Apollon NCx500ST Stereo Amplifier Review

[amirm]

In the graph below, it would seem to be 50 mW, and on the graph for the 8 ohm test, it went as low as 20 mW, you don't seem to have a consistent standard on the minimum, what's that?

Each amp has a different gain. Trying to equalize that to the same would be a lot of work. Nothing exciting is happening there anyway. The graph simply continues on that trajectory as we are noise limited. On lower gain amps, the measurement does go to much lower levels. I just don't show it on the graph. Here is that for this amp:

 

[lc6]

While the case is stamped steel, 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

Hypex NCx500 ST NCoreX Stereo Amplifier - Components:
"Aluminium enclosure with anti-vibration rubber feet"

 

[amirm]

2) You mentioned changing from continuous to burst, for the 2 ohm test, that's great, but can you tell us what are the test duration for "continuous" and "burst", I mean like X seconds versus Y milliseconds.

Actually, all the measurements there are using burst mode now. This is compliant with CEA-2006/490A. Here is the description from AP manual:

Burst signals for CEA-2006 in APx500 The burst signals in APx500 are designed to satisfy the requirements of the standard CEA-2006 “Testing & Measurement Methods for Mobile Audio Amplifiers,” section 5.2, Dynamic Power testing. Two signals are specified in the standard: for full-range amplifiers, the signal shall be a repetition of a burst of 20 cycles of a 1 kHz sine wave at 100%, followed by 480 cycles of 1 kHz at 10% (–20 dB). For limited-range amplifiers (subwoofer amplifiers), the signal shall be a repetition of a burst of 10 cycles of a 50 Hz sine wave at 100%, followed by 20 cycles of 50 Hz at 10% (–20 dB).

The PowerCube has a rating of just 200 watts for continuous but jumps to 2 KW for burst and hence my modifications of the test to use this. This is the same measurement method I have been using on the right for each amp:

As you see, for class D amps it typically doesn't help the amplifier much but does ease the load on the dummy load.

 

[amirm]

Hypex NCx500 ST NCoreX Stereo Amplifier - Components:
"Aluminium enclosure with anti-vibration rubber feet"

Thanks. Corrected.

 

[respice finem]

Thanks. Corrected.

Or maybe there are two enclosure versions? This would explain the weight discrepancy. A magnet could solve the "mystery".

 

[pablolie]

Agree. And completely disagree with those who said it looks cheap or not sturdy. Since I have one here, I can attest to how solid and well executed the build is. @Tom22, does yours feel cheap?

As an aside, the anodizing is done locally to Apollon per your order, the cases are not ordered that way.

It looks very well put together.

 

[Apollon Audio]

Or maybe there are two enclosure versions? This would explain the weight discrepancy. A magnet could solve the "mystery".

All our enclosures are made out of aluminum. The weight of this amplifier is 2.9kg.

 

[respice finem]

All our enclosures are made out of aluminium. The weight of this amplifier is 2.9kg.

Thanks a lot - and kudos for swift interaction

 

[pablolie]

Thanks a lot - and kudos for swift interaction

With that responsiveness cherry on top - this is certainly my way to go forward. Just looking for a DAC+preamp that has a configurable sub out and dirac that matches well with this now.

 

[Buckeye Amps]

May seem counterintuitive as a “competitor” but I applaud value alternatives/entries like this, it benefits the customers tremendously, which is the goal.

 

[capslock]

Then again - if results are all that matters, these seem to work pretty darn well. Note that they offer the choice to pick other OpAmp options, too (Sonic Imagery 994 or Sparkos Labs SS2590 pro or Opa 1656). I assume the one in the pic is the latter?

Amir wrote in post #1 that the amp came with the default op amps - so that would be the OPA1656? If so, his measurements are not with a discrete op amp.

From the manufacturer's post with THD+N vs. power, the discrete op amp has much lower distortion before clipping while it is on par with the OPA1656 at lower power. So yes, results are excellent. In particular, the lower distortion at high power probably means the LM4562 and OPA1656 are running out of gain when the output has to swing near the rails (which could be solved by increasing the rails if they aren't already at the limit) or that we start seeing slewing distortion. This is where a discrete output stage really can shine.

Edit:
@Dougey: are you the owner of the amp tested? In that case the measurements would be for the OPA1612?

