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Review and Measurements of Hypex NC400 DIY Amp

maty

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Hypex NCxxx modules

The SNR specified is at 4 Ohms and at max power as I suspected.

Verified with the stereo modules, xx2. When doubling the power, 3 dB is added.
  • NC122MP: 125 watts / 4 Ohms and 118 dB
  • NC252MP: 250 watts / 4 Ohms and 121 dB
  • NC252MP: 500 watts / 4 Ohms and 124 dB
The rule is not met with the power at 8 Ohms, therefore the above is true. 75 watts, 200 watts and 350 watts.

=> probably the same with NC400, NC500 and NC1200.
 
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Julf

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Hypex NCxxx modules

The SNR specified is at 4 Ohms and at max power as I suspected.

Well, yes. Noise level doesn't change with load impedance, output power does.
 

waltzingbear

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I use my NC400s with my Avocet with no noise or clicks.
If you have a hum with the ncore hooked to the speaker and no input, that is not correct and should be sorted out.
What vintage is your Avocet? (on the serial number tag)

Cheers
Alan
 
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rajapruk

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This amp measured better with only one channel driven, it is stated in the review.
@amirm what SINAD number did it get when only driving one channel, as a monoblock?
 

VintageFlanker

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This amp measured better with only one channel driven, it is stated in the review.
@amirm what SINAD number did it get when only driving one channel, as a monoblock?
At 5W/4ohms? Datasheet says approximately 0.0006% THD + N, so around 104dB SINAD (if I'm correct?)
This is a mono amp module, so all the specs are one channel driven. @amirm says power is limited with one PSU, not SINAD.
 

Julf

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Please read the first post in this thread fully.

All it says is "the power supply limits the amount of power these two hungry amps can generate".
 

rajapruk

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You did not read the first post carefully? :)

And if I turn one channel off, we get near perfect performance:

1545946997046.png

The second harmonic is now down to -130 dB!!! Pretty remarkable.


But this improvement was maybe hidden below the noise floor regarding SINAD?
 
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casual_audio_nerd

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Hi there. I am new to DIY and just finished my first DIY build of a mono NC400. Hoping someone might be kind enough to take a look at my build and tell me if I have something wrong - especially given I have these 5 black screws left over :facepalm:

Many thanks in advance for any help/guidance/confirmation

2.jpg3.jpg4.jpg5.jpg6.jpg
 

maty

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A common beginner's mistake is not scratching the paint to make a good contact the metal case with the ground wire. I guess you did it. It cannot be seen in the photos or you were very careful when scratching just the right amount of surface.

Can you increase the distance between the two modules? For the yellow transformer to interfere less. What real distance is there?

I like more with the NC400 module implemented like this:

Ghentaudio-Hypex-NC400-B.jpg



Like the amp of the ASR review:

index.php
 
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Julf

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Hi there. I am new to DIY and just finished my first DIY build of a mono NC400. Hoping someone might be kind enough to take a look at my build and tell me if I have something wrong

Nice and neat - the one issue I spotted is having the speaker leads coming out of the screw clamps in opposite directions, leading to a pretty big loop (as in "antenna") before the twisting starts.
 

pos

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Nice build @casual_audio_nerd!

One word regarding earthing/safety:

These modules and SMPS are class II, so you should not need safety earth, but then you should maintain class II throughout the assembly which in that case implies isolating the power wires (from the enclosure as well as other cables) with a second layer such as some electrical plastic tubing (not nice to look at, but effective and affordable).

If you prefer to rely on the safety earth, then you should make sure it is effective on the entirety of the enclosure, which first implies making sure the wire is appropriately connected to the lower part of the enclosure (sanding if necessary, toothed washer biting the enclosure, blocking nut, etc.), and that all enclosure parts are adequately connected together (sanding again).

There is also a small thermal "optimization" that can be done for the SMPS...
 
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Julf

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And you can try too, after you know well the sound of your diy amp, to add a two-stage RF / EMI inlet filter.

... that Bruno Putzeys, the designer, specifically has spoken against.
 
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