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Multi-Way Conventional loudspeakers with crossovers

Acoustic Horn Design - The Practical Way
Acoustic Horn Design - The Practical Way
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Old 22nd May 2020, 05:00 PM   #21
mabat is offline mabat  Czech Republic
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BTW, what bmc0 has shown will be hard to beat because of its relative simplicity (being still an axisymmetric device), yet the performance is stellar. This is the way to go.
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Old 22nd May 2020, 05:06 PM   #22
Bill Brown is offline Bill Brown  United States
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I would love to see more thoughts/models/sims on the Bliesma T-34B.

Probably crazy-sounding, but I have two ideas in mind- one based on the Bliesma and another with a CD/WG (Celestion Axisymmetric v other) that can XO down to ~ 300Hz to avoid the location of the crossover required for the Bliesma.

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Old 22nd May 2020, 05:32 PM   #23
diyiggy is offline diyiggy
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Default Off topic,

I try to follow that idea as well with a 3" mid/tweeter to load it circa 600/800hz -and try to know if it can smoothly marry with a 15" - instead a 10"-: 3"-75mm-apex diameter wave guide for SS 10FF -


But let's continue with your how to here and again thank you for the clarification effort and the huge soft work.
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Old 22nd May 2020, 10:08 PM   #24
bmc0 is offline bmc0  United States
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Thanks, everyone. I'm pretty pleased with the result myself.


Quote:
Originally Posted by Ro808 View Post
The woofer is an Eminence, judged by the cone and surround?

Yes, it's a Deltalite II 2512.


Quote:
Originally Posted by Ro808 View Post
What's is your (initial) subjective impression of the speaker(s) in the room?

Compared to my previous speakers, which were about half the size (6.5in woofer and 1in dome tweeter on a 3d printed waveguide), the biggest improvements seem to be imaging precision, clarity in the midrange, and dynamic capability. The first two are almost certainly due to the improved directivity control. I'll refrain from saying more as sighted subjective impressions are known to be highly unreliable (especially coming from the guy who designed and built the things! ).



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The mid seems a 10". Why did you choose (and many diyers) a compression driver for the horned uppermid/tweeter instead a classic dome driver which can benefits of the horn reenforcment and perhaps more linear that a compressiopn driver ?

It's 12in, actually. I used a compression driver partially because everyone else does . But also because the exit wavefront is a better match for the OS throat than what a dome produces. When you say "more linear" do you mean the frequency response, or the nonlinear distortion? I'm not personally convinced that either is really an audible problem in this case. The nonlinear distortion is actually quite low and the slightly rough frequency response above ~14kHz is probably not audible (I could be wrong, of course).
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Old 22nd May 2020, 11:06 PM   #25
bmc0 is offline bmc0  United States
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Quote:
Originally Posted by mabat View Post
BTW, what bmc0 has shown will be hard to beat because of its relative simplicity (being still an axisymmetric device), yet the performance is stellar. This is the way to go.
Thanks! For one-off designs, this method is low cost and produces highly accurate results (if you do it right ). It definitely takes some practice to get a good surface finish though.


As you well know, the termination appears to be very important for getting this kind of performance from an axisymmetric device.

Last edited by bmc0; 22nd May 2020 at 11:10 PM.
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Old 22nd May 2020, 11:17 PM   #26
Ro808 is offline Ro808  Netherlands
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Quote:
Originally Posted by bmc0 View Post

Compared to my previous speakers, which were about half the size (6.5in woofer and 1in dome tweeter on a 3d printed waveguide), the biggest improvements seem to be imaging precision, clarity in the midrange, and dynamic capability. The first two are almost certainly due to the improved directivity control. I'll refrain from saying more as sighted subjective impressions are known to be highly unreliable (especially coming from the guy who designed and built the things! ).

This aptly illustrates the differences between a "typical" hi-fi loudspeaker and a highly sensitive 2-way with controlled directivity.

Last edited by Ro808; 22nd May 2020 at 11:20 PM.
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Old 23rd May 2020, 06:13 AM   #27
Dave Zan is offline Dave Zan  Australia
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Quote:
Originally Posted by bmc0 View Post
I recently completed a speaker that I suppose would fit here...
Let me add my compliments to everyone else's.
That's really nice work - clever use of materials and methods, cost effective and looks excellent, what did you paint it with?
I notice that horn and woofer have been pushed closer until they intersect a little.
I assume this is to improve the polars, especially near crossover.
From your results it looks that you have been successful in this area.
I have considered this idea for a while but have only done back of envelope calculations.
Did you use some simple heuristic or rule of thumb to decide how much overlap?
Or did you try different simulations?

Best wishes
David
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Old 23rd May 2020, 07:19 AM   #28
bmc0 is offline bmc0  United States
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The paint is just acrylic latex furniture/trim paint sprayed with a cheap pneumatic gun (This one, specifically. The paint cup is pressurized, so it'll spray latex with little or no thinning). Believe me, the finish is far from perfect. You just can't really see the problems in the picture .


The driver spacing is 32cm (12.6in) and the crossover is 1050Hz, so they are about one wavelength apart. I didn't do any simulations of the complete loudspeaker, only the waveguide. Maybe I would have if ABEC3 was easier to use .
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Old 23rd May 2020, 07:43 AM   #29
bmc0 is offline bmc0  United States
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Here's the vertical contour plot, which I didn't post before:

Acoustic Horn Design - The Practical Way-directivity_contour_v-png

The crossover slopes are fairly steep (LR6 acoustic), so the nulls are narrow and have little impact on the sound power.
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File Type: png directivity_contour_v.png (400.8 KB, 725 views)
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Old 23rd May 2020, 08:17 AM   #30
Dave Zan is offline Dave Zan  Australia
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Quote:
Originally Posted by bmc0 View Post
The paint is just acrylic latex furniture/trim paint
Still looks very decent.
I spray 2 pack polyurethane with a similar(ish) small set up but hate the toxicity.
I have some waterborne epoxy to try.

Quote:
I didn't do any simulations of the complete loudspeaker...
Maybe I would have if ABEC3 was easier to use .
Exactly how I feel, I had hoped perhaps you had done it for me

Quote:
Originally Posted by bmc0 View Post
Here's the vertical contour plot, which I didn't post before...
so the nulls are narrow and have little impact on the sound power.
Thanks for the extra plot.
About as expected, for the separation and crossover slope you have.
As you say, not too much impact on sound power.
It would be nice to reduce it even further but eventually this starts to compromise the on-axis behaviour.
I'm not sure yet where the best trade-off is but think some overlap is desirable, as you have done.

Best wishes
David
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