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Old 12th March 2014, 04:35 PM   #11
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A Qts of 0.312 might be optimal, but it isn't critical to get good bass from a PPSL. A slightly higher or lower Q just means a larger or smaller box. Perhaps you could establish an acceptable deviance from the ideal Q in order to allow yourself more driver options? For instance, I was also considering the Kappalite 3012LF, instead of using a 15" driver.
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Old 12th March 2014, 09:42 PM   #12
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Right, I was still including drivers within a few qts points (.26-ish - .36-ish). I was mainly looking at 18" drivers, but I might want to look at 15" drivers due to the large port size increasing box volume quite a bit.
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Old 14th March 2014, 03:47 AM   #13
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Just as a personal preference, I would consider a 90-degree clamshell arrangement for a 2x18" box, hoping to reduce volume. Would it no longer be a true PPSL?
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File Type: jpg 2x18 Clamshell.jpg (89.4 KB, 116 views)
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Old 17th March 2014, 04:23 AM   #14
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That works, but saves no volume on the plenum.

The speaker in the photo is actually an open baffle PA speaker with dual 18's.

I will be building a (sealed) quad 12 version with a 60 V-angle later this spring.

Click the image to open in full size.
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Old 21st March 2014, 05:22 AM   #15
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Looks like a fun design, I'd like to hear some reviews. I've considered a 4x12" version with your original baffle for the Kappalite 3012LF. I also designed a variation of a 2x3012LF employing the same layout as those M&K subs for a bass guitar cabinet. The lower driver was lowpassed at 95Hz & the upper 12 was crossed at 400Hz 2nd order LR (insistence of the bassist; I would have crossed it at 800Hz) to a B&C 6.5" cone. He's happy with it.
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Old 26th March 2014, 11:05 PM   #16
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Is there much sonic difference between your standard PPSL and the 60 V-angle?
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Old 27th March 2014, 01:08 AM   #17
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I haven't auditioned the 60V type yet, the above photo is a hi-fi speaker.
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Old 27th March 2014, 10:58 AM   #18
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Cuppa Joe
earlier in the thread you referred to a DBX driverack as "not the best" what is your objection or dislike with it?
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Old 28th March 2014, 04:30 AM   #19
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My main objection is how it EQ's the system using pink noise. It works fine for mids & HF, but it over-attenuates most bass frequencies. Also, it tends to add +10dB spikes in the midbass region at or near 160Hz. I'm guessing that it's trying to compensate for baffle step loss. Basically, I have to re-EQ by ear everything below about 200Hz. Otherwise, I have no problems with it for crossover duty.
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Old 28th March 2014, 10:44 AM   #20
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i understand what your saying there.
although it's good guide/reference measurement i too find that final tuning is best done by ear
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