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Hi,
I plan on attempting a design of a midbass cabinet for live sound usage.
The two prior cabs I've built have all been failures. The last was a hyperbolic-exponential horn with T=0.7 and properly ported for reduced displacement for the operating range of 90-5K. Yeah, not a mis-print.. 5kHz. I was restricted by budget to a three-way system from ad-hoc components I had already. All in the fun of providing sound for benefits.
The tweeters are Electro-Voice DH3s on HPT94 horns and can not be crossed lower than 5k. I can mostly fill the gap with a DH1,DH2, or ND6x on an HP940 horn doing 1.2kHz-6kHz. Low-pass for that shouldn't be less than 1.2kHz due to loss of vertical. The docs say loading is all right for the driver, but coverage is going to suffer. That leaves me needing 90-1.2kHz.
But this time I have to pay undue attention to the horizontal pattern. As you all can guess, running a pair of twelves in a 20" deep horn became really beamy in the top end. That was the failure. I expected it, but was worse than I expected. The honkiness was fine, that just meant the horn was kicking in @ 170Hz. God made EQ to manage efficient speakers. See photo.
This time I want to attempt a horn mainly for coverage pattern using waveguide principles. There seems to be a lack of online docs, though. About the only freebie docs on waveguides I can seem to find was http://sound.westhost.com/articles/waveguides1.htm
Next would be spending on the AES pdfs to get Keele's papers, etc.
Anyone know any docs they can point me to?
The cab is obviously going to have to be for a single 12" instead of dual. The driver itself is going to need mods. Cut out the dust cap and lathe a nose cone (phase plug) for it.
Test the phase plug using a clear tube closed at the end filled with smoke and use a strobe keyed off a division of the oscillator frequency to observe the wavefront to see the effects of modifying the shape of the phase plug and manifold?
Project will fail here if compression ratio gets too high if the manifold has to get too small.
If that passes, the vertical part of waveguide seems tricky for which I need to delve into the math, that I don't have yet..
Yes, I'm a DIY nutt. Any thoughts on waveguides or CD horns in general?
Peace, out.
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