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Old 4th May 2010, 03:25 PM   #1
Dogue is offline Dogue  United States
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Default Omni-directional for live performance

I'd like an omni-directional speaker for use in live performance (primarily keyboards and electronics).

Here are some design goals:

-Capable of handling signals from keyboard/laptop
-Omni-directional so it excites the room in ways similar to acoustic instrument
-Integrated digital amplifier (perhaps from 41hz.com kit or similar)
-Simple design
-Loud enough for live use
-As small and lightweight as possible

I have not built speakers before, though I have built various guitar effects pedals and the like and can read schematics and solder. I am a musician, but I have not found anything quite like what I want, so I'd like to build something.

What advice do you have? Thanks a lot.
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Old 4th May 2010, 04:01 PM   #2
MaVo is offline MaVo  Germany
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Tendencially difficult, i guess, since for omnidirectional behaviour you need small drivers without waveguides or horns and for live performance (higher spl) you need big drivers with waveguides or horns.

For a hifi omni design, check siegfried linkwitz homepage... i think its called pluto.
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Old 4th May 2010, 04:03 PM   #3
Glowbug is offline Glowbug  United States
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If it's truly omnidirectional, I see tons of feedback issues down the road if you have any microphones
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Last edited by Glowbug; 4th May 2010 at 04:06 PM.
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Old 4th May 2010, 04:46 PM   #4
Dogue is offline Dogue  United States
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Quote:
Originally Posted by Glowbug View Post
If it's truly omnidirectional, I see tons of feedback issues down the road if you have any microphones
Yes, I had thought of that...I don't currently have plans to use microphones. Perhaps occasionally electro-magnetic pickups, but probably not air microphones.

Some people use these hemispheres:

Electrotap - Hemisphere

But it seems like there could be a more elegant solution.
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Old 4th May 2010, 05:06 PM   #5
Flaesh is offline Flaesh  Russian Federation
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http://www.cd-konzert.de/Produkte/EBLdia.shtml - pro speaker & driver inside

cheap and simple - 12" pro fullrange, direct it up and try different reflectors (conical etc)))
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Last edited by Flaesh; 4th May 2010 at 05:13 PM.
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Old 4th May 2010, 06:30 PM   #6
Flaesh is offline Flaesh  Russian Federation
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Surround speakers: mono/di/bi/tripolar?
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Old 4th May 2010, 08:38 PM   #7
Dogue is offline Dogue  United States
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Thanks for the ideas. For simplicity, one full-range would probably be easiest. For example,

Small speaker based on TB 3" bamboo

Though I'd probably want a more efficient speaker and one with better bass response.

My current keyboard amp has these specs:

Power Amplifier – 50-watts RMS/channel, (100-watt RMS total)
Speakers – Two 8” Eminence Alpha, 125-watt, 8 ohms
Horns – Two 80-watt 3.5X3.5 Ferro cooled dynamic
Frequency Responses – 70-17 kHz
Crossover – 3 kHz

Ignoring stereo for the moment, what would one suggest for components?

Would it be possible (or advisable) to build something like the PVC design above though with a larger, more efficient speaker?
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Old 4th May 2010, 08:38 PM   #8
el`Ol is offline el`Ol  Germany
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Suggestion:
Take a really large fullrange driver with high Fs and a very strong motor (e.g. Ciare CH321) and pack it in an ML-pipe with length ^= quarter wavelength of the driver's Fs (130 cm for the Ciare).
A diffusor cone on top, of course.
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Old 4th May 2010, 08:51 PM   #9
Dogue is offline Dogue  United States
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Quote:
Originally Posted by el`Ol View Post
Suggestion:
Take a really large fullrange driver with high Fs and a very strong motor (e.g. Ciare CH321) and pack it in an ML-pipe with length ^= quarter wavelength of the driver's Fs (130 cm for the Ciare).
A diffusor cone on top, of course.
Thanks for the suggestion. While that may sound quite nice, I worry that it would be larger and heavier than what I need (I'm going to be carrying this around in addition to keyboard, laptop, etc.). Ideally the speaker would be around 20 lbs. (9 kg) or less and fairly small. Is this a pipe dream? (Pardon the pun).
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Old 5th May 2010, 03:43 AM   #10
gooki is offline gooki  New Zealand
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Quote:
Thanks for the ideas. For simplicity, one full-range would probably be easiest. For example,

Small speaker based on TB 3" bamboo

Though I'd probably want a more efficient speaker and one with better bass response.
The problem with wanting better bass means you'll need a bigger driver, and a bigger driver will no longer be omni directional at high frequencies without a diffuser.

Quote:
Ideally the speaker would be around 20 lbs. (9 kg) or less and fairly small. Is this a pipe dream?
All depends on what compromises you are willing to accept. Try an answer these questions.

How loud do they need to be? (compared to your keyboards current speakers)
How heavy? (already answered - 9kg)
How low do they have to go? (a specific hz would be nice)
How large can the be?
How much are you willing to spend?

Last edited by gooki; 5th May 2010 at 03:47 AM.
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