A Thread for those interested in PPSL enclosures - Page 7 - diyAudio
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Old 9th May 2011, 03:54 AM   #61
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nope, no thread of my 18's (now owned by my neighbor) designed by a close friend. I feel them thumping my chest in my apartment every month or so. I'm rarely on this forum, but the ppsl thread caught my attention.

I ended up using 1 box (I used 2) crossed to a pair of 15" 3-way vega's at 100hz. Actually I blew the midranges on 2 different pairs of 3 way vegas (who's ever heard of doing that?). But I had used both sub boxes when running dual 15" per side, mid horn, piezo with active crossover points (24db LR) at 80hz, 500hz, and 5khz. Jeez that was loud. My kids said "You know when you told us not to crank it ? We didn't realize it was for our own hearing protection." lol.

Dimensions don't matter (maybe 2' x 3' x 4'). It was 16-18ft3 tuned to 27hz where the driver box was 9db down (6th order = high pass filter with a q=2 at tuning = 6db boost at tuning with subsonic filter below tuning). You are adding 6db boost at tuning, where the driver isn't moving much. Massive output from a pair of 4.6mm xmax 18's. It works well with lower qts drivers (higher spl 1w/1m), small box and deep with a squeek of boost, and inexpensive also. I'd crank it and people wouldn't believe 20hz wasn't there. It went lower without the booster box, but the volume also went down as the freq went below 60hz (27hz was 9db less than 60hz, and 20hz was there but maybe another 9db lower than 27hz).

The guy that built the box was scoffing as we brought them in. He was a car audio guy. "I don't like 18's" he said. We turned them on and he said "I've never heard 18's that quick and clean." I'd made a smaller prototype box with a pair of 12's. The 12" ported were quicker, cleaner, and punchier than his 3 x 10" sealed jl audios (qtc .707) in his pickup. There went his sealed vs ported quickness arguements.

If I was to build another sub, I'd only build a ppsl. Sealed / ported / passive radiator/ linkwitz transfer / 6th order, that's all up to you. I recommend lots of cone area. That way the driver isn't moving as far = less harmonic distortion, if you can tolerate the large box.

I don't even run a sub now. See my avatar.

Norman

Last edited by norman bates; 9th May 2011 at 04:00 AM.
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Old 9th May 2011, 04:35 AM   #62
tb46 is offline tb46  United States
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Hi Djim,

Enjoyed your Post #60, particularly the "...models of Partial Movement from a cone...". Hadn't thought about the PPSL that way.

Regards,
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Old 9th May 2011, 04:19 PM   #63
Djim is offline Djim  Netherlands
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Thanks Oliver, that's why high speed cam's come in handy...

Since last year we are working on this proto-concept (1/3WL@38Hz / 104dB / 4kW/ 18Sound15LW1500) to replace our 'traditional' 18Sound PP's. That might explain a little

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Old 9th May 2011, 04:27 PM   #64
hawkson is offline hawkson  United States
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Why go from 18's to 15s?
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Old 9th May 2011, 04:37 PM   #65
Djim is offline Djim  Netherlands
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The PP's we have are already loaded with that driver and we wanted to use them.

See LINK

Last edited by Djim; 9th May 2011 at 04:39 PM.
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Old 9th May 2011, 05:24 PM   #66
hawkson is offline hawkson  United States
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Ah, I misread the 18 sound drivers as 18"

Why is the prototype in development since *Last year? And who is we?

Finally, what is the rough size(cubic feet/liters/ dimensions) of the 15" ppsl with the above diagram?
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Old 9th May 2011, 06:47 PM   #67
Djim is offline Djim  Netherlands
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The idea is actually quiet simple, take two Tham TH style folding (pathlength should be at least 3m for 38Hz) and put them together. Make sure you make up for the volume of the driver or you will loose LF. You will get some strange resonances you have to deal with and make sure you use enough bracing to keep the panel flex under control. Can’t advice this driver because it lacks definition in the kick region (I suppose this is one of the reasons why Danley changed them in his TH115). Go instead for the latest generation extended LF drivers. For dimensions and weight think of Turbosound TSW218 (so make sure you truck is loaded with a hydraulic lift ) .
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Old 9th May 2011, 09:00 PM   #68
jbell is offline jbell  United States
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Quote:
Originally Posted by Djim View Post
The idea is actually quiet simple,
no flutes or clarinets??
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Old 9th May 2011, 09:30 PM   #69
Djim is offline Djim  Netherlands
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I was almost wondering if you were still alive, Jbell.
But yes, the 1/2WL resonances are still there... Just disguised them as "strange resonances"

Last edited by Djim; 9th May 2011 at 09:32 PM.
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Old 10th May 2011, 09:19 AM   #70
djk is offline djk
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"just a quick question - did you ever try building a PPSL where the vent exited through the plenum? I'm thinking a shelf port to the rear of the enclosure that vents into the back of the plenum. "

No, it doesn't seem like a good idea to me.

I have made the plenum with ports above and below the opening for the woofers. I made a dual 18 tuned to 28hz this way, and a dual 12 tuned to about 40hz. I am designing a dual 15 tuned to about 28hz this way too.
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