Hypex NCx500 Class D Amplifier Review

[pma]

I'm going to send Amir a wire in a box and call it an 'ultra low gain amplifier'. OEM DIY Prototype assembly of course. That should get top of the SINAD chart.

John, you have stolen my idea!
I was thinking about exactly same thing, yesterday. Maybe with 100 pF foil capacitor added.

 

[xaxxon]

What you've just said is one of the most insanely idiotic things I have ever heard. At no point in your rambling, incoherent response were you even close to anything that could be considered a rational thought. Everyone in this forum is now dumber for having listened to it. I award you no points, and may God have mercy on your soul.

I thought it was funny.

 

[restorer-john]

I thought it was funny.

Thunder was being sarcastic. Or at least I think he was...

 

[HarmonicTHD]

Updated the review with new suite with buffer enabled (27 dB):

Thanks.

Could you also publish the SINAD over Power graph please? Would be interesting in light that Buckeye is currently investigating the influence of its buffer on SINAD vs Power. Thx.

 

[amirm]

Thanks.

Could you also publish the SINAD over Power graph please? Would be interesting in light that Buckeye is currently investigating the influence of its buffer on SINAD vs Power. Thx.

See the first post which is now updated.

 

[JSmith]

Thunder

... only happens when it's raining.


JSmith

 

[HarmonicTHD]

See the first post which is now updated.

Sorry I missed that. Thx.

 

[Blumlein 88]

You know a great use for this amp unbuffered with only 12 db of gain? Heh, heh, heh.......

Use a low powered triode tube amp (valve amps to some) to feed into it. Then you get your tube sound and 400 watts of clean cool power. Load the tube amp outputs with an 8 ohm 20 watt resistor and use 15-40 watt amps. You'll have your cake and eat it too!

You could also use SETs, but some of them won't have enough voltage. Well they might from a 16 ohm tap. In any case you'll get 8 times or 16 times the power out that you put into it depending upon whether it is a 4 ohm or 8 ohm speaker you connect. Plus load intolerance. You could even include some coils or caps along with your 8 ohm dummy load for some crude EQ.

 

[ZgSTar]

I can't imagine any stereo system that 4 of those can't drive perfectly or am I missing something?

 

[DonH56]

@amirm : Given the lower distortion at HF with buffer, is it possible the AP is not happy driving the HF input load of the bufferless amp? Or maybe the amp itself needs a lower HF impedance drive?

Curious - Don

 

[amirm]

That was one of my guesses Don. I can try to simulate it with 600 ohm load and see if distortion rises the same way.

 

[Fidji]

So which one is better? Purifi (stronger one) or new HYPEX?

 

[restorer-john]

That was one of my guesses Don. I can try to simulate it with 600 ohm load and see if distortion rises the same way.

Measure the input impedance of the unbuffered amplifier vs frequency first. Many/most amplifiers' input impedance falls significantly at high frequencies. I wouldn't be surprised to see it fall under 1k above 15kHz.

Hence my comment about the poor AP needing a buffer.

 

[restorer-john]

Try this then remeasure.
View attachment 257409View attachment 257410

What a mess. I hope you are not responsible.

But I do like your counter-top.

 

[pma]

What a mess. I hope you are not responsible.

But I do like your counter-top.

Cold solder joints . And even company soldering is gray.

 

[Waxx]

And the first finished amps are in store i see, Rouge Audio Design (IT), who did sell OEM amp board from Hypex (and Purifi and Icepower) launghed the N-7X with 2 NCx500 boards for 1385€ excl VAT. They use OPA1612 opamps as buffer and the Hypex HxR discrete voltage regulators and the Hypex SMPS1200A700 PSU. So very stock...

STUDIO N-7x| Rouge Audio Design | Roma

HYPEX NCx500 Hypex Ncore serie X

en.rougeaudiodesign.com

https://en.rougeaudiodesign.com/product-page/studio-n-7x

Audiophonics (FR) is also busy developping their take on it i hear from people close to the guy behind it, and so is Sound Import/SoundImpress (NL) are taking a look at it. So most of the usual suspects in Europe will soon have amps based on this board it seems.

 

[restorer-john]

And the first finished amps are in store i see, Rouge Audio Design (IT), who did sell OEM amp board from Hypex (and Purifi and Icepower) launghed the N-7X with 2 NCx500 boards for 1385€ excl VAT. They use OPA1612 opamps as buffer and the Hypex HxR discrete voltage regulators and the Hypex SMPS1200A700 PSU. So very stock...

The Rouge (or is that Rogue?) Audio quoted S/N is somewhat 'optimistic' at 136dB...

 

[Waxx]

The Rouge (or is that Rogue?) Audio quoted S/N is somewhat 'optimistic' at 136dB...

It's Rouge (red in French), not Rogue. They are based in Roma, Italy, but like many Italians it seems that they aslo speak French.

French used to be the upperclass language all over Europe for centuries untill +/- 100 years ago (WOI) and in certain Italian (and not only Italian) upper class envirroments it's still like that. A lot of higher class European brands still prefer French names because it's more "chique" (showing of high class) like we call it here... I don't know that is the reason why they carry a French name, but it could be the reason...

 

[Sokel]

New measurements still show some rising distortion but is much better,specially at lows.
Previous one was really strange at 20Hz.

Thanks Amir!

 

[pma]

Here’s how the 4ohm buffer-less graph should look.

View attachment 257416

As you know very well, any THD+N vs. power level is pointless without declaring measuring bandwidth.