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Multi-Way Conventional loudspeakers with crossovers

Has anyone tried these MMTMM configurations?
Has anyone tried these MMTMM configurations?
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Old 11th April 2018, 10:17 PM   #21
Gnobuddy is offline Gnobuddy  Canada
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Quote:
Originally Posted by adason View Post
What's wrong with this arrangement?
Midranges spread apart - see arrows. The cluster of 4 or 2 midranges will behave somewhat like a single midrange that has an effective size of roughly the size of the red or violet arrow, respectively.

This is two to three times the diameter of a single midrange by itelf, which means problems with beaming and narrow dispersion will start at one half to one third the frequency of a single midrange driver by itself. You might say this arrangment cripples the midranges, and makes them unable to provide their normal high-frequency performance.

In other words, you'd have to move the crossover frequency down by a factor of about two or three times to avoid worse dispersion than a single midrange would have. Usually this is not possible, because tweeters are not able to work down to such low frequencies.

-Gnobuddy
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Old 12th April 2018, 04:53 AM   #22
hollowboy is offline hollowboy  Australia
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Originally Posted by Gnobuddy View Post
Midranges spread apart [...] This is two to three times the diameter of a single midrange by itelf, which means problems with beaming and narrow dispersion will start at one half to one third the frequency of a single midrange driver by itself.
The DNA might be better than that, if you consider the uneven distances that will exist between the drivers and your ears. This thread covers it well:
A Novel Loudspeaker Array
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Old 12th April 2018, 05:09 AM   #23
ewollowe is offline ewollowe  Australia
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[QUOTE=hollowboy;5402732]The DNA might be better than that, if you consider the uneven distances that will exist between the drivers and your ears. This thread covers it well:
A Novel Loudspeaker Array[/QUOTE

Here's the patent.

http://patft.uspto.gov/netacgi/nph-P...S=PN/6,801,631

DNA Sequence Speakers dipole open baffle woofer high efficiency point source array midrange tweeter treble loudspeaker
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Old 12th April 2018, 06:35 AM   #24
Juhazi is offline Juhazi  Finland
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DNA's mid has similar directivity as a 15" driver. The quadruple matches quite well with the dipole 15,5" driver in 18,5" frame. Directivity changes totally when tweeter starts to play! DNA doesn't tell xo points but my quess is 500/3000.

High directivity in midrange is a good thing, but this construction is tricky.
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Old 12th April 2018, 08:13 AM   #25
zmyrna is offline zmyrna  United Kingdom
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the DNA design (tilted quartet/square) seem to address comb filtering by way of averaging distance traveled - and does not address beaming or polar response.

however lowpassing some of the mids in the array has the potential of addressing both issues - comb filtering and polar response.

lowpassing can simply be done by a coil - but i was wondering whether inverting some of the mids would have a similar effect.
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Old 12th April 2018, 09:05 AM   #26
hollowboy is offline hollowboy  Australia
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Originally Posted by ewollowe View Post
Here's the patent.
Thanks. The difference between the 'typical' 2x2 array and the patent's skewed array (fig20 vs fig22) is pretty striking - but the skewing doesn't do what I thought it would (based on Patrick's ideas in the other thread I linked).

The main effect appears to be that it reduces the side lobes by ~15dB.
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Old 12th April 2018, 02:39 PM   #27
Juhazi is offline Juhazi  Finland
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The patent and measurements in it are just rubbish. The 4-driver flower is acoustically like a single 15" driver. They are just comparing it's directivity to a single 5" driver or a dome. Sure it is different above 500Hz and at wide angles!


U.S. Patent office makes me surprised again!
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Old 14th April 2018, 01:08 PM   #28
zmyrna is offline zmyrna  United Kingdom
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Originally Posted by Gnobuddy View Post

This doesn't compute - the front and back of a speaker behave pretty much identically, except for the magnet and basket blocking some of the treble radiation from the rear.

-Gnobuddy
compare dispersion of same size cone and dome mid (forget the open baffle scenario for a moment); they will be much different, agreed?

inverted cone driver ought to have different dispersion compared to normally mounted driver (again consider box speaker or a very wide OB) because of the convex radiating surface.

some OHM Walsh speakers use this type of driver mounting to extend the omnipolar radiation higher in the freq range (pic).

and as you say, the spider and magnet would also affect the radiation at higher freq.
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Old 14th April 2018, 05:13 PM   #29
Juhazi is offline Juhazi  Finland
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I have measured some small and medium mid(woofer) cones also from backside. Directivity is total mess, unpredictable and uneven. Total radiated power equals frontside obviously but... The spider and magnet structure mess everything above say 1000Hz. Just try it!
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Old 14th April 2018, 05:22 PM   #30
zmyrna is offline zmyrna  United Kingdom
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Originally Posted by Juhazi View Post
I have measured some small and medium mid(woofer) cones also from backside. Directivity is total mess, unpredictable and uneven. Total radiated power equals frontside obviously but... The spider and magnet structure mess everything above say 1000Hz. Just try it!
Again my question is

Can we use that "mess" in our benefit?

ie. to reduce beaming and or comb filtering of multiple mid arrays
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