Buckeye Nc502mp Review (6 Channel Amplifer)

[pras1011]

Misleading as music and sounds don't just occur at 1khz or 6khz.

 

[Jdunk54nl]

Misleading as music and sounds don't just occur at 1khz or 6khz.

Sure, but then you need to look into the imd graph.

As stated, music isn't a test tone and most can't even hear 1% distortion in a test tone. You definitely can't hear it in music. I know personally I start to hear distortion at a little more than 1% in test tones, like 2-3% and music is like 5-6% before I can hear it. Plenty of tests on this online that you can try out.

But, I think you also have a misinterpretation of power. It doesn't matter to the amp really what tone or tones it plays. It can output 500w with the energy distributed to a single tone, or 500w with the energy distributed amongst all the tones (music). IMD may be slightly different figures for this with multiple tones.

Then you have to look at if your speakers can even handle a continuous tone or even multiple tones at 500w sustained.

Then you get into if you have issues with this amps ratings, you have issues with literally every other amp. Hypex and purifi provide so much data that you can look at whatever graph you want to get whatever figures matter to you.

 

[peng]

Misleading as music and sounds don't just occur at 1khz or 6khz.

Well I would think that 8 to 9 kHz would be better, any higher than that it becomes academic because if you test at 10 kHz, the lowest harmonics from distortions you get will be 20 kHz, how well do you really hear 2nd harmonic at 20 kHz, not much I guess, many people would not hear it at all.. There are more important things in audio than distortions contents at such high frequencies.

I would also agree Hypex could have provided even more test data but relative to other popular amps such as Monolith, ATI, Parasound, Emotiva, Marantz, Yamaha, even McIntosh's they are arguably not that misleading. Again, that's relatively speaking.

 

[Buckeye Amps]

One of my next "small" housekeeping tasks is to update power figures on my product pages to provide more accurate and detailed information. I admit I got a little lazy in this regard as my business was primarily here on ASR for the first 18 months where most people would glean the power they could expect from any of the various Hypex reviews by Amir.

But with my company becoming more broad/open to the whole Internet, I do need to make all of the available information easier to access for those who do not frequent ASR.

 

[gabo4au]

I received my 6-channel NC502 build. Everything looks excellent, and dealing with Dylan was also excellent. He always kept me informed and was very open and honest about anything regarding delays or issues.

One question, during my order and build time there was a shortage of the 502 modules. I'm not sure if it was just a shortage or if there were problems that caused them to pause production. But I did get a snippet talking about testing of the "new" modules and at one point I think some of the tests either failed or weren't up to quality standards.

None of that was an issue for me, but I was curious if there was anything changed during that time? I wonder if the new modules would test the same as the ones in this review or if there might be minor changes or improvements. If anything, I'm sure they are slightly better as these things tend to get better not worse.

gabo

 

[Buckeye Amps]

I received my 6-channel NC502 build. Everything looks excellent, and dealing with Dylan was also excellent. He always kept me informed and was very open and honest about anything regarding delays or issues.

One question, during my order and build time there was a shortage of the 502 modules. I'm not sure if it was just a shortage or if there were problems that caused them to pause production. But I did get a snippet talking about testing of the "new" modules and at one point I think some of the tests either failed or weren't up to quality standards.

None of that was an issue for me, but I was curious if there was anything changed during that time? I wonder if the new modules would test the same as the ones in this review or if there might be minor changes or improvements. If anything, I'm sure they are slightly better as these things tend to get better not worse.

gabo

The full story is that during a QC run of testing at Hypex back in late Spring 2022 an issue (I do not have the specifics) was detected regarding the NC502MP's only.
The issue in question was related to the manufacturing process (again, no specifics, but I would guess it might have been due to the manufacturer having changed a process or part due to shortage issues globally).
Hypex then had to spend the next 4-6 months testing different production models to find the exact issue that caused the QC failure.

