BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Review

[thin bLue]

Review of

Buckeye Amps

Buckeye Amps utilizes the most advanced audio amplifier technologies available. Authorized seller for Hypex and Purifi Class D amplifiers. Based in the US. Free shipping and worldwide service!

www.buckeyeamp.com

햇병아리 the member of our community kindly purchased it himself with his own money and asked me to measure it.

Common-
AMP at Mode ON (On - Off = plug-in/unplug)
Load 4 Ohms (for power sweep, a pair of 4 x 16 Ohms 1000 W as 4 Ohms 4000 W Load)
AC filters external AUX-0040
DC filters internal
DMM Keysight 34465A Truevolt 6,5 digit
Analyser Audio Precision APx525B

On-Off DC test with 4 Ohm @ Gain Med Ch.1

DC offset as 4.2 mV

Strange DC behavior after unplug(Marker 1). Over 12 Min to return to bottom voltage.



On-Off AC test with 4 Ohm @ Gain Med Ch.1

Peak around 4 mVrms

Stabilised(?) after 32 min from turn ON, bulge around 47 min would be my mistake.



On-Off DC-45k test with 4 Ohm @ Gain Med both Ch.1, Ch.2

On-Off DC-45k test with 4 Ohm @ Gain Low both Ch.1, Ch.2

On-Off DC-45k test with 4 Ohm @ Gain High both Ch.1, Ch.2

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain Med 4 Ohm 5 W 20k SINAD 256k Temp 26.9 Humi 62%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain Med 4 Ohm 5 W 22.4k SINAD 256k Temp 26.5 Humi 59%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain Med 4 Ohm 5 W 40k SINAD 256k Temp 26.7 Humi 62%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain Med 4 Ohm 5 W Fr Temp 27.1 Humi 62%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain Med 4 Ohm 5 W Gain Temp 27.1 Humi 62%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain Med 4 Ohm 5 W GD Temp 27.1 Humi 62%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain Med 4 Ohm 5 W Impulse Temp 27.1 Humi 62%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain Med 4 Ohm 5 W Multitone Temp 27.1 Humi 62%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain Med 4 Ohm Power sweep Temp 26.8 Humi 54%

*This amplifier fails to repeatedly achieve top power of the right end of this graph.
Drive this amplifier to near 700 W as officially rated can cause serious irreversible damage.



BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain Low 4 Ohm 5 W 20k SINAD 256k Temp 26.8 Humi 54%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain Low 4 Ohm 5 W 22.4k SINAD 256k Temp 27 Humi 55%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain Low 4 Ohm 5 W 40k SINAD 256k Temp 26.9 Humi 54%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain Low 4 Ohm 5 W Fr Temp 26.8 Humi 54%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain Low 4 Ohm 5 W Gain Temp 26.8 Humi 54%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain Low 4 Ohm 5 W GD Temp 26.8 Humi 54%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain Low 4 Ohm 5 W Impulse Temp 26.8 Humi 54%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain Low 4 Ohm 5 W Multitone Temp 26.8 Humi 54%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain Low 4 Ohm Power sweep Temp 26.9 Humi 57%

*This amplifier fails to repeatedly achieve top power of the right end of this graph.
Drive this amplifier to near 700 W as officially rated can cause serious irreversible damage.

Important!
For 20 kHz <- Filter had set as 20 -20 kHz so, higher frequency's harmonic distortions are heavily filtered so, THD+N look way finer than real value. So It should be ignored or carefully considered.


Continued on the next post due to image limit up to 35.

 

[thin bLue]

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain High 4 Ohm 5 W 20k SINAD 256k Temp 26.8 Humi 53%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain High 4 Ohm 5 W 22.4k SINAD 256k Temp 26.8 Humi 54%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain High 4 Ohm 5 W 40k SINAD 256k Temp 26.8 Humi 53%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain High 4 Ohm 5 W Fr Temp 27 Humi 56%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain High 4 Ohm 5 W Gain Temp 27 Humi 56%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain High 4 Ohm 5 W GD Temp 27 Humi 56%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain High 4 Ohm 5 W Impulse Temp 27 Humi 56%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain High 4 Ohm 5 W Multitone Temp 27 Humi 56%

BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Gain High 4 Ohm Power sweep Temp 26.9 Humi 53%

*This amplifier fails to repeatedly achieve top power of the right end of this graph.
Drive this amplifier to near 700 W as officially rated can cause serious irreversible damage.

