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Marchaudio P422 Stereo Power Amplifier Renewed Review

wbenjin

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Thanks for your work, happy to see more and more reviewers using scientific approach to measure audio equipment.
 

peng

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To the OP: what was the amplifier gain on the P422 ?
20.5 db via XLr or 26.5 via RCA ?


According to the website, they are options, you have to choose one or the other when you place the order.
 

PeteL

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When the output is very low, the signal itself is so small that it is affected by external factors, so it shows a rather high noise + distortion level. As the output gradually increases, the signal strength becomes stronger, the purity of the signal increases, and when the finally reached to output limits, the noise and distortion increase rapid and sharp.
Very nice and thorough measurement report and review.
With all respect, and it might be a native langage thing, but this is a bit of a odd way to explain this phenomenon, or at the very least unclear.

The noise + distortion "level" is not higher at low volume. It's a ratio it's just closer relative to the signal, not in absolute terms. I would also not say that the "purity" of the signal increase or at least specify that by signal you mean the total signal + noise summation. But the purity of the signal don't increase, it just become farther from noise, in fact it may contain a bit more distortion as you bring it up, or no more, but not less. All this really say is that the sum of noise and distortion don't increase as fast as the signal level.
 

buxtehude

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112184792.2.jpg

Haha... that Golfing Panther!
 

Tks

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High waifu acceptance factor! People can enjoy crystal clear 2d to 3d soundstage conversion with these I bet!

Dragon Ball went 3D for their latest movie, please, no more >_<
 

amirm

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I don't see that in specsheets...
???
Unfortunately that is the norm. Sometimes if you contact the company they will provide it. Ultimately though, you start with a known low distortion load and reference it. I did that against the Dale loads that Benchmark provided me. And OP is doing the same with the ones that March gave him.

To expand, the load resistor gets subjected to complex mechanical and chemical transformation as it sees large voltage changes and heat dissipation. These cause nonlinearities that result in measured distortion. Problem has been known for a long time. See my write up here: https://www.audiosciencereview.com/...asr-dummy-load-configuration.8026/post-196116

Wasn't an issue until we started to get amplifiers with very low distortion. And analyzers that can measure the same.
 

sarumbear

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View attachment 230122
Look at the y-axis for 1% and find the corresponding x-axis value.
So 210 watts.
Note, this looks to be approximated by Matias.
It is not realistic to read a power value from a chart that shows amplifier is clipping and the distortion value is changing 100 fold within a few watts.

Bridge mode:
View attachment 230123
Amir shows 500 watts using the orange cursor.
The 500W reading is not 1% as it is listed on the post nor on the spreadsheet though is it?
 

sweetchaos

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It is not realistic to read a power value from a chart that shows amplifier is clipping and the distortion value is changing 100 fold within a few watts.
This is the best we can do with what we're given. Later, Amir and others started showing exact values, so it's no longer an issue.

The 500W reading is not 1% as it is listed on the post nor on the spreadsheet though is it?
That's because there's some kind of limiter.
Amir said: "Protection circuit shut the unit down after that so it is quite safe to try."
So we know this is the limit.
 

sarumbear

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That's because there's some kind of limiter.
Amir said: "Protection circuit shut the unit down after that so it is quite safe to try."
So we know this is the limit.
I respectfully disagree. The current data shows that the amplifier can distort up to 1%, which is not true. It either clips or shuts down but never distorts 1% while operating. Can you see where I am coming from?
 

PeteL

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I respectfully disagree. The current data shows that the amplifier can distort up to 1%, which is not true. It either clips or shuts down but never distorts 1% while operating. Can you see where I am coming from?
What is the point of this? Trying to specify max output power, What number do you want to use If those are not right? If it never get’s to 1% and you set as max the treshold of 1% for comparison sake, what is the max power then?
 

sarumbear

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What is the point of this? Trying to specify max output power, What number do you want to use If those are not right? If it never get’s to 1% and you set as max the treshold of 1% for comparison sake, what is the max power then?
I am sorry if I am not making myself clear and thank you for continuing the chat. I appreciate it.

