A Thread for those interested in PPSL enclosures - Page 36 - diyAudio
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Old 6th October 2012, 11:31 AM   #351
Scott L is offline Scott L  United States
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Default What kind of question ?

Quote:
Originally Posted by anubisgrau View Post
OK, whatever-phase, what's the benefit over face to face mount?
Consider the title: A Thread for those interested in PPSL enclosures

Consider reading from post #1
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Old 6th October 2012, 12:53 PM   #352
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cavity resonance. unerstandable, too much pressure in.
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Old 6th October 2012, 03:34 PM   #353
djk is offline djk
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Reduction of even harmonic distortion, typically by 20dB.
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Candidates for the Darwin Award should not read this author.
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Old 6th October 2012, 06:10 PM   #354
Djim is offline Djim  Netherlands
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Old 6th October 2012, 08:30 PM   #355
kees52 is offline kees52  Netherlands
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Originally Posted by Djim View Post
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Look this is clear, I see, like you all say calculate for a vented box, I presume the pipes have to big enough just to make not hear the air going in and out.

here I have a plot from my H frame, line level corrected, yes offtopic for a moment, but I want to make the PPSL so I stick here for a while, The slot has I also did read so small as the magnet conus of the driver kan be without touching each other, strange that two woofers are connected what does other normal boxes loose bass because of opposite fase, strange design and box who works with compression-decompression as I think I see, yes I am green behind the ears..
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File Type: jpg test-H frame final..jpg (650.7 KB, 394 views)
File Type: jpg H-frame spl test-corrected.jpg (194.3 KB, 376 views)

Last edited by kees52; 6th October 2012 at 08:38 PM.
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Old 6th October 2012, 09:01 PM   #356
Djim is offline Djim  Netherlands
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Hi Kees,

The plenum (cavity) makes it look more difficult than it actually is. You can even leave the plenum out if you want (see picture) but that lowers the functioning of the Push-Pull as frequency rises.

The trick behind PP(SL) is that drivers have different (electrical and mechanical) properties between moving forwards and backwards. By flipping around one driver you can eliminate part of these differences, that otherwise would lead to non-linear movement (distortion).

Click the image to open in full size.

Edit: This picture is only Push-Pull and not Push-Pull Slot Loaded... ;-) Sorry for the title...

Last edited by Djim; 6th October 2012 at 09:09 PM.
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Old 6th October 2012, 09:08 PM   #357
kees52 is offline kees52  Netherlands
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Quote:
Originally Posted by Djim View Post
Hi Kees,

The plenum (cavity) makes it look more difficult than it actually is. You can even leave the plenum out if you want (see picture) but that lowers the functioning of the PPSL as frequency rises.

The trick behind PP(SL) is that drivers have different (electrical and mechanical) properties between moving forwards and backwards of the cone. By flipping around one driver you can eliminate part of these differences, that otherwise would lead to non-linear movement (distortion).

Click the image to open in full size.
Hi Djim

I have no problem with the difficulties about the enclosure itself but how it is designed technical speaking, but you give me now a very good explanation about it, the total volume looks like designed as vented box with as extra a plenum.

I have try with software the visatons but a port of 2.30 meter is a little long, so I think that software has a to long equation.

in your example I see the drivers are in fase, with a plenum she are connected out fase, or see I something wrong.
Yes I am green behind the bla bla I am a amp designer, loudspeakers are new for me, so hard learning.

oke, thanks en een goede avond nog.

Last edited by kees52; 6th October 2012 at 09:10 PM.
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Old 6th October 2012, 09:15 PM   #358
Djim is offline Djim  Netherlands
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Your welcome. Yes its just a basreflex (or another enclosure type if you want) with two drivers and a plenum. If you make the basreflex-port(s) too long they will have a resonance in the subrange that you want to prevent. Try to keep the length of the port(s) below 80cm.
When you use WinSID (free software) you can model basreflex and see the resonance of the port.

(prettig weekend)

Last edited by Djim; 6th October 2012 at 09:19 PM.
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Old 6th October 2012, 09:28 PM   #359
kees52 is offline kees52  Netherlands
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Quote:
Originally Posted by Djim View Post
Your welcome. Yes its just a basreflex (or another enclosure type if you want) with two drivers and a plenum. If you make the basreflex-port(s) too long they will have a resonance in the subrange that you want to prevent. Try to keep the length of the port(s) below 80cm.
When you use WinSID (free software) you can model basreflex and see the resonance of the port.

(prettig weekend)
Dank je wel.

Oke, I wil try that.

Ik test net de H frames, wel hij gaat vlot naar 30 hz en lager alles rammelt hier maar he beperkte luidheid, maar ja het een of het ander.

I like the PPSL for testing, I have the martin sheets for testing the visatons WSP26S I do use for the tests, it are very good interesting woofers, the PPSL looks like a dipole, you say a vented box but there is more these box go low with a high efficienty as i did read because horns are involved as mid high.

groet
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Old 6th October 2012, 09:56 PM   #360
Djim is offline Djim  Netherlands
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In PA it is not uncommon to use two acoustic loads, each one loading one side of the driver. They do this in order to gain output level or to expand the bandwidth, BUT at cost of distortion.

For HiFi I wouldn’t recommend such system as it will introduce more THD. What you want for high quality sound is a minimum amount of system resonances.


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(tis altij 't-een of 't-aander )
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