yep, you can mask off quite a bit of a diaphragm and it will still work.
I did that with my 'black mirror' project that's documented on this forum
I also did this in a project named "soundbar bateman style"
both projects are on this forum.
The Nexo waveguides were my inspiration.
Here's the frequency response of the woofer and tweeter from the latter project. I'm too lazy to read my own thread, but iirc, this is the unfiltered response. You can see that the baffle over the woofer creates an acoustic second order low pass filter.
I did that with my 'black mirror' project that's documented on this forum
I also did this in a project named "soundbar bateman style"
both projects are on this forum.
The Nexo waveguides were my inspiration.
Here's the frequency response of the woofer and tweeter from the latter project. I'm too lazy to read my own thread, but iirc, this is the unfiltered response. You can see that the baffle over the woofer creates an acoustic second order low pass filter.
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Doug Winker used to use something similar when he competed with his car:
I speculated that Doug's waveguide was there to do two things:
1) reduce the apparent size of the woofer. Basically this lets you get the output of an 8" woofer, but it behaves like a smaller driver. This improves the polar response.
2) The ragged edges on the waveguide are there to improve the response. Basically when everything is equidistant you get peaks and nulls due to the sound combining or interfering at certain frequencies. By breaking up the symmetry you smooth the response. JBL does something similar in their new phase plugs on their compression drivers. (Look up the patents from their chief designer, Alexander Voishvillo.
Yes, to some extent.
http://www.diyaudio.com/forums/full...-aperture-z-baffle-dipole-19.html#post4355550
It's 7" midrange in my case, I felt it's not an all-rounder after a while, so eventually I dropped it.
http://www.diyaudio.com/forums/full...-aperture-z-baffle-dipole-19.html#post4355550
It's 7" midrange in my case, I felt it's not an all-rounder after a while, so eventually I dropped it.
KEF Concord, circa 1966.
An externally hosted image should be here but it was not working when we last tested it.
Nexo (still current)
.
An externally hosted image should be here but it was not working when we last tested it.
My friend djk, can you explain me your equation to calculate the phasing plug of Nexo for example?
What does it mean 7.40"?
Thank you.
What does it mean 7.40"?
Thank you.
"It may be calculated by the same method difraction slots are calculated by.
"My friend djk, can you explain me your equation to calculate the phasing plug of Nexo for example?"
The formula is for a center aperture, as the JBL example. It came from a 1977 JAES article from Altec engineers.
I would have to think on how to apply it to the NEXO plug (the reverse of the JBL slot).
It's just a function of the frequency and wavelengths though.
Easy enough to cut-and-try with cardboard, and test the results.
"What does it mean 7.40"?"
"(1,000,000/beamwidth (in degrees))/frequency=width
1000000/90/1500=7.40" "
"My friend djk, can you explain me your equation to calculate the phasing plug of Nexo for example?"
The formula is for a center aperture, as the JBL example. It came from a 1977 JAES article from Altec engineers.
I would have to think on how to apply it to the NEXO plug (the reverse of the JBL slot).
It's just a function of the frequency and wavelengths though.
Easy enough to cut-and-try with cardboard, and test the results.
"What does it mean 7.40"?"
"(1,000,000/beamwidth (in degrees))/frequency=width
1000000/90/1500=7.40" "
how did you create the template to cut this out by taking an image of the jbl and printing it off scaled to the appropriate size ? I'd like to make one of these
Here's a pic of the Kef Concord (the existing link was dead)
