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Multi-Way Conventional loudspeakers with crossovers

Wild Burro 'Betsy' and Eminence Alpha 15a - open baffle build
Wild Burro 'Betsy' and Eminence Alpha 15a - open baffle build
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Old 7th March 2016, 06:49 PM   #11
pcgab is offline pcgab  United States
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Wild Burro 'Betsy' and Eminence Alpha 15a - open baffle build
That's awesome, thank you very much guangui. I plan to run some sims this week, if time allows.
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Old 8th March 2016, 03:46 AM   #12
norman bates is offline norman bates  United States
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here is the freq response of the jamo R909 (from stereophile).

Notice the dip at 1khz.
That (green) is a 5.5" driver's response on a 19" wide baffle.
I figure driver to edge baffle is 7".
14" front to back, and the driver shorts out, wave is 180 degrees out of phase).
1129/(14"/12") = 967.
967hz, close to the 1khz dip in the measurement.
Click the image to open in full size.

And a peak a little less than an octave below that, where the front and back waveforms are 90 degrees out of phase, thusly adding.


The visaton no box has a similar response dip around 600hz (24" wide with wings). It is passive. They use 12db crossover under 100hz.

The VISATON NoBox BB Loudspeaker Kit Review By Dick Olsher

"To illustrate the point, one of the VISATON BGS-40 15-inch woofers, mounted on the NoBox baffle, was measured near field (to eliminate room effects), driven first by a conventional 300B SET amplifier, and then by the constant-current F2. In both cases, a second order low-pass network consisting of a series 13 mH steel-laminate coil and a 200 uF shunt capacitor was used to roll off the high frequencies. The measured frequency response is shown below."

But that is passive crossovers.

I look forward to your results.

Last edited by norman bates; 8th March 2016 at 03:48 AM.
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Old 8th March 2016, 08:56 AM   #13
adason is offline adason  United States
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dip is less audible then peak
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Old 8th March 2016, 11:37 AM   #14
guangui is offline guangui  Puerto Rico
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Quote:
Originally Posted by pcgab View Post
That's awesome, thank you very much guangui. I plan to run some sims this week, if time allows.
BTW, the T after Alpha 15A means Top, and the B means Bottom, referring to the woofer position on the baffle.
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Old 9th March 2016, 12:24 PM   #15
pcgab is offline pcgab  United States
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Wild Burro 'Betsy' and Eminence Alpha 15a - open baffle build
I got a little bit of time yesterday to make some small progress.

The 'supra-baffles' are glued and mostly trimmed on the first baffle:

Click the image to open in full size.


Rear View:

Click the image to open in full size.

Still need to do some final clean up in the cutouts/cavities for the Alpha 15A's, and a bit of trimming on the lower portion of the supra-baffles.

Mounted the Alpha 15A's to check for alignment and to check the gap. I think I'll need some grey foam weather stripping to seal the driver's face gaskets to the baffle. The slight hump of the tee-nuts may be in the way, just a tiny bit.


Click the image to open in full size.


Click the image to open in full size.


New MiniDSP 2x4 arrived yesterday as well, now to sort the amps out.

Unfortunately I may not have much time over the next week or so to get any appreciable progress. Work and other obligations are likely to consume all my time for a bit. We'll see, maybe I can sneak out here and there and chip away at it.


As far as testing, I have a Umik from MiniDSP, mac book pro retina(and several linux computers). I've not done any real driver/speaker measuring before. If anyone has some recommendations as far as software and setup, I'd love to hear about it. Maybe REW? I would like to measure/test them, especially to setup the DSP, and whatever needed EQ, etc.

Thanks y'all~
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Old 9th March 2016, 01:40 PM   #16
guangui is offline guangui  Puerto Rico
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Always satisfying to see progress of a project.
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Old 9th March 2016, 02:40 PM   #17
Pirmin is offline Pirmin  Norway
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Like this!
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Old 19th June 2016, 10:38 PM   #18
pcgab is offline pcgab  United States
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Wild Burro 'Betsy' and Eminence Alpha 15a - open baffle build
I finally got a bit of time to get back on these. I made some quick and dirty frames so I could start some of the testing, etc. Also, as these are for my dad, it worked out well that I was able to play them for him today.

I'll post more details of the crossover work, and when I get to testing them in the next week or so.

A few pics for now.....


Click the image to open in full size.


Click the image to open in full size.


Click the image to open in full size.


Hopefully I'll have more to post later this week.
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Old 8th November 2017, 07:32 PM   #19
jwjarch is offline jwjarch  United States
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Wild Burro 'Betsy' and Eminence Alpha 15a - open baffle build
Pcgab, interested to know how this build ended up. I'm contemplating something very similar.
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Old 13th November 2017, 04:32 PM   #20
pcgab is offline pcgab  United States
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Wild Burro 'Betsy' and Eminence Alpha 15a - open baffle build
Quote:
Originally Posted by jwjarch View Post
Pcgab, interested to know how this build ended up. I'm contemplating something very similar.
I never took it as far as I initially wanted to. Using a minidsp and various amps, I did tweak on it a bit, and by the end had a really nice sounding speaker.

However, the baffles really are just too narrow for LF. I might add some wings, and finish out the rear supports at some point. I think that would make the LF much easier to get to the right spot. They needed a lot of eq boost to get what I felt like was enough low end support.

IIRC, the 15a's were low passed @12db lr2, ~200Hz, and the betsy's high passed @12db lr2, ~300Hz.

at one point I tested them with a B&G Neo3 added, and that was much more to my liking, adding a nice bit up high.
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