Post by: Leo House on April 21, 2010, 05:39:08 PM
The light box, looks to be pretty much consumer-grade sliding dimmers, Here is a pic if that will help.
http://img204.imageshack.us/i/49495760.jpg/
http://img15.imageshack.us/i/dcfc0016.jpg/
(You can see in these pics, that the dimmer box is located right next to the sound equipment, and unfortunately, there isn't another place for it right now, and was done like this due to lack of volunteer workers to run everything)
Save for getting a new light system(which isn't possible at this time, as funding is a HUGE issue for this theater, and there are far greater needs in the restoration fund) so I am looking for a fairly cheap solution.
If I got some EMI shielding tape, like this http://cgi.ebay.com/Aluminum-Foil-EMI-Shield-HVAC-AIR-DUCT-T ape-58mmx25M-/180495605260?cmd=ViewItem&pt=Guitar_Access ories&hash=item2a06605e0c
and taped around the metal parts of the dimmer box (leaving the controls open obviously) do you think that would reduce the EMI enough to help? If not, what suggestions do you guys have that could help deal with this on a budget?
EDIT: I should also mention, as for as I can tell, there is no connection between the dimmer box's power, and the mixers power. The mixer is plugged into a regular wall outlet, as well as all the other equipment, but the Dimmer box is connected to more high voltage sources. There are lines, in blue tubeing, that run to it, and from it to another ox behind me(which also seems to emit a strong electrical field) and powers and controls 8-10 high powered stage lights. I'm still confused on how its setup exactly, but it appears that there is an awful lot of power running through that dimmer box.
Post by: Leo House on April 21, 2010, 05:52:26 PM
| Quote: |
The first thing to determine is if you have a radiated or conducted EMI problem. If your battery-powered camera picks up the noise, you may have a radiated noise issue, but my guess, since you can hear the noise, is that you have a conducted EMI problem. Shielding won't help you with this; you need to eliminate any connections between the equipment. Paying attention to proper grounding and shielding of the audio equipment will also help. |
Well, for starters, the camera is running off outlet power, if that makes a difference. But the camera does not pick up the noise, its only in the mains and recordings, when the gain is really hot on the channels, (Regardless if there is actually anything IN the channel or not, it buzzes even in an open channel, also the buzz increases when the dimmers are mid way, lessens when raised up all the way, and almost non existent when they are down.)
Also, as I mentioned, there is no sound in the video camera, but there is significant quality loss from recording over there less then a foot away from the dimmer, as opposed to the center of the balcony more then 5 feet away from the dimmer.
I don't know the first thing about checking the ground and all that, but I believe it is more radiant, as I can use a mic and get the buzz 100 fold if I place it near the box while turned up high, which tells me there is SOMETHING emanating from it, and being less to 2 inches away from the sound mixer, I imagine that would cause an issue.
I've already tested for dust in the lines, disconnecting all the inputs, using another mixer, none of it has made a difference. The only thing that DOES make a difference, is whether the dimmer is off/on, and where the sliders are at at the time.
Post by: Tony "T" Tissot on April 21, 2010, 06:33:19 PM
Power for lighting is usually not run through the control room.
Dimmers are usually closer to the fixture - i.e on-stage or in the wings.
Only small control voltage is usually feed to the control room, whether DMX or older analog control signals.
Many consumer-grade (home) dimmers will interfere with audio (you can search for information on how commercial-grade dimmers use chokes to mitigate RF, and various other schemes to reduce noise).
For about $300 you can buy a basic setup of 2 portable 4-circuit dimmer packs, and a 16 channel DMX control board (also works as a 2X8 (2-scene preset)). Just add DMX cable. Granted - not the greatest setup for flexibility or quality of dimmers in the world, but guaranteed to be better than what you have. It will probably cure your noise issues.
Post by: Jon Evans on April 21, 2010, 09:41:03 PM
I suggest trying to find the money to upgrade to a "real" light system like Tony suggested, but to integrate that with your existing lights would require some planning.
