...bits of electrical equipment!!
Hello once again, this is a plea to the knowledge base of you guys and gals to help me out with a power & sound problem that is driving me mad.
Last Saturday I did a gig at a large 400+ wedding where a marquee was used for the dining and the Disco Area. Upon arrival on Friday night (I live a few miles away so I thought 'd check out the state of things) I found that the power supply for all my 30+ items was a...two gang extension lead plugged into a four gang lead...which went off to the 3 phase supply that had been installed into the marquee.
I recently had all my gear P.A.tested, when it came to setting up and playing my gear I got a terrible 'hummmmm'...yes, I know you heard that before!
Even before I turned my lights on I got this noise?
Now, the question is: Firstly, all my cables were fine...perhaps the power leads could have been better i.e the heavy screened type...but at £20 a go...err I've not really got £300+ to spend on leads when normal IEC leads should be fine. Anyway...I digress, could the initial rubbish power supply cause this annoying problem? I guess all my power relying on 1.5mm cable can't be great (sic). Secondly, when I managed to get some half decent sound (I ended stripping down my system to basic Graphic - Full range speakers) is there any way on how I could prevent this annoying sound still being present?
I really thought I had a dodgy cable, either sound or power? But I guess it was all about the amount of power being sucked down this poor power line...
So, any thought Ladies & Gents?
When I plug everything into my home studio there is virtually no noise...and that's with Mid/Top JBL's x2 + 2x HH DUAL 15" Bass bins and a monitor...and all the deck/CD's along with a crossover etc...
Please can somebody reassure me that it ISN'T A CASE OF "ahh, it's got to be a dodgy lead mate" - Fingers crossed, but I've bought a Soundlab cable checker just in case...
Thank you in advance.
Graham @Disco24-7
Full Version: Power and sound problems.
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If all your leads were recently Pat'ed then I dont think its that...
Were you running of off a gennie if so this can cause problems for sound equipment due to the nature of how the power is produced...
Also it could be you were sharing the supply with say the caterers then they might have been draining alot of power or using something that dissagreed with your PA equipment...
Always try to get a seperate supply for your equipment minimum two independant feeds ie not a gang plug but two 13 amp supplies, then run say PA on one feed and lighting on the other.... If you have a really big rig you might need 3 or even 4 independant supplies....
Also you can buy from say maplins a mains filter plug that can take out all the nasties in your power feed. This might also help....
Other causes of hum are earth loops, Flouresent lighting and dimmer switches...
If your kit works OK at home or other venues then chances are it is not your kit...
But do look at getting that mains filter and an RCD for each power supply this should help out no end.... Hope this is of help to you
Nik
Were you running of off a gennie if so this can cause problems for sound equipment due to the nature of how the power is produced...
Also it could be you were sharing the supply with say the caterers then they might have been draining alot of power or using something that dissagreed with your PA equipment...
Always try to get a seperate supply for your equipment minimum two independant feeds ie not a gang plug but two 13 amp supplies, then run say PA on one feed and lighting on the other.... If you have a really big rig you might need 3 or even 4 independant supplies....
Also you can buy from say maplins a mains filter plug that can take out all the nasties in your power feed. This might also help....
Other causes of hum are earth loops, Flouresent lighting and dimmer switches...
If your kit works OK at home or other venues then chances are it is not your kit...
But do look at getting that mains filter and an RCD for each power supply this should help out no end.... Hope this is of help to you
Nik
I have had this when the mains supply sags down below the dropout voltage of the regulators in equipment. Chances are with all that loading you had 200V or less at the end of the line!
| QUOTE (Disco24-7 @ Sep 12 2006, 01:27 PM) |
| Last Saturday I did a gig at a large 400+ wedding where a marquee was used for the dining and the Disco Area. Upon arrival on Friday night (I live a few miles away so I thought 'd check out the state of things) I found that the power supply for all my 30+ items was a...two gang extension lead plugged into a four gang lead...which went off to the 3 phase supply that had been installed into the marquee. |
Did you specify your power requirements in advance?
I did a marquee based wedding a few weeks ago.
