Apollon NCx500ST Stereo Amplifier Review

[snip3r77]

is there much db difference between single vs balanced inputs ?
thanks

 

[CleanSound]

Just came on today, took forever, I ordered it on 12/26, got it on 2/26.

Dual Mono NCx500 Lux

The built quality and craftsmanship is just jaw dropping. Yes, there is a serious cost premium for this and yes, there are much more affordable options out there but this is my end game amp. . .or at least however long till it dies.

 

[da Choge]

Dual Mono NCx500 Lux
The built quality and craftsmanship is just jaw dropping.

Yes! This is the same amp I'm looking to get from Apollon; but, probably in piano black. I do need another for my bedroom rig, but that has to be in silver, so for that one, I don't know if I'll go with the dual mono lux, the stereo lux, or the less expensive stereo, in their more affordable case. Glad you're happy with you new acquisition!

 

[arminh]

This is a review and detailed measurements of the Apollon NCx500ST stereo class D amplifier based on Hypex NCOREx NCx500 modules. It was kindly drop shipped from the member and costs 1,090.00€ (US $1,168) with standard opamp.

View attachment 310220
While the case is stamped aluminum, it is a heavily customized one with attractive side vents. You get to select your color of choice. The back panel is where you notice the high value add:

View attachment 310221
You have no less than four gain settings and even an LED brightness switch! FYI, I will have to confirm which op-amp is included with this sample.
EDIT: the default TI OPA1612 op-amp was in this sample.
EDIT 2: turns the amp used Sonic Imagery op-amps (by mistake).

To make sure I didn't go mad given the combination of input types and four gain settings, I stayed with XLR testing.

If you are not familiar with the tests that are about to follow, please watch my video on understanding amplifier measurements.

Edit: just realized I left out the "n" out of the name on all the notations.

Apollon NCx500ST Amplifier Measurement
I started with the lowest gain setting:
View attachment 310222
While just a couple of dBs shy of the reference design, performance is good enough to easily land in our top 10 best amplifiers tested:
View attachment 310223
You need a ton of input voltage to get max power in this low gain setting so let's step up through the gain settings:
View attachment 310224

View attachment 310225
View attachment 310226

You can see the benefit of low gain in am amplifier for best noise performance especially since the dynamic range of the DAC improves as well with higher output.

Here are two SNR measurements:
View attachment 310227

I picked next to highest gain because it lets you drive it to max power with less than 4 volts on XLR:
View attachment 310228

In that reward, it would have been nice to have a different gain level optimized for 4 volts output from the source (here, we jump from 2.1 to 5 volts).

Notice how channel separation is also gain sensitive:
View attachment 310230

Frequency response is expectedly excellent and load independent:
View attachment 310229

Intermodulation is kept to very low levels:
View attachment 310231
View attachment 310232

This is one powerful amplifier:
View attachment 310233
View attachment 310234

View attachment 310235

The amp has a very robust protection circuit and did not mind at all being pushed way beyond clipping. This made it easy to measure with PowerCube:
View attachment 310236

An ideal amp would keep its voltage constant regardless of load. We almost have that at 4 ohm but at 2 ohms, the required current goes through the roof and output droops. Lest you get depressed about that, check out the amount of power you are getting:
View attachment 310237

For a moment, it produced 2.2 Killowatts on my 20 amp circuit! I should mention that I have modified these tests for burst rather than continuous power. With continues output, it is very easy to push the Powercube beyond its specs. The burst nature is the reason so much power was to be had at that 2 ohm load setting.

Anyway, the amplifier is extremely robust and doesn't care how difficult the load is.

Distortion is kept at a minimum at or below 1 kHz:
View attachment 310238
BTW, this test is also updated to have more frequencies represented than before (addition of 200 Hz).

Amplifier is stable on power up:
View attachment 310239

And is extremely quiet on power on/off:
View attachment 310240

Conclusions
The Apollon NCx500ST is a clear value added class D amplifier with lots of features compared to reference design. It gives up just a few dBs of noise performance but still manages to rank #6 in our list giving you confidence of transparency while producing copious amount of power. It is also easily sourced in Europe which is a benefit for many of our readers.

I am happy to put the Apollon NCx500ST amplifier on my recommended list.

