Apollon NCx500ST Stereo Amplifier Review

[EJ3]

You have around 68 W* total idle loss according to the specs,that's on the hot side.
It's not the worst idea to use active cooling but you have to take care of the fine dust from time to time.

* that's not definitive as the NC502MP datasheet reports separate idle losses for the PSU and amp sections,so take that as the minimum.

View attachment 369836 View attachment 369837

Edit:Also the mains IEC socket in the photos looks like a 10A one,for an amp with such spec'd power (500 W x 8 channels) it would need either 2 separate 10A ones or a 16A (barely adequate) for 240V mains in the very extreme case one would drive it to it's limits.

Puting a dryer sheet on the intake side of the screen will lower the rate of fine dust acumulation.

 

[Dougey_Jones]

I own a custom build NCx500 and it stays cool. I would send it to Apollon. There seems to be something wrong with the power supply. Did you order it with the correct mains voltage? The power supply can be switched with a jumper between 115 qand 230 volt.

Both of mine run hot, I reached out to Tibor regarding this and he said that this was to be expected..

Tibor?

 

[restorer-john]

Both of mine run hot, I reached out to Tibor regarding this and he said that this was to be expected..

Tibor?

As long as the modules and power supply outlast his warranty, "Tibor" won't care. Electronics are very resilient, but long term heat is the enemy of all components. They will fail prematurely, like all other poorly thermally considered devices.

 

[EJ3]

As long as the modules and power supply outlast his warranty, "Tibor" won't care. Electronics are very resilient, but long term heat is the enemy of all components. They will fail prematurely, like all other poorly thermally considered devices.

So all is OK as long as it fails the day AFTER the warranty expires?

 

[Dougey_Jones]

As long as the modules and power supply outlast his warranty, "Tibor" won't care. Electronics are very resilient, but long term heat is the enemy of all components. They will fail prematurely, like all other poorly thermally considered devices.

I just used an IR thermometer and the exterior case temp was 99.6f @ idle.

Not sure if that’s really that hot. Someone else said they were as hot as Class A amps, as a former Pass Labs owner I can tell you the heat difference between my X5 and these are an order of magnitude.

I never had any parts fail in that space heater, and it was 20+ years old, so I’m not sure why these would age prematurely.

 

[antcollinet]

I just used an IR thermometer and the exterior case temp was 99.6f @ idle.

Not sure if that’s really that hot. Someone else said they were as hot as Class A amps, as a former Pass Labs owner I can tell you the heat difference between my X5 and these are an order of magnitude.

I never had any parts fail in that space heater, and it was 20+ years old, so I’m not sure why these would age prematurely.

That is only a 16C rise above ambient (depending on your ambient). I'd say that is reasonable, especially as the case is used as heatsink.

 

[restorer-john]

That is only a 16C rise above ambient (depending on your ambient). I'd say that is reasonable, especially as the case is used as heatsink.

Using flat plate enclosed casework as a "heatsink" is really poor thermal design. The issue is not the temperature on the outside- that is the result of the temperature of the components producing the heat on the inside. They have no airflow, no convective cooling via heat transfer to moving air. Just look at the Apollon NCx "design". Some slots on each lower side- WTF? Hot air rises. Heat doesn't. It radiates.

Put holes in the top, sides and base, stand the unit on its side and/or pull/force air through it. Not rocket science, but clearly far too esoteric of a concept for some.

 

[Dougey_Jones]

I’m curious which parts you guys THINK are going to fail on these amps? My Pass Labs x5 was a literal Class A space heater that drew 200w at idle and had zero active cooling. Sure, it had fins on the side..

Performed one recap in 20+ years, and not because it stopped working, just out of boredom and for the potential audiophile performance boost.

Is that the risk here? That these will need a recap at some point?

 

[antcollinet]

Is that the risk here? That these will need a recap at some point?

That is a possibility - heat is the enemy of electrolytic caps of all sizes.

But the truth is we don't know and can't tell. Take the Topping PA5 problems. That was explained as a thermal issue within the potted modules. It is not clear to me if that was just heat failure internal to components - or if it was physical damage to the circuit as a result of differential expansion (I've seen that with potting in the past). Either way - it was a design weakness that caused the problem.

@restorer-john (I think it was) also identified a design weakness with one of the earlier versions of hypex amp modules where a PCB was used to clamp a power device to a heatsink. The resulting flex of the PCB caused failures.

We simply don't know what (if any) design weaknesses are sitting latent in any particular design. This can be in any class of amp - or any other electronic device come to that. What we do know though is high heat and/or heat cycling is a great way to turn a latent design weakness into an actual product failure.

 

[Dougey_Jones]

That is a possibility - heat is the enemy of electrolytic caps of all sizes.

But the truth is we don't know and can't tell. Take the Topping PA5 problems. That was explained as a thermal issue within the potted modules. It is not clear to me if that was just heat failure internal to components - or if it was physical damage to the circuit as a result of differential expansion (I've seen that with potting in the past). Either way - it was a design weakness that caused the problem.

@restorer-john (I think it was) also identified a design weakness with one of the earlier versions of hypex amp modules where a PCB was used to clamp a power device to a heatsink. The resulting flex of the PCB caused failures.

We simply don't know what (if any) design weaknesses are sitting latent in any particular design. This can be in any class of amp - or any other electronic device come to that. What we do know though is high heat and/or heat cycling is a great way to turn a latent design weakness into an actual product failure.