If the lighting system upgrade is something that you can take on the planning for, how about looking for model numbers / taking photos of your lighting fixtures so that we can recommend DMX hardware to get you started?
Also, you might want to see if you can find an electrician in your community who would donate an hour of his/her time to check out your existing dimming system. Bonus points if the electrician has ever heard of DMX or worked with stage lighting before.
Post by: Leo House on April 22, 2010, 01:09:23 AM
| Quote: |
Dimmers are usually closer to the fixture - i.e on-stage or in the wings. |
The light fixtures are actually pretty much right above me up there, maybe 7 to 9 feet up. They beam down to the stage.
Yeah, I'd much rather get a real light system going. $300 might be a bit much to layout for the theater right now, especially with everything else that needs to be fixed. The theater building is VERY VERY old, close to 100yo. We recently laid out quite a bit on the roof, before hand it leaked so bad, even leaking on stage. If we get one of those grants we're trying to get for it, that'll defiantly be one of the things I'll push for.
Unfortunately, its not something I can plan, cuz I have NO CLUE what needs to be done, or what we need for as that goes. I've only been running a sound board for alittle over a year, with no actual official training. I don't know anything about setting up lights, or working with electric stuff like that.
Funny that you mention finding an electrician, the president of the theater counsel is actually an electrician, and probably the one who set up that dimmer system to begin with.
There is a guy that might know more about setting something up, I'll have to talk to him more in-depth.
Is there nothing else that can be done in the meantime, as a temp fix? Like that tape or whatever? The box is metal, could I some how attach a grounding cable on it and make a faraday cage? If so, how would I go about attaching the cable to ground, cuz I dunno how to do it.
EDIT: Would it possibly help if I took better pics, or had video of the entire setup, and the lights and everything?
Post by: James Feenstra on April 22, 2010, 01:33:33 AM
my immediate thought would be to move the lighting dimmers (including cabling leading into them) away from the audio desk if possible (even a few feet would help), as this will probably help to cut down radiated EMI
won't solve the problem, but might make it tolerable enough until a better solution can be put in place
Post by: Gerry Seymour on April 22, 2010, 11:38:29 AM
| James Feenstra wrote on Thu, 22 April 2010 00:33 |
based on the wall dimmer type lighting control you have, i'd be inclined to say there would be very little you could do in regards to fixing EMI from it, as large amounts of current is passing at a variable voltage directly beside your audio console my immediate thought would be to move the lighting dimmers (including cabling leading into them) away from the audio desk if possible (even a few feet would help), as this will probably help to cut down radiated EMI won't solve the problem, but might make it tolerable enough until a better solution can be put in place |
+1
You've already stated that just a few feet away with the camera makes a big difference. I'd look at putting these two consoles as far apart as possible. I know that makes it tough to run both, but you should probably have someone else running sound, anyway. You don't want to miss a cue on one because you're dealing with a problem that pops up on the other system (I did lighting design in a similar situation for 3 years).
As for planning, the folks on here can help you with that. We just need more info. Take pictures of everything. Get pics from far enough away that we can see how it's set up, then close enough that we can see details of what we're looking at.
Don't sweat the $300 too much at this point. Let's figure out what you need, then we can talk about how to find that funding. Trust me, it can be had, if you have the will to pursue it. In the end, you'll have better capabilities than the current equipment, and will have learned something real about lighting.
Post by: Leo House on April 22, 2010, 06:35:39 PM
Jokes aside, I'm a sound guy at heart, so doing the lights it just something I'm stuck with as it where. I only do it, cuz there are so few volunteers, and the placement of it, doesn't allow room for another person to get over there right. (They just get in my way when I'm doing sound) Currently, all we do is dim for slow songs, or brighten or more upbeat songs. (All we really do here is live music performances, search on youtube for Dixie Theater New Madrid, or Anna Catherine Dehart to see what is done here)
I have some video here, that we took to send to home makeover and/or any other place that can help get this place fixed up!
(If you can't see it right away, its still processing, should be done soon)
Also, the good news is, is there is only 1 more major show I really have to worry about for this season. Got two more fundraiser things, but other then that, we're pretty much done till august, so maybe we can get some stuff done in the mean time!