I will say, from what I learned, Hypex has very strict QC. They would not have resumed NC502MP production if they did not think the modules were up to par again.
I also know there is no new revision of the NC502MP, meaning whatever QC fix they found was not major enough to warrant an entire revision change for the module.

 

[gabo4au]

Some pics of my 6-channel 502 amp. I'll follow up with some comments on performance as I get a chance to get it into it's environment and blow some electrons through it

 

[cavedriver]

Conclusions
While still way ahead of countless amplifier designs, the Hypex NC502MP modules are built more for power than ultra low distortion. Not a bad compromise considering the fact that running out of power is quite audible and rise in distortion probably not. Beauty of class D amplification is showcased by Buckeye in producing six times 600 watts of amplification in a light, and compact case. I will do a teardown later but so far, I am happy with what is there, sans the upside down XLR connectors.

When speakers reviewed here are praised for their ruler-flat response I'm surprised this amp was given a positive conclusion considering it's down half a dB at 20k and even shows some depression at 10k, when amps like the Schiit Tyr, an apparently solid A/B design is literally RULER FLAT right out to 20k (and down to 20 Hz, and with excellently low distortion and lots of power, although less than the class D amps).

 

[mdsimon2]

When speakers reviewed here are praised for their ruler-flat response I'm surprised this amp was given a positive conclusion considering it's down half a dB at 20k and even shows some depression at 10k, when amps like the Schiit Tyr, an apparently solid A/B design is literally RULER FLAT right out to 20k (and down to 20 Hz, and with excellently low distortion and lots of power, although less than the class D amps).

Flat on axis response is just one of many aspects of a speaker and having it without having other good characteristics would NOT make it worthy of praise.

Similarly amplifier frequency response is just one aspect of an amp review. I would even argue that the more important characteristic is load invariant frequency response, not ruler flat frequency response. With load invariant frequency response it is trivial to correct the roll off in frequency response with DSP. Of course you can do no such thing for other performance characteristics like power output, noise, distortion, etc.

The Tyr seems like a fine amplifier, definitely low noise with good power output. The Stereophile review shows an early increase in distortion that is also shown on the Schiit provided measurements, not likely audible but would prefer not to see it for the cost which is over 4X that of a Buckeye NC502MP stereo amp.

The Buckeye amp also shows an increase in distortion above 10 W which is actually unexpected based on the Hypex datasheet (EDIT: Rev 4 of datasheet shows a similar rise in distortion not present in earlier versions of the datasheet), still very good performance and a ton of power.

Overall the two amps actually have rather similar performance and I am sure that almost anyone would be happy with either.

Parameter	Schiit Tyr​	Buckeye NC502MP​
Gain	28​	26​
Input Sensitivity in to 4 ohm	1.5​	2.5​
Input Sensitivity in to 8 ohm	1.8​	2.5​
1 W in to 8 ohm SNR (dB)	97​	95​
5 W in to 8 ohm SNR (dB)	101​	99​
Residual Noise (uV)	41​	48​
5 W in to 4 ohm SINAD (dB)	82​	97​
5 W in to 4 ohm THD+N (%)	0.0075​	0.0014​
Power in to 4 ohm at 1% THD+N (W)	360​	600​
Power in to 8 ohm at 1% THD+N (W)	252​	310​
Cost (2 ch amp)	$3,198​	$749​

Michael

 

[cavedriver]

yeah, I was being a bit tongue-in-cheek. But to be clear, Amir's reviews, across all system components are generally not scored to include factors like cost or weight. Distortion, noise, etc. - performance metrics, appear to be the only area of concern for metric-based scoring of equipment and whether he recommends a given piece of equipment or not. Factors like cost and weight are then addressed in his comments (and in his recommendations for/against in extreme examples of cost). This approach is something I'm in complete agreement on.

