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Multi-Way Conventional loudspeakers with crossovers

Newform Research, SB, and Dayton Towers
Newform Research, SB, and Dayton Towers
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Old 7th August 2018, 03:23 AM   #1
perceptionchanges is offline perceptionchanges  Canada
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Default Newform Research, SB, and Dayton Towers

I've just finished the construction of these "somewhat" over the top speakers, save for some Minidsp tweaking. Just want to listen to them flatish before adjusting.

Woofers are Dayton Audio RS225-4
Mids are SB Acoustics SB15MFC30-8
Tweeters are a stack of 2 - 30" and 1 - 15" Newform Research Oval series.

I have some build photos coming. Today I have some more listening to do.
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Old 7th August 2018, 03:26 AM   #2
perceptionchanges is offline perceptionchanges  Canada
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The Pics
Attached Images
File Type: jpg 20180806_193007.jpg (137.8 KB, 334 views)
File Type: jpg 20180806_193038.jpg (103.1 KB, 330 views)
File Type: jpg 20180806_193051.jpg (97.3 KB, 329 views)
File Type: jpg 20180806_193104.jpg (138.1 KB, 323 views)
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Old 7th August 2018, 10:34 PM   #3
Old'n'Cranky is offline Old'n'Cranky  Australia
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I'm quite confident you could've made them a bit longer.
After all, look at all the space above them.
Then if you get rid of the castors at the bottom, you have even more space.

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Old 8th August 2018, 12:53 PM   #4
nc535 is offline nc535
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Looking forward to seeing some measurements on these!
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Old 9th August 2018, 05:27 AM   #5
perceptionchanges is offline perceptionchanges  Canada
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Here are my preliminary measurements, but still tweaking the crossover points, slopes, etc...
The graph shows 1/12 smoothed at listening position.

Crossover points are:

Mid to high = 1150hz with 48db slopes.
Mid to low = 125 hz with 12db slopes.
Low to sub = 45 hz
Mids to highs are so low to deal with lobing.

I built them so tall to have equal reflections with a standard 8' ceiling.
Attached Images
File Type: png Speaker Measurements.png (121.3 KB, 210 views)
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Old 9th August 2018, 06:57 AM   #6
Sonce is offline Sonce  Macedonia
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300 dB range (from -140 to +160 dB) is meaningless, nothing useful can be seen in a 20 dB vertical spacing.
Please use 5 dB vertical spacing.
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Old 9th August 2018, 02:20 PM   #7
perceptionchanges is offline perceptionchanges  Canada
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As requested.

I'd be super glad to hear any advice. I will try suggestions.

I'ts a minidsp 4x10 that I'm working off.
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Old 9th August 2018, 03:49 PM   #8
nc535 is offline nc535
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Chances are you have some early front and side wall reflections corrupting your frequency response. First look at the impulse response and see the time of arrival of reflections. If the reflections are early and strong, then some absorption panels might be in order. Then press the IR windows button at the top of the REW screen and configure frequency dependent windows. That should make it look a lot smoother and show you what the direct response is absent the reflections.
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Old 10th August 2018, 02:19 AM   #9
Sonce is offline Sonce  Macedonia
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If green and red graphs are representing left and right speaker, than something strange is happening with one of the speakers at 4.5 and 9 kHz (red curve), because green and red curves should be very similar above 1 kHz.
Mid to high crossover is not optimal - there is a dip just above 1 kHz. Try tweeter delay or some phase shift with MiniDSP.
Very impressive build!
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Old 13th August 2018, 12:29 AM   #10
perceptionchanges is offline perceptionchanges  Canada
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I spent some more time on them today, this time with a few differences.

- Used some room treatments to tame reflections.
- Measured at 5'6" from the speakers as they are so tall I wanted to avoid the woofers being too far off axis.
- Measured each driver separately, PEQ'ed major issues. Attached graphs after this adjustment.
- Found some definite variation in the Newform tweeters left to right. Photo attached.
- Mids too had some variation, but not as extreme.

- Last graph is at listening position, L+R. 8" delay set on the left speaker due to slightly off-center room. Subwoofers included set quite high (90hz) to deal with a 80hz mode I without them.

- Used all BW 24db crossovers.
- Had some big dips in the mids. Oddly I inverted on side of the mids and found that cleaned the dips up. I used a battery to check to see if I had accidentally mis-wired one side but they were good. I'd love to hear thoughts on this.
- When I set up to listen to them I switched back and forth with the inverted channel. Found that the sound seemed fuller with both in phase, but vocals were more pronounced in the right speaker. Played with delays, never helped. Inverted one side, vocals moved to center. Grrr.

- Post some listening I inserted a wide 3db dip at 2500 hz and a 2 db low shelf increase starting at 170 (for my preference).
Attached Images
File Type: jpg Highs.jpg (65.4 KB, 29 views)
File Type: jpg Mids.jpg (68.6 KB, 20 views)
File Type: jpg New Measurements.jpg (67.0 KB, 21 views)
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