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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 5th April 2018, 08:00 PM   #1
zmyrna is offline zmyrna  United Kingdom
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Default Has anyone tried these MMTMM configurations?

Any experience or thoughts on these configurations?
I am thinking 1x Beyma TPL-150 and 4x Faital Pro 6FE200 per speaker, open baffle.
Alternatively all 4 mids can be front firing.
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Old 6th April 2018, 03:05 AM   #2
hollowboy is offline hollowboy  Australia
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You could ask GM.

I remember him mentioning a project where he made a quasi coaxial by surrounding a compression driver with a ring of woofers. If I remember correctly, he said it mimicked a point source quite well.
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Old 6th April 2018, 09:42 AM   #3
chris661 is offline chris661  United Kingdom
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I don't understand why you'd spend all that money on a HF unit, and then cheap out on the next driver down.

Either way, you're going to need something reasonably hefty for OB bass. 1x15" per side minimum.

Chris
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Old 6th April 2018, 02:01 PM   #4
ewollowe is offline ewollowe  Australia
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This has been done before but for the life of me I cannot find the speaker online.

Here's something similar but sealed box. A diyer tried a similar arrangement here and loved the results.

DNA Sequence Speakers dipole open baffle woofer high efficiency point source array midrange tweeter treble loudspeaker

His white paper is interesting.
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Old 6th April 2018, 02:17 PM   #5
ewollowe is offline ewollowe  Australia
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Found em

Reflector audio
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Old 6th April 2018, 06:36 PM   #6
Gnobuddy is offline Gnobuddy  Canada
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Quote:
Originally Posted by zmyrna View Post
Any experience or thoughts on these configurations?
The audio would come from a source that is maybe fifteen inches wide (four 6" drivers spaced several inches apart) below the crossover frequency, and only about an inch wide above it.

This means you have an enormous jump in sound dispersion pattern as you transition through the crossover frequency. The sound is tightly beamed below the crossover, and widely dispersed above it.

This is the sort of thing that ruins stereo image and the size of the "sweet spot" for listening. IMO it would be a real shame to pay a lot of money for a good tweeter, and then ruin its good sound dispersion properties by engineering a speaker design like this.

Though Beyma suggests a crossover frequency of "1 kHz or higher" ( Beyma TPL-150 pleated diaphragm tweeter - Beyma TPL-150 - Beyma TPL-150 high frequency tweeter. Beyma TPL-150 high frequency tweeter is available here at US Speaker. Beyma TPL-150 speaker components. ), the published frequency response suggests a crossover above 2 kHz would be better.

Severe beaming occurs if the driver diameter is much larger than a half-wavelength of the highest frequency being emitted.

By 2 kHz, a 15" wide woofer (or cluster of four woofers) will suffer from a lot of treble beaming, because the half-wavelength of a 2 kHz tone is only about 3.5 inches, which is much smaller than 15 inches.

This is the reason why 3-way speakers were invented, with a midrange driver that is much smaller than the woofer, and therefore able to provide good treble dispersion all the way up to its tweeter crossover frequency. Meantime, the woofer-midrange crossover frequency is much lower, so that the big woofer still provides good dispersion all the way up to the frequency when it hands over to the midrange driver.

Back to your idea, if you must use multiple drivers driven from the same signal (i.e. operating over the same range of frequencies), stringing them all in one vertical line is "less-bad" than an arrangement that spreads them out horizontally.

This vertical-in-line driver arrangement causes less-bad beaming in the horizontal direction (than the vertical). Less-bad dispersion in the horizontal direction is at least a tiny step in the right direction, because our ears are spaced apart horizontally, not vertically, our stereo speakers are spaced apart horizontally, not vertically, and because we ourselves are more likely to move about horizontally than vertically.

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Old 7th April 2018, 04:13 PM   #7
zmyrna is offline zmyrna  United Kingdom
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Quote:
Originally Posted by chris661 View Post
I don't understand why you'd spend all that money on a HF unit, and then cheap out on the next driver down.

Either way, you're going to need something reasonably hefty for OB bass. 1x15" per side minimum.

Chris
I plan to use 2x or 4x 18" woofers per side; aiming for a high eff system.
4x 6FE200 per side is not that cheap
There are not many modern drivers that have the same specs as 6FE200.
Do you have any driver in mind?
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Old 7th April 2018, 04:16 PM   #8
zmyrna is offline zmyrna  United Kingdom
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Originally Posted by ewollowe View Post
This has been done before but for the life of me I cannot find the speaker online.

Here's something similar but sealed box. A diyer tried a similar arrangement here and loved the results.

DNA Sequence Speakers dipole open baffle woofer high efficiency point source array midrange tweeter treble loudspeaker

His white paper is interesting.
DNA guys could not make their minds either and went for the oblique
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Old 7th April 2018, 04:24 PM   #9
zmyrna is offline zmyrna  United Kingdom
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Originally Posted by ewollowe View Post
yes; similar idea

by inverting the drivers and using concave placement, they are trying to avoid beaming. Q is how effective is this?

if it helps beaming, what about lobing? (C to C distance vs. CO frequency)

my idea is similar; keep the MTM front firing and add two more inverted Ms.
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Old 7th April 2018, 09:47 PM   #10
chris661 is offline chris661  United Kingdom
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Quote:
Originally Posted by zmyrna View Post
I plan to use 2x or 4x 18" woofers per side; aiming for a high eff system.
4x 6FE200 per side is not that cheap
There are not many modern drivers that have the same specs as 6FE200.
Do you have any driver in mind?
I'd seriously consider one of the 18Sound 6.5" midbass units. I'm using the 6ND430 for my home HiFi. They also see use for acoustic gigs, without LF support.

IMO, better to have one or two good drivers instead of a bunch of not-as-good ones.

Chris
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