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Push-Pull in Open Baffle?
Push-Pull in Open Baffle?
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Old 17th April 2018, 08:49 PM   #1
vessk0 is offline vessk0
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Question Push-Pull in Open Baffle?

Hello, I'm making my first Open Baffle 3-way project (TMWW) and I'm planning to use two mid-bass drivers in a push-pull configuration (for reduced 2nd harmonics) - the upper one will be faced towards me and the bottom one will be facing me with its magnet. I heard that push-pull concept is working even in a free air like on an open baffle setup and the common volume is not necessary.

Is this true?
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Old 17th April 2018, 11:09 PM   #2
Sonce is offline Sonce  Macedonia
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Yes.
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Old 17th April 2018, 11:18 PM   #3
planet10 is offline planet10  Canada
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Push-Pull in Open Baffle?
If you have good woofers you will gain little. And there is an argument that lowering 2nd order below the 3rd level will leave things sounding poorer.

If you are crossing low enuff you might consider loading push-push (tricky on an OB) and reducing the load on the “cabinet”

dave
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Old 18th April 2018, 02:03 AM   #4
Sonce is offline Sonce  Macedonia
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Argument about 2nd/3rd ratio may be valid for "classic" woofer-midrange crossover frequency of about 500 Hz, because 3rd harmonic falls in the mid-high frequency range where ear is more sensitive to harmonic distortion. But, open baffle woofer crosses over mid driver at about 250 Hz, one octave lower, so the 3rd harmonic is in the lower frequency range where ear is proportionally less sensitive to distortion. Reduction of the woofers 2nd harmonic in the open baffle brings better sound quality.
The real problem from the speaker which faces its rear side to the listener can be the noise from the air moving around speaker chassis parts.

Last edited by Sonce; 18th April 2018 at 02:08 AM.
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Old 18th April 2018, 04:08 AM   #5
Cableaddict is offline Cableaddict
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Quote:
Originally Posted by Sonce View Post
Argument about 2nd/3rd ratio may be valid for "classic" woofer-midrange crossover frequency of about 500 Hz, because 3rd harmonic falls in the mid-high frequency range where ear is more sensitive to harmonic distortion. But, open baffle woofer crosses over mid driver at about 250 Hz, one octave lower, so the 3rd harmonic is in the lower frequency range where ear is proportionally less sensitive to distortion. Reduction of the woofers 2nd harmonic in the open baffle brings better sound quality.

The real problem from the speaker which faces its rear side to the listener can be the noise from the air moving around speaker chassis parts.
Indeed. I have been experiment with a "simple" (not slot loaded) P-P system recently, except for subwoofers.
Although the sound is VASTLY improved over the stock BR mounting (I mean night & day) there is indeed quite a bit of noise coming from the reversed driver. I know this because I record both drivers separately with a close mic, to compare them. (And yes, I adjust the ports accordingly.) - But isn't this a problem also with an open baffle? I mean, it's OPEN, after all.

In a PPSL mounting, (something I have not yet tried) I would guess that this is much less of a problem, since the speakers are sideways to the listening position. Also, depending upon your upper frequency needs, & how you plan to install / mount the drivers, you could make the slot fairly narrow, which would further shield the exposed cone.

You could probably even fill the slot with sound absorbing material like mineral wool, to absorb much of whatever noise is there.

-----------------------

But I digress. Open baffle is a different can of worms. Still I don't see why you couldn't make a PPSL "plenum box" and then just mount THAT into an open baffle. - or just place it on the floor, as is.

Last edited by Cableaddict; 18th April 2018 at 04:18 AM.
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