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Marchaudio P501 Mono Block Power Amplifier Review

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boXem

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To point 'the point where THD begins to go vertical to determine amp power' is not that easy and simple.
That's why so many members are hotly debating right now.

With loose resolution(lower counts of point) we can see significant One red hot inflection point.
But, more and more points we get, we got high resolution continuous curve, not the one extruded point. so defining certain point with meaningful consistency is really hard work.


View attachment 247518
View attachment 247520

32 vs 200 points with various ranges each.
It's complicated.
This is true, it is complicated. Metrology is a discipline by itself.
This is why if you want to compare measurements, they must be done following the same protocol. In this case, spacing between points and starting frequency seem to be a minimum.
So you have two solutions:
1. continue following your own protocol, which you are perfectly entitled to. But then you must accept that comparing your measurements with measurements done with another protocol like the one from Amir has no value, and can even be misleading.
2. use the exact same protocol as Amir. This would allow to compare your measurement with the ones made by Amir. More generally, in my opinion, this would bring a lot more value to ASR. I am sure that @amirm is ready to help you in this direction.
 

Rick Sykora

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One aspect that is lacking in this review is no mention of the price...

Since was curious, went to the March website and I quoted for one to be shipped to me. It was about $1700. This is almost twice what Buckeye charges for a comparable amp. While I realize the March unit has a higher voltage supply and a nicer case, not worth the premium for me. :eek:
 

Mnyb

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Well the readership sure likes to nitpick :) my takeaway this is another version of an amp with the latest purifi module .
It’s different due to using another power supply , you migth scrounge some more dynamic short term power out of it ( exactly how much fills this tread with heated arguments to no ones benefit , I’m fine with “a bit more” ;) ).
It’s performance is very good nonetheless, hats of well deserved review it’s sure is nice .

One has to consider the alternatives , the price and where in the world you live and how much you want exactly this kind of implementation.
To judge a complete product is more than the raw performance. It includes the exterior design and subjective value judgements about the company’s commitment to customers warranties etc and history 100’s of factors that’s not about the actual “sound” . It’s hard for new companies to build brand recognition and reputation and other hard to measure factors.

Yeah let’s zoom out and see the greater picture all well built built amps with these modules are excellent amplifiers.

It’s good with diverse offerings, you decide what you like .

It’s also nice with another source of measurement reviews willing to participate on ASR so thanks to @thin bLue for the work hopefully you will try the comply to the typical ASR credo and present your findings as unbiased as you can do it and in cases where you find yourself biased present this to us readers so that we know what we are reading and what is fact and what’s your own judgement and thoughts .
 

amper42

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One aspect that is lacking in this review is no mention of the price...

Since was curious, went to the March website and I quoted for one to be shipped to me. It was about $1700. This is almost twice what Buckeye charges for a comparable amp. While I realize the March unit has a higher voltage supply and a nicer case, not worth the premium for me. :eek:

Rick - while price might be a concern for you and me, it certainly seems less important in general amp buying than I would expect. The March Audio P422 (Purifi 1ET400A) is $1,596.98 plus $126.48 US Shipping = $1725.46 compared to Buckeye Amps $1189 Purifi shipped. That's a $536.46 premium for the March Audio Purifi. You really gotta want that fabulous looking case. If I could find a $500 off coupon I would go with the March Purifi again. :p

The March Audio P501 is the same price as the P422 or $1725 shipped. Buckeye charges $949 for 1ET7040SA shipped in US. That's a $776 premium for the March Audio P501 which looks prettier on your shelf. But is it $700 better?

At the same time, the Buckeye NC502MP stereo amp is $749 shipped. What's funny is I can't hear much difference between my March Purifi, Buckeye Purifi and Buckeye NC502MP. So how dumb am I that I bought two Purifi amps to find this out. :facepalm::D
 

PeteL

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This is true, it is complicated. Metrology is a discipline by itself.
This is why if you want to compare measurements, they must be done following the same protocol. In this case, spacing between points and starting frequency seem to be a minimum.
So you have two solutions:
1. continue following your own protocol, which you are perfectly entitled to. But then you must accept that comparing your measurements with measurements done with another protocol like the one from Amir has no value, and can even be misleading.
2. use the exact same protocol as Amir. This would allow to compare your measurement with the ones made by Amir. More generally, in my opinion, this would bring a lot more value to ASR. I am sure that @amirm is ready to help you in this direction.
I think even Amir's protocol changes and evolve over time. Do we really care if it gives a momentary 50W more, or is it 30, or zero. It's about 1 dB...
 

doug2761

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One aspect that is lacking in this review is no mention of the price...