Manufacturer Specifications:

Frequency Response: 0 – 70k Hz +0/-3dB
Low Distortion: THD+N – – 0.0002 % 20Hz-20kHz
High Input Impedance 50K
Signal to noise ratio: 137dB
Gain (dB) 12,8/20,5/27,5/29
Ultra High Damping Factor
High Current Output
Power rating: 675W @ 2ohm | 650W @ 4ohm | 380W @ 8ohm
Case Dimensions: 350mm depth x 90mm height (with feet) x 280 mm width
Weight: 2.9 kg

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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Amir, with these excellent test results, does it make any sense to consider paying more for the (Apollon) Nilai stereo amplifier which overall does not seem to look better in your tests, even though it is claimed to be the latest/greatest from Hypex? https://apollonaudio.com/product/hypex-nilai-500-dm-dual-mono-stereo-amplifier/

 

[Xcaliber]

I'm considering getting this amp from Apollon, more specifically the Hypex NCx500 ST NCOREx Stereo Amplifier to power my Polk R200 in stereo mode, is it way too much power and going to fry my speakers even if I were to set the lowest gain at 12.8 or 20.5dB on the amp, and keep the preamp level (Topping D10s or Denon AVR) relatively low? The R200 Speakers are about 6ft from listening position, typically listening to music at 80~85dB.
Or should I better off going for the less powerful Purifi 1ET400A ST version instead? I may add the Polk R700 towers in the future hence why I consider either NCx500 or 1ET400A for the extra headroom instead of the smaller NC252MP.

 

[CleanSound]

I'm considering getting this amp from Apollon, more specifically the Hypex NCx500 ST NCOREx Stereo Amplifier to power my Polk R200 in stereo mode, is it way too much power and going to fry my speakers even if I were to set the lowest gain at 12.8 or 20.5dB on the amp, and keep the preamp level (Topping D10s or Denon AVR) relatively low? The R200 Speakers are about 6ft from listening position, typically listening to music at 80~85dB.
Or should I better off going for the less powerful Purifi 1ET400A ST version instead? I may add the Polk R700 towers in the future hence why I consider either NCx500 or 1ET400A for the extra headroom instead of the smaller NC252MP.

Some will tell you that there is no such thing as too much power.

The only thing I will say is that make sure that the volume pot is low before you turn it on each time so you don't blow your speakers out by accident.

 

[Julf]

Some will tell you that there is no such thing as too much power.

The only thing I will say is that make sure that the volume pot is low before you turn it on each time so you don't blow your speakers out by accident.

And make sure you don't have any teenagers in the house.

 

[JeremyFife]

Genuinely: might be worth adding attenuation to your chain between pre and power. Depends on how risk averse you are
I have a 9yo ... he gets into everything!

 

[Ze Frog]

Decided if I don't go powered monitor route, now increasingly unlikely, this is going to be my end game amplifier choice. What a bit of kit, and pricing around the price of a good integrated mainstream choice. Kudos to Apollon.

 

[CleanSound]

For those who have a very high performing amp of the likes of Benchmark, Hypex, Purifi, Topping, possibly some of the McIntosh and Bryston class AB amps.

Do this (and make sure you do this very carefully otherwise you will blow your speakers and worse you go deaf): make sure you source is off and unplugged and make sure the gain is not unreasonably high. Crank up the output of your preamp all the way up slowly, making sure nothing is playing while you are cranking up the volume.

Now, put your ears next to the tweeter. No hissing, no noise, completely silence. . .isn't that satisfying?

In all of my years in this hobby, I never had any amp that can do this. That is how clean three 0's are when it comes to SINAD. Yes, I am a proud SINAD chaser.

 

[Julf]

For those who have a very high performing amp of the likes of Benchmark, Hypex, Purifi, Topping, possibly some of the McIntosh and Bryston class AB amps.

Do this (and make sure you do this very carefully otherwise you will blow your speakers and worse you go deaf): make sure you source is off and unplugged and make sure the gain is not unreasonably high. Crank up the output of your preamp all the way up slowly, making sure nothing is playing while you are cranking up the volume.

Now, put your ears next to the tweeter. No hissing, no noise, completely silence. . .isn't that satisfying?

In all of my years in this hobby, I never had any amp that can do this. That is how clean three 0's are when it comes to SINAD. Yes, I am a proud SINAD chaser.

Does it matter? How often do you have your system cranked up to full? And even if you do, the music you play masks the noise. Sure, perfect silence is nice to have, but not a big deal.

 

[Xcaliber]

For those who have a very high performing amp of the likes of Benchmark, Hypex, Purifi, Topping, possibly some of the McIntosh and Bryston class AB amps.

