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March Audio P502 Stereo Amplifier Measurements

AudioTodd

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That's where something like the 502 or 452 with a Tube pre (Schiit Freya + for example) could be a formidable combination. Or even a simple Schiit SYS for tone controls.
I have actually experimented with driving various amps with a SYS for volume and a Loki equalizer to play with tonal changes and to act as a buffer so I could drive long cables to the amps with the Modi(and other DACs)/SYS/Loki combo next to my listening chair. Every combo I tried like that sounded great. Once Schiit started doing the things @amirm requested, whether that was a contributing reason or not, they have produced some bargains. I have the Saga + and the sadly discontinued Saga S, which are both great IMHO. You can really build a great sounding system for less money today than I spent on my first decent system about 1984.
 

blodsbror

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I guess that brings me to my last question then. Is the new Purifi 452, worth the 50% increase in price over the 502 (Ncore) sonically, if both are essentially transparent ? Am not sure if people here have been able to compare both..
 

SIY

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Right. So a well designed, and transparent (as possible) class AB design is basically pointless.

Not pointless, just that the reasons will be other than sonic. I've had quite a few of both linear and Class D amps through my lab and listening room, and as always, if frequency response into the speaker load is reasonably flat, the sound is unchanged.
 

blodsbror

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Not pointless, just that the reasons will be other than sonic. I've had quite a few of both linear and Class D amps through my lab and listening room, and as always, if frequency response into the speaker load is reasonably flat, the sound is unchanged.

I'm guessing then it has to be one of: features, build quality, or design then ? It's becoming more apparent to me, that a good transparent Class D implementation, with Tone controls in the chain, would give the best of both worlds.
 

arisholm

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Class AB designs with switching power supplies are an interesting area of technology—but there aren’t many of those to choose from. Still, the topology is extremely inefficient compared to class D. I don’t see any compelling reason to purchase a class AB (with a linear power supply) amp over a class D. Further, most class AB amps are going to be audibly transparent and can’t be used as a “tone control” the way class A and tube amps can be. So, with a choice between class D and class AB, class D will win for me every time.
The though HAS crossed my mind that perhaps I could replace my dCS Bartok DAC and ASR Emitter II A/B amp and ASR Basis Exclusive Riaa with a NAD M33... it does it all :) That would be a reduction from 7 boxes at 200kg total including 40kg worth of batteries and two external linear power supplies that makes the ceiling lights dim when they turn on and a bunch of expensive power and signal cables, down to a 18kg 1 box with almost the same power and similar specs.. And then I would even have Dirac room correction and digital crossover for subs built-in, instead of external crossovers and room correction via PC/Audiolense... I've made my live very difficult... and especially if I cannot hear any difference but that I don't know yet. But I suspect it will be some of the same experience as with a Lyngdorf TDAI-3400. Some magic will be missing, or perhaps it is all imagined. But I could save a lot of cash! And my back :)
 

blodsbror

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The though HAS crossed my mind that perhaps I could replace my dCS Bartok DAC and ASR Emitter II A/B amp and ASR Basis Exclusive Riaa with a NAD M33... it does it all :) That would be a reduction from 7 boxes at 200kg total including 40kg worth of batteries and two external linear power supplies that makes the ceiling lights dim when they turn on and a bunch of expensive power and signal cables, down to a 18kg 1 box with almost the same power and similar specs.. And then I would even have Dirac room correction and digital crossover for subs built-in, instead of external crossovers and room correction via PC/Audiolense... I've made my live very difficult... and especially if I cannot hear any difference but that I don't know yet. But I suspect it will be some of the same experience as with a Lyngdorf TDAI-3400. Some magic will be missing, or perhaps it is all imagined. But I could save a lot of cash! And my back :)

haha, great post!. Yes, it really requires re-wiring your brain - and potentially your ego from all the money spent ;) . But that's just the terrible thing with advancing technology and hindsight :)
 

SIY

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I'm guessing then it has to be one of: features, build quality, or design then ?

Yes. There's also other esthetic issues potentially at play, like an irrational attraction to old fashioned ways of doing things (e.g., my tube designs, Pavel's love of big, heavy discrete solid state...).
 

Matias

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To all who are considering switching to an NC502MP or a Purifi based amplifiers, remember that many vendors allow to have home trials or money back, so that you can test them in your system, compare with what you have and decide for yourselves. Best way to make a safe decision.
 
