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Marchaudio P501 Mono Block Power Amplifier Review

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amirm

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So which is max power. the 1% thd bar graph, or the 0.001% power sweep.
Both are. No amplifier has one single power number, ever. The power rating for example differs between max and peak at 1% THD. Different measurement, different results. The one at the knee is the power at near limit of the amplifier. Different measurement, different result.

The knee power is the conservative one and is less precise. The 1% are aggressive one and precise. Both pieces of information are provided and consistency is observed across all reviews. I don't put the cursor at max of the sweep to please one company at the expense of another showing it at the knee.
 

JSmith

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you are the only person i have seen who doesnt rate power at a fixed thd level. no one anywhere else rates max power at 0.001%, or the other similarly arbitrary low levels you do.
?


JSmith
 

JasonWells

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Both are. No amplifier has one single power number, ever. The power rating for example differs between max and peak at 1% THD. Different measurement, different results. The one at the knee is the power at near limit of the amplifier. Different measurement, different result.

The knee power is the conservative one and is less precise. The 1% are aggressive one and precise. Both pieces of information are provided and consistency is observed across all reviews. I don't put the cursor at max of the sweep to please one company at the expense of another showing it at the knee.
Different between 0.001% and 1%, different between 159 and 240 Watts.
I dont think you can blame the measurement. You label both as max power, which one is max power?

You have already said repeatedly that 1% is too high. are you now saying it's acceptable?

There is no scientific discipline here and a total unwillingness to consider improvement.

Why don't you improve the clarity of your data by reporting 2 or more power levels and not calling them max power. I previously suggested 1%, 0.1%, and you want the level you consider where it changes from linearity? this will greatly increase the clarity of the data, especially for those readers with less technical knowledge. it also provides a firm basis for comparisons, and a clear basis for thin blue to follow.

This is all I suggested. I'm not sure why all the obfuscation, evasion and hostility.
 
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Holmz

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Not sure why. Didn't he ask to be banned at some point, as a way of spectacularly marking his discontent?

I forgot about that gauntlet…

Up until the repackage khadas tone board 'crisis' (Alan was selling a Khadas Tone Board in a nicer box with a steep, but understandable markup - some people complained it was not disclosed and Alan handled the situation very poorly from a PR point of view imho), Alan was a very nice, very competent and very helpful member of this board. I can certainly credit him for a few of the things I learned here. I certainly do miss that version of Alan.

But it went very, very much downhill from there...

He could probably use a PR and marketing assistant.


I don't miss Alan 2.0

I was unable to close on speakers, after we had what I thought was a solid agreement… So I think I caught the transition to 2.0 .

@PierreV I think you put some BiQuad suggestions in another thread... thanks!
I’ll need to implement those.,, next week.
(Or it was another Pierre.)


It's abundantly clear that Amir has a personal problem with Alan. This sort of blatant bias and his inability to take on any criticism of his methods paints a pretty black picture of him and his forum.
I'm obviously not welcome here so it's time to go. plenty of other forums out there.

Whether there is a “personal problem“ is a true statement or not, just the perception of a strong bias is not helpful to the reputations of the forum and its member writ large.
There may, or may not be good reasons, but the visitor may just see and interpret something else.
 

JasonWells

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?


JSmith
Thanks for this. my Chinese is a bit rusty but from what I see there, L7 is not making starements about what max power is. he is just presenting the data.
 
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thin bLue

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Oh my..
I can't believe the Massive amount of comments.
I'm trying to response as possible as I can, but It'll take time.

I can only check massive comments really roughly. But, main discussion seems the cursor not the graph.

Why..?
I could not understand the cursor. It's just for easy.

At this time, Its trigger was about Purifi unit's spec and possible ability. And Purifi's spec sheets was claimed there power as 1% point. So I used 1% to check what they claim and is it real or not.

If I thought that tiny point of full set of data is only the thing, I would not post graphs but the Watts at one pont. And If i did that I would not be humiliated based on my graphs like this.

OP compared the power rating of your amp at full distortion in the sweep, to the minimum distortion of a competing product.

If anyone really believe I did like that, I can't change your mind.

I do want to people compare to graph to graph and judge them with their own criteria.

I already partially provided additional points following ASR members suggestions and Amirm's way. I had plan to add more


The simplest solution for this, I'll just get rid of cursor with all of data next time. Or up load project file and Let members download AP viewer software. Anyone Can read data demo mode for free. In that case I don't even need to capture images.


Anyway some of comments make me philosophical to use my time for this.

I travel several 1000km round trips a month nowdays. and during that schedule I produce measurements just for my satisfaction nobody pays.

Do I deserve to handle all of blames for free?
Please can we rise the fidelity of threads?

I have a plan for get further datas of this amp. but should I? for see another aimless claims?

I just provide all of datas and some, because I can.

And many members including Amirm provided important teachings of techniques and technical facts for me. Because just they can!

