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Multi-Way Conventional loudspeakers with crossovers

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Old 15th February 2013, 09:28 PM   #21
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Originally Posted by john k... View Post
Curious, what was the measurement distance?
About 40cm (16").
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Old 16th February 2013, 12:23 PM   #22
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[QUOTE=markus76;3369563]Yes. You can't pack two 12" woofers any smaller.

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Surely the output of such topology is Dipole??
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Old 16th February 2013, 12:30 PM   #23
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Click the image to open in full size.

Red = front chamber
Blue = back chamber
Gray = side

Mic was placed 10cm from enclosure.
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Old 16th February 2013, 08:40 PM   #24
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So it is a dipole from that measurement
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Old 17th February 2013, 02:14 AM   #25
puppet is offline puppet  United States
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markus76 .... back chamber(s) resonance around 180hz ... front around 320hz ... is that about right?
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Old 17th February 2013, 06:29 AM   #26
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So it is a dipole from that measurement
Yes. A little bit less output at the back.
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Old 17th February 2013, 06:34 AM   #27
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markus76 .... back chamber(s) resonance around 180hz ... front around 320hz ... is that about right?
Chamber resonanz is about 270Hz. Here's the impedance:

Click the image to open in full size.

Note how the driver resonance decreased from 31Hz to 21Hz.
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Last edited by markus76; 17th February 2013 at 06:40 AM.
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Old 19th February 2013, 04:02 AM   #28
Face is offline Face  United States
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Not as pretty as the one above due to only being a test box. Drivers are JBL GT5-15: GT5-15 | 15? single voice coil subwoofer | JBL US

Click the image to open in full size.

Except at the extreme LFs, distortion is only ok...(taken at 1M).

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On axis.

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90 deg.

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180 deg.

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Only looks usable up to 100-125hz, which should be fine as the mid I have in mind is an AE TD-15M.

What intrigues me is the spider venting is exposed on the outside. I may cover it with another layer of ply on the outside just to see what happens to the response. It may help with LF extension, but it also may make the dipole peak worse, no?
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Old 20th February 2013, 10:11 PM   #29
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No love for my ghetto box?
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Old 20th February 2013, 10:16 PM   #30
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The issue I see with that (and other 'slot loaded') is the difference between front and rear output.

If you notch the front output quarterwave, what happens to the back output ?

If smooth dipole radiation is desired then the front and back output needs to be as symmetrical as possible.
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