My point is not about the power capacity but the distortion. The column header says at the shown power value distortion is 1%. But, it isn’t. Amplifier either shuts down or clips. In the former there is no distortion as there’s no signal, in the latter it is a value read from a chart that shows hard clipping. Neither value is in anyway an operating value.
 

PeteL

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I am sorry if I am not making myself clear and thank you for continuing the chat. I appreciate it.

My point is not about the power capacity but the distortion. The column header says at the shown power value distortion is 1%. But, it isn’t. Amplifier either shuts down or clips. In the former there is no distortion as there’s no signal, in the latter it is a value read from a chart that shows hard clipping. Neither value is in anyway an operating value.
I hear you, but comparing output power specs, You have to set up a treshold where it is considered the amp is clipping and therefore the max power is attained. If an amp never clips, well max power is attained, Ok it should maybe say, at 1% with « when protection circuit allows it. » in parethesis, maybe but what can you do, if it never clips you are still not going any more power than that, that’s what matter if what you are comparing power specs and not distortion specs. Wheter you put the treshold at 0.1, 1, 10%, you need to have a reference value when comparing power specs, but it’s only to assess what’s considered max! If it max out before getting there well, you just don’t need the treshold it’s max is obvious. Sure, let’s put a asterix and say » this amp never got to 1% » ok, but you can still compare the value and it’s obvious what goes in thatbox if an amp shut down before clipping.
 

sweetchaos

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If someone asks "What's the max power (at 4ohm) when you put the AHB2 into bridge mode?"
The answer is still 500 watt.
Amir measured it, so we know this is the limit.
It doesn't matter if this is clipping normally due to high noise/distortion or there's a limiter cutting off the power.
The average consumer (including me) doesn't care about these type of distinctions.
 

sarumbear

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I hear you, but comparing output power specs, You have to set up a treshold where it is considered the amp is clipping and therefore the max power is attained.
But why use such a high distortion value (1%) in this day and age? It will be more useful, in my view, if the distortion value is lowered and the asterisk is used for amplifier that have high distortion levels. Or simply rename the column as max power.
 

sarumbear

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The average consumer (including me) doesn't care about these type of distinctions.
But ASR readers are not average consumers, are they?

Anyway, thank you listening.
 

PeteL

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But why use such a high distortion value (1%) in this day and age? It will be more useful, in my view, if the distortion value is lowered and the asterisk is used for amplifier that have high distortion levels. Or simply rename the column as max power.
Ok, but in the end, we still have many manufacturers that don’t specify any, that’s way worst. What matter is to know exactly how it’s measured. It’s been showed in these pages that many topping amps, for exemple specify max power at 10% distortion and don’t even tell you. (To there credit yes many have measurment reports but not all). 1% may be high, but what if you want to specify the max power of a tube amp where it’ll get there and never really hard clip. The fact is there is no standard. I would of course like if it was srandardized. 1% is as good as any, at least it’s something.
 

amirm

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But why use such a high distortion value (1%) in this day and age?
It is an empirical value. If you pick much lower number, due to variability of noise+distortion, you get different run to run numbers. At 1% there is enough distortion that the computed power at that distortion has very small variation. I spent good bit of time testing before arriving at this value (and used 0.1% at one point).
 

sarumbear

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Ok, but in the end, we still have many manufacturers that don’t specify any, that’s way worst. What matter is to know exactly how it’s measured. It’s been showed in these pages that many topping amps, for exemple specify max power at 10% distortion and don’t even tell you. (To there credit yes many have measurment reports but not all).
That’s the reason d’être of ASR, isn’t it, to out those naughty manufacturers.

1% may be high, but what if you want to specify the max power of a tube amp where it’ll get there and never really hard clip.
That’s when you use the asterisks.

The fact is there is no standard. I would of course like if it was srandardized. 1% is as good as any, at least it’s something.
I was simply hoping that as ASR making SINAD a standard it could create a modern standard that is fit for the era and current market. Other than at powers they are not designed for (but sometimes advertised as by marketers) all modern amplifiers operates at less than 1% distortion.

To repeat, I’m simply writing my views, not critiquing anyone.
 
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