable is connected to black terminal instead of red. So the two channels were out of phase from each other. I can just imagine someone buying this and raving about soundstage and such, only to realize that it is a defect, not a feature. Anyway, I fixed it for the measurements you are about to see.

I am pretty sure this is intentional and that you should not had changed it. In fact you may have modified the amplifier into a ticking self destruct device. The positive lead on right channel is connected to common ground. As I had it explained to me it's to prevent something called "power supply pumping". So either the leads on the board for one channel is connected out of phase, or the leads to one set of binding posts. Some of this is explained here: https://www.analog.com/en/technical...resses-by-minimizing-powersupply-pumping.html As far as I understand it, this is per design and the end result will not actually be out of phase.

This is very likely the reason why the amplifier tested poorly, and why you had power supply noise. This is also one of the reasons why most hypex / purify builders use all black or all red cables, so that you won't think it's connected wrong by mistake.

 

[amirm]

I am pretty sure this is intentional and that you should not had changed it.

My memory is a bit hazy but I am 99% sure the owner checked with the company and they said the wiring was a mistake.

 

[Xaero]

My memory is a bit hazy but I am 99% sure the owner checked with the company and they said the wiring was a mistake.

That's really weird, because I was told that it isn't. Well it's 4 years ago now, so maybe it doesn't matter. But this can maybe be kept in mind for the future, because it is indeed intentional on almost all class D amplifiers that use a single power supply.

"In most audio tracks, the low-frequency energy in the music is mono (i.e., the same for the left and the right channels). Therefore, one can reverse the polarities of Channel 2 with respect to Channel 1. As shown in Figure 3, the audio input on Channel 2 is inverted. The Channel 1 and Channel 2 outputs are out of phase with respect to each other, so the power-supply pumping that occurs in one channel cancels the pumping in the other channel. In this case the audio connection at the speaker terminals on Channel 2 need to be connected in opposite polarity. This configuration will "un-invert" the output signal of Channel 2 so that the audio content of Channel 1 and Channel 2 are now in phase with each other."

 

[amirm]

That's really weird, because I was told that it isn't. Well it's 4 years ago now, so maybe it doesn't matter. But this can maybe be kept in mind for the future, because it is indeed intentional on almost all class D amplifiers that use a single power supply.

That doesn't mean anything (some amps are that way, some are not). If the speaker terminals were reversed after my fix, the output waveforms on the left would be out of phase which they are not:

 

[audio_tony]

That's really weird, because I was told that it isn't. Well it's 4 years ago now, so maybe it doesn't matter. But this can maybe be kept in mind for the future, because it is indeed intentional on almost all class D amplifiers that use a single power supply.

"In most audio tracks, the low-frequency energy in the music is mono (i.e., the same for the left and the right channels). Therefore, one can reverse the polarities of Channel 2 with respect to Channel 1. As shown in Figure 3, the audio input on Channel 2 is inverted. The Channel 1 and Channel 2 outputs are out of phase with respect to each other, so the power-supply pumping that occurs in one channel cancels the pumping in the other channel. In this case the audio connection at the speaker terminals on Channel 2 need to be connected in opposite polarity. This configuration will "un-invert" the output signal of Channel 2 so that the audio content of Channel 1 and Channel 2 are now in phase with each other."

This technique was used by B&O back in the 70's (they may even have developed it). Very clever way of distributing power supply load across channels.