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March Audio P502 Stereo Amplifier Measurements

amirm

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#1
This is the measurements of the March Audio P502 class D amplifier based on Hypex (?) modules. It was kindly send to me by a member for testing. The P502 costs US $1,075 from the company direct.

This is not a review because the @March Audio is a long time member of the forum and I like to avoid conflict of interest.

The unit comes in attractive aluminum packaging:
March Audio P502 Hypex Stereo Class D Amplifier  Review.jpg

On off control is a touch button which is unusual in power amplifiers.

Here is a shot of the back:

March Audio P502 Hypex Stereo Class D Amplifier  Back Panel Review.jpg

In hard use, the bottom plate gets quite warm. Make sure you have plenty of ventilation from below. A taller set of feet would help with this.

My heavy stress test of frequency versus power caused the unit to shut down momentarily. I did not retry it as I don't want to risk damaging the unit.

Warm Up Test
As is my standard practice now, I warm up and measure distortion and noise until the device stabilizes. For amps, I do this at 5 watts. Here are the results:

March Audio P502 Hypex Stereo Class D Amplifier Warm up Audio Measurements.png


As you see the channel in red is having a harder time, showing fair bit worse performance than the other. It did improve momentarily after power up but then went back to the same state. I checked all of my cabling and it was all secure. So don't know if this is an assembly issue or sample to sample variation.

Amplifier Audio Measurements
As usual we start with our dashboard:

March Audio P502 Hypex Stereo Class D Amplifier  Audio Measurements.png


Per warm up test, we see one channel with higher noise floor and differing distortion products. Averaging the two channels still puts the P502 well above average amplifier:
best class D stereo amplifier.png


Frequency response was essentially flat in audible band with a resistive dummy load or my speaker simulator:
March Audio P502 Hypex Stereo Class D Amplifier  Frequency Response Audio Measurements.png


March Audio P502 Hypex Stereo Class D Amplifier  Frequency Response Simulated Speaker Audio Me...png


Crosstalk was good enough and predictable:
March Audio P502 Hypex Stereo Class D Amplifier  Crosstalk Audio Measurements.png


32-tone test simulating "music" shows that 1 kHz is actually the point of higher distortion. Below and above performance improves:

March Audio P502 Hypex Stereo Class D Amplifier Multitone Audio Measurements.png


Signal to noise ratio is quite good:
March Audio P502 Hypex Stereo Class D Amplifier SNR Audio Measurements.png


Except for the one channel lagging behind. We are talking about 16+ bits at 5 watts reaching up to nearly 20 bits at full power.

Amplifier Power Measurements

Let's start with 4 ohm load:

March Audio P502 Hypex Stereo Class D Amplifier Power into 4 Ohm Audio Measurements.png


That is a ton of power with very low distortion. Letting the distortion go up to 1% gets us even more:
March Audio P502 Hypex Stereo Class D Amplifier Peak and Burst Power into 4 Ohm Audio Measurem...png



Switching to 8 ohm load we get:
March Audio P502 Hypex Stereo Class D Amplifier Power into 8 Ohm Audio Measurements.png


Conclusions
Lots and lots of power in above average performance and small package. If you are going to drive a sub with it at full power, you may want to deploy more cooling/ventilation on the bottom.

------------
As always, questions, comments, recommendations, etc. are welcome.

I don't want to come across as too obvious with respect to asking for money. It just isn't me. But please do me a favor and donate what you can using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 

Spocko

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#2
Running this amp right now, with the new RME ADI2 DAC FS as the DAC/preamp front end and my speakers are a pair of Revel m126be monitors and no complaints. When an amplifier just works, you don't notice it. I love that it's powerful and TINY, so I can literally just pick it up and move it around as I'm adding/removing components.
 

March Audio

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#5
Thanks Amir

I am obviously concerned about the mains 60Hz + harmonics which does indicate there might be an issue on channel 2. Its not something I see in the measurements normally . I will check in with you via PM on that just to check something and sort it out for the customer as needed.

