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DIY Waveguide loudspeaker kit

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Any other specific reasons besides size and cost? Why is the magic number for directivity 1000 Hz and not 500 Hz or even lower where geometric acoustics still is a valid concept?

My understanding is that lowering the crossover frequency from 1 kHz to 500 Hz would necessitate adding a high frequency driver because (like Earl said) drivers which can go that low cannot also go high enough, and the inevitable compromises arising from the additional complexity would likely more than offset any advantages from maintaining constant directivity down to 500 Hz.
 
Any other specific reasons besides size and cost? Why is the magic number for directivity 1000 Hz and not 500 Hz or even lower where geometric acoustics still is a valid concept?

well, size and cost certainly are significant issues- I guess the other part of it would be that unless you were going to attempt full-bandwidth, you'd have to find a woofer that's directional at the XO while still behaving well, and there are a VERY limited selection of good 30" drivers.

Would love to see you do one with the ginormous fostex woofer and a 30+" waveguide though!
 
My understanding is that lowering the crossover frequency from 1 kHz to 500 Hz would necessitate adding a high frequency driver because (like Earl said) drivers which can go that low cannot also go high enough, and the inevitable compromises arising from the additional complexity would likely more than offset any advantages from maintaining constant directivity down to 500 Hz.

Yes that's what he said but Earl also didn't answer my question here http://www.diyaudio.com/forums/gedlee/122318-diy-waveguide-loudspeaker-kit-154.html#post2024941 ;)
 
well, size and cost certainly are significant issues- I guess the other part of it would be that unless you were going to attempt full-bandwidth, you'd have to find a woofer that's directional at the XO while still behaving well, and there are a VERY limited selection of good 30" drivers.

Would love to see you do one with the ginormous fostex woofer and a 30+" waveguide though!


Was looking recently at multicellular horns... came across this midbass horn:

HiFiForum.nu - En man...*Midbashornmätningar*

Graph is about half way down the page... looks pretty CD from 100-500hz...

Whats to be gained from having directivity this low?
 
Any other specific reasons besides size and cost? Why is the magic number for directivity 1000 Hz and not 500 Hz or even lower where geometric acoustics still is a valid concept?

My house is twenty eight hundred square feet, and it's a challenge to find room for the Summas. If I did it again, I go with the twelves.

Originally I had them in a basement, and having all that space to work with was nice. It's hard to grasp how much space these things take up.

 
"I'd think an important reason is that we're less sensitive to imaging cues at 500 Hz with resulting less benefit from CD characteristics."

"Do you have any scientific data to support this claim?"

I don't personally possess the data, it's just what I've read several times.

To be clear, I've read what I said about freq at which imaging cues occur, and am inferring the lack of as much benefit from extending CD below that.

Do you have reason to dispute it?
 
Noah

I don't personally possess the data, it's just what I've read several times.

Did you read it in a scientific paper or somewhere else?

To be clear, I've read what I said about freq at which imaging cues occur, and am inferring the lack of as much benefit from extending CD below that.

Do you have reason to dispute it?

Unfortunately yes. You have Toole's book, right? Look up page 238. He's talking about stereo bass and cites a study by Martens et al. that found localization cues down to 80 Hz.

Best, Markus
 
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