I actually brought up this review because I was looking at the extent and types of inaccuracies in different tube amp topologies and how they compared to solid state and digital amps and I was surprised to see anything other than ruler-flat responses (or square wave responses in Atkinson's reviews) for a digital amp. I agree that it's probably easier to fix the inaccuracy on the class D amps with DSP than on a tube amp where you could ramp up distortion on the tube amp if you try to do too much frequency-specific correction via the input signal. It would have been fun to say a highly recommended digital amp has worse measured performance than a reasonably good tube amp. Some peoples' heads would spin.
Note: to be clear, I do not have a specific "reasonably good tube amp" that has that better performance although there are some very expensive ones that use banks of 845 tubes but audibly are probably indistinguishable from an A/B or D amp.

 

[Doodski]

It would have been fun to say a highly recommended digital amp has worse measured performance than a reasonably good tube amp.

Are you referring to class D when you state, "Digital amp?"

 

[cavedriver]

Are you referring to class D when you state, "Digital amp?"

yes, in that case I was referring to the 502MP amp in the review. I know that earlier I compared it to a solid state A/B amp (the Tyr) and then later referred to tube amps. The Tyr was just to illustrate a flaw in the 502MP. Comparing the 502MP to a tube amp was for the entertainment value.

 

[AdamG]

Reminder that this is an Official Review Thread about a specific Product. We try to keep these threads on topic and tidy. Your help will be appreciated.

Thank you!

 

[Doodski]

yes, in that case I was referring to the 502MP amp in the review. I know that earlier I compared it to a solid state A/B amp (the Tyr) and then later referred to tube amps. The Tyr was just to illustrate a flaw in the 502MP. Comparing the 502MP to a tube amp was for the entertainment value.

I see. Class D amps are not digital. I know they use square waves that make things seem digital although the analogue signal is riding on the flats of those square waves and the entire process is analogue. So they are not digital amps.

 

[DonH56]

Class D amp workings, sort-of: https://www.audiosciencereview.com/forum/index.php?threads/class-d-amplifiers-101.7355/

Not digital...

 

[cavedriver]

I see. Class D amps are not digital. I know they use square waves that make things seem digital although the analogue signal is riding on the flats of those square waves and the entire process is analogue. So they are not digital amps.

oh noes, you caught me. yes, not digital...

And although my underlying point was invalidated by the ease of using DSP on class D amp inputs, it's disappointing that out of the whole conversation we're wasting time on semantics.

Edit: ugh, I used "digital" incorrectly again, arrrrgh

 

[xaxxon]

That's kinda tough without knowing what wall issues there are as a new home run will need to be pulled.

and at that point you may as well just pull a 30 amp 3 conductor. No point in screwing around. Keep the old one and add 7,200 watts more.

 

[xaxxon]

Amir has stated on so many occasions he never factors in price.

This may have been true but is no longer.

 

[jimk1963]

I have what may be a silly question, but here goes. I see a ribbon cable coming from the back panel, feeding the amp. Appears to be carrying the balanced XLR input signals. Immediately next to the ribbon cable connector on the amp PCB, I see another 2-wire connector carrying what I think are the high-power speaker outputs, going back to the back panel. In RF amps routing the output anywhere near the input is a huge no-no, an instant recipe for creating an oscillator. Understanding that EM coupling is very limited at Baseband, I still can’t help but wonder - why are the Hypex modules designed this way? Why not physically separate the input from output?

I know one obvious answer: the amp works, so why are you asking? Just wanting to understand if there is some practical reason for this design choice, i.e., has to do with how the overall amp is laid out, or “it just doesn’t matter at all at audio frequencies, ever”, or whatever the answer is. With all the care taken in these designs overall, from grounding to shielded cables to spatial separation, etc., this Hypex layout choice seems very curious to me. Especially curious when I consider Amir’s testIng, with well over 100 dB measurement dynamic range. He’s literally finding the electron-needle in the haystack. And yet, who cares if input and output sit right on top of each other…? Head scratcher.

 

[Mxman]

I don't think there's any bad questions... If anything it's admirable to want to understand or learn. Nobody assumes you have ill intent