BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Review

[xaxxon]

The old FTC spec is BS if you are trying to see how well an amp can actually play music. When I say Hi-Fi I mean it is desgined to play back recorded music not pass an arbitrary "test" which requires the same power produced at 20 Hz has to be produced at 20 Khz. I could argue making an amp that does this is a "bad" design. Why spend engineering effort and money on "solving" a problem that has nothing to do with playing back music?

because without a good standardized test, there is no way to compare. Defining "good at playing music" is worthless. Your music is different than my music. Look at the BS excuses that tidal used for MQA not being lossless for signals that "weren't musical enough"

Audio companies, of course, would love that, because then it's just an emotional sale. They don't want objective comparisons. You already need used-car-style sales people that are good at manipulating emotions, so proper engineering just adds cost.

 

[Chrispy]

No need for insults. An amp that can produce more LF power than HF power would be rated by its HF power according to the FTC test. An amp like this will indeed play music better than an amp with the same FTC power rating that plays LF and HF with the same amount power.

No need for odd analogies either. Let alone your conclusions.

 

[tmtomh]

No need for odd analogies either. Let alone your conclusions.

It's not an analogy. It's a hypothetical example, but one that has real-world correlates. An amp that can provide 325 continuous watts 20Hz-20kHz but 700 continuous watts 20Hz-5khz will in use have more power available for music playback than an amp that can provide 325 continuous watts 20Hz-20kHz without that extra 375 watts available in the 20Hz-5kHz range.

How to rate such an amp to the public is a question of ethics, safety, and standardization. But how to assess such an amp's performance is a different question, which is what I take to be @levimax 's point.

 

[PeteL]

Think all of this just goes to having a consistent spec amp to amp. Not crazy about the allusion to the capabilities of the module with vague spec....

The data sheets of the Hypex module or SMPS are not vague, in fact they are quite comprehensive. They should be. That's not what ASR test for and I agree with you that for the end customer, that's the performance of the whole amp we are interested in. But component clear specifications always extremely important in Amp design. They are made to be studied by engineers and that's key in what ends up being the end result.

 

[levimax]

It's not an analogy. It's a hypothetical example, but one that has real-world correlates. An amp that can provide 325 continuous watts 20Hz-20kHz but 700 continuous watts 20Hz-5khz will in use have more power available for music playback than an amp that can provide 325 continuous watts 20Hz-20kHz without that extra 375 watts available in the 20Hz-5kHz range.

How to rate such an amp to the public is question of ethics, safety, and standardization. But how to assess such an amp's performance is different question, which is what I take to be @levimax 's point.

Thank you for explaining my point better than I did. The other part of my point is that these Hypex modules are well designed for the job of playing back music but the problem is how they ( or the brands they are used in) advertise the specs.

 

[xaxxon]

the problem is how they ( or the brands they are used in) advertise the specs.

Yeah I had no idea these numbers weren't sustained numbers.

 

[thin bLue]

Regarding reproducibility: I can say we have stressed tested a few different NCx builds with the SMPS1200A700 and never had an issue leading to the SMPS "frying" itself. As of right now I am considering it a one off, which can happen unfortunately. Hence getting a new SMPS sent out right away per warranty.

Regarding a "beefier" SMPS....there are things in the works to possible switch away from all Hypex SMPS models, yes. But no timeline for that at all.

A bad PSU is a bad PSU, wouldn't matter if it was a dual mono setup, that SMPS was likely to fail IMO, as there was obviously defective.

Looking forward to the new test!
If you have any additional tests or information you would like, please feel free to let us know!

 

[thin bLue]

I guess retest with replacement psu

100% Sure!

 

[thin bLue]

What's 'truly impressive' (not) is you quoting a best case distortion figure on a non continuous (about to shutdown) at a frequency (15kHz) where your measurement bandwidth is deliberately not even considering even a single harmonic component. LOL.

Let's talk about continuous rated power from 20Hz-20kHz. That means driving the amplifier up to 20kHz continuously to determine its actual capability. And measuring those harmonics with an adedquate measurement bandwidth.