The 20 Hz sweep @ High Gain was my final signal from this amp. After I finished all 4 ohms sweep test, it starts endless relay clicking about in a minute.


Few points to consider

1. Mistaken rated power marking

To produce 700 W x 2 Ch output, It needs way more power consumption.

After I fried the amp and checked, It uses a Hypex SMPS1200A700 power supply. This is rated up to 1200 W which is less than 600 W per Ch.

Possible Efficiency of Class D AMP -> about up to 90%.

600 W x 90% = 540 W but, this is just an ideal value, so in practice a value of about 10 W less than this may be the rated output.
So, current setting could be rated as near 530 W or under.

How about 700 W?
700 W x Ch = Power supply output W x Efficiency of Class D AMP -10W x Ch
1420 W / 90% = Power supply output 1578 W

Due to calculation, About 1600 W PSU is required to stably output 2 channels of 700 W is estimated.
And additional point, they should change gain. To reach 4 Ohms 700W full power (about 53 Vrms) with standard 2 Vrms 4 Vrms input signal, It needs 28.5 dB/22.5 dB instead of 24.4 dB/19.3 dB (Lower gain increases the SINAD numbers). However, you may have different preferences depending on your output device.

So, they seem to need to properly change the rated output numbers or change the power supply unit to a high-power one and change the gain structure as an option.


2. Protection did not work properly until amp finally self-destructed.

Most of AMP builds for consumer are made to leave out protections and don't spell out the specs properly. But For a modern Class-D amplifier like this level of high performance, we expect to not follow the bad habits of the past and give consumers the right thing.

3. Amp's fidelity is so High, so APx525B Analyser limiting the SINAD of this AMP.

Above SINAD numbers of 100, It is getting closer to characteristics of the analyzer itself.
The higher the SINAD, the further away we are from the characteristics of the amplifier(DUT) and the more inaccurate the result.

Otherwise, it's a modern, high-performance Hi-Fi amplifier that works well in almost any situation.


Additional Information : Owner of this Amp has contacted to company, and reported this data. And I heard that the company has agreed to provide a replacement power supply unit to the owner free of charge. We look forward to they continuing to provide adequate service and continuing their reputation at ASR.

 

[kongkong]

thanks for your effort! This papaer shows very detail measurement... so amazing.
I believe the company can make enhanced amplifier with appropriate psu.

 

[thin bLue]

thanks for your effort! This papaer shows very detail measurement... so amazing.
I believe the company can make enhanced amplifier with appropriate psu.

As far as I know they apply feedback from ASR pretty quickly. I agree with what you said.

 

[GXAlan]

Great work. I vote for main page promotion, @amirm.

@thin bLue , any update on your Yamaha A8A measurement?

 

[thin bLue]

Great work. I vote for main page promotion, @amirm.

@thin bLue , any update on your Yamaha A8A measurement?

I have raw data for sure. But I'm somewhat hesitating now. Due to my many mistakes, I need leeeengthy commentary with it. But anyway I will definitely upload it.

 

[thin bLue]

Great work. I vote for main page promotion, @amirm.

@thin bLue , any update on your Yamaha A8A measurement?

For pre view of Yamaha RX-A8A

Amp out

Pre out

Pre out @ -6 dB IN

 

[GXAlan]

Thanks for the A8A. Seems to be about on par with the CX-A5100. They liked the nominal 1V out, so it is neat to see that it can put out 3.3V to unbalanced out with decent SINAD.

The amp itself has a nice harmonic pattern if you believe in the harmonics being audible. More importantly, the concept of a “Yamaha House Sound” becomes plausible with 5W SINAD of 70 dB.

Sorry to go off topic! Great work on the Buckeye!

 

[thin bLue]

Thanks for the A8A. Seems to be about on par with the CX-A5100. They liked the nominal 1V out, so it is neat to see that it can put out 3.3V to unbalanced out with decent SINAD.

The amp itself has a nice harmonic pattern if you believe in the harmonics being audible. More importantly, the concept of a “Yamaha House Sound” becomes plausible with 5W SINAD of 70 dB.

Sorry to go off topic! Great work on the Buckeye!

Both Pre-out are XLR out!


For RCA Pre-out of Yamaha RX-A8A

 

[Sokel]

That's a really detailed review,amazing job that leaves little room to interpretation or guessing.
Kudos to the company agreeing on replacement by the way.

 

[thin bLue]

That's a really detailed review,amazing job that leaves little room to interpretation or guessing.
Kudos to the company agreeing on replacement by the way.

