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Multi-Way Conventional loudspeakers with crossovers

MTM - TMM Shoot Out
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Old 4th December 2017, 01:17 PM   #21
augerpro is offline augerpro  United States
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Quote:
Originally Posted by ODougbo View Post
AllenB how would I know if that is happening?
Are you not working from measurements?
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Old 4th December 2017, 05:30 PM   #22
wushuliu is offline wushuliu  United States
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Quote:
Originally Posted by ODougbo View Post

Eclipse/W6520R interesting, what size box are you using?
The PE .75cuft/20L MTM cabs.
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Old 4th December 2017, 08:58 PM   #23
ODougbo is offline ODougbo  United States
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augerpro, they measure well as is, and only making small changes to the tweeter resistor and the fill for now. But will get back around to re-measuring them someday.

wushuliu, I have a exchange program going on with the 8 x 20 baffles.
FYI, very easy to make unfinished banks with two slabs of 1/2" mdf, glue and weights.

FYI II just called PE about the missing RS28F-4, it will be re-made by a different manufacture -- very soon.
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Old 5th December 2017, 05:17 AM   #24
AllenB is offline AllenB  Australia
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Originally Posted by ODougbo View Post
AllenB how would I know if that is happening?
Just thinking what difference there could actually be between the two. Lobing - between the woofers at their top end, and between the two ways around the crossover.

The result could be the direct level at the crossover, and the reflected contribution (level and spectrum). I thought I'd ask on what you based the two different crossovers.
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Old 6th December 2017, 08:36 AM   #25
ODougbo is offline ODougbo  United States
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Allen,
Thank you, I believe that is the word I was looking for.
The xo's were modeled, attached:

The heaver coils are on the way, should be here the end of the week, and will dive back into that this weekend.

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All these changes......



Quote:
Originally Posted by AllenB View Post
Just thinking what difference there could actually be between the two. Lobing - between the woofers at their top end, and between the two ways around the crossover.

The result could be the direct level at the crossover, and the reflected contribution (level and spectrum). I thought I'd ask on what you based the two different crossovers.
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Old 7th December 2017, 07:25 AM   #26
AllenB is offline AllenB  Australia
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It looks as though you have modelled that crossover on making a perfect null on axis with reversed polarity. Now, I'm only guessing here but when I design a crossover it doesn't always do that because all directions are being considered (for TM or MTM). Another example, IIRC D'Appolito explored 90 degrees phase difference to splay the two inverted sets of lobes to fill the gaps.

What I would be interested in here, is vertical polars. Woofers on their own, and all drivers combined. I'd also wonder if there is any difference between the two speaker types if their response was the same and there were ceiling absorbers. -Just thinking aloud, please carry on.
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Old 9th December 2017, 10:40 AM   #27
LewinskiH01 is offline LewinskiH01  Argentina
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Hey ODougbo.

What's the xo frequency and the M-to-M center-to-center separation? I'm considering MTM with a very large tweeter and models predict lobing to be an issue. Would appreciate your input as to how much you can perceive lobing effects in your build. Maybe your design adheres by established rules and hence not perceivable - hence I was asking for distance and xo frequency.

Cheers!
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Old 11th December 2017, 08:28 AM   #28
ODougbo is offline ODougbo  United States
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Allen, I thought a perfect null was the always the goal.

No ceiling damping, but was just thinking this room with a 9' ceiling is way better the the old house (we moved).

Again, crazy bass from the TMM, we watched KONG 2017 and sounded like my 50lb CSS 12" woofer was hooked up, but no, it is in storage. Even more inexpressive tho, is all this crazy sound from a 100 watt HT receiver, turned up about 1/3 of the way.
FYI The receiver is connected to the STB via Toslink, set to stereo.

Quote:
Originally Posted by AllenB View Post
It looks as though you have modelled that crossover on making a perfect null on axis with reversed polarity. Now, I'm only guessing here but when I design a crossover it doesn't always do that because all directions are being considered (for TM or MTM). Another example, IIRC D'Appolito explored 90 degrees phase difference to splay the two inverted sets of lobes to fill the gaps.

What I would be interested in here, is vertical polars. Woofers on their own, and all drivers combined. I'd also wonder if there is any difference between the two speaker types if their response was the same and there were ceiling absorbers. -Just thinking aloud, please carry on.
Lewinski, sounds like you are starting from scratch, my best advice would be build some test boxes and start experimenting.
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Old 11th December 2017, 10:33 AM   #29
AllenB is offline AllenB  Australia
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Quote:
Originally Posted by ODougbo View Post
Allen, I thought a perfect null was the always the goal.
If you consider the overall sound power, also the nature of the reflections, you can adjust the direct ratio by being off on the phase if it works out that way. Preferably up away from the floor as well
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Old 11th December 2017, 03:24 PM   #30
Boden is offline Boden  Netherlands
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Hello Allen,

Would you care you clarify your post above?

Considering the soundpower response in the filter design and optimization is fine, but how to adjust the direct ratio by being off on phase?

I am afraid I do not understand this statement.

Thanx.
Eelco
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