@thin bLue Please retest the amplifier at elevated powers if and when you receive the replacement power supply. It will likely fail in the same way.

However, they are one of the few manufacturers that provide actual measurement results, and they readily agreed to show 150 point sweep. I think that should be highly appreciated. I'd love to see a 20 Hz sweep as well.
I'm trying to find out more how they handle such power with the same PSU.


Replacement alone does not prove that it has been completely repaired, so a true replacement naturally involves testing. It's also one of the things I must offer to amp owner.

 

[thin bLue]

Will add, that the board designer tests Buckeye amps as white box, I test them as black box as a contract tester and Dylan tests operationally. As some here already know, I tested at 4 ohms and 2 ohms and attained the rated Hypex specs without issue. I tested 2 different Buckeye NCx500 amps and still use a stereo one in my reference system. My power tests are set to terminate at 1% THD though and it does not appear the OPs testing does.

As this is not his first destructive test, the OP should look harder at his test settings. For that matter, should try a Power vs THD (rather than THD+N). The amount of wiring for his dummy load (or something else) may be adding noise and could cause an early power test abort. Still would hope that the amp is robust enough to self protect, but amp protections are not designed to prevent every possible situation either.

This is my first destructive test near the specified rated power @ 4 Ohms. If I was testing an unreliable kind of product without knowing anything, I would have monitored current consumption as suggested in ASR. However, this was not that type, it was a newer NCOREx product, and specifications from manufacturers with a long history of active activity in ASR are considered reliable.


And even when tested by an idiot (<- Including me a while ago, who had little test experience and didn't care about 2 ohms.), any decent amp should have its protection kick in and prevent permanent damage before it enters the red zone.

 

[Chrispy]

The data sheets of the Hypex module or SMPS are not vague, in fact they are quite comprehensive. They should be. That's not what ASR test for and I agree with you that for the end customer, that's the performance of the whole amp we are interested in. But component clear specifications always extremely important in Amp design. They are made to be studied by engineers and that's key in what ends up being the end result.

But the details aren't in the general spec for the amp quoted.

 

[Chrispy]

It's not an analogy. It's a hypothetical example, but one that has real-world correlates. An amp that can provide 325 continuous watts 20Hz-20kHz but 700 continuous watts 20Hz-5khz will in use have more power available for music playback than an amp that can provide 325 continuous watts 20Hz-20kHz without that extra 375 watts available in the 20Hz-5kHz range.

How to rate such an amp to the public is a question of ethics, safety, and standardization. But how to assess such an amp's performance is a different question, which is what I take to be @levimax 's point.

The only actual rating is that by the final product manufacturer, tho. You can verify it/dispute it, but it's still what the manufacturer/brand provides for the finished product. It's not easy to find the full details with some using these modules....let alone verified for the finished product vs the module's ideal spec.

 

[thin bLue]

I think that one of the key questions is how long every of this test lasts.
SMPS's .pdf clearly states that it's PEAK power (1200 watt) is only for 10 seconds and that it's continuous power is 325 watt:

View attachment 303830

https://www.hypex.nl/media/8c/22/86/1646037796/SMPS1200Axx0_10xx.pdf

Would it be fair to ask an output of 1200 watt for longer than that?No.
Is it also fair to advertise specs based on that without mentioning this condition?Also no.
Should the mentioned PSU shut down long before according to it's advertised specs about it's protections?It certainly should.

Maybe we should not blame the messenger for exposing the obvious.More than that,we should embrace such efforts and thank both the reviewer and the owner who accepted to take that risk.

In the case of power sweep, since it is a sweep, there is a big difference from a continuous test of fixed power. It is true that large amount-of-point-sweeps are relatively time-consuming than fewer pointed one, but still unlike continuous tests, they are only instantaneous for certain powers. Usually, fun and fries arise out of these uncertainties.

Thank you for your kind words!

