A Thread for those interested in PPSL enclosures - Page 28 - diyAudio
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Old 25th April 2012, 10:08 PM   #271
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Default Dispersion horisontal vs vertical

Have any of you measured the dispersion on a PPSL? How does it measure closer to its useful upper frequency range? Horisontal versus vertical dispersion?

As the frequency extension is limited by how well you optimise the design of the plenum, I guess this also limits/controls the dispersion as well.

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Old 25th April 2012, 11:07 PM   #272
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With a typical 7" wide plenum oriented vertical, the horizontal dispersion is about 180 increasing to 360 below the baffle-step width.
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Old 25th April 2012, 11:10 PM   #273
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Thank you! How far up in frequency does it stay 180 degrees?
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Old 26th April 2012, 01:12 AM   #274
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It would narrow above the slot width, 800hz for 7", but the 1/4W notch from the cavity depth will be lower than this.

http://http://forum.speakerplans.com...1000000#550941
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Old 26th April 2012, 01:40 AM   #275
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Old 7th June 2012, 10:47 AM   #276
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reading this topic a few times ,got me intrested.
when truck space is an issue ,and amp power isn't,th are out of the picture.
only way to get more output is higher x-max drivers like the 18nlw 9600.
taking this driver as an example,with an x-max of 14mm,it has enormus vd at full trust.
what wil be the minimum width of the plenum,without getting compression issue's ,using djim config.
they wil be crossed at 80~100 hz max
the driver height is total 24 cm.
Click the image to open in full size.
edit/ if one would give the plenum also a horizontal v-shape will this undo the "ppsl"effect?

erik
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Last edited by epa; 7th June 2012 at 10:55 AM.
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Old 7th June 2012, 11:55 AM   #277
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I don't like the T/S parameters on that driver for a reflex design, have you tried a design on a computer and seen what kind of a port you will need?
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Old 7th June 2012, 12:48 PM   #278
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Quote:
Originally Posted by djk View Post
I don't like the T/S parameters on that driver for a reflex design, have you tried a design on a computer and seen what kind of a port you will need?
it is just an example ,i was leaning to the 18nlw 9000 or maybe cheaper the b&c18 tbw100,anyway looking for big vd drivers.
a port 1000cm2* 40cm or 2 500*40 ?
size of the cab wil be determent when we decide what driver.
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Last edited by epa; 7th June 2012 at 12:55 PM.
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Old 8th June 2012, 12:22 AM   #279
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I was considering designing a PPSL with the woofers mounted from the back of the slot manifold instead from the inside of manifold slot. I figured it would be easier to mount them that way if I used passive radiators that were a little larger so I can access the woofers (I had designed a PPSL with access panels and realized the hole is same as would be for PR ). The PR's would be on the sides of the cabinet which is perfect for cancelling movement. I will post a pic when I do some google sketchup. Worth going PR? I have not seen one yet, and have not designed with PR. My version of WinISD can't do PR's. I have some free 10" sony car subs that model well in BR on WinISD. Many car subs cannot be rear mounted (like my sony's) due to thier stupid need to make the speakers pretty (with crappy plastic surround covers and basket covers). I will most likely build these with on speaker mounted normal, and one from rear, but plan on doing different woofers in future and will build cabinet with both mounted from rear.
I built some speakers years ago that had a PR, and they sounded great. PR will also be good for speakers that need weird port lengths...
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Old 8th June 2012, 01:11 AM   #280
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The first PPSL I did had a very narrow slot, the woofers had to be mounted through access panels.

I did one with a PR because the box was so small a regular port was impractical.
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