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March Audio P701 Mono Block Power Amp

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March Audio

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@andrew Please see the P701 plots below

1564478241352.png
 

andrew

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@March Audio Thanks. What, with all the talk of the input buffer, is the input impedance / recommended pre-amp output impedance? (Existing valve pre-amp is 600Ohms)
 
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@g29 A unit is on its way tomorrow.

Current build standard. Very similar to the P451 shown the other day,
https://www.audiosciencereview.com/...ds/march-audio-p451-purifi-mono-blocks.10138/
but obviously Hypex NC1200 module and without the input buffer. Also using both output connections on the NC1200 board to minimise output impedance.

We are moving all amps over to the ETI Research speaker post to allow easier access for large cables and spades, but they are also better being solid copper gold plated and caressed by blonde virgins before installation.


P701 2.jpg


P701 1.jpg


P701 3.jpg


P701 4.jpg



A P252 amp is also being sent.
 
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Sal1950

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We are moving all amps over to the ETI Research speaker post to allow easier access for large cables and spades, but they are also better being solid copper gold plated and caressed by blonde virgins before installation.
But have they be cryogenically treated?
 

jjk

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I would like to add that I have purchased 5 amplifiers from Alan. 3 x P451, 252, and a 122. I could not be happier with my purchases.
Alan has been a pleasure to work with and a total professional all the way.
I have a 5.1+1+1 system, composed of Revel F208s; the synergy (without going all Stereophile/Darko) is excellent.
I also have an office system of Revel M105s driven by the 122. Sweet.
Alan is building a custom piece for me as well. When it is delivered, and Alan adds his concurrence, I will be happy to share that information.
Highest Recommendation!
Stay safe.
 

AnLaoJin

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Just a quck update on the forthcoming P701 monoblock power amp.

I was going to be releasing a NC500 based mono block amp next month, however the NC1200 module has just been released and I will be utlising this module instead. The NC1200 has basically the same or better performance than the NC500. Major difference is that its drive capabilities have been greatly improved. The NC1200 8 ohm rating is 400 watts, 4 ohm is 700 watts and 2 ohms is 1200 watts. Current output is now 38 amps. The NC500 would manage 400 Watts, 700 Watts and 550 Watts and 26 amps respectively. As such this will drive the most difficult of speaker loads. Noise and distortion levels really are superb. In the typically used range, around 5 watts THD is about 0.0007% or -103 dB.

Note the buffered 128dB SNR and 20uV noise levels

Some Hypex data

View attachment 22304
View attachment 22301
View attachment 22302
View attachment 22303

As a large floor speaker (parallel subwoofer) user, I need NC2K. . The power of NC1.2K is not enough to meet my needs. . Although NC1.2K 1200W seems very attractive, but according to the theory of the best performance at 50%, NC2K is still needed
 
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March Audio

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As a large floor speaker (parallel subwoofer) user, I need NC2K. . The power of NC1.2K is not enough to meet my needs. . Although NC1.2K 1200W seems very attractive, but according to the theory of the best performance at 50%, NC2K is still needed
Hi @AnLaoJin

May I ask what speakers you are using? Very few domestic speakers will handle the 2.5kW the nc2k is capable of delivering into 4 ohms.

There is no basis to presume any amplifier will give best performance at 50% power. I will post the THD+Noise plots for the nc1200 and nc2k later to show how they perform.
 
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Many audiophiles vastly over-estimate the power required by their speakers. Even subwoofers that have the driver(s) installed in too small a box can still be powered with an amp of nominal rating.
Some of the older designs like Apogee's were notoriously inefficient, but preferred amplifiers for those speakers fell into the 100-200 watt range.....assuming they could deliver the current associated with voltage.

The "50% rule" is one of those audiophile nonsense things that has become entrenched in the lingo, unfortunately.

I can't imagine the P701 amp not being able to power any domestic speaker in existence.

Dave.
 
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DonH56

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I've never heard of a "50% rule" for optimum performance of audio amps. A look at the curves for almost any amp (save some tube amps with high noise and very soft clipping) shows best performance in terms of SNR and THD just a little before clipping. A few percent, not 50%.

