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March Audio Hypex Ncore Power Amplifiers

March Audio

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Yup, no go

bridging two 1ET400A Designs will result in performance degradation as the circuit is not configured
to sense the voltage differential that exists between the (now unused) OUT- terminals of the two 1ET400A
Designs. Bridging is therefore not recommended. All operation and performance specs are void in this
configuration
.
 

March Audio

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@March Audio any comment on the temperature observation that I made ?
The case is designed to be the heatsink. It should only be getting to around 40 deg C after a few hours use.

How is the amp situated, on a stand or in an enclosure?

Class D is efficient but less so at lower power outputs so it still has to dissipate some heat. Remember it is a kW in a shoe box :)

1567669205458.png
 
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March Audio

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Same here. I wonder whats causing it to be so hot and if the P701s are the same, or runs cooler.
They do seem to run a little cooler from my measurements, typically about 38 deg C after a few hours. Which makes sense being 1 channel of losses.

This pair had been on around an hour.

IMG20190905153522.jpg


P252 is more like 34 deg C and P122 around 32 Deg C
 

Burning Sounds

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Same here. I wonder whats causing it to be so hot and if the P701s are the same, or runs cooler.
I had the same concerns when I got my Apollon NC8350 - four NC502 modules in a single box. It certainly runs hotter when left at idle for some time compared to when it is playing music, but I've never seen case temps higher than about 35 C and the heatsinks don't exceed that temperature either.

However, in the NC8350 the modules are on their sides and there are a few small electrolytics that sit under some larger caps so airflow is blocked and I've measured those at about 60 C. Some of the coils also reach this temperature. I still don't think this is excessive, but wanting the amp to last I do now use an AC Infinity cooler on top of my amp case. As it comes the AC Infinity is noisy, but replacing the stock fans with slow running Noctuas - 6.9dB (A) makes for complete silence. I think it's probably OTT, really.

I wouldn't think this is an issue at all with March's amps as the modules are horizontal as far as I can see so easier for all components to get rid of any heat.
 

Olli

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That's an unusual setup.
The F8s make a nice stand for the TADs. And since the F8 is not very deep, I could squeeze one into the bookshelf behind me. The bigger JL E112 is in the back right corner. I was lucky that it sounds good and also measures relatively well (at least L speakers) - the sub postions are 90% based upon optics.

1567691183134.png


1567691251389.png


1567691321892.png
 

maty

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...As it comes the AC Infinity is noisy, but replacing the stock fans with slow running Noctuas - 6.9dB (A) makes for complete silence. I think it's probably OTT, really.
Very quiet!!! Ear human starts listening from 19-21 dBA. With two: 9.9 dBA. With three: 11.7 dBA << 19-21 dBA.

But AC Infinity S9 - Airflow: 210 CFM | Noise: 21 dBA

with three silent and slow Noctua: 33.5 CFM x3 = 100.5 CFM

The noise is measured at 1 meter. Two meter: -3 dBA.

- End off topic -
 
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tw99

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The case is designed to be the heatsink. It should only be getting to around 40 deg C after a few hours use.

How is the amp situated, on a stand or in an enclosure?

Class D is efficient but less so at lower power outputs so it still has to dissipate some heat. Remember it is a kW in a shoe box :)
It's on an open shelf so has plenty of ventilation. Never gets too hot to touch, but hotter than just "warm" if you see what I mean. Anyway, sounds like it's expected behaviour if the entire case acts as a heatsink, and given the power loss graph you showed above. Thanks.
 

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I waded through this thread. Unfortunately, there was some bad behavior.

@amirm did you ever receive a sample to test? My guess is these will not be better than the NC500, but not a lot worse either.

Somewhere it's said that the 2V output from an unbalanced DAC would be enough. That looks right only for the lower powered 122 module. The spec sheet for the 252 says 2.35v @4 ohms for full output and using the provided formulas a few 10th's higher for 8 ohms.

I observe Nord has the lowest price on a complete 252 amp, although the Pound recovered a bit over the last few days. Should I wait for the Brexit discount?

One reader above said bass was better but treble less smooth than whatever he had before. This is a bit like some other folks impressions of Crown amps that don't measure nearly as well.

Implementation does matter, but in this situation there doesn't seem to be a lot of ways to go wrong.

Just random thoughts.
 
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Somewhere it's said that the 2V output from an unbalanced DAC would be enough. That looks right only for the lower powered 122 module. The spec sheet for the 252 says 2.35v @4 ohms for full output and using the provided formulas a few 10th's higher for 8 ohms.
The NC252MP develops 150 W RMS in 8 Ohms with a gain of 25.6 dB, thus it needs 1.8 V RMS, which is ok for an unbalanced DAC, not for a phone or PC.
The NC502MP needs a bit more juice at 2.2 V RMS to provide 350 W RMS in 8 Ohms.
 

Ron Texas

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The NC252MP develops 150 W RMS in 8 Ohms with a gain of 25.6 dB, thus it needs 1.8 V RMS, which is ok for an unbalanced DAC, not for a phone or PC.
The NC502MP needs a bit more juice at 2.2 V RMS to provide 350 W RMS in 8 Ohms.
There are 2 versions of the 252. The one used by March and Nord do 200W @ 8 ohms. On the Hypex site you will find 2 different data sheets both containing their formulas. By the way 8x150 is more than 4x250, so even to get to 150 watts @ 8 ohms will take more input voltage than 250 @ 4 ohms.
 
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By the way 8x150 is more than 4x250, so even to get to 150 watts @ 8 ohms will take more input voltage than 250 @ 4 ohms.
That's why I calculated 1.8V for 150 watts @ 8 ohms and not 1.566 V for 250 @ 4 ohms.

Edit - typo corrected 1.56 -> 1.66V
 
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I think you need to check out those data sheets again.
I saw there are 2 datasheet. I am referring to version 02 150W 8 ohms.
There is no magic in their formula, it's based on P = U*U/Z.
Sqrt(150*8)/10^(25.6/20)=1.8, unless the android calculator is bugged...
 
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I believe version 1 is the correct data sheet. You also have to multiply by 1.41.
On the correct datasheet version, only Hypex knows :).

Multiplying by 1.41 will give peak values. They are useless for what we are looking at.

Standard unbalanced stuff delivers 2V RMS, Hypex Data are in W RMS. So checking with RMS values allows to compare apples to apples.

If you want to look at peak values:
Sqrt(150*8)/10^(25.6/20)=1.8 V RMS
1.8 * sqrt(2) = 2.54 V Peak
Unbal 2 V RMS: 2 * 1.41 = 2.82 V Peak
2.54 < 2.82 => everything is fine, at least for modules rev. 02

Edited for softer tone, sorry
 
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