Pleas Let Us Stop ruin all of good circulations.
 

restorer-john

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I have a plan for get further datas of this amp. but should I?

Definitely do it. :)

I suggest a maximum power at 1% THD vs Frequency. Let's see what the amplifier can maintain across the frequency range at full power.

Then see if it can survive full output short circuit on the speaker terminals. You got it for free, so no great loss if it explodes. Purifi make a whole bunch of claims regarding protection and most reviewers are too scared to destroy review samples (fair enough). It'd be good to hear/see the results.
 

JasonWells

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At least I appreciate your work.
Me too. anyway, i think the point has been made. it's up to amir if he wants to improve what he does.
@amirm please don't respond with any more spurious justifications. I'm not getting further involved. The soccer is more important and better use of my time.
I'm off to bed, early start tomorrow.
 

Holmz

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Me too. anyway, i think the point has been made. it's up to amir if he wants to improve what he does.
@amirm please don't respond with any more spurious justifications. I'm not getting further involved. The soccer is more important and better use of my time.
I'm off to bed, early start tomorrow.

If you were in Albany, then noon is a pretty early time to hit the sack.
 

pma

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How about to make a poll, the question would be at which point/level to measure maximum power. Voting would be open only to those who are actively involved in amplifier design, testing and measuring.
 

Doodski

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How about to make a poll, the question would be at which point/level to measure maximum power. Voting would be open only to those who are actively involved in amplifier design, testing and measuring.
I think clipping is the point where increased trace brightness occurs at the sine wave clipping point. The graph is sometimes wonky as a source for determining the clipping point. I suppose increased accuracy is desired with the distortion vs power method but sometimes it's just weird.
 

restorer-john

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Pavel, as you know, there's plenty of amplifiers where the clipping point visually or measurably is not a hard line in the sand. Plenty of amps will clip and then fall back. Others will sit right on the edge or their current limiters will starve the drivers. Some others will modulate the top of the sine as they clip.

Then we have amps where the THD climbs slowly, well past .1% before hitting the rails. Others, it all happens so fast (vertical), determining even 0.1% can be difficult. The interactions between two channels can affect the clipping behaviour of many commercial amplifiers, especially the vintage class ABs.

On the weekend I was considering all this myself, with all the arguments in this thread. My attitude has always been the onset on visible waveform clipping. In my testing, that happens reliably (on my THD analyser and analogue scope) at 0.08%. Easy to see and easily repeatable. 0.1% is clearly into clipping and at 1% the feedback loop has lost control IMO. What do you think?

All the more reason to do an overload recovery test instead of arguing about where to draw the line for power output.
 

Doodski

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One needs to keep the test parameters as non-destructive testing (NDT). Setting clipping too high could result in some blown circuitry.
 

tonycollinet

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I have followed this discussion and understood most of it, but I’m a noob when it comes to class D. I’ve used vintage solid state class A/B McIntosh amps for some time now.

I’m planning on purchasing a pair of Monitor Audio’s new Platinum 300 3G speakers. They present a four ohm load, efficiency is rated at 88dB, and Monitor Audio recommends amps offering 200 - 800 wpc. I’m considering some new, more powerful amps and on my shortlist are Van Alstine DVA M750’s rated at 1,000 watts into a four ohm load, and several different Buckeye class D amps rated at 500 watts into a four ohm load. If I chose the class D amps I would consider bi-amping the Monitor audio’s.

When I emailed Monitor Audio’s US distributor (Kevro International in Canada) for their thoughts, they recommended using a single 1,000 wpc amp on these speakers rather than bi-amping with two Buckeye 500 wpc amps.

So I’m soliciting thoughts on this, and if choose the 500 wpc class D amps, should I consider Buckeye Purifi or Buckeye Hypex?

TIA :rolleyes:
Your reply is getting lost in the noise in this thread.

I'm happy to give my thoughts, but here is not really the place since here is specifically for discussion of the March Audio review.

Can you repost your question as a separate thread in the amplifiers or general audio section? Or tack it on @Buckeye Amps line up announcement thread here:

Feel free to link it to me in PM.
 

BDWoody

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sarumbear

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How do you and the rest of the ASR community feel we can continue to move forward and assist music lovers to get the best possible sound (for the least amount of $). What's ASR's next step in helping consumers get the best bang for their buck.#
Disagree 100%. Audio is a hobby for almost all of us. Why would I want value for money all the time?
 

Holmz

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@restorer-john
I received an email from Alan about an hour ago. I am a couple of Timezones away from his general location at the moment.

He asked me to post this video for you.


And guys, I am just the messenger here.
Our houses are about 15 miles apart, and we frequent the same place for wood working, so I met him through the craftsman.

And the Jason fellow has signed on to the MA website… maybe he uses a VPN, it is pretty common in europe for people there, so who knows.

Once again… please don’t shoot the messenger.
 
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