Hypex NCx500 Class D Amplifier Review

[NikolasA]

I have 3 NILAI mono and they all have a low pop on turn off. I can’t help with measurements but I can definitely hear the pop on power down.

 

[pma]

I have 3 NILAI mono and they all have a low pop on turn off. I can’t help with measurements but I can definitely hear the pop on power down.

You may try to measure output DC voltage when they are on. Cheap multimeter is enough. If there is a DC more than some 20 mV, you will probably always here a low pop on turn-off.

 

[Rick Sykora]

And is this behavior inherent in NcoreX and Purifi modules as well?

Not in my experience.

 

[jmillar]

Seriously, those 'preamps' are hardly anything more than obscure products. Their sales would be insignificant and their installed base, even less significant. They are not, nor ever will be mainstream HiFi preamplifiers. Probably sold 10 thousand between all of them.

Let's get real. The standard input sensitivity for domestic HiFi power amplifiers has been 1.0-2.0V for 50 years. Even with balanced, you can double that on a bad day. So 2.0-4.0V. Anything else it utterly stupid.

Yes, I have preamps that will output 30V RMS, but they are outliers and their rated output is 1.5V.

12dB is a joke. Nobody takes that seriously. Power amplifiers are ~26-29dB. Even Amir tweaks his integrated levels to be somewhere near that.

Topping with their transparent and low noise designs could make a preamp outputting 12 V. This is what Topping does best.
That signal could then be amplified to clean "behemoth" levels by Hypex or Purifi. I wonder what Hypex has in mind for their Nilai preamp (but it's not cheap, for what I've read). I've got an RME ADI-2, but I'm thinking of a wider swathe of users.

 

[jmillar]

The Pre90 has max 16dB gain and 17.7Vrms max output.
To get 10Vrms out of the Pre90, you have to input 1.7Vrms at max gain.

Many DACs can supply this in XLR mode. I have to recheck what the A90 in preamp mode can output.

 

[cicastol]

Many DACs can supply this in XLR mode. I have to recheck what the A90 in preamp mode can output.

I'm using Purify at low gain (12.8dB) with A90 as preamp.

 

[Sokel]

If you want to make things simple just educate the manufacturers the proper way:
Instantly return whatever pops,misbehaves,etc,I have done this twice in the past and those amps where no cheap.
Of course price doesn't matter,as long as someone sells an amp/pre/whatever must make sure to be pop free or specify the conditions where it's not in layman terms if it's a wide consumer product.
If it's not proper it's their job to find the fix,not ours,even if I enjoy the tips from our skilled members.

 

[restorer-john]

Small clicks and pops are normal. Large ones are not. The most sophisticated protection systems monitor the rails, control the front end muting and the back end speaker connections. Relays were traditional, but MOSFETs on the speaker terminals are better.

Where people have their amplifiers attached to deskmounted speakers only a few feet away from their ears, all these minor noises are exacerbated. And with buffer stages attached to the various Hypex/Purifi implementations, there will be variations clicks and pops as the various parts power up and down.

Clearly some assemblers do a better job than others.

 

[Doodski]

MOSFETs on the speaker terminals are better.

Wonderful examples of this use of MOSFETs is in the Accuphase speaker output MOSFET switching.

 

[restorer-john]

Wonderful examples of this use of MOSFETs is in the Accuphase speaker output MOSFET switching.

Yes, discussed here

DIY 250W/4ohm amplifier based on "blameless" topology, and measurements

@pma have you experimented with bias currents to see the effect this has? Yes. There is not much effect if you stay between 15 - 25mV per one Re resistor.

www.audiosciencereview.com

 

[dtaylo1066]

Works well for me:

 

[multisport4me]

Works well for me:

View attachment 259989

These didn't work for me with the NC400s (which is intermittent and very faint for me). I have two brand new in the box sitting on the shelf if anyone is interested to try it on other NCore or NCx amps.

Also, I just installed the AMP10 and gave it a listen with mains only and I didn't hear a single pop turning it on/off a few times as I experimented with BTL and standard connections or even just turning off the AV10 and having it use Amp Control to turn on/off the AMP10.

 

[goryu]

Works well for me:

View attachment 259989

How does a soft start module help with turn off thumps?

 

[restorer-john]

Wonderful examples of this use of MOSFETs is in the Accuphase speaker output MOSFET switching.

Accuphase's PCBs have always been a work of visual beauty, right from their very first products.

 

[jmillar]

You can have this in stereo configuration, and I'd best it will be the most popular builds in the market.

700w @4r is way above la90 can do even in bridge mode. I did a quick search and apparently you can have dual channel ncx500 at around 1500-1600 eur. Not exactly cheap. But well, if you need serious power...

The Nilai kit from Hypex has been announced at 1250€. "Assembly required"
Audiophonics and others will probably have Hypex ncx500 based ready built amps in a few weeks.

 

[roog]

Nilai does look like a neat assembly.

 

[musicforcities]

It is my understanding that your review provides a baseline of what the modules can accomplish. That provides a point of comparison to check the final products of the "box" that NAD, Boxem, McIntosh, Marantz or whomever assambles.

This. It is good to have a baseline to compare to; for example if NAD uses the module with an in house buffer, single ended (rca) inputs etc, knowing the performance of module without buffer and with ncores own buffer is very useful in determining what is being gained (pun intended) or lost, if anything.

 

[jmillar]

That is correct. 20-20kHz, UNWTD, or DC-200kHz A-WTD etc.

The wider the bandwidth, the more the noise. Even using the 20kHz as opposed to the 22kHz filter will gain a dB or 2.

When I thought I was getting it, now this. Please excuse my naivete. Precisely why is "brush" or "grass" in the ultrasonic range relevant? Will it cause harmonic distortion in the audible range that does not appear in the test results if the freq range sweep ends prematurely? And at the speaker (or xover) level does it degrade the signal even if the transducers themselves don't reproduce beyond 20 kHz or so?

 

[jmillar]

My issue is testing an OEM supplied building block product, DIY assembled into a box and then pinning it on the so-called "SINAD leaderboard" which is for commercially available and commercially sold products. No prototypes, kit-builds, or bodged-up pre-release circuit boards was the rule. What happened to that?

It's not fair to people like Boxem, March, Buckeye, Apollon etc who build gear we can buy, with (hopefully) realistic specs and usable sensitivity/gain.

If it's just a showcase of the latest Hypex module- test it and discuss it as such. Use disclaimers in the title and make it clear- it cannot be purchased as tested. And now we've got @Hypexsales trying to distort our discussion to suit their narrative.

Disappointing, and not a good look for ASR.

Hypex Nilai is a kit build, and I think very many people would find it useful to have it tested.

 

[jmillar]

@Hypexsales It would still be nice if those NCx boards also come availeble to the diycrowd, now most get Purifi boards as they are availeble and better than what you offer (UcD boards and full kits) on your diy store for their custom builds. Many want a more fancy custom case for their amp and make their own buffer section (with the opamps they want). I know quiet a few projects where they used Purifi or even (inferior) Icepower amp modules just for that, as they were very interested in Ncore amps but could not get them barebone.

I think the company's current policy re the DIY market is to sell various Nilai components and complete kits that include buffers, PSU, etc, etc. There is absolutely nothing "second rate" about them and they are not hobbled by the "stigma of low cost", either. ;-)

The Hypex NCx range (QUITE similar to the Nilai in engineering and measurements) is targeted to OEMs who personalize and integrate their gear with their own buffers, psu, triggers, casings, even DSP and other fancy configurations at various price points.