localzuk Posted November 21, 2012 Posted November 21, 2012 We have had to add some speakers to our PA system in the hall and they buzz like crazy. When plugged into an amp away from power sources, they're fine but due to the way our stage is laid out, the cabling runs past power sockets etc... and therefore the buzz appears. Any ideas how we can resolve this? Are we going to have to bite the bullet and start crawling around under our stage in order to route the cables via non-power interfering routes (will be a big faff). Or is there such a thing as shielded speaker cable?
chazzy2501 Posted November 21, 2012 Posted November 21, 2012 Ferrite cores and ground loop isolators all cheap at maplins. it's normally the source input. I used one on a macbook its like night and day.
Educare_AV Posted November 21, 2012 Posted November 21, 2012 Hi, I agree with Chazzy the issue is more likely to be a ground loop issue. you could try one of these Ground Loop Isolator : Speakers : Maplin Electronics
localzuk Posted November 21, 2012 Author Posted November 21, 2012 Any such thing using speakon? As that's what we've got everywhere here for the speakers... My technician might just kill me if I ask him to do more with it.
sonofsanta Posted November 21, 2012 Posted November 21, 2012 Those ground loop isolators - do they do the job wherever they're plugged in? As we often have problems when guest speakers bring laptops in, and the long audio cable has to run alongside the extension cable for the power brick. If I can plug it in just before the phono cables go into the XLR inputs (to go back to the soundboard), it'll make life much more pleasant and be well worth the £4 from CPC.
Majenta-AV Posted November 21, 2012 Posted November 21, 2012 Any such thing using speakon? As that's what we've got everywhere here for the speakers... My technician might just kill me if I ask him to do more with it. Just to clarify - That isolator goes between the audio source and the amplifier. It doesn't go between the amplifier and the speakers. What type and size speaker cable are you using ?
localzuk Posted November 21, 2012 Author Posted November 21, 2012 Just to clarify - That isolator goes between the audio source and the amplifier. It doesn't go between the amplifier and the speakers. What type and size speaker cable are you using ? It isn't the source - we have 2 speakers already in which don't buzz, wired via the roof space. Its definitely the speaker cables. This is the cable: Sommer Meridian 2 X 2.5mm Fireproof at Studiospares
Andrew_C Posted November 21, 2012 Posted November 21, 2012 (edited) As above it is really unlikely to be the speaker wiring. The level is so much higher than in the signal side. Unless someone has grounded something he shouldn't have... Like maybe a metal back-box connected to earth and the ground of the amp? Edited November 21, 2012 by Andrew_C
soveryapt Posted November 21, 2012 Posted November 21, 2012 We have had to add some speakers to our PA system in the hall and they buzz like crazy. When plugged into an amp away from power sources, they're fine but due to the way our stage is laid out, the cabling runs past power sockets etc... and therefore the buzz appears. Any ideas how we can resolve this? Are we going to have to bite the bullet and start crawling around under our stage in order to route the cables via non-power interfering routes (will be a big faff). Or is there such a thing as shielded speaker cable? You say when plugged into an amp away from power sources. Is this the same amp that you're trying to use in situ or a different amp? Just a simple thing, could it be the amp that's the issue? Failing that, it's not ideal running alongside power for speakers and all that, but it shouldn't cause such a huge buzz as you seem to be describing. What kind of cable are you using presently? The other thing it could be is if the sources are all on different ring mains, which can often cause issues with earthing and what not, so it's worth checking that too.
localzuk Posted November 21, 2012 Author Posted November 21, 2012 Same cable, same amp, different route (ie. draped across the centre of the stage, rather than tacked to the wall). As I said above, the sources are definitely not the issue - we have 2 speakers in place already without any buzzing.
Majenta-AV Posted November 25, 2012 Posted November 25, 2012 It isn't the source - we have 2 speakers already in which don't buzz, wired via the roof space. Its definitely the speaker cables. This is the cable: Sommer Meridian 2 X 2.5mm Fireproof at Studiospares Hi again, Apologies if this has already been asked. Have you tested both speaker cables with a meter just in case you have a stray strand anywhere? Is this a low impedance or high impedance (100v) system? Have you swapped the speakers around to confirm that it isn't a speaker? Does the amplifier only have 2x outputs? ie left & right Jeff
webman Posted November 25, 2012 Posted November 25, 2012 Try a ferrite ring at the speaker end of the speaker wire.
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