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amirm

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Just a general question.
The price to power ration of the 502 looks fantastic on paper. (as in general for Class D) Given that, is there really any reason to go down the Class A/B route, aside from simply getting a different sonic presentation in addition to using more power ? As an example (I'm in Norway) The Hegel H30 power amplifier gives you 350 watts into 8 ohms, and is 10,000 USD.
Hegel sells through dealer channel. Most dealers don't want to mess with high hassle of selling high-end gear if it doesn't have enough margin. A rule of thumb used to be that $5000 to $7000 is 'no man's land" so you better be above or below that.

Also, Hegel is selling you an amp with proper support, regulatory certification, etc. All of this costs money.

The other issue is weight and cost of mechanicals. Traditional amp topologies generate a lot of heat and are inefficient. Just shipping these heavy boxes costs a ton.

In comparison you are looking at a Class D amp sold by an individual, building these at his house. If you have problems with it, you can't just take it to your local dealer, get a loaner while waiting for repairs and such.

So economics are hard to compare.
 

blodsbror

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Hegel sells through dealer channel. Most dealers don't want to mess with high hassle of selling high-end gear if it doesn't have enough margin. A rule of thumb used to be that $5000 to $7000 is 'no man's land" so you better be above or below that.

Also, Hegel is selling you an amp with proper support, regulatory certification, etc. All of this costs money.

The other issue is weight and cost of mechanicals. Traditional amp topologies generate a lot of heat and are inefficient. Just shipping these heavy boxes costs a ton.

In comparison you are looking at a Class D amp sold by an individual, building these at his house. If you have problems with it, you can't just take it to your local dealer, get a loaner while waiting for repairs and such.

So economics are hard to compare.

Makes sense. Although, if i run a traditional "total cost of ownership", through my brain, something like the 502 comes out very much on top, taking all things into consideration :).
 

maverickronin

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Right. So a well designed, and transparent (as possible) class AB design is basically pointless.

I don’t see any compelling reason to purchase a class AB (with a linear power supply) amp over a class D.

The class AB with a linear power supply will almost certainly have greater longevity and be easier to repair when something does eventually fail.
 

liquidman101

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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/
Thanks again, for the advice on this product. If I'm running a sub with this amp how is it cooled?
 

arczar

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You've talked a lot about ground and ground loop in this thread, so....

I have a question: when building an amplifier on 2 mono modules (for example 2xnc500mp), can I switch them on with one switch, shortening pins 3 and 9 and connecting it to pin 9 in the other module? Once on thread: https://www.audiosciencereview.com/...p-amplifier-teardown.18614/page-2#post-609782

Francis Vaughan questioned the correctness of this solution. My guess is that it would be best to have a 2-channel switch and turn on both modules separately without connecting them, but ...
 

Matias

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FYI this is on sale for 876 usd.
 

tktran303

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Well it depends. The cottage industry type Class A/B power amp with discrete components and point to point wiring will be repairable.

I had a dual mono class A/B integrated amp which failed due to overheating (I was living in the tropical north of Australia). It used SMDs, so I had to have the whole board replaced at a cost of 4 figures.

The transformers and heat sink and case and connectors was all that was kept.

Designed and Made in Sweden.

I guess they don’t have as much sunshine or heat or humidity (things that kill electronics) as Australia…
 
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restorer-john

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FYI this is on sale for 876 usd.

Just had a look at his site. He's advertising every product on his website, for sale to Australians, in Australian dollars excluding the GST. Unbelievable. :facepalm:

1635466541580.png


We've had the Goods and Services Tax for over 20 years and you cannot advertise a product to the public with a headline price that is GST exclusive.

1635466063654.png



1635466015827.png


Just one person calling the ACCC and he could get fined or warned. But hopefully, he'll see the error of his ways and correct his website fast, before that happens...
 

JSmith

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He's advertising every product on his website, for sale to Australians, in Australian dollars excluding the GST. Unbelievable. :facepalm:
I did notice this previously actually and thought exactly the same thing. The site was in USD before this change I believe? I suppose it's because international customers won't be paying the GST, which may be the majority of his business, so shows the ex-GST price. Alan should probably list 2 prices, ex-GST and inc-GST, just to be clearer.



JSmith
 
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