I decided to play around with some designs for improved space-filling effect for surround/rear channel speakers. After a few cogitations and iterations I settled on a combination of designs that did some of the job well.
For the low end I went with an upward firing woofer with an inverse hyperolic (or some such shape) cone over it -- the old Zenith Circle Of Sound 360 degree dispersion thing. The test woofer was a Goldwood 5.25" poly cone.
For the high end I put some Boston Acoustics metal dome tweeters into a vertical 1.5" diameter Karlson K-tube. I've always liked the reverb effect from the frequency dependent dispersion, but more so in the higher freqs. I mounted these into some PVC couplers, and those onto the top of the woofer's dispersion cones. Xover for these was just 6 dB/oct @ 3.5 kHz. Power was a pair of Audiosource AMP100s, one running stereo @ 50 wRMS for front and rear L/R, one at 100 wRMS mono for the sub and center channel
Here's a couple pics: a finished product, and the complete system I tested them in. Testing was outdoors so not to drag room acoustics into the mess.
The subjective output was low compared to the front speakers, but then it ought to be. It's not supposed to act like a point source but rather fill the space. The Goldwoods were a bit crunchy at the full 50 w but the BA's held their own. The reverb effect from the K-tubes was only easily detectable in the sweet spot, but there it added a vertical dimension to the surround.
I'm considering actually using a surround sound system with these to see how good it can get (or go down the tubes -- pun unintended but I'll take it). And frankly the woofers' dispersion cones came from a set of 40w full range surround sound towers that came with a JVC SU-A7 decoder and "rear" channel amp. But first I needed to see if these would work at all, and they did. Maybe well enough that I don't need all that extra hardware. I'm moving them indoors and giving them a good long listen with some favorite old material. But as for the design itself, I'd say it was very successful for a first build.
For the low end I went with an upward firing woofer with an inverse hyperolic (or some such shape) cone over it -- the old Zenith Circle Of Sound 360 degree dispersion thing. The test woofer was a Goldwood 5.25" poly cone.
For the high end I put some Boston Acoustics metal dome tweeters into a vertical 1.5" diameter Karlson K-tube. I've always liked the reverb effect from the frequency dependent dispersion, but more so in the higher freqs. I mounted these into some PVC couplers, and those onto the top of the woofer's dispersion cones. Xover for these was just 6 dB/oct @ 3.5 kHz. Power was a pair of Audiosource AMP100s, one running stereo @ 50 wRMS for front and rear L/R, one at 100 wRMS mono for the sub and center channel
Here's a couple pics: a finished product, and the complete system I tested them in. Testing was outdoors so not to drag room acoustics into the mess.
The subjective output was low compared to the front speakers, but then it ought to be. It's not supposed to act like a point source but rather fill the space. The Goldwoods were a bit crunchy at the full 50 w but the BA's held their own. The reverb effect from the K-tubes was only easily detectable in the sweet spot, but there it added a vertical dimension to the surround.
I'm considering actually using a surround sound system with these to see how good it can get (or go down the tubes -- pun unintended but I'll take it). And frankly the woofers' dispersion cones came from a set of 40w full range surround sound towers that came with a JVC SU-A7 decoder and "rear" channel amp. But first I needed to see if these would work at all, and they did. Maybe well enough that I don't need all that extra hardware. I'm moving them indoors and giving them a good long listen with some favorite old material. But as for the design itself, I'd say it was very successful for a first build.