Post by: Dan Mills on April 25, 2010, 11:29:02 AM
| Quote: |
EDIT: I should also mention, as for as I can tell, there is no connection between the dimmer box's power, and the mixers power. The mixer is plugged into a regular wall outlet, as well as all the other equipment, but the Dimmer box is connected to more high voltage sources. There are lines, in blue tubeing, that run to it, and from it to another ox behind me(which also seems to emit a strong electrical field) and powers and controls 8-10 high powered stage lights. I'm still confused on how its setup exactly, but it appears that there is an awful lot of power running through that dimmer box. |
If it is anything like a standard theatrical setup of say 15+ years ago, then the control box just handles small signals (say 10 or 15V max) and will not radiate much interference, it is the main dimmer rack that handles the power (the box behind you that probably buzzes when you move the controls).
You do seem to have some additional (possibly mains voltage controls beside the desk, which is a whole other can of worms).
Now dimmers work by chopping the mains and it is this action that generates the interference, getting audio cabling away from lighting cables (especially dimmer output cables) will help, as will common mode chokes on the audio lines.
Most of the interference will be being radiated by the cables between the dimmer and the lamps, with (probably) some getting back into the mains supply, so screening the dimmer itself will probably not help much.
To give you some idea of the energy involved, a standard theatrical lantern starts at 500W and 1KW is probably more common, so you could easily have 10+ KW running through that box (and being switched on and off 120 times a second).
FWIW, sound system buzz from dimmers is usually a symptom of a problem with the AUDIO wiring, not the lighting wiring (But this may or may not be true given your somewhat strange setup).
It might be worth asking the chief at another local theatre if they would take a look, most will do it for a beer, and they will typically be able to offer good advice (and may even know of some old theatrical dimmers in a junk room somewhere).
HTH.
Regards, Dan.
Post by: Leo House on April 25, 2010, 04:26:17 PM
Have to see if he is able to install aswell, or how that would work.
I'm not exactly sure what that other box this is behind me, but it doesn't have any controls that are accesable, its looks kinda like a small beaker box. (Its that thing on the wall in the beginning of the vid I posted)
I know there is quite a bit coming from both boxes actually, cuz the noise appears in audio recordings aswell, whenever its present in the speakers. Possibly the EMI is effecting the actual board, and not the audio snake, or even both. The board itself is atleast 10 years old, maybe older so I dunno.
Not sure what you mean here tho.
| Quote: |
You do seem to have some additional (possibly mains voltage controls beside the desk, which is a whole other can of worms). |
Post by: Erick Swihart on April 26, 2010, 04:43:34 PM
Those fixtures are likely going to require something a little beefier than the 300 dollar portable dimmer packs that have been suggested here. Check around for used dimming. You can get old analog packs really cheap and if you have a qualified electrician in the theatre getting them setup with dmx converters might be a cheap option. A theater I worked at with similar money issues picked up 24x2.4k channels of old NSI dimmers with the Dove DMX converter and a bunch of spare triacs for $350. Though the dimmers are old and some of triacs needed to be replaced, they work great for the venue until they get the grants needed to get everything fixed up properly.
Does the noise go away when the dimmers are turned all the way up effectively running the lights at full power? If that is the case, maybe you can come up with a way to switch/diffuse the light on a couple of fixtures and only run them when you need less light.
Also, not sure where you are located but there are a few chains of large supermarkets that are actively replacing fixtures used to light produce with newer energy efficient lighting. Our theatre managed to get 36 Altman elipsoidals and a bunch of lamps donated. Worth looking into.
Just a couple thoughts.
Post by: Leo House on April 26, 2010, 07:08:14 PM
| Quote: |
You mentioned earlier that the noise will come through channels with nothing in them. Have you tried unplugging the snake entirely and recording something through the board checking for the noise. It may be as simple as moving the snake when you have time. |
No, I haven't tired that, prolly should tho.(Its somewhat difficult to go down anytime to record, not that I don't have access to the theater, but the fact that I have to use my sisters laptop since I don't have one of my own HAHA) I'll have to get her to let me use it sometime during the week to try that.