In terms of power margin, you can drive yourself crazy. For example, 3 dB is a factor of two in power, so arguably that would be the basis for a 50% margin number, but you have to decide what that is referenced to and if it is even applicable. I have read recommendations for 6 dB (4x in power) but not really seen a solid reason why. I prefer to calculate and estimate my peak power needs based on SPL and what my speakers (and ears) can take and figure that's good enough. A pair of my (pretty insensitive) speakers will deliver about 100 dB SPL at the MLP without considering any room reinforcement. I somewhat arbitrarily choose to meet the 105 dB reference spec, but for a pair instead of a single speaker, as that is plenty loud for me. That means 300 W from the amp, and is (not coincidentally) what my amps are rated. A 600 W amp would be much more money and simply overkill for my use. It would also almost certainly have a higher noise floor and waste more power just sitting there at my normal listening levels. Chances are good that if my amps should clip, it is going to be on something loud and brassy, or some big explosion where clipping is not going to be heard anyway.

Subs do generally take more power, loudness curves and all that, but I suspect a driver that can handle 2 kW+ is a rare thing.
 
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Hi @AnLaoJin

As mentioned below is the THD+N data for the NC1200 and NC2K

NC1200
1597196219529.png


NC2K
1597196262878.png


To explain the graphs, they depict the ratio of total harmonic distortion and noise to the output signal. At lower power outputs noise is the dominant factor. As power output and the output signal increases the ratio between the noise and signal increases hence you see a falling slope. On both amplifiers at around 10 watts output the THD starts to rise and becomes the dominant factor. As the amps approach clipping the distortion will rapidly rise and you see a sharp increase in the line.

So both amps achieve their best THD+N (SINAD) at about 6 watts output. 0.0007% (-103dB) for the NC1200 and 0.0045% (-107dB) for the NC2K.

This very low noise and distortion continues until we near clipping. Question is at what point do we deem the distortion to have reached an unacceptable level? Well Hypex, like most manufacturers, base their power ratings at a distortion level of 1%. Some would argue this is too high.

So lets take it at 0.1%
NC1200 is over 600 watts (rated at 700 watts into 4 ohms 1%)
NC2K is over 1900 watts (rated at 2500 watts into 4 ohms at 1%)

So you can see the "50% best performance" power figure you have quoted is not correct. Both amps perform superbly beyond 85% and 77% respectively. You speakers will be distorting far more at these power levels, and in the case of the NC2K at 1900watts your speakers will probably break, hit their end stops and release some magic smoke! For further examples please refer to Amirs many amplifier tests in this forum, they all show similar things.

hope that helps

Alan
 
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DonH56

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I really doubt you'd hear 1% THD on musical or movie content. The catch is that, with feedback, the curve is so steep at 1% that hard clipping (which is audible) happens right after (over) that. Of course, assuming you can hear anything with that much power to the speakers, and the speakers themselves are distorting madly...
 
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Sal1950

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As a large floor speaker (parallel subwoofer) user, I need NC2K. . The power of NC1.2K is not enough to meet my needs. . Although NC1.2K 1200W seems very attractive, but according to the theory of the best performance at 50%, NC2K is still needed
I think your situation dwells more in the "want" area of emotion than the "need" area of technology. ;)
 

AnLaoJin

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Hi @AnLaoJin

May I ask what speakers you are using? Very few domestic speakers will handle the 2.5kW the nc2k is capable of delivering into 4 ohms.

There is no basis to presume any amplifier will give best performance at 50% power. I will post the THD+Noise plots for the nc1200 and nc2k later to show how they perform.
ELAC Concentro,4 subwoofers are connected in parallel, and the impedance is very low. I use a 100W power amplifier to push it, and the sound pressure is very small, and the power amplifier is protected.
 

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ELAC Concentro,4 subwoofers are connected in parallel, and the impedance is very low. I use a 100W power amplifier to push it, and the sound pressure is very small, and the power amplifier is protected.
Here is what the manufacturer specifies. With NC1200 you would be fine.

Recommended amplifier power: 80 – 600 [W/Channel]
Suitable for amplifier rated between: 4-8 Ω
Rated power (Continuous): 400 [W]
Rated power (Dynamic): 600 [W]
Rated impedance: 4 Ω
 

AnLaoJin

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Here is what the manufacturer specifies. With NC1200 you would be fine.

Recommended amplifier power: 80 – 600 [W/Channel]
Suitable for amplifier rated between: 4-8 Ω
Rated power (Continuous): 400 [W]
Rated power (Dynamic): 600 [W]
Rated impedance: 4 Ω
But the 400/700/1200W of the NC1200 seems to be very amazing. In fact, they are at extremely high distortion output power. If it becomes 0.01% distortion output power, it may only be half of the original. . 200/500/700W???
 
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