Apollon NCx500ST Stereo Amplifier Review

[Extreme_Boky]

The evidence is right there in front of my eyes. The combined heat dissipation is too much for that design. Even with the minimal heat dissipation mentioned above, if the amp is placed in a rack (quite possible... after all, it is a class D amp that supposedly runs cold, so an average user may be tempted to place it on the middle shelf, for example), it will overheat. The capacitor electrolyte will dry - especially in that harsh high-frequency switching environment, and hot spots will develop.

Apollon can take my constructive feedback on board or choose to ignore it. The start would be to actually measure the power usage from the mains socket, and take the temperature measurements under the conditions I stated earlier, with the top lid closed. I trust that a sensible decision will be made to insert a current hungry OPAmp in DIL8s, to mimic the actual use case.

This has nothing to do with you. You have no idea what my background is, so you should be quiet instead of polluting the thread trying to prove you know stuff/have experience in electronics design.

With external temperature approaching 50degC, what do you think the internal temp would be??? Do you think that the side vent will help circulate the air and provide any sort of conventional cooling inside that thing???

 

[antcollinet]

The evidence is right there in front of my eyes. The combined heat dissipation is too much for that design. Even with the minimal heat dissipation mentioned above, if the amp is placed in a rack (quite possible... after all, it is a class D amp that supposedly runs cold, so an average user may be tempted to place it on the middle shelf, for example), it will overheat. The capacitor electrolyte will dry - especially in that harsh high-frequency switching environment, and hot spots will develop.

More un-evidenced statements. Please stop. You are actually libelling @Apollon right now.


Equipment is thermally tested to operate in defined conditions (normally for consumer gear, at typical room temperature in free air). If someone wants to use it in other conditions (such as in a rack with other heat generating gear, and restricted airflow) then it is their responsibility to ensure cooling in the rack is sufficient.

This applies to all equipment, not just this amp. Any amp (as pointed out by @NTK above) of any class and any design will overheat if you reduce airflow over it, and put it in the vicinity of other heat sources.

The start would be to actually measure the power usage from the mains socket, and take the temperature measurements under the conditions I stated earlier, with the top lid closed.

1 - where is your evidence that the testing already done by @Apollon is insufficient.
2 - where is your evidence (documented measurements under defined test conditions) that the cooling performance of this amp is insufficient.

any more evidence free slurs will be brought to the attention of the mods. This is completely out of line.

 

[Extreme_Boky]

Why threaten with mods' action???? I asked for a simple test. Amps manufacturers use this site as a product placement platform - adverts are out there for everyone to read and base their decision on what is stated in these forums.

What amazes me is the lengths to which people here are ready to go to prove a point and feed their egos. It is a simple test!! If they do what I am telling them to do, it will save Apollon a lot of headaches a couple of years down the road.

Now, care to actually answer the questions below? Here they are... this time, I highlighted them in bold for you... so you can't miss them again.

With the external temperature approaching 50degC (already measured with AN OPEN lid), what do you think the internal temp would be? Do you think that the side vent will help circulate the air and provide any sort of conventional cooling inside that thing?

 

[Apollon Audio]

Why threaten with mods' action???? I asked for a simple test. Amps manufacturers use this site as a product placement platform - adverts are out there for everyone to read and base their decision on what is stated in these forums.

What amazes me is the lengths to which people here are ready to go to prove a point and feed their egos. It is a simple test!! If they do what I am telling them to do, it will save Apollon a lot of headaches a couple of years down the road.

Now, care to actually answer the questions below? Here they are... this time, I highlighted them in bold for you... so you can't miss them again.

With the external temperature approaching 50degC (already measured with AN OPEN lid), what do you think the internal temp would be? Do you think that the side vent will help circulate the air and provide any sort of conventional cooling inside that thing?

What I would like to ask is why you are spreading false information.

First, you claimed that our amplifier is made of sheet metal, when in fact, it is constructed from aluminum.

Second, you stated that the modules dissipate 60 watts of heat, whereas the actual dissipation is only 20 watts—a significant discrepancy of 40 watts.

Third, you asserted that the temperature in our demonstration video reached 50°C, while the actual recorded temperature was 32-42°C. Even under extreme testing conditions—where the amplifier was driven to its limits with a continuous 20 kHz sine wave at 500 watts—the components on the module did not exceed 42°C (baseplate temperature 27°C). These conditions are far more demanding than real-world usage, where actual operating temperatures remain significantly lower when playing dynamic music.