Do this (and make sure you do this very carefully otherwise you will blow your speakers and worse you go deaf): make sure you source is off and unplugged and make sure the gain is not unreasonably high. Crank up the output of your preamp all the way up slowly, making sure nothing is playing while you are cranking up the volume.

Now, put your ears next to the tweeter. No hissing, no noise, completely silence. . .isn't that satisfying?

In all of my years in this hobby, I never had any amp that can do this. That is how clean three 0's are when it comes to SINAD. Yes, I am a proud SINAD chaser.

Most of us listen to our speakers from at least 3 to 6ft away, even in nearfield setting like desktop setup the speakers will be about 2~3ft from our ears, the noise generated by computer/GPU fan, central HVAC, or ambient noises are often significantly louder than any hissing noise from receivers and amps.

In real world application, I think the majority of these amplifiers have more than acceptable noise floor even if the SINAD number is less than stellar, yes?

 

[CleanSound]

Does it matter? How often do you have your system cranked up to full? And even if you do, the music you play masks the noise. Sure, perfect silence is nice to have, but not a big deal.

Most of us listen to our speakers from at least 3 to 6ft away, even in nearfield setting like desktop setup the speakers will be about 2~3ft from our ears, the noise generated by computer/GPU fan, central HVAC, or ambient noises are often significantly louder than any hissing noise from receivers and amps.

In real world application, I think the majority of these amplifiers have more than acceptable noise floor even if the SINAD number is less than stellar, yes?

No, you will not hear it at listening distance. I was merely stating that it is satisfying.

 

[Overseas]

For those who have a very high performing amp of the likes of Benchmark, Hypex, Purifi, Topping, possibly some of the McIntosh and Bryston class AB amps.

Do this (and make sure you do this very carefully otherwise you will blow your speakers and worse you go deaf): make sure you source is off and unplugged and make sure the gain is not unreasonably high. Crank up the output of your preamp all the way up slowly, making sure nothing is playing while you are cranking up the volume.

Now, put your ears next to the tweeter. No hissing, no noise, completely silence. . .isn't that satisfying?

In all of my years in this hobby, I never had any amp that can do this. That is how clean three 0's are when it comes to SINAD. Yes, I am a proud SINAD chaser.

Nice, especially that you do not have to pay for a source, streaming,nada.
How many hours per day do you listen that way?

 

[Sokel]

For those who have a very high performing amp of the likes of Benchmark, Hypex, Purifi, Topping, possibly some of the McIntosh and Bryston class AB amps.

Do this (and make sure you do this very carefully otherwise you will blow your speakers and worse you go deaf): make sure you source is off and unplugged and make sure the gain is not unreasonably high. Crank up the output of your preamp all the way up slowly, making sure nothing is playing while you are cranking up the volume.

Now, put your ears next to the tweeter. No hissing, no noise, completely silence. . .isn't that satisfying?

In all of my years in this hobby, I never had any amp that can do this. That is how clean three 0's are when it comes to SINAD. Yes, I am a proud SINAD chaser.

It doesn't have to have high SINAD to do this,only low noise.
It can have a 75db SINAD and still be absolutely silent if distortion is what makes it so.
SNR is a more meaningful metric in that matter.

 

[CleanSound]

It doesn't have to have high SINAD to do this,only low noise.
It can have a 75db SINAD and still be absolutely silent if distortion is what makes it so.
SNR is a more meaningful metric in that matter.

I'm no expert in measurements, but I thought SINAD includes THD+N?

 

[Sokel]

I'm no expert in measurements, but I thought SINAD includes THD+N?

SINAD is distortion+Noise.
Either one can determine it.
In that amp's case what determines it is Noise cause distortion is vanishingly low.
There are other cases,with the same noise but way higher distortion,these will be also silent.

 

[CleanSound]

SINAD is distortion+Noise.
Either one can determine it.
In that amp's case what determine it is Noise cause distortion is vanishingly low.
There are other cases,with the same noise but way higher distortion,these will be also silent.

It's very satisfying to have am amp this clean. It really accentuates the pride of ownership and gives you meat for bragging rights.

 

[Overseas]

It is satisfying to see you satisfied for the price you paid. Some pay for pride, some just need an electronic device to play the music.

 

[lordhumungous]

This amp is the quietest amp Ive ever owned . a great bargain at the price its sold for.