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Old 31st December 2004, 08:16 AM   #1
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Join Date: Dec 2004
Location: chicago
Default Relay question - advice needed!!

Hello - I am new to this forum and am only somewhat tecnical. I am doing some feasibility research for a permanent sound installation in Chicago. They loved the concept and now want to see costs.
Basically here's the setup: a series of 30-50 speakers that run down a 50' coridor driven by a single sound source. The sound would travel down the speakers much like a lighted marquis. The effect is a moving sound source.
I initially envisioned a distributor with multiple points driven by a variable speed motor, basically making contact to one speaker, then the next, and so on. Not a bad idea I thought, but then it seemed that relays might offer a better solution.
I know nothing about them. I found one source that makes a 32 point (the largest I could find) relay but it's mechanical and I fear DC pops.
Knowing what I'm trying to do (I hope I explained it well enough) can any of you gurus kindly lend a hand and offer some suggestions?
I need to be able to address the relays and I want them to be silent and 'soft' - a slight ramp up and down. They need to be after the amplified signal (very low volume) unless you guys have a reason to do it differently.
Thanks so much and I hope I've come to the right place! Happy New Year, Mike.
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Old 2nd January 2005, 08:16 PM   #2
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What a lovely idea.

It's not easy to adjust levels between amp and speaker. I'd drive each speaker from its own amp and use the contactor or a solid-state counter to soft-switch the amps...

http://tinyurl.com/3wfgf

these are 81p each at 10+ and need only a few cheap passives and 5 to 9 volts to make into 1W amps with voltage-controlled gain, easily controlled with your contactor.

I'd be happy to draw you a circuit (I've used these chips before) if this seems sensible.

What is the sound going to consist of?
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Old 2nd January 2005, 08:57 PM   #3
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Default Re: Relay question - advice needed!!

Quote:
Originally posted by mlapchick
The sound would travel down the speakers much like a lighted marquis. The effect is a moving sound source.
You've got me wondering what the point is.
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Old 6th January 2005, 11:52 AM   #4
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Trying to do this with realys is jus crazyness itll never work or sound good.
you need some serious hardware.

One of the DSP systems would be the place I would look because you are ealy lookin at a gaincontroll & mixing concept.

This is theme park type trickery.

You will probably be best to reduce the number of points to 20 or so &rely on our fuzzy brains.

I thaught media matrix might be able to do the job but I dont know?
Its sounding more like a multitrack playback thing.

Depending on the sound & desired effect what you would do.

If it was just noise or looow fi stuff like a haunted house effect.

you might get by with a chaser type circuit driving some sort VCA ramping up & down maybee even just fets.

Is this a serious job or something to fiddle with???
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Old 8th January 2005, 02:21 AM   #5
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What if you put a digital pot on each speaker to control the volume, the ones that can be daizy chained so you only need one controller. Then you can smoothly ramp up the volume in whatever pattern you want. You could put some cheap low power opamp after each pot for the gain. I think the relays would make popping sounds every time they turn on
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Old 8th January 2005, 08:51 AM   #6
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Quote:
Originally posted by srfranci
What if you put a digital pot on each speaker to control the volume, the ones that can be daizy chained so you only need one controller. Then you can smoothly ramp up the volume in whatever pattern you want. You could put some cheap low power opamp after each pot for the gain.
tda7052a is a vca and amp in one chip, would accomplish all that a lot simpler.

I don't think Mlapchick has been reading any of these replies. Wish he would, I'm really intrigued about what sounds he intends to chase up and down his corridors.
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Old 9th January 2005, 06:08 AM   #7
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Hello all,
For some reason I haven't been able to get on the forum for a number of days and today to find some good feedback. To answer a few questions, this is a serious project for the Chicago Park District. The prototype phase will require dinking a bit. But it is funded at something like $2.5MM from the NSF - about $40k for the sound installation. So it DOES have to be right. We have a prototype phase in March and then phase 2 which will run from June to Sept 05, final install between 1/05 through 6/06 - grand opening.
Basically, the sounds are atmospheric, mimicking (interpreting) different natural processes that occur in photosynthetic process.
The visitors walk down corridors as either air, CO2, water, or sugar. They are 50-60 feet long and all lead to a center. We want to suggest the direction of the flow of the process without sineage and other visual usuals. Traveling sound I think is a wonderful idea and solution that I have never seen done... which of course makes me like it more.
Amplifying each speaker individually seemed not possible. Can you describe what you mean - and what kind of costs would be associated please.
Lowlevel, it does work with relays. I've tried it. It does pop which is one of the reasons I turned to you guys. Talking about gain control and mixing concept doesn't seem to apply to my scenario, so perhaps I wasn't clear on what I was trying to do. Just think of lights in a marquis, and replace the bulbs with speakers and the electricity with white noise, for instance.
Bill, does that answer your question, too? Bremen, your idea intrigues me. Tes, I need to soft switch for sure. I want almost a "cross fade" between speakers. When you all are talking about individually amping the speakers, we're looking at about 720 speakers total in the installation - does that change your opinion?
Thanks all so much for your help - it's a really worthwhile project!