Furthermore, I find it curious that you are raising concerns about overheating when no such issues have been reported by any users. You have not conducted a single test with our amplifier, yet you continue to make unfounded claims. If thermal performance is truly your concern, why not question manufacturers of Class A amplifiers, where capacitor temperatures frequently reach 60–80°C? In comparison, the capacitors in our amplifiers operate at roughly half that temperature. The Rubycon caps on the NCx500 module are rated 105°C and 4.000 hours btw.

The lifespan of an electrolytic capacitor is heavily influenced by its operating temperature. A widely accepted rule of thumb, based on the Arrhenius Law, states that for every 10°C reduction in temperature, the capacitor's lifespan doubles.

Let's apply this principle to a capacitor rated for 4,000 hours at 105°C, but operating at 40°C for instance. The temperature difference is 65°C (105°C - 40°C). Using the doubling rule, we can estimate the lifespan step by step:

• At 95°C, the lifespan increases to 8,000 hours
• At 85°C, it doubles again to 16,000 hours
• At 75°C, it extends to 32,000 hours
• At 65°C, it reaches 64,000 hours
• At 55°C, it further increases to 128,000 hours
• At 45°C, the lifespan grows to 256,000 hours
• Finally, at 40°C, the estimated lifespan is approximately 362,000 hours

This means that under these "perfect" conditions, the capacitor could last over 41 years of continuous operation. This example assumes ideal conditions, but it illustrates how temperature significantly impacts capacitor lifespan. Real-world factors such as voltage stress, ripple current, humidity, and material degradation can also affect capacitor life.

Your statements are not helping us prevent future issues; instead, they are generating unnecessary confusion.

Trust me, we have conducted comprehensive and rigorous testing on our amplifiers, pushing them to their absolute limits and beyond.

Misleading statements based on opinion, rather than facts or actual testing, do not contribute to constructive discussion. I would appreciate it if we could maintain accuracy and fairness when discussing technical aspects of our products.

 

[Mnyb]

it's bad standards even for troll to go after manufacturers representatives on the forum , they have to answer politely even if the posters has no honest intent with their posts.
I have put this person on the ignore list way back . But Apollon Audio can not do that as he need to see what's said about his products . This makes manufacturers vulnerable to trolling ?

 

[Jimbob54]

Why threaten with mods' action???? I asked for a simple test. Amps manufacturers use this site as a product placement platform - adverts are out there for everyone to read and base their decision on what is stated in these forums.

What amazes me is the lengths to which people here are ready to go to prove a point and feed their egos. It is a simple test!! If they do what I am telling them to do, it will save Apollon a lot of headaches a couple of years down the road.

Now, care to actually answer the questions below? Here they are... this time, I highlighted them in bold for you... so you can't miss them again.

With the external temperature approaching 50degC (already measured with AN OPEN lid), what do you think the internal temp would be? Do you think that the side vent will help circulate the air and provide any sort of conventional cooling inside that thing?

This is starting to look like badgering . And familiar .

Posting like this will result in sanctions including thread bans and possibly site bans .

 

[tmtomh]

Why threaten with mods' action???? I asked for a simple test. Amps manufacturers use this site as a product placement platform - adverts are out there for everyone to read and base their decision on what is stated in these forums.

What amazes me is the lengths to which people here are ready to go to prove a point and feed their egos. It is a simple test!! If they do what I am telling them to do, it will save Apollon a lot of headaches a couple of years down the road.

Now, care to actually answer the questions below? Here they are... this time, I highlighted them in bold for you... so you can't miss them again.

With the external temperature approaching 50degC (already measured with AN OPEN lid), what do you think the internal temp would be? Do you think that the side vent will help circulate the air and provide any sort of conventional cooling inside that thing?

1. Please acknowledge that the Apollon amp is made of aluminum, not sheet metal.

2. Please acknowledge that the modules dissipate 20W, not 60.

3. Please acknowledge that the temperature in the video was not "approaching 50degC" but rather maxed out at 42C.

Unless or until you do that, you should refrain from posting further . That's not about censorship, it's about being an adult and taking accountability for your claims and statements.

What amazes me is the lengths to which people here are ready to go to prove a point and feed their egos.

Indeed - if you want to see the most prominent recent example of that, take a look in a mirror.

