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Multi-Way Conventional loudspeakers with crossovers

Bass driver with concentric port.
Bass driver with concentric port.
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Old 7th September 2003, 12:17 PM   #1
Circlotron is offline Circlotron  Australia
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Default Bass driver with concentric port.

I read a while back about some loudspeaker box having an annular port around the periphery of the driver (well, tautologically speaking anyway ) The puprpose was something to do with the phase realtionship of the driver and port waveform time relationship because they now share a common centre.

Anyway, if I could wave a magic wand and make any kind of driver at all, I would try something like I drew in the attached drawing. (Will someone please call the tautology police? )

The port is now incorporated as part of the centre pole piece. Both cone as port share a common centre. Also, centre pole cooling would be great! Over to you...
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File Type: png concentric port.png (22.8 KB, 309 views)
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Old 7th September 2003, 12:34 PM   #2
SY is offline SY  United States
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Bass driver with concentric port.
What's the point? At the wavelengths involved, the port can be quite a distance away without affecting "phase" or "time relationships" in any meaningful way. One more example of creating problems while trying to solve one that doesn't exist...
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Old 7th September 2003, 12:47 PM   #3
mikee12345 is offline mikee12345  New Zealand
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Default trust not just any book.

50hz=6.8metres long,so no 1/4 or 1/2 wave effects can harm anything as i understand it.....

but long box dimensions, could get into it.

it looks cool anyway
port in the cone
who wouldve thought!
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Old 7th September 2003, 12:55 PM   #4
Pjotr is offline Pjotr
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Hi,

Agree with SY. In fact you create more problems because the mutual coupling between bass port and driver canít be neglected anymore. The work of Thiele and Small ignores mutual coupling.

Note what counts for a bass reflex port is the mass of air herein. For substantial mass you need substantial cross section area of the port. This means a large hole in the pole piece.

Cheers
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Old 8th September 2003, 12:32 PM   #5
mrfeedback is offline mrfeedback  Australia
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Graham,
By fitting a dustcap, mounting that driver in the middle of a door, and extending that tube out long enough you could make a dipole with TL loading.

Eric / - More crazy ideas inspired by Graham.
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Old 8th September 2003, 06:59 PM   #6
roddyama is offline roddyama  United States
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Leave Graham alone.

Remember, they thought Galileo's ideas were crazy.
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Old 8th September 2003, 07:57 PM   #7
phase_accurate is offline phase_accurate
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I think I also once mentioned that Graham was an unlimited source for crazy ideas.

But I don't regard this as a negative attribute !

Regards

Charles
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Old 8th September 2003, 09:21 PM   #8
SY is offline SY  United States
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Bass driver with concentric port.
They said Edison was crazy. They said Einstein was crazy. They said Joe M. Varilla was crazy.
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Old 8th September 2003, 09:50 PM   #9
mwmkravchenko is offline mwmkravchenko  Canada
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Bass driver with concentric port.
Default Co-Drive

Such a driver allready exists. There was quite a writeup in Voice coil a year ago or so.

Mark
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Old 8th September 2003, 09:54 PM   #10
Rotellian is offline Rotellian  United Kingdom
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Actually, all modern tannoy dual concentrics have a bass driver with a hole through the middle for the HF unit. Ive got a pair salvaged. Doesnt sound that great without something there.
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