Members Telecruiser Posted August 22, 2010 Members Share Posted August 22, 2010 When doing sound for gigs do you or how do you handle dividing or separating power between the sound equip. and lighting equip. to prevent any hums, buzzes generated by lighting from gettining into the audio? Ihave heard you can transformer isolate the power but not sure. Link to comment Share on other sites More sharing options...
Members roadweiry Posted August 22, 2010 Members Share Posted August 22, 2010 How much power are your system's drawing ? We just use two separate 20a outlets and have no problems. Is there a specific problem you are having ? Link to comment Share on other sites More sharing options...
Members Red Hawk Posted August 22, 2010 Members Share Posted August 22, 2010 in our rig, everything that makes sound gets plugged into our 220. The lights get plugged into the wall. The only time we've had a problem with that was at a bar gig when someone decided to plug the popcorn machine into the same circuit as the lights. We played in the dark for the rest of the song... Link to comment Share on other sites More sharing options...
Members tlbonehead Posted August 22, 2010 Members Share Posted August 22, 2010 in our rig, everything that makes sound gets plugged into our 220. The lights get plugged into the wall.The only time we've had a problem with that was at a bar gig when someone decided to plug the popcorn machine into the same circuit as the lights. We played in the dark for the rest of the song... Yes, if there is a 220 outlet to use, we run one thing out of that and use 2-3 wall circuits for the other. Link to comment Share on other sites More sharing options...
Members BillESC Posted August 22, 2010 Members Share Posted August 22, 2010 Easiest method is to have sound on one phase of the service and lighting on a different phase. Link to comment Share on other sites More sharing options...
Members tlbonehead Posted August 22, 2010 Members Share Posted August 22, 2010 How much power are your system's drawing ? We just use two separate 20a outlets and have no problems. Is there a specific problem you are having ?Are you using LED lighting? Regular lighting would be pretty tough on a single 20 amp circuit. Link to comment Share on other sites More sharing options...
Members Telecruiser Posted August 22, 2010 Author Members Share Posted August 22, 2010 How much power are your system's drawing ? We just use two separate 20a outlets and have no problems. Is there a specific problem you are having ? Never said I was having a problem, it was just a question. I know lights can cause problems in the audio. You see large shows with huge lighting and sound systems and I was just wondering how different folks do things to eliminate any problems. Link to comment Share on other sites More sharing options...
Members agedhorse Posted August 22, 2010 Members Share Posted August 22, 2010 Easiest method is to have sound on one phase of the service and lighting on a different phase. Easiest maybe, but just about the worst thing you can do for noise. All the noise currents will then be present on the neutral shared by the sound at full amplitude without any benefits of sharing neutral currents or reducing the amplitude if the current components (and importantly, their harmonics). Ideally, you have a 120/240 or 120/208V feeder for lights and a seperate one for sound. The less conductor shared, going as far back to the service transformer, the better. It's the sharing of conduictors that is responsible for conducted noise. In practice, put the lighting on branch circuits that share the least with the sound circuits... at least seperate the branch circuits. Not necessicarily by phase though. Noise voltage (due to noise currents) sum directly on neutrals with like phases, they vector sum where the phases are different, so the way to get the amplitude down is to balance the loads across phases. For dimmed circuits, there will not be perfect cancelling or isolation because the current turn-on point of phase cxontrol dimmers shifts depending on the dimmer percentage. This is how traditional phase controlled dimmers work. For LED lighting, since most is controlled by switchmode current drivers that are high frequency devices, and the currents are relatively low, it won't make much difference whatever you do. Link to comment Share on other sites More sharing options...
Members roadweiry Posted August 22, 2010 Members Share Posted August 22, 2010 Are you using LED lighting? Regular lighting would be pretty tough on a single 20 amp circuit. This all runs on 20amps, The only non-led cans were wash lights in the back corners on the vertical truss. Rock those guys too much and ur over 20a. Never had a problem yet. Link to comment Share on other sites More sharing options...
Members twostone Posted August 22, 2010 Members Share Posted August 22, 2010 This all runs on 20amps, The only non-led cans were wash lights in the back corners on the vertical truss. Rock those guys too much and ur over 20a. Never had a problem yet. Same here with my LED system nice LED rig bro Link to comment Share on other sites More sharing options...
Members W. M. Hellinger Posted August 23, 2010 Members Share Posted August 23, 2010 In practice, put the lighting on branch circuits that share the least with the sound circuits... at least seperate the branch circuits. Not necessicarily by phase though. I agree with Andy: Load the supply as equally as possible... putting lighting on branch circuits fully sharing both or all three legs of the load... sharing the over-all load. Judge the impact on the main service and distro by the voltage drop in the over-all distro and never energize lighting above a level that brown-outs the entire system. Link to comment Share on other sites More sharing options...
Members agedhorse Posted August 23, 2010 Members Share Posted August 23, 2010 Analyzing the currents and the residual voltage caused by the currents along with the true neutral impedance is an eye opening excercise. I developed a lot of this due to designing power amps back in the day. Even a "linear" power supply on a power amp is full of 120 Hz current pulses which translate into voltage pulses on the neutral. Link to comment Share on other sites More sharing options...
Members tlbonehead Posted August 23, 2010 Members Share Posted August 23, 2010 This all runs on 20amps, The only non-led cans were wash lights in the back corners on the vertical truss. Rock those guys too much and ur over 20a. Never had a problem yet. looks great! So those 10? par cans in front up on the truss are also LED? Link to comment Share on other sites More sharing options...
Members StratGuy22 Posted August 23, 2010 Members Share Posted August 23, 2010 I have a 220 board, it has four separate 20amp beakers. One breaker is enough for the lights... Link to comment Share on other sites More sharing options...
Members roadweiry Posted August 23, 2010 Members Share Posted August 23, 2010 looks great! So those 10? par cans in front up on the truss are also LED? Correct. Link to comment Share on other sites More sharing options...
Members tlbonehead Posted August 23, 2010 Members Share Posted August 23, 2010 Correct. what brand/model? Link to comment Share on other sites More sharing options...
Members roadweiry Posted August 23, 2010 Members Share Posted August 23, 2010 what brand/model? Not sure on the model and make of the par cans. I own the PA and we subcontract the lights. They do 98% of our shows. I couldn't afford not to use them. There work is amazing. The rig pictured is there smallest. Here is there biggest. Link to comment Share on other sites More sharing options...
Members agedhorse Posted August 23, 2010 Members Share Posted August 23, 2010 In the top photo, it looks like the top truss is deflecting (bending) a lot. Maybe it's the angle of the shot but worth a second look any time you see something like this. Just did a show where during my safety check on some Vertecs a stagehand did not fully insert a pin in the fly hardware. Under load it was jammed tight at an angle. This is one of the jobs a tech director who is in charge of a show must do. Generally I get a bit of attitude but that changes when I find something like this. Large shows usually have somebody who double-checks safety oriented issues... may be the head rigger, the union steward, or a subcontracted (real) engineer depending on the level of complexity of the show. Link to comment Share on other sites More sharing options...
Members kevinnem Posted August 23, 2010 Members Share Posted August 23, 2010 In the top photo, it looks like the top truss is deflecting (bending) a lot. Maybe it's the angle of the shot but worth a second look any time you see something like this.. Noticed that as well. For lighting we use seprate feed (branch cuircuit) form the house power, usally a 3 phase, 200 amps service. Kev. Link to comment Share on other sites More sharing options...
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