Since was curious, went to the March website and I quoted for one to be shipped to me. It was about $1700. This is almost twice what Buckeye charges for a comparable amp. While I realize the March unit has a higher voltage supply and a nicer case, not worth the premium for me. :eek:
I have an NC252 from Buckeye that I like a lot. It's really just OEM stuff in a Ghent box. In my view, his pricing is super generous. It looks like his cut is whatever discount rate he can get as a wholesale buyer. A customer can get one of these amps assembled for about what they would pay to buy the parts and assemble themselves plus some warranty support. It's a great deal. March has put this into a case that looks much more attractive to me and a bit more effort around power supply and still only asks only a $500 premium over Buckeye. Still a heckava deal compared to something multi-k in a major brand wrapper. Unless you really need a lot of power, and most speakers don't, one really doesn't even need to pay a premium over an NC252 build. Times are good!
 

Sokel

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I think even Amir's protocol changes and evolve over time. Do we really care if it gives a momentary 50W more, or is it 30, or zero. It's about 1 dB...
That depends on the amp and power.
At least they are honest...
(Ice power edge 2000as2)


1-10.PNG
 

DualTriode

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Hello All,

This thread has my attention. There is more focus on what it is that we are measuring, why and how it is done.

@amirm is more lofty and less likely to share why & how he selects and performs his measurements.

@thin bLue seems to be be more open about sharing thoughts about his methods and procedures. To me this is a breath of fresh air.

Some here voice the thought, "If it is not auditable, why measure it". To me this seems a be subjective when we have instruments that can measure a flea fart in a hurricane.

Just a fleeting thought:

If we humans can not hear it why do we want to measure it? Because we can?

Some will pay the difference in price between the APx555B and the APx525B. For even less money (by a bunch) the QA403 analyzer does as well.

If you want the APx500 software go with APx Flex and a AP recommended sound card.

Just Musing
DT
 

boXem

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I think even Amir's protocol changes and evolve over time. Do we really care if it gives a momentary 50W more, or is it 30, or zero. It's about 1 dB...
If you want to seriously compare measurements, they must be done with the same protocol.
For the moment the difference is almost 500W. Do we care or not?
 

Sokel

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If you want to seriously compare measurements, they must be done with the same protocol.
For the moment the difference is almost 500W. Do we care or not?
So it's all about the current?
Cause such small differences plus a little worst measurements compared with the smaller module wouldn't make sense otherwise.
 

ex audiophile

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Hello All,

This thread has my attention. There is more focus on what it is that we are measuring, why and how it is done.

@amirm is more lofty and less likely to share why & how he selects and performs his measurements.

@thin bLue seems to be be more open about sharing thoughts about his methods and procedures. To me this is a breath of fresh air.

Some here voice the thought, "If it is not auditable, why measure it". To me this seems a be subjective when we have instruments that can measure a flea fart in a hurricane.

Just a fleeting thought:

If we humans can not hear it why do we want to measure it? Because we can?

Some will pay the difference in price between the APx555B and the APx525B. For even less money (by a bunch) the QA403 analyzer does as well.

If you want the APx500 software go with APx Flex and a AP recommended sound card.

Just Musing
DT
As a licensed veterinarian, I believe I can make an authoritative statement that flea farts are indeed inaudible to humans even in highly reflective rooms. However, many owners have reported that when their dog farts the sudden turbulence (combined with room modal effects) often results in a simultaneous flea fart from flea(s) occupying the perianal area. Whether the flea farts are from one or more fleas is not clear, but the end result is the well documented, and very audible, CFCF (Combined Flea Canine Fart) phenomena.
 

