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Where did I go wrong with my design? (2-way horn speaker)
Where did I go wrong with my design? (2-way horn speaker)
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Old 22nd February 2019, 06:39 PM   #1
Defo is offline Defo  Norway
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Default Where did I go wrong with my design? (2-way horn speaker)

Hi!

I'ts been some years now since I last designed a speaker.
This was a speaker I spent considerable time doing research on.
But in the end, I never got it to sound "right", even do I did everything "by the book" (as far as I knew).

The design was a B&C DE250 in a SEOS-12 waveguide crossed to a B&C 10HPL64 at 1600 hz to match dispersion. Crossover, baffle step and CD horn roll off was all handled by the miniDSP.

I did hundreds of measurements, and tried all kinds of possible XO slopes and XO points, but to no avail. In the end, I gave up on it and sold the whole deal.

But I'm still kind of curious how a design that theoretically should've sounded quite good just didn't.

Maybe some smart folks here on this forum could shed some theory on what I might've been the issue here, looking back in hindsight?

Picture below:
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Last edited by Defo; 22nd February 2019 at 07:10 PM.
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Old 22nd February 2019, 06:43 PM   #2
Cal Weldon is offline Cal Weldon  Canada
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Where did I go wrong with my design? (2-way horn speaker)
Why don't you tell us what was wrong with them and show us some measurements.
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Old 22nd February 2019, 07:09 PM   #3
Defo is offline Defo  Norway
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Originally Posted by Cal Weldon View Post
Why don't you tell us what was wrong with them and show us some measurements.
It's 4 years since I sold the drivers and threw away the cabinets, so they're long gone unfortunately This thread was meant to see if there might have been any obvious flaw I overlooked, so I can learn from it in hindsight.

They sounded okey. But there was something off with them.
Kind of hard to describe, but they just sounded kind of weird.
Almost the kind of sound you get with one speaker out of phase.

Last edited by Defo; 22nd February 2019 at 07:13 PM.
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Old 22nd February 2019, 07:24 PM   #4
plasnu is offline plasnu  United States
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This is sometimes a problem with DIY speakers. No published specification, no help...
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Old 22nd February 2019, 08:03 PM   #5
Pallas is offline Pallas  Pakistan
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Quote:
Originally Posted by Defo View Post
Hi!

I'ts been some years now since I last designed a speaker.
This was a speaker I spent considerable time doing research on.
But in the end, I never got it to sound "right", even do I did everything "by the book" (as far as I knew).

The design was a B&C DE250 in a SEOS-12 waveguide crossed to a B&C 10HPL64 at 1600 hz to match dispersion. Crossover, baffle step and CD horn roll off was all handled by the miniDSP.

I did hundreds of measurements, and tried all kinds of possible XO slopes and XO points, but to no avail. In the end, I gave up on it and sold the whole deal.

But I'm still kind of curious how a design that theoretically should've sounded quite good just didn't.

Maybe some smart folks here on this forum could shed some theory on what I might've been the issue here, looking back in hindsight?

Picture below:
Measurement errors, inadequate measurements (not enough angles), crossover design, build errors, or defective drivers are likely culprits. Without seeing any data who's to know?

The unterminated waveguide and surface mounted woofer may have had some effect as well. Those attributes both generally fall into the category "bad design."
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Old 22nd February 2019, 08:25 PM   #6
norman bates is offline norman bates  United States
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Hmm, horn looks flawless.

Lack of under 100hz making it dissatifying maybe ?
61hz fs and qts .31, not much below 100hz.
I find porting above 30hz to sound "wrong", just me.
And all the boxy midrange flying out the port isn't helpfull either.
Even with eq, may not be satisfying, and woof not on floor either, maybe floor bounce dropping midbass.

I just went through that.

Perhaps you needed 24db slopes, then slide tweet forward till time aligned.
This can be a frustrating hobby initially.
And even pricy.
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Old 22nd February 2019, 08:45 PM   #7
tonitonitoni is offline tonitonitoni  Croatia
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Originally Posted by norman bates View Post
...
And all the boxy midrange flying out the port isn't helpfull either.
...
this , it can be overwhelming.
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Old 22nd February 2019, 09:16 PM   #8
John Busch is offline John Busch  United States
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This is where we get into the "art" side of things. Plus experience... Getting a short horn and 12" woofer to sing is not an easy task. Why your project did not work will always be a mystery..... However....

Suspect three things.... lack of blending .... not enough overlap. At the crossover point, your two drivers sound VERY different.... a large heavy direct radiator vs. a small very light weight, horn loaded diaphragm.

Phase issues due to different vertical and horizontal acoustic centers.

And due to very different natural roll off profiles for each driver, a VERY asymmetrical spread frequency crossover topology is required.

A lot of your dissatisfaction is typical for poorly integrated coaxial drivers, especially larger ones. Base this on working with coaxial drivers from 4" up to 18". Measurement and theory can get you moving in the right direction, but the ear, experience and a bit of luck is required to make it all work.
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Old 22nd February 2019, 09:23 PM   #9
gabdx is offline gabdx  Canada
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minidsp is one problem, I never liked the sound of processors and B&C are built for power over frequency flatness.

With a normal XO there is almost everything you can fix but it is very complicated.

I think you could have made a cardboard model before building the real thing and see if driver offsets could fix some frequency or perception problems.

Horn speakers are especially hard to XO from what I heard of them, including diy builds.

In commercial speakers they have a team of experts. send speakers to labs and test for multiple parameters with detail logs. One person cannot do that even full time for years.

If you start digging into speaker XO you will see few knows how to do it right.

so, you have 5 things which are why it went wrong:

1. Choosing PA drivers
2. Hoping DSP will fix the sound (it is more complex than DSP can do)
3. Not building a prototype before final built which can have impossible to correct flaws due to speaker shape and driver placement, offsets, cabinet type
4. Not having a proper XO modeling and log book with years of improvements
5. Not having the team and tool to measure the speakers in all parameters possible, including Z, R, time delay, port, room gain, dispersion, Frequency response.
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Old 22nd February 2019, 09:25 PM   #10
Godzilla is offline Godzilla  United States
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>>> any obvious flaw...

I tried to do a 10" two way using a compression driver and waveguide and had a difficult time too. The problem with my project was that I was using a cabinet that was too small. Whenever I simulated a larger cabinet I wanted to use a 12" or even a 15" which required a different crossover. Ultimately, I enjoyed the 10" two-way for a few weeks - played with stuffing and crossover parts - even moved the port from the front to the back (which reduced the boxy sound) - until finally deciding to dismantle it. The parts remain in boxes in the closet. After looking up the woofer you used, it appears to be in an 'optimal' cabinet but no matter how you use that woofer I doubt you'd get meaningful bass from it. 99db efficiency and low bass don't go hand in hand so I think you were not getting enough bass to balance out the sound. What you experienced was mostly the compression driver's sound paired with a large midrange.

>>> Kind of hard to describe, but they just sounded kind of weird.

I've never been a fan of the SEOs waveguide. Here I described the sound using the very same B&C DE250.

B&C DE250-8 Compression Driver in Various Waveguides | Speaker Projects by Zilla
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