I take issue with you comparing the reliability of Hypex modules and power supplies to Topping.

 

[antcollinet]

I take issue with you comparing the reliability of Hypex modules and power supplies to Topping.

I don't remember making a comparison.

 

[earik]

I've got an active 4-way system powered by four Apollon amps. Three of them are Purifi 1et400-based, and one of them (for the subs) is ncx500-based. They are all the same form-factor as the one Amir reviewed here. The ncx500 one gets a little hotter than the Purifis, but none of them ever get more than warm to the touch, even after long periods of time at higher volumes. The build quality is great, the sound is great, each has tons of power, and the price was affordable enough that my wife didn't kill me after I bought four. The only thing they're missing is an auto-detect soft-start feature. I think any concerns about poor thermal design are seriously overblown, and probably more due the nature of audiophiles overthinking things on the internet than any actual issues with the amps.

 

[sandeep_s300]

I heard that there been a significant upgrade to the integrated opamp. I wonder what difference to be expected in compare to Sonic imagery 990 or 994 op amp. Any thoughts?

 

[earik]

Any upgrades at this level of performance are theoretical. Sure, the numbers can improve, but you won't hear a difference compared to the previous tech. I think the only way you might be able to hear a difference due to the opamps is if you compared against something exotic like a tube buffer, and even then I wouldn't bet money on it... I've got a Purifi+old Apollon op amp, and a ncx500+new op amp, and there's no way I'd be able to tell them apart in a blind test. In fact, the only way I know the difference is because I got them in different colors.

 

[sandeep_s300]

Any upgrades at this level of performance are theoretical. Sure, the numbers can improve, but you won't hear a difference compared to the previous tech. I think the only way you might be able to hear a difference due to the opamps is if you compared against something exotic like a tube buffer, and even then I wouldn't bet money on it... I've got a Purifi+old Apollon op amp, and a ncx500+new op amp, and there's no way I'd be able to tell them apart in a blind test. In fact, the only way I know the difference is because I got them in different colors.

Nord Acoustics | Nord One NCx500 MKII Dual Mono Stereo Amp

Nord One NCx500 MKII: Dual mono stereo amp. Experience unparalleled audio performance. Delivering exceptional sound quality and power.

nordacoustics.co.uk

I was comparing Nord vs Apollon and came across the opamp options . They give choice of soft warmer sound vs airy dynamic by choosing the relevant opamp.

 

[Julf]

Nord Acoustics | Nord One NCx500 MKII Dual Mono Stereo Amp

Nord One NCx500 MKII: Dual mono stereo amp. Experience unparalleled audio performance. Delivering exceptional sound quality and power.

nordacoustics.co.uk

I was comparing Nord vs Apollon and came across the opamp options . They give choice of soft warmer sound vs airy dynamic by choosing the relevant opamp.

Tone controls by opamp choice? The "soft warmer sound" or "airy dynamic" would be coloration/distortion if it actually existed outside the BS marketing department.

 

[sandeep_s300]

The review done as written in page 1, shows higher SNR in compare to the amp itself, I wonder if it has to do with Sonic imagery 990 opamp that was later found.

Anyone have any insights on build quality between Nord and Apollon ?

 

[earik]

Nord Acoustics | Nord One NCx500 MKII Dual Mono Stereo Amp

Nord One NCx500 MKII: Dual mono stereo amp. Experience unparalleled audio performance. Delivering exceptional sound quality and power.

nordacoustics.co.uk

I was comparing Nord vs Apollon and came across the opamp options . They give choice of soft warmer sound vs airy dynamic by choosing the relevant opamp.

From my own personal experience, my life got a lot easier once I had the realization (from direct experience) that I couldn't tell amps apart from each other. Maybe a really old fashioned tube amp with tons of harmonics vs something modern, but as long as you're not clipping, all these amps all sound exactly the same (they don't add anything). Opamps fall into the same category as color. Some people like black, some people like silver. You won't hear a difference. The only reason to spend more on that is if you think you'll always be wondering if your system was somehow better with that opamp in there, and it gnaws at you. Sighted bias actually does matter in a weird way, but just realize that you're buying opamps for the idea of what they do, not for anything that happens in the actual process of amplification.

 

[earik]

Anyone have any insights on build quality between Nord and Apollon ?

I can't speak to Nord, but Apollon is right at the top of the build quality list as far as class D stuff goes. That was actually my main reason for going with them. Tear downs of examples from both vendors should be posted around this forum if you search.

 

[sandeep_s300]

Placed my order last night for the ST version. I am going to pair with Topping D90III Sabre. https://www.toppingaudio.com/product-item/d90-iii-sabre

Can anyone suggest if I should be choosing XLR 4V out on the Topping and Lowest gain on the Apollon to achieve the best technical outcome?

Topping says: "In addition to the more universal XLR 4V and RCA 2V outputs, the D90 III
SABRE also adds XLR 5V and RCA 2.5V.
When XLR 4V and RCA 2V are selected, more devices can be adapted. When XLR 5V and RCA 2.5V are selected, the performance will be
pushed from extreme to more extreme."

What happens if I select XLR 5V on topping , should the Apollon be set to medium gain settings?

Speakers are M&K sound S300 - max rated power 500w @ 4ohms.