Mike
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Old 9th January 2005, 07:18 AM   #8
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I for one need more details before I could offer any suggestions.

Let's see if I have this clear.

You have 4 corridors leading to a central room. That's 1
corridor each for air, water, sugar and CO2. The corridors are 50-60 feet long and contain 180 speakers each. That's a speaker about every 4 inches. The sound, I'm assuming is travelling down the corridor faster than the visitor(s). How long should it take the sound to travel from one end to the other? After it travels the distance will it repeat immediately?

For the water corridor the sound is flowing, gurgling, bubbling water that seems to be coming from behind the travelling visitor and then disappears in the distance in front of them. Visitors may be bunched or spread out as they see fit.

Exactly what are the 4 sounds? I assume a digital origin and looped every so often? What kind of speakers do you imagine? Do they need bass response
or would 4" full ranges do the job?

There will be four amplifiers.

Is that about it?

Will the person who contributed the used suggestion be compensated out of the budget?
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Old 9th January 2005, 05:06 PM   #9
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Quote:
Originally posted by mlapchick
Bremen, your idea intrigues me. Tes, I need to soft switch for sure. I want almost a "cross fade" between speakers. When you all are talking about individually amping the speakers, we're looking at about 720 speakers total in the installation - does that change your opinion?
Thanks all so much for your help - it's a really worthwhile project!

Mike
If you want a cross-fade you need an amp per speaker. Needn't be expensive if the fi doesn't need to be particularly hi.

Can you give us a clue as to the speakers you envisage using, and the sound level required?
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Old 10th January 2005, 12:42 AM   #10
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Bill: I for one need more details before I could offer any suggestions.

Let's see if I have this clear.

You have 4 corridors leading to a central room. That's 1
corridor each for air, water, sugar and CO2.

Me: Sorry, air and CO2 are one, Sun is #4.

Bill: The corridors are 50-60 feet long and contain 180 speakers each. That's a speaker about every 4 inches.

Me: The corridors are 50-60 ft long, yes, however the speaker spacing is something I still need to work out.. looking for the least amount of stuttering as it travels down the line.

Bill: The sound, I'm assuming is travelling down the corridor faster than the visitor(s). How long should it take the sound to travel from one end to the other? After it travels the distance will it repeat immediately?

Me: I am figuring about 12 mph, perhaps a little slower. We don't want people to feel rushed. And yes, the sound source is constant and the relays (or whatever) will go from the last speaker to the first.

Bill: For the water corridor the sound is flowing, gurgling, bubbling water that seems to be coming from behind the travelling visitor and then disappears in the distance in front of them. Visitors may be bunched or spread out as they see fit.

Me: Exactly

Bill: Exactly what are the 4 sounds? I assume a digital origin and looped every so often? What kind of speakers do you imagine? Do they need bass response or would 4" full ranges do the job?

Me: Full range will have to do. The sound design might change from time to time. The sounds for the first installation have not been designed yet. They will be abstract and supportive - probably not be recognizeable on their own but will make sense in their respective context.

Bill: There will be four amplifiers.

Me: Well, yes. Sort of. One amp per sound source, but to be specific, two of the corridors are bi directional - sugar and air (c02 and Oxygen) so that's six, plus the center area which has four more snakes, each with their own amp. So in all, there are 10-12 independent systems. Each with up to 60 speakers.

Bill: Is that about it?
Me: Yeah, at this point.

Bill: Will the person who contributed the used suggestion be compensated out of the budget?

Me: I'll be shocked if I make a dime off this. I like the "contribute" part But credit will be given, most certainly.

Thanks again for all your help!

Mike
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