 

[amirm]

FYI member let me know that the TI OPA1612 op-amp is what is in this unit.

 

[Dougey_Jones]

Amir wrote in post #1 that the amp came with the default op amps - so that would be the OPA1656? If so, his measurements are not with a discrete op amp.

From the manufacturer's post with THD+N vs. power, the discrete op amp has much lower distortion before clipping while it is on par with the OPA1656 at lower power. So yes, results are excellent. In particular, the lower distortion at high power probably means the LM4562 and OPA1656 are running out of gain when the output has to swing near the rails (which could be solved by increasing the rails if they aren't already at the limit) or that we start seeing slewing distortion. This is where a discrete output stage really can shine.

Edit:
@Dougey: are you the owner of the amp tested? In that case the measurements would be for the OPA1612?

I’ve posted this twice, but I’ll repeat. I’m the one who drop shipped this unit to Amir, I own two of them, and they were ordered with OPA1612.

I don’t see OPA1612 as an option anymore on their site, but that’s what they were configured with.

 

[pablolie]

May seem counterintuitive as a “competitor” but I applaud value alternatives/entries like this, it benefits the customers tremendously, which is the goal.

Companies like yours and Apollon clearly are changing the game. I wish you all immense success by providing these new performance envelopes with the rationally designed and priced (and stellar) products you collectively provide. I truly think this stuff marks the beginning of the downfall of some big audio brands' reputation - it seems inevitable.

 

[Dougey_Jones]

Companies like yours and Apollon clearly are changing the game. I wish you all immense success by providing these new performance envelopes with the rationally designed and priced (and stellar) products you collectively provide. I truly think this stuff marks the beginning of the downfall of some big audio brands' reputation - it seems inevitable.

I sold my Pass Labs X5 to fund the purchase of these two stereo units. One is powering my F206’s and the other will bi-amp a Revel C208 when I upgrade this winter from the C205.

Does anybody really need a 1,200w bi-amplified center channel? The answer is almost certainly yes.

Downfall indeed.

 

[TK750]

Hypex NCx500 ST NCoreX Stereo Amplifier - Components:
"Aluminium enclosure with anti-vibration rubber feet"

In fairness to Amir, it might have been confusing for him to see it spelt correctly...


(I joke I joke, please don't come after me)

 

[Matias]

I’ve posted this twice, but I’ll repeat. I’m the one who drop shipped this unit to Amir, I own two of them, and they were ordered with OPA1612.

I don’t see OPA1612 as an option anymore on their site, but that’s what they were configured with.

Yes, Tibor explained the recent change here:

Hypex NCx500 Class D Amplifier Review

https://audiosciencereview.com/forum/index.php?threads/the-state-of-the-art-class-d-audiophonics-hpa-s600nc-and-audiophonics-hpa-s400et-sound-different-though-there-is-a-caveat-here.47377/post-1696152 @Apollon Audio It's nice to have some insight about the differences in sound using these op...

www.audiosciencereview.com

 

[Dougey_Jones]

Yes, Tibor explained the recent change here:

Hypex NCx500 Class D Amplifier Review

https://audiosciencereview.com/forum/index.php?threads/the-state-of-the-art-class-d-audiophonics-hpa-s600nc-and-audiophonics-hpa-s400et-sound-different-though-there-is-a-caveat-here.47377/post-1696152 @Apollon Audio It's nice to have some insight about the differences in sound using these op...

www.audiosciencereview.com

People claimed that OPA1612 measured slightly better than OPA1656 in the DIY Audio thread I linked, but that people seem to prefer the sound of the 1656..

Either way, I believe both are more transparent than the NCx500ST, so besides subjective preference it shouldn’t matter.

 

[pseudoid]

Does anybody really need a 1,200w bi-amplified center channel? The answer is almost certainly yes.

I don't have to row a boat fan to get 1200W, canoe?

 

[pablolie]

People claimed that OPA1612 measured slightly better than OPA1656 in the DIY Audio thread I linked, but that people seem to prefer the sound of the 1656..

Either way, I believe both are more transparent than the NCx500ST, so besides subjective preference it shouldn’t matter.

At that level, we know that people hear what they want to hear - and it is OK. The performance level is stunning. Stuff like this renders all those $30k+ metal sculpture amps as an extremely bad investment.