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Old 20th September 2007, 05:59 PM   #1
freedom is offline freedom  Denmark
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Default PA Sound system: Phase problems


I need help.

The big question is: How to gain extra power without having phase problems.

The ideal answer to this is simple: Invent a driver that is capable of playing all audible frequencies at 150 dB with at sensitivity of 120 dB and 2 pi coverage at all frequencies. However, Ronnie Rackham has so far failed to invent such a driver (he did try though!)

The next answer (and thats where you guys come in) - is more drivers, each taking care of a specific frequency-area.
Now - if I want to use more drivers for one specifik frequency area, then troubles are at my feet!

In particular I am having troubles with the treble horns.


18" bass bins (Turbosound design)

12" ATC PA75-314 BLCR drivers, 4 pr. side, in a standard reflex cabinet. 2 units pr. cabinet.

1" Beyma CP350/Ti with a horn in front. Currently with a 90 x 40 degrees horn. One driver and horn pr. cabinet, 2 cabinets pr. side.

I am thinking of using a 60 x 40 horn and then put the 2 speakers at an angle of 30 degrees, and by this way try to avoid that they mix up and therefore avoid phase problems. However, i would like more power in this area! How to gain this?

2 drivers pr. horn with a V-piece?

Another solution is to use a Beyma 6MI80 mid-high speaker, that has a phaseplug, and is capable of playing quite loud up to about 4,5 kHz... However, how would I then avoid phase problems, when I have 2 drivers side by side? (Vertical alignment is not an option due to transportation of the PA-system)

Looking forward to hear from you wise men! Please Help!

Cheers, Hans-Henning, Denmark

PS: Im getting frustrated with these phaseproblems. Currently the sound changes quite remarkebly as one move around on the dance floor.

Any good suggestions?
If you cannot measure it - you cannot improve it!
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Old 20th September 2007, 06:30 PM   #2
-CGL- is offline -CGL-  Finland
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If you are talking about "comb-filtering", I could suggest the following combo:

Eighteensound XT1464 horns (60 x 50 deg), BMS 4554 drivers.
Splay them with care and you should have minimum comb.

I had.

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Old 20th September 2007, 08:14 PM   #3
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Tom Danley's unity concept seems the most elegant solution to this kind of problem. I would expect there exists an upper limit in terms of level his stuff can do.

community sites,, ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
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Old 21st September 2007, 11:46 AM   #4
Pano is offline Pano  United States
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Default Re: PA Sound system: Phase problems

Originally posted by freedom
sensitivity of 120 dB and 2 pi coverage
AFAIK, not possible into 2 pi space. 112 dB/watt would be 100% effiecent into 2 pi at 1 meter. Right?
Take the Speaker Voltage Test!
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Old 21st September 2007, 11:59 AM   #5
freedom is offline freedom  Denmark
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Talking Possibility

Hi there

Of course, an ideal speaker will have an efficiency far above 100% - it will as a matter of fact be able to generate more energy than has been put into it, and thereby be able to provide it self with energy needed, plus, of course, supply the coffe-machine at the same time!!!

Cheers, Hans-Henning
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