Very noisy Hypex UCD400HG

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I have a Hypex amp with 2 UCD400HG (with HXR) and two SMPS400A400 power supplies. I've had it 3 or 4 years now. It was fine for a long time but has now started making a lot of hiss, and also some strange kind of 'interference' crackling type sounds. It can vary in loudness from time to time. If I unplug the audio input XLR cables, the noise gets very loud, which makes me wonder if this is somehow related to grounding issues? It happens in both channels of the amp and if I only power up one side at a time, I still have the problem so it would seem odd for both independent channels to develop the same fault.

Any suggestions on a solution before I try and ship it to Hypex for possible repair?

Here is a photograph:
 

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I have a Hypex amp with 2 UCD400HG (with HXR) and two SMPS400A400 power supplies. I've had it 3 or 4 years now. It was fine for a long time but has now started making a lot of hiss, and also some strange kind of 'interference' crackling type sounds. It can vary in loudness from time to time. If I unplug the audio input XLR cables, the noise gets very loud, which makes me wonder if this is somehow related to grounding issues? It happens in both channels of the amp and if I only power up one side at a time, I still have the problem so it would seem odd for both independent channels to develop the same fault.

Any suggestions on a solution before I try and ship it to Hypex for possible repair?

Here is a photograph:

Such expensive amplifiers, for the price...I no longer trust Hypex products they seem like a hyped up audio brand, I was evaluating these for a friend so no more.
 
Not related to hiss or crackling, but for your own safety I would recommend to look at the case earth connection again. The earth wire must be longer than the neutral and live wires. Furthermore, routing it through a terminal block does not seem safe to me.
 
Such expensive amplifiers, for the price...I no longer trust Hypex products they seem like a hyped up audio brand, I was evaluating these for a friend so no more.

Just for the record: I strongly disagree with your opinion having 2 UCD400HG (with HXR) and two SMPS400A400 power supplies for several years.

Top notch solution for the asking price. They can be even further improved with some careful tweaking.
 
I have a Hypex amp with 2 UCD400HG (with HXR) and two SMPS400A400 power supplies. I've had it 3 or 4 years now. It was fine for a long time but has now started making a lot of hiss, and also some strange kind of 'interference' crackling type sounds. It can vary in loudness from time to time. If I unplug the audio input XLR cables, the noise gets very loud, which makes me wonder if this is somehow related to grounding issues? It happens in both channels of the amp and if I only power up one side at a time, I still have the problem so it would seem odd for both independent channels to develop the same fault.

Any suggestions on a solution before I try and ship it to Hypex for possible repair?

Here is a photograph:

How was it going on? sent them back to the factory? I am going to use these two module for my new project. just afraid of the quality of Hypex modules.
 
Not related to hiss or crackling, but for your own safety I would recommend to look at the case earth connection again. The earth wire must be longer than the neutral and live wires. Furthermore, routing it through a terminal block does not seem safe to me.


jop...
please check the bottom plate and scratch the black collered surface away and reconnect the earth connection. mybe this black collered surface has to scratched away at other points too.
 
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