I wrote to the clients and met them and told them of my electrical and space needs on both occasions. I said that I would need 2 separate 13 amp feeds, not shared with any other application.
I visited the marquee a couple of days before and saw that I had a 2 gang extension lead plugged into a 13 amp outlet on a distribution board from a generator. The trouble is, of course, not everybody understands that a 1 x 2 gang extension will not equal 2 x 13 amp sockets if plugged into 1 x 13 amp outlet.
2 separate feeds were then arranged and worked at set-up time. When I returned in the evening one feed didn't work so that there was no power for the audio! Eventually a cable drum was run from the distribution board although it wasn't fully unwound so probably would only support 6 amps. Just as well I was running my amp at around 12 O'clock.
Unless its a properly installed generator, i won't use it.... as i think i have mentioned before, i have more than enough cable to do 2 runs to mains power, from the venues building.
I back up what has allready been said: RCD's a definate, 2 13A feeds direct from the generators distro, also a must!
I back up what has allready been said: RCD's a definate, 2 13A feeds direct from the generators distro, also a must!
Sound to me like you had an earth problem on the supply. When doing marquees, we drive an earth spike into the ground near the disco mainly for safety. Also, I carry a mains test plug which shows if any faults are present like this one:
With regards to what is supplied in marquees, I always used to ask for 2 x 13A sockets, and 9 times out of 10 always got 1 x 13A feed with 2 or 4 sockets
Having thought about this, I now ask for 2 x independent, clean 16A sockets like these:
I carry 2 distribution cables which connect to these sockets, problem solved!
With regards to what is supplied in marquees, I always used to ask for 2 x 13A sockets, and 9 times out of 10 always got 1 x 13A feed with 2 or 4 sockets
Having thought about this, I now ask for 2 x independent, clean 16A sockets like these:
I carry 2 distribution cables which connect to these sockets, problem solved!
| QUOTE (UKHero @ Sep 12 2006, 07:23 PM) |
| If all your leads were recently Pat'ed then I dont think its that... Were you running of off a gennie if so this can cause problems for sound equipment due to the nature of how the power is produced... Also it could be you were sharing the supply with say the caterers then they might have been draining alot of power or using something that dissagreed with your PA equipment... Always try to get a seperate supply for your equipment minimum two independant feeds ie not a gang plug but two 13 amp supplies, then run say PA on one feed and lighting on the other.... If you have a really big rig you might need 3 or even 4 independant supplies.... Also you can buy from say maplins a mains filter plug that can take out all the nasties in your power feed. This might also help.... Other causes of hum are earth loops, Flouresent lighting and dimmer switches... If your kit works OK at home or other venues then chances are it is not your kit... But do look at getting that mains filter and an RCD for each power supply this should help out no end.... Hope this is of help to you Nik |
To Nik (UKHero) and the rest of the replies from you chaps, many thanks.
I know for a fact that my 'four' gang to 'two' gang extension was sharing a supply with large fridges...which would account possibly to the problems.
As ever I asked for a decent supply well in advance, however on the evening before the event I discovered this major problem, which was by then too late to rectify. I had no choice but to work around any possible noise problems...which I got in a BIG way!
I'll take on board the excellent advice and tips from yourselves, I certainly will try to run the lighting and audio on different 13a sockets. I must also state that a few months back I also had a problem with an air-conditioning unit which was obviously having a major effect on my system...and the noise it was causing to my speakers.
I guess, wherever possible it has to be a totally independant supply for the audio. In the meantime I'll check out the Maplin site regarding the filters as suggested.
Regards
and many thanks once again!
Graham@ Disco24-7
| QUOTE (brianmole @ Sep 13 2006, 06:38 AM) |
| we drive an earth spike into the ground |
....and run a cable to it from the back of one of your electrical items?
Or do you do it another way?
| QUOTE (iany @ Sep 13 2006, 10:05 AM) | ||
....and run a cable to it from the back of one of your electrical items? Or do you do it another way? |
I have a 6 way socket with an earth bonding point I connect the spike to.
Sounds like a ground loop to me.
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