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Author Topic: Two LO Drivers - use DSP to roll off one of them?  (Read 4792 times)

Art Welter

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Re: Two LO Drivers - use DSP to roll off one of them?
« Reply #10 on: October 14, 2016, 12:23:01 pm »

No particular problem, and there's no comb filtering that stands out when all bands are un-muted.  I always get good comments on the rig when run vanilla 3-way.

As I began exploring the application of the lower corner freq to the "distant" driver (43" distant from the MID with which it's crossed over), it was intriguing to hear a more localized image of the vocal signal from the tightly clustered LO/MID driver pair of the top cabinet, without those vocals emitting from the bottom LO driver.

Merlijn posted regarding the need to avoid using a filter with 180 deg phase shift at the f=cutoff freq for that bottom LO driver.
Shane,
Since the cob filtering is primarily in the vertical axis, it would be hard to notice unless you were changing your ear position vertically, like when sitting and standing.

You could try a passive solution, stuff a breathable bag (or a T shirt, using string tied around the openings) with fiberglass or open cell foam and place it in front of the lower 18", the acoustical low pass filter won't have the same phase shift as the electrical "poles" in a crossover.

The depth and density of the fill will determine the LP frequency.

Art "aggressively passive" Welter
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Len Zenith Jr

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Re: Two LO Drivers - use DSP to roll off one of them?
« Reply #11 on: October 16, 2016, 05:23:54 am »

You could try a passive solution,

Interesting, I haven't seen passive (acoustic) low pass filters in use since the old TOA's. They used slot loading instead of T-shirts ;D. They were an interesting design and had decent mids for what they were.



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Shane Ervin

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Re: Two LO Drivers - use DSP to roll off one of them?
« Reply #12 on: October 16, 2016, 03:29:02 pm »

Since the comb filtering is primarily in the vertical axis, it would be hard to notice unless you were changing your ear position vertically, like when sitting and standing.

Very good point, especially for deployment in venues having flat floors in the audience area (i.e., seating not raked upwards), where this rig is used mostly.
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Shane

Newer: EAW 8" MicroWedges; QSC PLD 4.2 PLD 4.3; QSC TouchMix-16; UAD Apollo 16; Sennheiser G3 IEM wireless
Older: JBL SR 4738 / SR4718; BSS MiniDrive; Klark Teknik DN-301; Yorkville AP4040 AP2020; Motion Labs Rac Pac;

Art Welter

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Re: Two LO Drivers - use DSP to roll off one of them?
« Reply #13 on: October 17, 2016, 11:24:43 am »

Interesting, I haven't seen passive (acoustic) low pass filters in use since the old TOA's. They used slot loading instead of T-shirts ;D. They were an interesting design and had decent mids for what they were.
Len,
As well as an acoustic low pass filter, the slot reduces the apparent acoustic width of the driver, increasing horizontal dispersion in the woofer's upper pass band, allowing a higher crossover point without "beaming".

Art
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Len Zenith Jr

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Re: Two LO Drivers - use DSP to roll off one of them?
« Reply #14 on: October 18, 2016, 06:06:33 am »

Len,
As well as an acoustic low pass filter, the slot reduces the apparent acoustic width of the driver, increasing horizontal dispersion in the woofer's upper pass band, allowing a higher crossover point without "beaming".

Art

For sure. That's why I mentioned that they had decent mids. They didn't have that off-axis hole that other 15" + horn speakers of the day had.
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Re: Two LO Drivers - use DSP to roll off one of them?
« Reply #14 on: October 18, 2016, 06:06:33 am »


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