A speaker physics question.

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Originally Posted by cradeldorf

When sound comes out of the back of the speaker does it come out perpendicular to the cone or perpendicular to the face?

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Ignoring any potential HF reflections off the frame/motor:

Radiation from a Baffled Piston
Radiation from monopoles, dipoles, quadrupoles
Sound Radiation from Cylindrical Radiators

GM

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Originally Posted by VolvoHeretic

So, if the horn or port is facing forwards, the sound coming out will have turned 180 degrees and be in faze with the speaker, and facing rewards will be out of faze and requires the sound to bounce off of the back wall 180 degrees to be in faze? How about these speakers with the ports or PR aimed out the sides, are they 90 degrees out of faze?

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No amount of degrees is going to make them in phase, it is just impossible.

They will be in and out at different wavelengths. it is a flawed design period, you just can NOT cheat physics.

Imperfect speakers can still sound decent. But don't think you are gonna find a magic trick that ain't there.

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Originally Posted by cradeldorf

Ok here's a couple of pics....they sound open that's for sure but I need to work on the bass. I shot some small vids of them in action. I might post one up later depending how it sounds. I think I'm gonna try some sides and top tomorrow. they'll stick out 6 inches from the baffle forward.

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Hate to be a critic, but the first thing a baffle does is separate front and back waves. Since your design does not you put one foot in the grave. Bad idea in my book.

If you want a flat baffle you have to make it large enough so that sounds from the back and front are isolated.

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Originally Posted by Old Guy

Hate to be a critic, but the first thing a baffle does is separate front and back waves. Since your design does not you put one foot in the grave. Bad idea in my book.

If you want a flat baffle you have to make it large enough so that sounds from the back and front are isolated.

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Yep I agree. LOL although It took the long way to get through my head.

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Originally Posted by Old Guy

No amount of degrees is going to make them in phase, it is just impossible.

They will be in and out at different wavelengths. it is a flawed design period, you just can NOT cheat physics.

Imperfect speakers can still sound decent. But don't think you are gonna find a magic trick that ain't there.

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Yep, BLHs can sum to sound as one out to the rear pipe's/horn's 3rd harmonic, so only good for ~2 octaves before the frequency response turns into an increasingly sawtooth looking one. For wide BW use then, the horn either needs some throat damping and/or folded in such a manner to mechanically attenuate its higher BW off the back of the driver.

GM

Quote:

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Originally Posted by GM

Ignoring any potential HF reflections off the frame/motor:

Radiation from a Baffled Piston
Radiation from monopoles, dipoles, quadrupoles
Sound Radiation from Cylindrical Radiators

GM

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Thanks for the sites GM. This will take a while to absorb. Will report back with couple more questions when Iv'e reread it a few more times.

Quote:

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Originally Posted by GM

Yep, BLHs can sum to sound as one out to the rear pipe's/horn's 3rd harmonic, so only good for ~2 octaves before the frequency response turns into an increasingly sawtooth looking one. For wide BW use then, the horn either needs some throat damping and/or folded in such a manner to mechanically attenuate its higher BW off the back of the driver.

GM

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Totally agree, they can only be used over a limited bandwidth which is why they are pretty much just pro sound subs these days....

I might have said "close enough to sound as one" but lets not quibble semantics.:D

They can be made to work well in wide BW apps such as with 'full-range' drivers, but for best performance overall they must be designed with a fairly low acoustic XO, which is too often ignored and why so many designs I've auditioned or seen posted on the various forums either have a 'hole in the middle' of its response and/or sound too 'phasey'/'muddy' through the mids due to excessive front/rear output timing errors to qualify as 'HIFI' for me.

Agreed, that wasn't my intent. ;)

GM

Duh...meant to mention what you said about designing in HPF beige quite useful. Just dropped out of brain.:D

Kinda doubt the average user could do that though, so I do try and err on the safe side.

My attention span is too short these days to walk a newb thru a large can of worms.:confused: So I just try to not get into doing it. I'll be talking about something else before the conversation is over.:D

Since were on the subject of BLH's is there an easy way to calculate the horn? I read all night different pages on horn design, downloaded hornResponse and got nowhere. Here is a design I came up with. It's 40 w x 30 H x 18 d. The horn will exit out the side.