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Why is my sub constantly buzzing

T

thingsandstuff

Guest
I have a mordaunt short premiere set of speakers, and a pioneer VSX 1015 amp. The sub is connected with an Ixos cable and a splitter so that the mono output from the amp connects to both the left and right inputs on the sub. My problem is that the sub is constantly buzzing when there is no signal to it. It doesn't do it while the amp isn't connected, and I have checked all the mains cables nearby and it doesn't seem to be getting any interference from any of them. Doea anyone have any suggestions as to what might be causing this?
 

Knyght_byte

Distinguished Member
is the splitter a very cheap nasty Maplins type thing?..if so it could be picking up interference there.....
 
T

thingsandstuff

Guest
Nope it is an Ixos one too. It was actually buzzing before I used the splitter anyway. I got it to see if that would solve the buzzing by using L+R inputs instead of just one like I was before!
 
D

Deleted member 30535

Guest
It may be a ground loop (earthing) problem. Do a search in this forum for "ground loop" or hum/humming. There's much advice along the way!
 
T

thingsandstuff

Guest
OK, I've done a bit more checking into this, and I've found that if I try to connect with only one end of the sub cable earthed, the buzzing is much worse! I've tried plugging the Sub into the same socket as the amp to make sure there is no difference between the earths, and this makes no difference, but when I trail a length of wire (any old wire) from the outer (earth) of the sub signal cable at the sub end to the amp casing, then the buzzing pretty much goes. However if I do the same thing at the amp and it makes no difference. Surely this means the fault is with the cable, and if so should I be Pi**ed of that I spent £20 on an Ixos Subwoofer cable that isn't doing it's job properly?!!
 
D

Deleted member 30535

Guest
If you have a test meter see if there is a circuit between each earth at the end of the IXOS cable. If there is a circuit then it may be that by putting your old bit of wire between the earth connections between the sub end to the amp casing has added a "better" earthing system c.f. the IXOS.

Some people have disconnected the earth on the sub power plug, but unless you have an RCD (residual current detector) (like on the lawn mower protection sysem when outdoors) EITHER as a plugin unit on your socket OR a as a "proper" built in unit in your mains distribution board, then you could run the risk of an electric shock should a fault occur in the sub's amp and it makes any metal casing live. Use with caution and you'll be OK.
 
T

thingsandstuff

Guest
I have metered the Ixos cable, and I have continuity along the outer part of it. I do have RCDs in my consumer unit, so I dissed the earth from the Sub plug, but it still buzzes!! :confused: :confused:
 
D

Deleted member 30535

Guest
Right, put the earth back on your sub plug, and with an old cable to practice on, see if you can disconnect the earth/shiled on the cable to isolate the sub from the amp. Obviously the sub is finding a ground loop back through the amp's earthing circuit. You just need to isolate the two of them.
 
T

thingsandstuff

Guest
I'll try that over the next few days, but I did connect the cable enough for the signal part to connect but not enough for the outer to make contact and that was loads worse. For now I've run a length of cable from the sub end to the amp and attached it to a screw on the amp. I've emailed the retailers I got the cable from to see if they will refund and let me get the better cable in the Ixos range to see if that solves the problem!
 
C

chris_harris

Guest
i am having the same problem with a pioneer vsx 1014 amp and KEF sub (pre ground switch model :( , there is no buzzing when the reciever is on, but when switched off, the sub starts buzzing and will not auto power off, if i disconnect the rca, the buzzing stops.

I have a feeling that it may be some sort of feedback problem, as it still hums when the reciever is unplugged. I have tried a wire from the sub amp panel case to the reciever case but it does nothing.

I shall try the wire between the sub plug earth and the reciever case. Will let you know the outcome.
 
D

Deleted member 30535

Guest
Funny how things go! l noticed that my amp had started to buzz (via speakers) and traced it to the Sub/BFD/interconnect . As l made the power chord for the amp l knew that did not have an earth. So l swapped it with the Sub power lead. Still buzzing! So 1 swapped the sub power (now earthless) with tie BFD power lead (earthed) . Buzzing gone!

A bit of. trial & error and detective work can work! Don't know why the amp had decided to buzz. ! :confused:
 

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