 

[Glarioo]

I have a Purifi amp.
This one: https://apollonaudio.com/product/apollon-audio-purifi-1et7040sa-st-stereo-amplifier/.
At first, I was uneasy about it because the amp is in an almost completely closed cabinet, with an opening of about 10 square centimetres at the back/top side. For many weeks there was a temperature gauge lying on top of the amp. The highest temperature I measured was 41°C at a room temperature of about 25°C. The volume for about two hours so high that I could hear the music on the terrace outside, very high in other words. I couldn't stay inside for long, too many decibels.

 

[livinon2wheels]

I don't like the curved side corners. Not a major flaw, just not good industrial design IMHO.

The more I see class-D amps filling the top ranks of the amplifier ratings, the more respect I have for Benchmark in designing a class AB amp that is right up there with them. I think class AB design and manufacturing to that exalted standard is very difficult. Seems to me that once the methods for top-quality class D amps have been worked out, it's somewhat easier to achieve this level of performance - especially if you are going to use a Hypex or Purifi module.

Good amps all sound good. I don't think there's an inherent sonic advantage in choosing class-D or class-AB; but class-D does have power consumption, weight and heat advantages over traditional class-AB designs.

good points its much like what class AB offers over pure class A...more efficiency and less power consumption. And less need to for additional HVAC to counteract the amplifier's heat output.

 

[Deleted member 20765]

I received my Apollon amp yesterday, their implementation of the Hypex NCx500 ST NCOREx Stereo Amp. No owner's manual nor power cord (I need 117VAC, US). It's probably OK since connecting to it is similar to other amps. I am using a 14 gauge cord that's good for up to 15 amps. But it is a bit strange.


I bought it as the backup for the ML #27, which is 30+ years old. The Apollon will fill this role nicely and for a fraction of the cost of a class A or A/B amp with a similar drive, $1.2K vs ??? Amir's findings are so good, I had to give it a try.


I listened to this amp today with my SP-6 preamp and Revel f108 speakers (full range). I sit about 2m from the speakers. I normally listen about 85-90 dB at listening position. I've measured the voltage on the speakers in real time. I found the max power I'm calling for is around 10 watts. Not much. Comparison amp is my old and trusty ML #27 with new blue can capacitors in the PS.


Here's my impressions after only an hour of critical listening... The Apollon sounds airier than the ML, but there's no sibilance or accentuated highs. It doesn't have the same bass impact. But male voices were very clear and human-sounding. It's a good break from the darker ML sound. I'm running boh amps at the same gain, which is about 26dB. More listening definitely needed as the differences are quite small and may moderate after longer listening. I am assuming that there's no "break-in" involvbed. My overall impression is that this is a very clear and clean amp with a quite neutral presentation, but not cold and clinical.


I did have to pay an additional $140 for the new US tariff. This is a big concern as a lot of gear is more expensive than the Apollon amp. Speakers for example.

 

[Ecaroh]

I received my Apollon amp yesterday, their implementation of the Hypex NCx500 ST NCOREx Stereo Amp. No owner's manual nor power cord (I need 117VAC, US). It's probably OK since connecting to it is similar to other amps. I am using a 14 gauge cord that's good for up to 15 amps. But it is a bit strange.


I bought it as the backup for the ML #27, which is 30+ years old. The Apollon will fill this role nicely and for a fraction of the cost of a class A or A/B amp with a similar drive, $1.2K vs ??? Amir's findings are so good, I had to give it a try.


I listened to this amp today with my SP-6 preamp and Revel f108 speakers (full range). I sit about 2m from the speakers. I normally listen about 85-90 dB at listening position. I've measured the voltage on the speakers in real time. I found the max power I'm calling for is around 10 watts. Not much. Comparison amp is my old and trusty ML #27 with new blue can capacitors in the PS.


Here's my impressions after only an hour of critical listening... The Apollon sounds airier than the ML, but there's no sibilance or accentuated highs. It doesn't have the same bass impact. But male voices were very clear and human-sounding. It's a good break from the darker ML sound. I'm running boh amps at the same gain, which is about 26dB. More listening definitely needed as the differences are quite small and may moderate after longer listening. I am assuming that there's no "break-in" involvbed. My overall impression is that this is a very clear and clean amp with a quite neutral presentation, but not cold and clinical.


I did have to pay an additional $140 for the new US tariff. This is a big concern as a lot of gear is more expensive than the Apollon amp. Speakers for example.

How hot did it get?

Thanks.

 

[Deleted member 20765]

How hot did it get?

Thanks.

