Audio

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Jim W in Tampa

Senior Member
Location
Tampa Florida
Do we have any audio exsperts here? I need help in trying to cancell sound in the unwanted areas in night club.Thinking there is a way similar to headphones.Basically want it loud only on dance floor
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
I don't understand what you're saying. :confused:

What I'm thinking about (and you've probably already thought about) is a ring of speakers around the dance floor, mounted on soffits to direct the sound in, leaving the surrounding area quieter. If there's more than one room, then all the better.

I think accoustics are more effective than technology. Placement of speakers is often 9/10's the battle when optimizing these sorts of things. Of course, my experience isn't on that scale, but the priniciple should carry over.
 

Smart $

Esteemed Member
Location
Ohio
Jim W in Tampa said:
Not suggesting head phones but simply the method.I have been trying to do this with polarity to some degree it works
When you compare to headphones, do you mean noise-cancelling technology?

I believe noise-cancelling technology samples external sounds penetraing the "ear cup", then adds the sample to the electrical impulses for the internal speakers in reverse polarity... thereby cancelling those external sounds that otherwise wouold reach the eardrum.

How does the sound get to the areas you want to be at a lower volume? ...directly from the same drivers as the dance floor, or separate drivers? If separate drivers, are they connected to the same amp(s), or discreet amp(s)?

Need more info...
 

Jim W in Tampa

Senior Member
Location
Tampa Florida
6 speakers are now grouped together (1,000 watts peak) and aimed at dance floor aprox 12 x 16.Dancers want it loud but tables near it want it bit lower.Trying to keep it aimed at floor.
 

Smart $

Esteemed Member
Location
Ohio
Jim W in Tampa said:
6 speakers are now grouped together (1,000 watts peak) and aimed at dance floor aprox 12 x 16.Dancers want it loud but tables near it want it bit lower.Trying to keep it aimed at floor.
1,000 watts peak isn't all that much in my book :wink: I have 1750 Wrms in my compact-size car :grin:

Are you running 6 full-range cabinets, or a bi-amp/tri-amp system? There's not a whole lot you can do other than focus the sound to the dance floor. I'm assuming you have the 6 speakers at one end. Is it possible to position them around and pointing at the center of the dance floor?

Usually the objectionable sounds are in the mid to mid-hiigh range of the sound spectrum (i.e. the vocal frequency bands). These spectral bands are acoustically attenuated off the backside of cabinets, whereas the lows (100Hz and down) tend to be nearly 360?. People can carry on a conversation with mids and highs attenuated.
 

cadpoint

Senior Member
Location
Durham, NC
Just a thought

Just a thought

Is there a wall that goes from floor to ceiling that even creates a separation ? If you don't have this, I believe it'd be next impossible to very expensive to hold down the dB's.

There's also a Perma Base Brand Cement board www.permabase.com that you might run up one side to the ceiling, and with sound batten insulation might be the ticket.
This is installed in the bath rooms of present jobs and its basically cement with small white foam particles, and not cheap.

At present job I'm on http://google.oit.duke.edu/search?q=construction&site=duke_collection&client=fuqua&proxystylesheet=fuqua&output=xml_no_dtd the "team rooms" to be assigned to the people studying for there master degree have double sheet rock and sound dampen insulation between each room. All rooms have the rock to ceiling and sealed around anything that penetrates any part of the room. Ducts through all walls are backed filled with the same insulation and flashed. In all cases rock wool if pipe or conduit and chalk around all that aren't flashed. I believe they got there required result, I want to say it echo's but it sounds hollow when one is in one of these rooms...

Do you have any GC's that you could tap there brain ? You could get a quick over-view of this type of construction on some of the other forums like http://www.contractortalk.com/, or the like, hope that helps.

The student addition of AIA Architecture Standards is also a very good purchase and tons of technical illustrations of how and why things are put together.

Enjoy

edit for phonics ...
 
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Jim W in Tampa

Senior Member
Location
Tampa Florida
Smart $ said:
1,000 watts peak isn't all that much in my book :wink: I have 1750 Wrms in my compact-size car :grin:

Are you running 6 full-range cabinets, or a bi-amp/tri-amp system? There's not a whole lot you can do other than focus the sound to the dance floor. I'm assuming you have the 6 speakers at one end. Is it possible to position them around and pointing at the center of the dance floor?

Usually the objectionable sounds are in the mid to mid-hiigh range of the sound spectrum (i.e. the vocal frequency bands). These spectral bands are acoustically attenuated off the backside of cabinets, whereas the lows (100Hz and down) tend to be nearly 360?. People can carry on a conversation with mids and highs attenuated.


They are 6 full range,about 25 feet from DJ booth.Walls are 12 inches thick and well insulated to keep neighbors happy.No way i can have walls between tables and dance floor as they want to see the girls at the pole.Most likely we will just try to keep level reasonable.Strange thing about people is they like it loud after a few too many.Might try a small wall on each side to help direct.Thanks for the help.Also might add a few in ceiling directly above floor.This is not a huge club,we max out at about 80 people.
 

mdshunk

Senior Member
Location
Right here.
True active noise cancelling is done by sampling the "noise" and repeating that waveform 180 degrees out of phase. In the case of the nightclub, that sounds like the impossible task. Sound resistant construction methods would be the route you'd want to take.
 

brantmacga

Señor Member
Location
Georgia
Occupation
Former Child
i'd say search your local yellow pages and get an audio expert in there. the only way to do it is w/ diffusers and bass traps properly located around the dance floor. may take some trial and error, but a pro audio tech will probably have the software that can determine where the problem areas are and where to locate the diffusers and traps.
 

