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Hypex Ncore NC502MP - audible hum on one channel?

mdsimon2

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I see that the OP’s amp has both RCA and XLR inputs. When I was researching Hypex amps I remember reading that this configuration was more susceptible to ground loops and it was best to have XLR inputs only and use an RCA to XLR cable. Has anyone else heard this?

Michael
 
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MoreCowBell

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A bit like drop bears here in Australia...
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Back in the 70s black bears were severely endangered in Florida due to hunting and habitat destruction. They are thriving now due to conservation efforts
 

Lawhaus

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I have the exact same amp. Audiophonics NC502MP. No issues with hum. Connected to SMSL SU-8 or other dacs.
 
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MoreCowBell

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@Lawhaus, your previous informative post on the nc502 helped me make my decision to purchase it. Seems like I got a dud.
 

boXem | audio

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Despite your claim that my hum/buzz issue is well known across all hypex nxxx modules others members who own various hypex Ncore amps (including members who own the same identical amp that I had issues with and March audio amps) all indicated that their amps are silent and do not present my issue. I will provide an update when I receive the p502 amp.
I will not argue longer on the matter. Alan cannot defend himself, so it not fair. Believe whatever bs you whish, not my business.
 

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tiagobdonoso

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I just bought a NC252mp from Audiophonics and I'm experiencing the same issue. It is a buzz that goes to speakers, but the same buzz is inside the amp. When I turn the amp off, sometimes the buzz keeps going without any power on. Sometimes it is perfect, dead silent. I thought it was my sub, so I took it out of the chain. It got a little better, the buzz was not so intense. I just e-maild Audiophonics and will post here if I have an answer.
 

tiagobdonoso

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I also must add something: I didn't have the buzz problem before I connected the sub for the first time. I used a xlr splitter to send the signal from my little bear mc2 (a potentiometer, to split signal from my two sources) to amp and sub (a svs sb2000pro). From then on, the noise appeared and didn't left me, except sometimes, without the sub, that it suddenly goes away to return once more.
The xlr splitter had something wrong with it, I don't know (I'm a newbie in audio). When I turned the amplifier on, I heard a strong noise in the subwoofer, but in theory they were not connected to each other, obviously.
Well, I'm thinking about removing pin1 after reading the hypex paper. Do you guys have any advice on that? I guess it's simple, right?
Thanks
 

toddverrone

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I also must add something: I didn't have the buzz problem before I connected the sub for the first time. I used a xlr splitter to send the signal from my little bear mc2 (a potentiometer, to split signal from my two sources) to amp and sub (a svs sb2000pro). From then on, the noise appeared and didn't left me, except sometimes, without the sub, that it suddenly goes away to return once more.
The xlr splitter had something wrong with it, I don't know (I'm a newbie in audio). When I turned the amplifier on, I heard a strong noise in the subwoofer, but in theory they were not connected to each other, obviously.
Well, I'm thinking about removing pin1 after reading the hypex paper. Do you guys have any advice on that? I guess it's simple, right?
Thanks

Check to see if the Y-splitter is causing the hum. Take the y-splitters out of your system and hook everything up as it was before you installed the splitters and sub. If the hum/buzz is still present, then it's not the splitter's fault and the hum is caused elsewhere. If the hum goes away, it's the splitter and you should get a different pair.
 

tiagobdonoso

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Check to see if the Y-splitter is causing the hum. Take the y-splitters out of your system and hook everything up as it was before you installed the splitters and sub. If the hum/buzz is still present, then it's not the splitter's fault and the hum is caused elsewhere. If the hum goes away, it's the splitter and you should get a different pair.
Thanks @toddverrone , I really apreciate your input.
It's not the Y splitter, then. It still has the noise. I guess it's wrong grounding, but I wouldn't change anything, except if anybody has a video of how to do it properly. I'm not very handy at that.
But I must say, except for the buzz, the sound is rather extraordinary. I used to have midfi, like old Sansui - and God, what a change! Thanks to all of you guys and Amir for all your help.
 

toddverrone

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Thanks @toddverrone , I really apreciate your input.
It's not the Y splitter, then. It still has the noise. I guess it's wrong grounding, but I wouldn't change anything, except if anybody has a video of how to do it properly. I'm not very handy at that.
But I must say, except for the buzz, the sound is rather extraordinary. I used to have midfi, like old Sansui - and God, what a change! Thanks to all of you guys and Amir for all your help.

Is the subwoofer plugged into the same electrical outlet as your amps? Sometimes you can get a ground loop if things are plugged into different circuits, or even different areas on the same circuit, and are connected by single ended interconnects or balanced interconnects that aren't connected to a truly balanced circuit.
 

Matias

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A good way to trouble shoot "hum" (ground loop) is to disconnect everything from the amplifier, source, subs, etc. Leave only the speakers connected to the amplifier and mains. Turn on. There should be no "hum". Then turn the amp off, one by one start reconnecting the devices and turning the amp on and checking for "hum". You will find who is causing the ground loop, and then take measures to fix it.
 

tiagobdonoso

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Is the subwoofer plugged into the same electrical outlet as your amps? Sometimes you can get a ground loop if things are plugged into different circuits, or even different areas on the same circuit, and are connected by single ended interconnects or balanced interconnects that aren't connected to a truly balanced circuit.
They are connected to different outlets. But I took the sub off of my system and the hum remains. I don't have the third pin for ground here (I don't mean the XLR, but the sheer electrical connection to the outlet), so I use an adaptor - can that be the problem?
And @Matias , I took all off except for speakers and the hum remains. Even when I turn the amplifier power off, the buzz remains for a while. It's electrical, inside the amp box, and the same noise goes to the speakers.
I only use XLR - I took off the y splitter. I'm waiting for the arrival of my Gustard X16 to use the sub connected there. For the turntable (my other source), I gave up the use of the subwoofer. The turntable (a LP120x with preamp built in) is RCA to Little Bear then XLR to amp.
 

toddverrone

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They are connected to different outlets. But I took the sub off of my system and the hum remains. I don't have the third pin for ground here (I don't mean the XLR, but the sheer electrical connection to the outlet), so I use an adaptor - can that be the problem?
And @Matias , I took all off except for speakers and the hum remains. Even when I turn the amplifier power off, the buzz remains for a while. It's electrical, inside the amp box, and the same noise goes to the speakers.
I only use XLR - I took off the y splitter. I'm waiting for the arrival of my Gustard X16 to use the sub connected there. For the turntable (my other source), I gave up the use of the subwoofer. The turntable (a LP120x with preamp built in) is RCA to Little Bear then XLR to amp.

It sounds like you have a faulty module in your amp. I would contact the manufacturer regarding a replacement board.
 

Matias

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tiagobdonoso

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Matias

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Thank you both, guys.
@Matias, I see you are from Brazil. I'm from Ribeirão Preto. Do you still recommend the Ifi, or is there something else that works to be bought around here?
SP aqui.
Before we had Emotiva CMX-2 line strip that removes DC, but I think it is discontinued. With luck you can find a used one somewhere.
I don't know of other DC blocking devices in the market.
 

Matias

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Another idea: try running the amp in 220V (phase + phase) and see if it solves the issue.
 
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