Channel 1 is behaving more as I would expect and very close to the published Hypex spec of about 96dB SINAD at 5 watts into 4 ohms and about 98dB into 8 ohms.

Also interesting to see its getting a fair way past the Hypex spec of 500 watts into 4 ohms at 1%. Spec is 350 watts into 8 ohms 1%. I think your figure of 238 watts is at about 0.0035%

1579073772722.png


1579074355927.png


I have also sent a P122 in for test and I have measurements here so we can compare when you get that on test.

Oh, I like the addition of the burst test and simulated speaker load. Just need the risidual noise level in uV ;)
 
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March Audio

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#7
Possibly a good place to mention that we have just started shipping all amps with ETI solid copper gold plated binding posts. These offer better access for large cables and spades than the previous ones shown in the review. The materials used will also provide significantly improved audiophile satisfaction ;)

https://eti-research.com.au/binding-post-bp-20c/
1579076611574.png
eti.jpg
 

March Audio

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#8
It always blows me away the size difference between this March Audio P502 and a Class A/AB amp. A teardown c/w pics would be sooperb >@^_*@<
All our amps follow the same basic build.

Mains cable is booted, twisted, double insulated and routed as far as practicable away from speaker and signal cables.
Speaker cables are tightly twisted, minimising loop area, as per correct practice with switching amps.
Signal cable is Mogami balanced with screen taken to chassis at different place to the XLR socket chassis termination.
RF filter board on the back of the XLR.

Below is a P122, the baby 125 watter. The P502 is the same except for the larger amp module.


p122.jpg
 
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Matias

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#11
Very strange to have this difference between channels and the mains noise. I will be following this thread to see what caused it and how to fix it.
 

pma

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#12
Just for info, this is a measurement at 5 watts 4 ohms I took earlier on a P122. The mains spuria seen above is not present, so something is amiss.

View attachment 45943
But your measurement (system) has much higher noise than Amir's. Your THD+N is -83.3dB which maked SINAD = 83.3dB only. Yes I know it is most probably the soundcard noise. However you cannot directly correlate with Amir's measurement of noise floor and 60Hz mains line component, your measurement is masking it.
 

March Audio

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#13
But your measurement (system) has much higher noise than Amir's. Your THD+N is -83.3dB which maked SINAD = 83.3dB only. Yes I know it is most probably the soundcard noise. However you cannot directly correlate with Amir's measurement of noise floor and 60Hz mains line component, your measurement is masking it.
? The mains spuria Amir has measured are up to -105dB which is significantly above the FFT noise floor of my measurements of less than -120dB, so it would be evident in both. Need to do a bit of digging to figure out what the issue is.
 
Last edited:

AudioSceptic

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#14
This is the measurements of the March Audio P502 class D amplifier based on Hypex (?) modules. It was kindly send to me by a member for testing. The P502 costs US $1,075 from the company direct.

This is not a review because the @March Audio is a long time member of the forum and I like to avoid conflict of interest.

The unit comes in attractive aluminum packaging:

On off control is a touch button which is unusual in power amplifiers.

Here is a shot of the back:


In hard use, the bottom plate gets quite warm. Make sure you have plenty of ventilation from below. A taller set of feet would help with this.

My heavy stress test of frequency versus power caused the unit to shut down momentarily. I did not retry it as I don't want to risk damaging the unit.

Warm Up Test
As is my standard practice now, I warm up and measure distortion and noise until the device stabilizes. For amps, I do this at 5 watts. Here are the results:

View attachment 45908

As you see the channel in red is having a harder time, showing fair bit worse performance than the other. It did improve momentarily after power up but then went back to the same state. I checked all of my cabling and it was all secure. So don't know if this is an assembly issue or sample to sample variation.