Thank you for your words, It just make me smile!

 

[MaxwellsEq]

This is a very thorough and helpful review. There has been quite a lot of debate about stereo vs dual mono vs monoblocks. Your review suggests that if people are expecting to run the amps at maximum (unless this is with very inefficient speakers I can't imagine how loud this would be!), they should go for monoblocks or dual mono operation.

For normal use, I suspect it's unlikely to be a problem!

 

[Sokel]

This is a very thorough and helpful review. There has been quite a lot of debate about stereo vs dual mono vs monoblocks. Your review suggests that if people are expecting to run the amps at maximum (unless this is with very inefficient speakers I can't imagine how loud this would be!), they should go for monoblocks or dual mono operation.

For normal use, I suspect it's unlikely to be a problem!

The alarming issue here is not the lack of advertised power,is the self destruction of the PSU (if I got it right since that's the part the company offered to replace).
Maybe a deeper dive and test of the protections involved in that Hypex PSU (they do state lots of them in the PSU's paper) would be truly useful for their users.

 

[thin bLue]

This is a very thorough and helpful review. There has been quite a lot of debate about stereo vs dual mono vs monoblocks. Your review suggests that if people are expecting to run the amps at maximum (unless this is with very inefficient speakers I can't imagine how loud this would be!), they should go for monoblocks or dual mono operation.

For normal use, I suspect it's unlikely to be a problem!

Esp. considering US 120 V AC power and the IEC 60320, to use common C13 Connector and C14 Inlet(10A/250VAC international and 15A/250VAC North America) your opinion is 100% right!

US 120 V with international C14 -> 1200 W max = Stereo with over 600 W per each Ch needs multiple inlets.
in Japan it gets worse, JP 100 V with international C14 -> 1000 W max = Stereo with over 500 W per each Ch needs multiple inlets.
So, multiple mono block with one inlet seems way cool for many reason.


To avoid using multiple inlets with high power need this pair.
C19 & C20 16A/250VAC international and 20A/125 or 250VAC North America.
(Some heavy PC users would have experienced this with high power power supply on their PC)

 

[thin bLue]

The alarming issue here is not the lack of advertised power,is the self destruction of the PSU (if I got it right since that's the part the company offered to replace).
Maybe a deeper dive and test of the protections involved in that Hypex PSU (they do state lots of them in the PSU's paper) would be truly useful for their users.

Yeeeees! That's the point! Power is more than enough.
All we need is the Amp do not blown up and just stop really well before any damage and go again nicely!

 

[sweetchaos]

2. Protection did not work properly until amp finally self-destructed.

That’s concerning.

Would love to find out if this was a one-off event or is this reproducible?

Other than that, thanks for the review.
Keep them coming.

 

[Matias]

Very nice. So this gave about 490-500W per channel at 1% THD+N more or less? Still high power though.

In 230V the PS gives some 640W per channel as per Apollon measurements.

 

[thin bLue]

That’s concerning.

Would love to find out if this was a one-off event or is this reproducible?

Other than that, thanks for the review.
Keep them coming.

When I ran test and fried the amp, I didn't know the amp uses a Hypex SMPS1200A700 power supply.
This is rated up to 1200 W which is less than 600 W per Ch. as I mentioned. We can see the power sweep plot and confirm my aim was way above 600 W.

The amplifier repeatedly put out 600 W or more. However, considering the capacity of the power supply, if the protection works normally, IMHO it should have been shut down obviously at least around 540 W.

So, I think this is highly reproducible at max output range. User should set safety manually(Strict limiting of the input level with proper calculation.).

 

[thin bLue]

Very nice. So this gave about 490-500W per channel at 1% THD+N more or less? Still high power though.

In 230V the PS gives some 640W per channel as per Apollon measurements.

@ 220 V 60 Hz
THD+N 1% point with this data (May have been partially reduced by overheating).

Med gain
20 Hz @ 1% about 365 W
100 Hz @ 1% about 415 W
1 kHz @ 1% about 480 W

Low gain
20 Hz @ 1% about 342 W
100 Hz @ 1% about 398 W
1 kHz @ 1% about 464 W

High gain
20 Hz @ 1% about 355 W
100 Hz @ 1% about 396 W
1 kHz @ 1% about 456 W

 

[Matias]

Wow so in 220V. Then I don't understand this.

Apollon Audio Class-D Amp Build Quality

read again :) Ok, is the difference ... got it. Sorry.

www.audiosciencereview.com