RayS

Senior Member
Location
Cincinnati
Jim, there are products using active noise cancellation for HVAC units that have a mic in the plenum and a ring of speakers to cancel some of the air noise, but I don't know of anything for a whole room.
http://www.aes.org/e-lib/browse.cfm?elib=6757

Only other suggestion I have is a plexiglass barrier at the ceiling behind the speakers, like a drum booth.

Also they may want to look at absorbing sound at the quiet areas, (general level reduction) and at the back wall the speakers reflect off (reverberant control). Make sure that any acoustical materials have the right fire rating tho. Control
 

Jim W in Tampa

Senior Member
Location
Tampa Florida
RayS said:
Jim, there are products using active noise cancellation for HVAC units that have a mic in the plenum and a ring of speakers to cancel some of the air noise, but I don't know of anything for a whole room.
http://www.aes.org/e-lib/browse.cfm?elib=6757

Only other suggestion I have is a plexiglass barrier at the ceiling behind the speakers, like a drum booth.

Also they may want to look at absorbing sound at the quiet areas, (general level reduction) and at the back wall the speakers reflect off (reverberant control). Make sure that any acoustical materials have the right fire rating tho. Control

Speakers are on outside wall now.I am going to try a 2' side wall on each side and a few in ceiling.Beyond that not much i can change.Perhaps will toy with reversing polarity from one set.I do have 2 channels.Thanks for all the ideas.If i find a cure i will post it.
 

mxslick

Senior Member
Location
SE Idaho
In theory,...but...

In theory,...but...

Jim W in Tampa said:
Speakers are on outside wall now.I am going to try a 2' side wall on each side and a few in ceiling.Beyond that not much i can change.Perhaps will toy with reversing polarity from one set.I do have 2 channels.Thanks for all the ideas.If i find a cure i will post it.


Reversing the polarity (or "phase") of one set of speakers on the dance floor will create very unsatisfactory sound on the dance floor, you will lose a lot of bass in particular. (Not something you want to lose in a dance establishment.)

So far one of the best ideas I've seen in this thread for "active" cancellation would be the ceiling speakers, placed above the dining tables spaced for slightly overlapping coverage.

Forget trying to cancel the bass (anything below say 100Hz or so) and focus on the midrange to high freqs. (250-15,000hz.) Use the following, fed from both channels of the DJ's mixer:

  • stereo eq unit, 1/3 octave;
  • audio delay processor, two channel;
  • stereo amplifier of at least 350w RMS per channel.

Wire the ceiling speakers to the amp, observing proper series/parallel wiring to present no less than 4 ohms per channel, then connect each GROUP of speakers to the amp with the polarity reversed.

By playing with the eq, put full cut in all bands below 250hz; then adjust the others by ear to get the most cancellation effect at the tables.

Set the audio delays by ear, start with 3ms and go up (or possibly down) from there, again getting best cancellation.

This is a crude but fairly effective way to get the effect you desire without killing the sound quality on the dance floor.

PM me and I will get some info to you on specific equipment and a sample speaker hookup diagram.
 

Jim W in Tampa

Senior Member
Location
Tampa Florida
mxslick said:
Reversing the polarity (or "phase") of one set of speakers on the dance floor will create very unsatisfactory sound on the dance floor, you will lose a lot of bass in particular. (Not something you want to lose in a dance establishment.)

So far one of the best ideas I've seen in this thread for "active" cancellation would be the ceiling speakers, placed above the dining tables spaced for slightly overlapping coverage.

Forget trying to cancel the bass (anything below say 100Hz or so) and focus on the midrange to high freqs. (250-15,000hz.) Use the following, fed from both channels of the DJ's mixer:

  • stereo eq unit, 1/3 octave;
  • audio delay processor, two channel;
  • stereo amplifier of at least 350w RMS per channel.

Wire the ceiling speakers to the amp, observing proper series/parallel wiring to present no less than 4 ohms per channel, then connect each GROUP of speakers to the amp with the polarity reversed.

By playing with the eq, put full cut in all bands below 250hz; then adjust the others by ear to get the most cancellation effect at the tables.

Set the audio delays by ear, start with 3ms and go up (or possibly down) from there, again getting best cancellation.

This is a crude but fairly effective way to get the effect you desire without killing the sound quality on the dance floor.

PM me and I will get some info to you on specific equipment and a sample speaker hookup diagram.

I will toy with this ceiling speaker next weekend.I think that has a chance.Only 2 tables actually fall into the too loud area.I assumed it would waste some watts but thats fine
 
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blue spark

Senior Member
Location
MN
Brant, Smart, and MX are all on the right track and between the three you could nail this problem. Spendy though. Short of building my own studio I haven't had alot of experience with acoustics. There is software out there but most is designed for eliminating problem spots in the listening field. If most of the problem is in the mid to upper frequencies, I would think that some diffusion panels above the dance floor would take care of some of the problem. Let us know what you come up with. Pics please:wink:
 
Baffolding

Baffolding

Canceling sound,redirecting,absorbtion.
Canceling sound by transmitting the same frequencies that are 180 degrees of the sent signal.
Redirecting using insulated baffolding to channel the sound to arrive later in those area's example inside a speaker encloser.
Absorbtion by sound damping material in ceiling, and or walls and doors. Yamaha has a good sound book on the market. hope this helps.
 
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