I do apologize about my poor english first.
I builded a pair of nc400-monoamps several days ago ,for these days them worked well until yesterday night.I noted some noise from one of them(I call it "A"),of cource, from the speaker I mean.It sound a little like ESD，intermittently.
For test,I exchanged interconnect cables,smps600s,power switch……even speaker.But "A" still got this problem while another one always OK.
And now,I've no idea.
I builded a pair of nc400-monoamps several days ago ,for these days them worked well until yesterday night.I noted some noise from one of them(I call it "A"),of cource, from the speaker I mean.It sound a little like ESD，intermittently.
For test,I exchanged interconnect cables,smps600s,power switch……even speaker.But "A" still got this problem while another one always OK.
And now,I've no idea.
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Can you describe the noise a bit more precisely? How frequently does it happen? For how long a time?
But have you tried swapping nc400's?
Looking at your picture, I am a bit concerned about the chassis connections (both the one from the nc400 to chassis and the one from the input connector to chassis) forming pretty big loops - and the fact that you have two chassis connection points forms a loop in itself.
I also notice you have a power inlet with a built-in T filter with a capacitor bypass to earth - I think Bruno specifically stated that that is a bad idea (as it forms a noise path).
Thank you very much,Julf.🙂
It sound like an old volume VR while its rotating，but the volume of the noise is contantly no matter play or not play music（even no matter connect or not connect to the preamp）. The noise is so unstable, I can't tell you the frequence. Sometimes for one or two seconds,it's gone,sound normal!But sometimes it could last one or two seconds.Obviously，it's there.
No,I didn't swap them.
The one from the nc400 (red text)is nAMPON,another(blue text) is GND.
I tested the abnormal one individually without connect another monoamp，but still……🙁
I did not note this，thank you again，I‘ll try.
It sound like an old volume VR while its rotating，but the volume of the noise is contantly no matter play or not play music（even no matter connect or not connect to the preamp）. The noise is so unstable, I can't tell you the frequence. Sometimes for one or two seconds,it's gone,sound normal!But sometimes it could last one or two seconds.Obviously，it's there.
No,I didn't swap them.
The one from the nc400 (red text)is nAMPON,another(blue text) is GND.
I tested the abnormal one individually without connect another monoamp，but still……🙁
I did not note this，thank you again，I‘ll try.
That sounds almost like a bad connection or cold solder joint somewhere. Have you tried wiggling wires and pushing down on things to see if the noise is affected?
It would be good to determine is the problem is with the nc400 itself, or with the installation.
Are we talking about the green and the yellow wires?
Thank you for your Patience，Julf.
I soldered XLR jacks again，but didn't work.
I swapped them just now ,"A" still got this problem while another one still OK.🙁
I misunderstand your words，sorry！😛
At this time ，I tear down the yellow wire，but nothing changed……
then tear down the yellow wire
~~~~~
I soldered XLR jacks again，but didn't work.
I swapped them just now ,"A" still got this problem while another one still OK.🙁
I misunderstand your words，sorry！😛
At this time ，I tear down the yellow wire，but nothing changed……
then tear down the yellow wire
~~~~~
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OK, so the problem is with your nc400, not with your wiring or installation. I suggest you contact hypex customer service, they are usually very helpful. Of course, you might want to inspect the module for anything obvious (bad connection, dirt or solder spots).
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