Amplifier Audio Measurements
As usual we start with our dashboard:

View attachment 45907

Per warm up test, we see one channel with higher noise floor and differing distortion products. Averaging the two channels still puts the P502 well above average amplifier:
View attachment 45909

Frequency response was essentially flat in audible band with a resistive dummy load or my speaker simulator:
View attachment 45910

View attachment 45911

Crosstalk was good enough and predictable:
View attachment 45912

32-tone test simulating "music" shows that 1 kHz is actually the point of higher distortion. Below and above performance improves:

View attachment 45913

Signal to noise ratio is quite good:
View attachment 45916

Except for the one channel lagging behind. We are talking about 16+ bits at 5 watts reaching up to nearly 20 bits at full power.

Amplifier Power Measurements

Let's start with 4 ohm load:

View attachment 45914

That is a ton of power with very low distortion. Letting the distortion go up to 1% gets us even more:
View attachment 45915


Switching to 8 ohm load we get:
View attachment 45917

Conclusions
Lots and lots of power in above average performance and small package. If you are going to drive a sub with it at full power, you may want to deploy more cooling/ventilation on the bottom.

------------
As always, questions, comments, recommendations, etc. are welcome.

I don't want to come across as too obvious with respect to asking for money. It just isn't me. But please do me a favor and donate what you can using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Hypex fans will also be interested in Archimago's build and test of an NC252MP-based amp <http://archimago.blogspot.com/2020/01/measurements-hypex-ncore-nc252mp.html>
 

AudioSceptic

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#16
Possibly a good place to mention that we have just started shipping all amps with ETI solid copper gold plated binding posts. These offer better access for large cables and spades than the previous ones shown in the review. The materials used will also provide significantly improved audiophile satisfaction ;)

https://eti-research.com.au/binding-post-bp-20c/
View attachment 45939 View attachment 45940
Love the look of the amp, but from the front L/R are reversed. Is there a reason for that, such as enabling better routing of the internal wiring? Most would like to minimise any crossing of external cables, and it's also common for cables to be attached to the rear of equipment without needing to read the labels, so isn't it better to stick to the usual L-is-L, R-is-R, as seen from the front?
 

March Audio

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#17
Love the look of the amp, but from the front L/R are reversed. Is there a reason for that, such as enabling better routing of the internal wiring? Most would like to minimise any crossing of external cables, and it's also common for cables to be attached to the rear of equipment without needing to read the labels, so isn't it better to stick to the usual L-is-L, R-is-R, as seen from the front?
:) oh thats a long story, to do originally with a cock up by the case manufacturer. The next batch of cases will be around the other way, and in fact I may even mark channel 1 and 2 as Benchmark do. Remember it is just labelling. For a power amp it has no relevance which way you actually hook the cables up so long as the correct input goes to the correct output, no need to look :) The XLR goes to the posts directly underneath.
 

AudioSceptic

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#18
:) oh thats a long story, to do originally with a cock up by the case manufacturer. The next batch of cases will be around the other way, and in fact I may even mark channel 1 and 2 as Benchmark do. Remember it is just labelling. For a power amp it has no relevance which way you actually hook the cables up so long as the correct input goes to the correct output, no need to look :) The XLR goes to the posts directly underneath.
True. It doesn't matter which input is used for each channel, as long as the matching output is also used. :)
 

anmpr1

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#19
It always blows me away the size difference between this March Audio P502 and a Class A/AB amp. A teardown c/w pics would be sooperb >@^_*@<
We're at the point where large monster amplifiers are becoming irrelevant. If this trend continues, and it will, in the next ten years, McIntosh won't have any chassis real estate they can use in order to tack on their meters.
 

March Audio

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#20
Just taking a look at this mains 60Hz spuria. I have grabbed a P502 module out of stock and very quickly and crudely hooked it up on the bench.

502.jpg


Getting late here so just one quick measurement. looking for mains spuria (its 50Hz here not 60Hz as in Amirs measurements).

Lests compare to Archimagos measurements linked above of a 252. They are very similar beasts.

1579099300099.png



2volts
1579099121317.png

Other channel

1579100041547.png


Nothing to see.

I have an idea I have asked Amir to look at. More later
 
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