Moving it would be difficult, cuz the snake is run through the walls. Lord knows how old it is, and probably DOES need to be replaced, but it'd take more then me to be able to get it all out and rewired to the stage HAHA.
| Quote: |
Those fixtures are likely going to require something a little beefier than the 300 dollar portable dimmer packs that have been suggested here. Check around for used dimming. You can get old analog packs really cheap and if you have a qualified electrician in the theatre getting them setup with dmx converters might be a cheap option. A theater I worked at with similar money issues picked up 24x2.4k channels of old NSI dimmers with the Dove DMX converter and a bunch of spare triacs for $350. Though the dimmers are old and some of triacs needed to be replaced, they work great for the venue until they get the grants needed to get everything fixed up properly. |
Yeah. Ideally, I wouldn't mind getting new light fixtures aswell, something that takes less power, but same amount of light, aswell as give us color options and stuff! We have a new light setup at church in the fellowship hall, and its all LEDs, we can change colors, and probably do all kinds of other stuff that isn't setup at the moment. I'd love something like that, but it'd probably have to be somewhat bigger lights to beam down to the stage that far.
| Quote: |
Does the noise go away when the dimmers are turned all the way up effectively running the lights at full power? If that is the case, maybe you can come up with a way to switch/diffuse the light on a couple of fixtures and only run them when you need less light. |
For the most part yes. To get the noise really bad, the gain has to be cranked up pretty far, and the noise it increased when the lights are mid range, but lessen when they are full, or almost off. For the most part, it would not be too much of an issue, but a couple of the kids, need those mics REALLY hot to be able to hear them.(No matter how much coaching they get to sing out.)
On a different note, since there is only one more major show this season, is there any way I might be able to shield my camera? Like aluminum foil over the tape compartment or something easy like that? Just something to help keep any EMI away from the tape?
Post by: Duane Massey on April 27, 2010, 12:25:29 AM
Post by: Leo House on April 27, 2010, 01:11:41 AM
Kinda might as well have just told me to replace the coal burning generator with a nuclear reactor, cuz I know bout as much at doing that as what you just told me LOL.
Post by: Jon Evans on April 27, 2010, 01:15:55 AM
If you cannot find an electrician to figure out exactly how your system works and therefore what the best part to replace would be, you need to figure out how to move your sound and video to a better location.
I would start by setting up the camera in a different part of the house, and on a different circuit than the lighting.
If possible, figure out how to move your mixer and gear for the show. If the lighting dimmer switches can't be moved, you can buy/rent/borrow/find some XLR extension cables and move your whole rig away from the snake position (assuming you have no snake leeway since the snake is built into the wall).
Basically, what everyone is trying to tell you is that if you can't replace the sketchy light setup, there is NO WAY to get rid of that hum that doesn't involve moving the sound gear away from the lighting gear (physically and electrically).
Post by: Leo House on April 27, 2010, 02:56:31 AM
I do know that the lighting, and the audio(and my camera) are on two completely separate breakers already. I can't be sure, but I think the lights have their own breaker. I was hoping maybe some foil, or shield plats could be used to help block EMI from the tape alittle bit. I moved it over there, so I could control it and zoom in/out during performances. Its my personal cam, and I am an amateur filmmaker on the side, so I'm nervous about letting just anyone use it LOL.
I doubt its feasible to do anything for this show them, but I'm defiantly going to work on some things in the off season to try to get it better. I'll talk to that guy, he knows some people that might be able to get us some newer used equipment pretty cheap. We also are trying to start a 4H group, so fixing things up upstairs might be a good project. Right next to the table on the floor, is a drop off, where the heating/air blowers are, that's why we can't just set up tables anywhere.
I guess its not a huge deal right now, its been setup like this for a very long time, but I was just hoping there was some type of cheap fix that could help in the mean time.