I could baerely feel that the temp was warm. The top cover was colder than thr ML 27 with the same program material and SPL.
But remember, I'm not asking for much power.

 

[Julf]

Here's my impressions after only an hour of critical listening... The Apollon sounds airier than the ML, but there's no sibilance or accentuated highs. It doesn't have the same bass impact. But male voices were very clear and human-sounding. It's a good break from the darker ML sound. I'm running boh amps at the same gain, which is about 26dB. More listening definitely needed as the differences are quite small and may moderate after longer listening. I am assuming that there's no "break-in" involvbed. My overall impression is that this is a very clear and clean amp with a quite neutral presentation, but not cold and clinical.

Did you verify the gain?

 

[EJ3]

I received my Apollon amp yesterday, their implementation of the Hypex NCx500 ST NCOREx Stereo Amp. No owner's manual nor power cord (I need 117VAC, US). It's probably OK since connecting to it is similar to other amps. I am using a 14 gauge cord that's good for up to 15 amps. But it is a bit strange.

No basic startup instructions, specs or power cord. odd indeed.
Of course, I'm quite sure that most of us here know the basics of getting started.
But nothing to let the neighbor's kid look at while you show them the ropes of putting a system together?
And they wonder why the audio as a hobby field is going downhill?

 

[Julf]

And they wonder why the audio as a hobby field is going downhill?

I doubt it is because lack of manuals.

 

[EJ3]

I doubt it is because lack of manuals.

I have have a valid opinion.
As do you.
But, because you slammed me:
Ever been a mentor to anyone for anything?
Or does everyone that you have ever talked to accept what you say without you showing them anything?
That's a pretty special talent that you have: worlds greatest teacher of everything because no one asks to be shown something.
Please show me how that works?
Oh, that's right, you can't.
Because I must just accept what you say is fact.
U'mm. NO, that does not work for me.
And I suspect that I am not the only one.
Blind Faith in what someone says. Without any documentation. Sure thing.

 

[Julf]

I have have a valid opinion.

Yes. You have an opinion. It is valid to you.

Blind Faith in what someone says. Without any documentation. Sure thing.

Exactly. Blind faith is accepting things without questioning and without evidence.

 

[Julf]

I have have a valid opinion.
As do you.

So...

But, because you slammed me

Ah, having an opinion is "slamming" you?

 

[Jimbob54]

I have have a valid opinion.
As do you.
But, because you slammed me:
Ever been a mentor to anyone for anything?
Or does everyone that you have ever talked to accept what you say without you showing them anything?
That's a pretty special talent that you have: worlds greatest teacher of everything because no one asks to be shown something.
Please show me how that works?
Oh, that's right, you can't.
Because I must just accept what you say is fact.
U'mm. NO, that does not work for me.
And I suspect that I am not the only one.
Blind Faith in what someone says. Without any documentation. Sure thing.

Calm down

 

[fadetoblackbs]

I received my Apollon amp yesterday, their implementation of the Hypex NCx500 ST NCOREx Stereo Amp. No owner's manual nor power cord (I need 117VAC, US). It's probably OK since connecting to it is similar to other amps. I am using a 14 gauge cord that's good for up to 15 amps. But it is a bit strange.


I bought it as the backup for the ML #27, which is 30+ years old. The Apollon will fill this role nicely and for a fraction of the cost of a class A or A/B amp with a similar drive, $1.2K vs ??? Amir's findings are so good, I had to give it a try.


I listened to this amp today with my SP-6 preamp and Revel f108 speakers (full range). I sit about 2m from the speakers. I normally listen about 85-90 dB at listening position. I've measured the voltage on the speakers in real time. I found the max power I'm calling for is around 10 watts. Not much. Comparison amp is my old and trusty ML #27 with new blue can capacitors in the PS.


Here's my impressions after only an hour of critical listening... The Apollon sounds airier than the ML, but there's no sibilance or accentuated highs. It doesn't have the same bass impact. But male voices were very clear and human-sounding. It's a good break from the darker ML sound. I'm running boh amps at the same gain, which is about 26dB. More listening definitely needed as the differences are quite small and may moderate after longer listening. I am assuming that there's no "break-in" involvbed. My overall impression is that this is a very clear and clean amp with a quite neutral presentation, but not cold and clinical.


I did have to pay an additional $140 for the new US tariff. This is a big concern as a lot of gear is more expensive than the Apollon amp. Speakers for example.

Thanks for sharing =)