When sound comes out of the back of the speaker does it come out perpendicular to the cone or perpendicular to the face?
Direction is frequency dependent, same as front of cone. Lower frequencies are less directional. Since HF is too short to make the turn in a reflex or too short to flow around a finite "infinite" baffle, my answer is neither.
GM should chime in here, more his area than mine.
Your neighbors called. They like your music.
I did a test with a 3 x 3 block of 1/2 plywood in a cookie pan of water, as i tapped one corner the waves came off perpendicular to the two opposite sides. I'm betting that the sound comes out perpendicular to the cone. call me corny but it's one way of seeing it. In case your wondering I'm trying to come up with a back loaded horn cabinet design for a winter project.
I'm not sure that test holds water.
You are using the force from the speaker to accelerate water. A test with something much lower in mass would be in order.
Regardless sound just plain does not travel in a perpendicular line. An ideal point source has a spherical pattern.
The sound is gonna emanate in a pattern of some sort. Never perpendicular. And you really don't need that info to design a rear loaded cab.
I would suggest looking at successful designs for inspiration, cobble and try works, eventually. Must better to modify existing designs to your needs.
Padding the sides deals with reflections. Just concentrate on the loading itself.
Your neighbors called. They like your music.
I hear you OG but if you yell hello in a cave and it hit's a wall parrallel to you it will come back. Same with yodelers in the Swiss alps so if you direct the sound in an orderly manner out of the cab instead of letting it rattle around inside you'll reinforce the SPL and eliminate that sound waves bouncing around in a wooden box sound. Here is a couple I'm working on the first one is 40W by 24D by 36H The second one is 48W by 24D by 36H. I reread what you said and I agree that the sound waves expand as they leave the source but only because they are not directed by a hard surface, For instance when people are talking in a boat on a calm lake. Even if they're way out you can almost hear what there saying because their voices are directed along the hard flat surface of the water. By loading do you mean creating some back pressure? Because I would think the basket does that to a degree on the back of the speaker.
Last edited by cradeldorf; September 14th, 2011 at 03:01 PM.
Yes, if you yell at a parallel wall it comes back, that still does not mean the sound travels in only one direction.
The box designs you show will work, but won't have anything resembling flat response.
Splitting the horn in two creates two small mouths, to a certain extent LF response is dependent on mouth area . Designs like you show were abandoned some 50 years ago.
A "scoop" like the JBL is a much better idea. You still are gonna have massive phase issues. The response graph is gonna look like a roller coaster. Not so much an issue for a sub, problem for wider range.
If you can blunder thru French have a look here...
Liste des plans
Your neighbors called. They like your music.
I agree that sound radiates outward, But If you yell at a wall and a person is standing in front of the wall sideways so their ear is pointing towards you your yell will be louder to them than it would be to two people standing on either side of the wall because you pointed your mouth directly at the wall. So your saying 2 small mouths don't equal one big one? I have seen some bass horns and I agree they do get crazy large. My other design was modified A7 cab. see below.
Two small mouths do not equal one big one unless they are right next to each other. You can make small modules where most of the cab front is mouth, and stack them. But separate them and you lose response and efficiency.
We built modded A-7's like that back in the 70's. Again, if you try to use a cab like that wide range your response graph is gonna have peaks and dips like the Himalayas. You can pick a wide peak and use it only at that frequency band...like 40-120 Hz. But as you go outside that band it will get peaky and dippy...
ANY...let me be emphatic...ANY rear loaded horn is gonna be anything but flat due to phase issues between front and rear paths. The design is only used these days as pro sound subs. Like the one I posted.
Wavelength of sound changes with frequency but the horn path length stays the same, so some frequencies will combine, some will cancel.
Designing cabs like that is very intensive, I couldn't do it. I might be able to take an existing design and by "cut and try" improve on it's performance.
Last edited by Old Guy; September 14th, 2011 at 09:37 PM.
Your neighbors called. They like your music.
Ok just to be on the same wavelength, by flat response do you mean that all the frequency's are coming out at the same volume or decibel? I understand the phase part...I think.
Last edited by cradeldorf; September 15th, 2011 at 01:20 AM.
Apparently you never met my ex wife and her two sisters.Originally Posted by Old Guy
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