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Multi-Way Conventional loudspeakers with crossovers

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Old 21st August 2009, 02:15 AM   #101
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Quote:
Originally Posted by kstlfido View Post
Hmm, yes, similar indeed. Are they using an Eminence unit?
B&C 8CXT.

Augerpro subsequently measured them:

http://sites.google.com/site/driverv...pr300/b-c-8cxt

I thought we might have been unfair to APT-50, measuring with a filter, so I redid two samples with none, below.

Familiar....
Attached Images
File Type: jpg APT-50 Polar #1.jpg (70.1 KB, 534 views)
File Type: jpg APT-50 Polar #2+.jpg (69.8 KB, 525 views)

Last edited by ZilchLab; 21st August 2009 at 02:54 AM.
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Old 21st August 2009, 03:12 AM   #102
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With Selenium D220Ti, we tried several EconoWave filter combinations, ending up with additional BSC for use outdoors in the lowpass, and the standard low-sensitivity highpass running full on. The acoustic crossover frequency is presently at 1.436 kHz:

Click the image to open in full size.

Yes, it has 5 dB of extra "sizzle" on axis, but we opted to leave that there in favor of better spectral balance out to 30°, i.e., 60° beamwidth. Kent is adding fiberglass damping and completing the second unit for listening tests outside. If we have an opportunity before they are "deployed," we'll measure to determine where these are tuned, and maybe tweak that a bit, but we're getting surprisingly good bass extension presently....
Attached Images
File Type: jpg D220Ti Polar.jpg (74.6 KB, 640 views)
File Type: jpg LHF 0.jpg (68.2 KB, 488 views)
File Type: jpg LHF 30.jpg (64.8 KB, 78 views)
File Type: jpg CSD.jpg (106.8 KB, 80 views)
File Type: jpg D220Ti SG.jpg (54.4 KB, 48 views)

Last edited by ZilchLab; 21st August 2009 at 07:13 AM.
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Old 21st August 2009, 04:02 AM   #103
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Quote:
With Selenium D220Ti, we tried several EconoWave filter combinations, ending up with additional BSC for use outdoors in the lowpass, and the standard low-sensitivity highpass running full on. The acoustic crossover frequency ended up at 1.436 kHz:


but we're getting surprisingly good bass extension presently....
Hi Zilch
Back at the honing grind stone I see.

Interesting there is that 10" woofer midrange suckout again. As seen on the US speaker Eminence chart, wondering if that was real before...guess so. Not too much help with using a passive Xover for that.

FWIW What was the rational for all the changes ie more BSC and reverting to the low eff Xover version, Considering 1) you got good/better bass. 2) IMO lower crossover may measure better but a trade off sound wise (music) at higher SPL? Not questioning any judgement just wanting to know your thought processes. edit>The woofer at 95dB eff is just at the eff cut off and with the mid suck out and extra BSC (tiny baffle) you will need to use the low eff Xover.
BTW Good work you guys!
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Last edited by infinia; 21st August 2009 at 04:27 AM.
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Old 21st August 2009, 04:38 AM   #104
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FWIW What was the rational for all the changes ie more BSC and reverting to the low eff Xover version, Considering 1) you got good/better bass. 2) IMO lower crossover may measure better but a trade off sound wise (music) at higher SPL? Not questioning any judgement just wanting to know your thought processes
The high-efficiency variant would require an L-Pad to balance; I wanted to avoid having one at all in the hostile environment of the intended use. I could set the attenuation almost anywhere desired by varying the values in Wayne Parham's HF comp filter, so I tried to bracket the range by running on the <95 dB version, which balanced well with the L-pad bypassed. In the previous testing, ~5 dB "hotter," we ignored this element entirely.

Baffle step, we shot from the hip, trying different lowpass values, measuring, and listening, because 200 Hz is as low as I go with MLS indoors. I acknowledge that we may have overshot it, as the acoustic crossover frequency came out a bit lower than I was anticipating, and you suggested maybe a bit higher, instead, but we did crank it and heard no distress. I wasn't watching the cone excursion, but perhaps Kent might pay particular attention to that when he runs his listening tests outdoors. Can we talk you into modeling the filter for us? Here's the circuit, except L2 is 3.5 mH, DCR 0.36 Ohms:
Attached Images
File Type: jpg LoSens XO Schematic A.jpg (36.2 KB, 196 views)

Last edited by ZilchLab; 22nd August 2009 at 06:30 PM.
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Old 21st August 2009, 04:45 AM   #105
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I'll model it fer sure, just not sure when. It might be OK for BSC 1st order if woofer doesn't breakup high? use a parallel resistor with the big inductor?
Any high pass changes?
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Old 21st August 2009, 04:53 AM   #106
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I'll model it fer sure, just not sure when. It might be OK for BSC 1st order if woofer doesn't breakup high? use a parallel resistor with the big inductor? Any high pass changes?
Highpass is as shown, but with the L-pad bypassed. Lowpass is 2nd order; the 12 uF remains. You can see they are summing reasonably, but there's still time to tweak. We may have kicked up the VLF too much is the concern. Kent can tell us if the amp he'll be using has a highpass filter to protect the woofer when they start bumping on the Playa....

Last edited by ZilchLab; 21st August 2009 at 05:05 AM.
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Old 21st August 2009, 05:57 AM   #107
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Quote:
Highpass is as shown, but with the L-pad bypassed. Lowpass is 2nd order; the 12 uF remains. You can see they are summing reasonably, but there's still time to tweak. We may have kicked up the VLF too much is the concern. Kent can tell us if the amp he'll be using has a highpass filter to protect the woofer when they start bumping on the Playa....
Yup SPL vs SQ/BSC outdoors... my concern from the git go. Try and get a little more SPLs with 1st order and then you can adjust the HPF to match the natural woofer rolloff, say 30 degrees or so (horn directivity up high). But Kent knows the application best, so a tradeoff decision is his ultimately, with your sweat and good will of course. Id say you got it pretty good so far as SQ, but will it be loud enough? SQ bass bump maybe best with amp tone controls YMMV.
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Last edited by infinia; 21st August 2009 at 06:01 AM.
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Old 22nd August 2009, 05:28 PM   #108
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I haven't got both set-up yet, but I've been listening to one. I did the insulation which helped the bass clarity, less boxy sound. There is a fair amount of bass. This was in the garage, so not a true 'playa' test. Will prob. do that monday.

The intended amp does have simple tone controls.

A big thank you to you, Zilch; seeing the test results as we tweaked was really informative. I could see how one can play with that for hours! Hat's off to you!

-Kent
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Old 22nd August 2009, 06:34 PM   #109
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A big thank you to you, Zilch; seeing the test results as we tweaked was really informative.
You are very welcome, of course.
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I could see how one can play with that for hours! Hat's off to you!
A quick check of the time stamps says we did, actually.

[Time flies when yer havin' fun.... ]
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Old 23rd August 2009, 06:44 PM   #110
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Default Black Rock City Xover Version 1.0

Here ya go...
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File Type: jpg Zilch Xover Beta 10cx + 220i.JPG (180.3 KB, 223 views)
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