PeteL

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If you want to seriously compare measurements, they must be done with the same protocol.
For the moment the difference is almost 500W. Do we care or not?
???? Where do you see the 500 W? I see 294W vs 348 watts at inflexion...
Anyway, ok yes but I guess instead of nitpicking about the numbers of point at inflexion, especially since it's not clear what it is exactly, it's not the lowest THD point, it's not at a fix THD just a wide angle and not curve to define what is max power... Even Amir once suggested to not use this metric for comparison, so I agree that this comparison should not be there. You just look at the 2 graph as a whole, not the exact point!. A simple answer to this would be to just post that measurment, with the same metric as yours and call it done, nobody would then have this arguments which is a bit pointless.
1670100509127.png
 

Sokel

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Sorry, not following you
In every measurement and according Amir's,Thin blue's (and others) power of both Purifi's 400 or 700,the later both with smaller and bigger PS's seems to land in the 250-300 watt area*.
So,the point of the bigger module is more current and that's it?

*Edit:According to the ASR protocol,needless to say.
 

Buckeye Amps

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In every measurement and according Amir's,Thin blue's (and others) power of both Purifi's 400 or 700,the later both with smaller and bigger PS's seems to land in the 250-300 watt area*.
So,the point of the bigger module is more current and that's it?

*Edit:According to the ASR protocol,needless to say.
The main selling point (IMO) for the 7040SA is for anyone driving sub 4ohm speakers.

Sometimes I think people are inclined to want the newest model just because it is the newest. I myself will not shy away from steering a customer appropriately to save them money.
 

amirm

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A lot of criticisms of how I measure amps is already addressed. Let me summarize:

1. My disagreement with OP was picking the highest/worst clipping point for one amp, and comparing it to my measurement where I pick the bottom of the hocky stick. You can argue that my measurement gives variable power rating for amps of different design. But you can't argue that picking the highest, worst clipping point for an amp is valid. That point can too vary depending on amp design and not at all correspond to 1% THD as it happens to do in this measurement. Had OP used a higher input level, it is possible that it could get worse than 1% THD as well.

Picking the knee of the curve gives the *design parameter* for the amp as far as power. It generates conservative watts rating as well but with variability due to lack of resolution of the graph at that point especially if the peak is very vertical. This is addressed in #2.

2. To deal with variability above, good while ago I added a new measurement that uses the same THD+N for the power measurements. It does this for both "continuous" and "peak" ratings:

index.php


3. I do run power vs frequency tests. Here it is:
index.php


This is superior to picking one power output and running the sweep vs frequency. You see full data for complete power sweep, albeit at discrete frequencies. Notice how picking the "knee" helps here to show the limited power at 20 Hz.
 

Sokel

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The main selling point (IMO) for the 7040SA is for anyone driving sub 4ohm speakers.

Sometimes I think people are inclined to want the newest model just because it is the newest. I myself will not shy away from steering a customer appropriately to save them money.
Smaller one is also very capable of driving them,if I'm not wrong can also do 2ohm.
It's about ease I suppose,thank you!
 

Buckeye Amps

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Smaller one is also very capable of driving them,if I'm not wrong can also do 2ohm.
It's about ease I suppose,thank you!
Sorry, yes, ease of driving 2ohm would be a good way of putting it. Didn't mean to imply the 400a can't drive 2ohm.

But in Purifi's own words "the 7040sa is better designed to handle 2ohm loads".
 

amper42

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Sorry, yes, ease of driving 2ohm would be a good way of putting it. Didn't mean to imply the 400a can't drive 2ohm.

But in Purifi's own words "the 7040sa is better designed to handle 2ohm loads".

I would be very surprised if 1% of trained listeners can identify the Purifi 7040SA versus the Purifi 400A in a level matched blind listening test. You might find a rare system that offers a tell but I would really have to dig to find a speaker configuration where the difference is easily identifiable.
 

xaxxon

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A few questions:

...

4. In order to stick with ASR policy, could you please measure the max power at distortion corner, not at 1%?
There is a "policy" on how you have to review amps? Can you link to it please?

Or did you just mean Amir has a convention?
 
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