Post by: Duane Massey on April 27, 2010, 11:21:50 AM
There is no low$$ easy solution that will not require at least some electrical skills. At the very least the audio and lighting gear need to be physically separated as far as possible. Even that would not probably solve the problem completely, but it might make the problem more workable.
Post by: Leo House on April 27, 2010, 03:41:08 PM
Its probably going to have to come down, to simply finding someone other then myself, that knows what they are doing here, and will be able to install/wire, or do whatever to hook up a new system.
On a different note, would anyone here know, if I have something that has bed, black and ground wires, and something that has blue, white and ground wires, and I had to connect them. What color would go to what? Obviously ground to ground, but I'm not familiar with the blue and white wire color scheme. Its for one of the stage XLR inputs. The new XLR jack for the stage has blue and white, but the "snake" I guess, is red and black wiring.
Post by: Tony "T" Tissot on April 27, 2010, 04:38:14 PM
| Leo House wrote on Tue, 27 April 2010 12:41 |
I know, I didn't mean to reply harshly. Its just my utter lack of knowledge in this area, I really wouldn't know where to even begin on doing that much I'm afraid. Its probably going to have to come down, to simply finding someone other then myself, that knows what they are doing here, and will be able to install/wire, or do whatever to hook up a new system. On a different note, would anyone here know, if I have something that has bed, black and ground wires, and something that has blue, white and ground wires, and I had to connect them. What color would go to what? Obviously ground to ground, but I'm not familiar with the blue and white wire color scheme. Its for one of the stage XLR inputs. The new XLR jack for the stage has blue and white, but the "snake" I guess, is red and black wiring. |
Color is "untrustworthy" if you don't know the provenience of the cables. You need to know how someone before you wired them.
I NEVER trust any installed cable, unless it's a venue I know - or the gear is of a certain professional, "branded" standard. I always check with a cable tester for an installed snake (just string an XLR cable to the booth and have someone plug subsequent channels as you go. Takes only 5 to 10 minutes.) If you have a raw, un-terminated end to deal with, do a visual inspection of the far-end to see which pins are which. Then test.
It's a simple as pin 1 to 1, pin 2 to 2, 3 to 3.
Post by: Leo House on April 27, 2010, 05:03:05 PM
Maybe it'll help you guys, tell me what I need to do HAHA
http://img227.imageshack.us/img227/5404/stage.pngThe under the stage pic, the little brown dots, represent holes in the wood, about an inch thick that go to the actual XLR jack, so I can't see where each cable is connected at. The wires are alittle neater then what I was able to show with my poor artist skills.
The 6th jack, the wires are completely removed from the old jack, so I also can not see where each one was on that either. (Mostly my fault, I tried to remove the broken one, not knowing there wasn't enough wire to come out without pulling them off.)
The new jack, has about 8" of cable already attached, but as I mentioned, the colors are different. The ends need to be striped on both, and twisted together I guess, but I don't know how to tell which is positive and which is negative. (Ground on both is silver, so that's easy.
Post by: Tony "T" Tissot on April 27, 2010, 05:16:22 PM
How is it terminated on the other end?
All you need to do is preserve pin 1 to 1, 2 to 2, 3 to 3.
Post by: Leo House on April 27, 2010, 07:01:50 PM
How can I preserve pin 1 to 1, 2 to 2, 3 to 3, if I don't know which wires are suppose to go to Pin 1 Pin2 and Pin 3?
Wouldn't it mess something up, if I attach the black wire, to pin 1 for example, but on all the others, red actually connects to Pin 1? I cannot see what pins the red and black wire attach to.
Post by: Duane Massey on April 27, 2010, 07:17:05 PM
Post by: Leo House on April 27, 2010, 07:54:06 PM
Post by: Tony "T" Tissot on April 27, 2010, 08:31:58 PM
Hopefully it will be the same wires -- but you never know.
Post by: Leo House on April 27, 2010, 08:44:54 PM
I don't think there is, but if there is, it would be either somewhere in the wall, or under/around the stage somewhere, I'll have to check it tomorrow when I'm going to be in town.