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Old 5th May 2010, 04:50 AM   #11
gedlee is offline gedlee  United States
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Quote:
Originally Posted by Dogue View Post
I'd like an omni-directional speaker for use in live performance (primarily keyboards and electronics).

What advice do you have? Thanks a lot.
Don't ever use an omni in a live venue! Many live venues tend to be reverberant and an omni will agravate this situation immensely.

Unless you are trying to hide your playing in the reverberation.
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Old 5th May 2010, 04:57 AM   #12
Dogue is offline Dogue  United States
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Originally Posted by gedlee View Post
Don't ever use an omni in a live venue! Many live venues tend to be reverberant and an omni will agravate this situation immensely.

Unless you are trying to hide your playing in the reverberation.
Well, as a lot of playing I do is electro-acoustic free improvisation, a good venue will be a decent sounding room, and my point in doing this is to engage the acoustics of the room as an acoustic instrument wood.
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Old 5th May 2010, 04:57 AM   #13
ScottG is offline ScottG  United States
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Considering that the "average" of fundamentals only extends to just below 5 kHz..

Perhaps a Visaton B200 inverted and used as as a "walsh" driver in a 1.5 to 2 cubic foot aperiodic vented cabinet? (..and it could be made from cardboard "pipe".) EDIT: actually I think a custom "flight" case (with ABS panels) would be pretty nice.. top that removes to reveal the B200, ect.. (about a 9 inch square opening that's about 33 inches in length including the 4 inch removable top - with "wheels" and a collapsable luggage handle.)

If you want to go really loud (and lower in freq.) then use a subwoofer with a high-pass filter for the B200. (..which is also more portable.)
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Last edited by ScottG; 5th May 2010 at 05:21 AM.
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Old 5th May 2010, 05:04 AM   #14
Dogue is offline Dogue  United States
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Quote:
Originally Posted by gooki View Post
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.



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)
Ideally roughly as loud, though not quite as loud wouldn't be terrible -- I generally never go above 8 on the volume.

Quote:
How heavy? (already answered - 9kg)
Some leeway here, but, yes, around that weight or less would be ideal.

Quote:
How low do they have to go? (a specific hz would be nice)
60Hz, I'd say.

Quote:
How large can the be?
Ideal would be maybe 8" x 8" x 30" or smaller. I'm going to be carrying this on the subway with keyboards, laptop, and other sensors.

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How much are you willing to spend?
$350? Though again, the less the better. :-)

I know these put some constraints on what I'm able to do, but I appreciate any help or suggestions. Thanks.
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Old 5th May 2010, 05:05 PM   #15
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.
Quote:
Originally Posted by Dogue View Post
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).
OK, this is roughly what was done in the 3" Tang Band design above, correct? Since the Fs of that driver is 105Hz, the quarter wavelength is about 32", just longer than the 30" long pipe used.

Anyways, I could imagine a similar design with a larger driver working for my application, as the PVC is lightweight. I could live with a relatively tall speaker as long as it were not too heavy.

However, assuming I were to pursue a similar design, the main issue seems to be the power rating of the drivers. The Eminence Alphas that are in my current keyboard amp seem to be rated at 125W RMS / 250W music, whereas even the Fostex FE206Ens are only 30W / 90W music. Suggestions?

Last edited by Dogue; 5th May 2010 at 05:09 PM.
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Old 5th May 2010, 05:29 PM   #16
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Quote:
Originally Posted by Dogue View Post
Here are some design goals:
-Omni-directional so it excites the room in ways similar to acoustic instrument
There are a number of acoustic instruments which are not omni-directional.
For example all wind instruments are directional, a grand piano is only omni- directional if the lid is closed, drums (other than bass drums ie kick-, kettle-drums and floor toms may be) are directional, string instruments have sound holes from which the bulk of sound emanates added to that the player masks a lot of the other, spurious output etc.
In fact I have problems thinking of an instrument which actually is omni directional, well a triangle might be and the largest organ pipes due to their fundamental frequency.
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Old 5th May 2010, 05:57 PM   #17
Dogue is offline Dogue  United States
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Quote:
Originally Posted by Charles Darwin View Post
There are a number of acoustic instruments which are not omni-directional.
For example all wind instruments are directional, a grand piano is only omni- directional if the lid is closed, drums (other than bass drums ie kick-, kettle-drums and floor toms may be) are directional, string instruments have sound holes from which the bulk of sound emanates added to that the player masks a lot of the other, spurious output etc.
In fact I have problems thinking of an instrument which actually is omni directional, well a triangle might be and the largest organ pipes due to their fundamental frequency.
While it is true that many instruments are not omni-directional, many are multi-directional, or at the least not uni-directional.

The import of this perhaps becomes most obvious when integrating electric instruments (electric guitar) with acoustic instruments in an acoustic setting. Immediately the sound becomes an issue -- if the guitar amp is not positioned well, half the band won't hear the guitar; the easy thing to do is then to turn the amp up, which then, depending upon where one is listening, destroys the acoustic balance of the group.

Similarly with a keyboard as opposed to a piano. When playing the piano, the sound that I hear is fairly close to what the rest of the band hears. Whereas oftentimes when playing keyboard, I think I'm very loud when other musicians find it hard to hear me.

So again, while pure omni-directionality may not be the ultimate goal, a move a way from severe directionality is desired.
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Old 5th May 2010, 10:03 PM   #18
Dogue is offline Dogue  United States
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Quote:
Originally Posted by ScottG View Post
Considering that the "average" of fundamentals only extends to just below 5 kHz..

Perhaps a Visaton B200 inverted and used as as a "walsh" driver in a 1.5 to 2 cubic foot aperiodic vented cabinet? (..and it could be made from cardboard "pipe".) EDIT: actually I think a custom "flight" case (with ABS panels) would be pretty nice.. top that removes to reveal the B200, ect.. (about a 9 inch square opening that's about 33 inches in length including the 4 inch removable top - with "wheels" and a collapsable luggage handle.)
In this design would it be advisable to have a tweeter to make up for the loss of highs by placing the B200 off axis?

And, relating to my earlier question, would the B200 be able to handle power from an instrument amp?
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Old 5th May 2010, 10:11 PM   #19
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.
Obviously I've been thinking a lot more about this.

If I could use a slightly smaller / lighter speaker, this might make sense. The Ciares seem to be able to handle higher watts than many other full ranges I've been coming across. The Ciare CH 250 looks promising.

1) Are there sources for Ciare in the US? I haven't been able to find many.

2) If not, are there suitable alternatives? High efficiency, wide frequency response, large power handling, not ridiculously heavy or expensive. The closest I've found is this: Beyma Speakers - Beyma 12GA50 fullrange speaker - Beyma 12GA50 500 watt 12" fullrange speaker for lead or bass guitar, organ and loudspeaker applications. Beyma 12GA50 fullrange speakers here.

3) Assuming I locate an appropriate full-range, to be pointed up with a diffuser above, what would be the simplest way to construct a suitable enclosure? At all advisable to use PVC or sonotube?

Thanks!
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Old 5th May 2010, 10:17 PM   #20
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The beyma 8AG/N and 10AG/N could also be good candidates. (I.e; there are more high Fs/strong motor speakers out there ). Try some PA sellers.
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