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Review and Measurements of Hypex NC400 DIY Amp

AndreaT

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One simple and maybe silly question: would you use the -10dB, - 20dB or the 0 dB jumpers in the Benchmark DAC3 DX to drive the Hypex NC400? The Benchmark manual suggests the setting that puts the volume around 11 o’clock to achieve the typical listening level..
 

timkritz

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Another lightweight. :D My Proceed Amp-5 is rated the same 125 watts a 8 ohm but weighs 115 pounds!

1405895240225087301.JPG

Amirm,

Any chance you have had issues with yours going into protection mode? I just picked up one with 3 dead channels. It seems to be a common problem, but not too much information online. There's a few spot's that have some heat issues (undersized resistors I believe), but they are measuring ok out of circuit. If you know the "secret" fix that would be awesome. Obviously Harman is not providing schematics, so I'm having a harder time than usual determining root cause.
 

Oscar21

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Hi,
I have built a ncore 400 stereo amp.
Unfortunately, I can only hear the music very quietly from my speakers at full volume.
To be precise, I have to press my ear directly in front of the speakers to hear anything.

I'm at a loss and would like to ask you what the problem could be.

My setup:
Rapsberry Pi 4 with Hifiberry Dac 2 hd (RCA to XLR cable) - Ncore Power Amp - KEF R3.
I use Volumio as player software.

Thanks for your help!

Oscar
 

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TheGhostOfEugeneDebs

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This may be a dumb question, but what are you using to control the volume and are you sure all of the volume controls in the chain are set to appropriate levels?
 

somebodyelse

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How are your RCA to XLR cables wired? Some only connect hot and ground, leaving cold floating. I don't think those work with the nc400.
For future reference inserting JPG images is easier to view than attaching PDFs.
 

Oscar21

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it is working with my old amp. denon avr.
i use dac volume control.
i have no preamp.
 

Julf

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How are your RCA to XLR cables wired? Some only connect hot and ground, leaving cold floating.

I think those are usually referred to as "broken".
 

Hayabusa

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it is working with my old amp. denon avr.
i use dac volume control.
i have no preamp.

So then wire an other (working) source to the rca to xlr cable.
If then also no sound, its the cable.
 

Hayabusa

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So then wire an other (working) source to the rca to xlr cable.
If then also no sound, its the cable.

100% sure there is no short between the speaker cables at the nc400 pcb? They are very close....
 

doug2761

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Hi,
I have built a ncore 400 stereo amp.
Unfortunately, I can only hear the music very quietly from my speakers at full volume.
To be precise, I have to press my ear directly in front of the speakers to hear anything.

I'm at a loss and would like to ask you what the problem could be.

My setup:
Rapsberry Pi 4 with Hifiberry Dac 2 hd (RCA to XLR cable) - Ncore Power Amp - KEF R3.
I use Volumio as player software.

Thanks for your help!

Oscar
When I zoom in on the binding posts in one of your pictures it looks like you may have the plastic washers backwards. I'm wondering if you are getting a short on binding posts to the chassis. Those plastic washers should be oriented such that it prevents the binding posts from sliding around and accidentally coming into contact with the chassis. They should be oriented such that the small inner ring goes inside the hole in the chassis for the binding posts.
 

JimB

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When I zoom in on the binding posts in one of your pictures it looks like you may have the plastic washers backwards. I'm wondering if you are getting a short on binding posts to the chassis. Those plastic washers should be oriented such that it prevents the binding posts from sliding around and accidentally coming into contact with the chassis. They should be oriented such that the small inner ring goes inside the hole in the chassis for the binding posts.
Right. So you'll have to unsolder the wires to disassemble the post mount. While you are at it, this applies to both sides of the panel - both of the colored plastic rings on a post. It's a bit of work to dig them out and reverse them, but it should be done. Also, pay attention to the rotation of the washer - that it orients properly for the 'key' in the panel. On my recent kits, some of the washers for the outside were reversed. Pictures over here:
https://www.audiosciencereview.com/...y-purifi-amp-builds.10478/page-96#post-613473

EDIT: Sorry. I'll disagree now. I think the apparent reversal of your washers is just the reflection of the outer edge on the nut. I see the little radial ribs on the faces of yours, so I think you're good.
 
Last edited:

Oscar21

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How are your RCA to XLR cables wired? Some only connect hot and ground, leaving cold floating. I don't think those work with the nc400.
For future reference inserting JPG images is easier to view than attaching PDFs.

Sorry for the pdf format.

i use a cordial xlr to rca cable. this is functional.
I soldered the xlr terminal in the amp like this:
Pin1 - Ground
Pin 2 - hot
Pin 3 - cold
nAMPON to the nc400 x2 connection kit
 

Oscar21

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When I zoom in on the binding posts in one of your pictures it looks like you may have the plastic washers backwards. I'm wondering if you are getting a short on binding posts to the chassis. Those plastic washers should be oriented such that it prevents the binding posts from sliding around and accidentally coming into contact with the chassis. They should be oriented such that the small inner ring goes inside the hole in the chassis for the binding posts.

I don't know exactly, because I don't have the amp open in front of me, but the plastic washers should all be in the right position.
I will correct this if it is not the case.
But that shouldn't be the problem, should it?

My feeling is that it might also have something to do with the internal speaker cables.
Maybe I didn't solder them well to the binding posts.

Do you have any experience with this, could it be because of that?
 

Oscar21

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Right. So you'll have to unsolder the wires to disassemble the post mount. While you are at it, this applies to both sides of the panel - both of the colored plastic rings on a post. It's a bit of work to dig them out and reverse them, but it should be done. Also, pay attention to the rotation of the washer - that it orients properly for the 'key' in the panel. On my recent kits, some of the washers for the outside were reversed. Pictures over here:
https://www.audiosciencereview.com/...y-purifi-amp-builds.10478/page-96#post-613473

EDIT: Sorry. I'll disagree now. I think the apparent reversal of your washers is just the reflection of the outer edge on the nut. I see the little radial ribs on the faces of yours, so I think you're good.

Yes i think so too.

Thanks for the qick answers!
 

Oscar21

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Is nAMPON grounded?
No I don’t think so.
I soldered both nampon to the connection kit as in the instructions from Hypex.
at first i also thought that nampon should be soldered via the metal eyelet on pin 1, but then i decided to go for the other variant; should i try that?
 
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