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Balanced Hum |
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The Builder 
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Joined: 03 January 2010 Status: Offline Points: 3107 |
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 Topic: Balanced HumPosted: 01 August 2010 at 7:37pm |
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Citronic 10-4
Straight to DCX
Loads of noise balanced out.
Not loads of noise unbalanced.
Same with other mixer.
Same with other crossover.
Cables fine, tried others.
Amps earth lift or not, no difference.
Noise is from (whatever) mixer.
This has to be some sort of mains issue???? Edited by The Builder - 01 August 2010 at 7:41pm |
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puresoundglasgow
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Joined: 20 September 2009 Location: Glasgow Status: Offline Points: 266 |
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Posted: 01 August 2010 at 8:54pm |
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Could also be something plugged into the mixer that's causing the hum, try mixer with nothing plugged in (if not already tried), laptops are a particular culprit.
Also had loads of similar hassle with tv's plugged into an av mixer. |
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subbass
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Joined: 30 March 2009 Location: bristol Status: Offline Points: 1683 |
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Posted: 01 August 2010 at 10:19pm |
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mic channel is on?
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kedwardsleisure
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Posted: 01 August 2010 at 10:27pm |
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This is good advice, also check for ground loop if mixer is bolted into metal rack with something else. |
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Kevin
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neilpoints
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Posted: 02 August 2010 at 12:46am |
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Try using balanced leads with pin 1 disconnected from mixer to crossover?
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former Eurovision contestant
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The Builder
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Posted: 02 August 2010 at 12:48am |
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Thanks all, none of the above though |
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It just is.
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audiomik
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Joined: 06 April 2010 Location: Bath, UK Status: Offline Points: 2956 |
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Posted: 02 August 2010 at 3:04am |
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did you use the same DC Power Supply unit for the 2 Mixers?
Might be a fault in it? Mik |
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The Builder
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Posted: 02 August 2010 at 9:44am |
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It just is.
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demanddeepbass
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Posted: 02 August 2010 at 11:05am |
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No it just breaks the ground between the mixer and the DCX to stop current flowing down it, the + and - signals are still preserved. So long as it's grounded at one end it wont cause problems. Note that 48v phantom power will not work down cables without a ground connection at both ends.
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"These amps go up to 11"
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The Builder
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Posted: 02 August 2010 at 7:16pm |
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It just is.
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neilpoints
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Posted: 03 August 2010 at 12:46am |
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Yes, it helps. I use un-grounded cables on all the short connections, just thin 2-core cable, connect pins 2 and 3 only, with no shield at all. Shielded cable on longer runs but with the shield connected at only one end.
 There's probably some minor power-supply problem somewhere, something running to ground enough to hum but not enough to trip an RCD, maybe a poor connection on a blue wire in a mains plug, maybe a bad bit of solder. < id="gwProxy" ="">< ="jsCall;" id="jsProxy" =""> |
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demanddeepbass
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Posted: 03 August 2010 at 10:04am |
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Neil's right but be sure that whatever cable you use is a decently tightly twisted pair - Bell wire will not work! If you're a cheapskate cat 5 works remarkably well for line level over pretty long distances and if you need to you can get 4 channels down one run. The better the CMMR of your kit at the receiving end the more you can get away with but in harsh environments you'll start to hear buzzes. Route away from mains wiring or dimmer packs.
It doesn't necessarily follow that the equipment is faulty but it is possible. It could just be that you're conecting to the mains on a different circuit and there are slightly different resistances in the paths to ground. That said RCD checking and PAT checking is never a bad thing to do. |
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"These amps go up to 11"
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Could also be something plugged into the mixer that's causing the hum