 

[thin bLue]

Think all of this just goes to having a consistent spec amp to amp. Not crazy about the allusion to the capabilities of the module with vague spec....

We'd all be happy in most case if any manufacturer put more details on the specs!

 

[thin bLue]

The old FTC spec in US tried to deal with this issue but went overboard the other way. To me it looks these Purfi modules are designed to be Hi-Fi music amps... not PA amps or sine wave amps and certainly not designed for the old FTC test. However for playing music they seem perfectly fine with exceptional performance. Is there really any point to 700 watts @ 20 Khz for playing music? None that I can think of.

What has always puzzled me about these specs is that the "real" specs - the continuous power ratings - are pretty darned good as-is. In addition to being misleading, the top-line specs also seem unnecessary for making the case that these are good modules and PSUs.

EDIT: @levimax makes essentially the same point, albeit in a different way, just above. Agree.

Even if it is assumed that it is not needed at all for reproduction, I believe that protection should intervene and prevent any damage when an abnormal output is requested at a normal load (4 ohms).

This seems to be agreed upon by the manufacturer too, and is probably one of the reasons why the PSU is assumed to be defective and planed to be replaced.

 

[thin bLue]

Here you go. I would say that it is truly impressive what this little NCx500 module can do. 20Khz and 15Khz @ 500 watts with 0.0001% THD+N. Mind blowing. Haven't seen this with any other class D module on the market.

View attachment 303811

Even looking back again, it's still interesting! Could you lend one to Korea for measurement?

 

[MaxwellsEq]

To me it looks these Purfi modules are designed to be Hi-Fi music amps... not PA amps or sine wave amps and certainly not designed for the old FTC test.

They are Ncore.

 

[MaxwellsEq]

Re-reading the thread, it looks like the limit was the (possibly faulty) PSU. So all the back and forth about the module specs up to 20kHz vs real music is unproven.

Possibly the most important fact is the PSU is only rated for "full power" for 10s but can sustain 300+W indefinitely. That should be the spec for the amp as a whole, not the spec based on what the modules can do.

 

[Toni Mas]

Dial back the attitude and snark or you will be removed from the conversation Sir.

I was just suggesting that Hypex cannot be held responsible of the bad implementation of its modules, nor bad interpretation (over promissing) of their specs,by any assembler, pro or diy.
In this case It looks that the psu is not strong enough for 2 modules amps.

 

[PeteL]

A few toughts:

• I am also in the camp that peak power is the spec that matter more for music and program reproduction but it doesn't change the fact that it should be clear in the specs of the amp.
• Whatever the advertised power spec is, their is no excuse on the amp not shutting down per circuit protection before being damaged. If Hypex own protection is insufficient, you design some.
• Manufacturer claims a faulty power supply, maybe, we are not fully sure of that by the information provided. Manufacturer offered a replacement PSU, it's fair but in my book it's not what a great warranty is. You provide shipping labels, you get the whole amp, You fix it, pass it trough quality control and send it back. If that's too long you ship a new amp.
• That said, I get it. This is very inexpensive for what you get, profit on this is extremely tight. Sometime you get what you are willing to pay for.
• As other have said specs appears to be misleading when put against Hypex specs for Power supply, but also maybe the module (the x version is not freely available but general construction and heat management suggest no major changes in continuous power capabilities). It is not up to the reviewer to dig what theoretically the amp can do. He is provided with the manufacturer's advertised specs, but for the rest of us, It could be interesting to know how long it was demanded to this amp to run over 100W continuously, If it had been running above 325W more than 10 sec, if proper cooling time was done in between tests. Again not that he should have, but good info to assess.
• I personally had a NC500 module (previous) die. I initially suspected the PSU too because nothing was powering on but it was the module. Not sure how the manufacturer, from remote knows for sure that it's the PSU that died. Are we sure? Has the amp been opened? In all cases yes, shit may happen, but it is still a fail. I seem to understand that the manufacturer rely on some third party for test and measurements. It also suggest that the QC capacity may be a bit limited. Again, I get it. Cost.