Thanks for the input, both 
My box building guy is onto the veneering stage of building the subs now, then there are some risers to build, connections and cabling to sort, and then getting them stacked on top of each other,lol
Noted for future reference!
I think I should (hopefully) be fine with regards to levels because I am already running M&K speakers rated down to 80Hz or so (IIRC) and my current setup has them crossed over between 100Hz (LCR) and 150Hz (Surrounds) with decent resultsdjk said:
My box building guy is onto the veneering stage of building the subs now, then there are some risers to build, connections and cabling to sort, and then getting them stacked on top of each other
,lol
4x12" dayton st305 series 2 i think (8mm, low qts).
12ft3 tuned around 28hz (f9).
I've yet to hook up boost/highpass (+6db at 28hz then subsonic filter below that). With room gain, it sounds like a lean deep sealed, but very clean. Instant improvement over shorting ringed double 15's tuned to 27hz. It disappears audibly too.
Simulates 1,200 watts to skip past xmax around 40hz.
I've yet to crank it, but this weekend I will.
12ft3 tuned around 28hz (f9).
I've yet to hook up boost/highpass (+6db at 28hz then subsonic filter below that). With room gain, it sounds like a lean deep sealed, but very clean. Instant improvement over shorting ringed double 15's tuned to 27hz. It disappears audibly too.
Simulates 1,200 watts to skip past xmax around 40hz.
I've yet to crank it, but this weekend I will.
Very nice! Is it a sealed box with the push pull drivers in a slot that is not connected to rear volume? What are the dimensions of the slot?
Must sound very nice.
upper limit ?
Hi Norman,
I would be VERY interested in hearing what you think the upper frequency coverage could/or/should be (?)
Both by measuring and by subjective observations. Nice work, by the way !
Hi Norman,
I would be VERY interested in hearing what you think the upper frequency coverage could/or/should be (?)
Both by measuring and by subjective observations. Nice work, by the way !
There are several variants of PPSL speakers. There is the sealed where slot acts as depression in otherwise sealed box (PPSL-S), the bandpass SL (PPSL-BP) where the vent goes through the a slot, the separate vented like the one shown by Norman Bates here (PPSL-BR), the open back or open baffle slot loaded (PPSL-OB) speaker, and I am sure there is yet another one. Maybe we need specific names for all of these?
lol, clean ?
When you push the tuning to below 30hz, they sound fast. I think that at twice the tuning frequency, it has the same delay as a sealed. And the drivers arn't moving near tuning (= less distortion). And the drivers are canceling harmonic distortion (push pull). And you are 90 degrees off axis from the driver. They can be sealed, ported, tapped horn, bandpass, whatever you want.
A friend said my double 12 (27hz ported) was deeper, faster, cleaner, and punchier than his 3 jl audio 10's sealed in his pickup.
How high ?
Don't know, but I'm sure I could go up to 200hz or so.
When you push the tuning to below 30hz, they sound fast. I think that at twice the tuning frequency, it has the same delay as a sealed. And the drivers arn't moving near tuning (= less distortion). And the drivers are canceling harmonic distortion (push pull). And you are 90 degrees off axis from the driver. They can be sealed, ported, tapped horn, bandpass, whatever you want.
A friend said my double 12 (27hz ported) was deeper, faster, cleaner, and punchier than his 3 jl audio 10's sealed in his pickup.
How high ?
Don't know, but I'm sure I could go up to 200hz or so.
DSL has used in-line push pull orientation on the TH-812 and the 2x8" "Spud" tapped horns.
Wayne P. used a PPSL arrangement on his 12 Pi spiral horn, a wider version of Tom Danley's Lab Sub FLH.
Whatever benefits PPSL yield would apply to any cabinet design utilizing PPSL.
Art
PPSL does reduce even order harmonic distortion, but all loudspeakers exhibit phase shift at low frequencies, regardless of cabinet type.I'm still slightly confused by making PPSL boxes ported - I thought that the phase shift etc around the box tune would make them sound less clean, which is the whole point of PPSL??
A reduction of THD may make a speaker sound more "clean", but I would not associate a gradual LF phase shift (as seen in any design) as "dirty".
Tapped horn/tapped pipe (darker trace) has quite small phase distortion (at least potential to to it) compared to closed box (lighter trace). Band of interest = below 100Hz.
Ported boxes have even larger phase shift due to port being 180deg out of phase. I think that also front loaded horns have larger phase shift than tapped horns.
edit. never mind, brain fart regarding the phase shift and distortion cancellation.
edit2. Hmm, maybe, and just maybe, some "harmonic" benefit could be theorized to exist, IF the harmonics distortion components are close to same phase than the signal vs. if they are in a different phase. Them being in the same phase sounds more harmonic/harmonically richer?
An externally hosted image should be here but it was not working when we last tested it.
Ported boxes have even larger phase shift due to port being 180deg out of phase. I think that also front loaded horns have larger phase shift than tapped horns.
edit. never mind, brain fart regarding the phase shift and distortion cancellation.
edit2. Hmm, maybe, and just maybe, some "harmonic" benefit could be theorized to exist, IF the harmonics distortion components are close to same phase than the signal vs. if they are in a different phase. Them being in the same phase sounds more harmonic/harmonically richer?
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sure.
The tapped horn sound different as they are 90 degrees out, while a ported is 180 degrees out at tuning.
I'm running the sub out of my active crossover (80hz@18db), not on a dolby .1 subwoofer channel.
I can also run it as a deep 3-way crossing at 100-200hz, but havn't yet.
I'm enjoying my sub, but not enjoying that it wakes my wife up when she's sleeping (at low volumes, such as in Silent Hill when the mom walks down the stairs in the alley). She ran out (half asleep) saying "Who's banging on the door?". So I'm having trouble not upsetting neighbors (apartment). But it adds some nice bass at micro volume levels.
Mine sounds like a deep but leanish sealed sub. I'm already plenty capable of ******* everyone off at low volumes, let alone adding another 6db @27hz. At low volume, I easily hear it in the back rooms. It doesn't sound lean, and I like the running it especially below 100db (like a loudness button). It adds a lot to movies (adding tension) compared to my double 15 running wide open (down low).
"Turn down for what" makes your belly message from across the room. It's impressive. Adding in the x-over cleans up the mids of my double 15's at mid volume. I've yet to try LOTR or SW.
And I'm not in a hurry to add the boost box. Anechoically mine would be F9 around 25hz (I suspect), but sitting on a slab, they seem like they arn't missing anything.
Overall, a great project.
The tapped horn sound different as they are 90 degrees out, while a ported is 180 degrees out at tuning.
I'm running the sub out of my active crossover (80hz@18db), not on a dolby .1 subwoofer channel.
I can also run it as a deep 3-way crossing at 100-200hz, but havn't yet.
I'm enjoying my sub, but not enjoying that it wakes my wife up when she's sleeping (at low volumes, such as in Silent Hill when the mom walks down the stairs in the alley). She ran out (half asleep) saying "Who's banging on the door?". So I'm having trouble not upsetting neighbors (apartment). But it adds some nice bass at micro volume levels.
Mine sounds like a deep but leanish sealed sub. I'm already plenty capable of ******* everyone off at low volumes, let alone adding another 6db @27hz. At low volume, I easily hear it in the back rooms. It doesn't sound lean, and I like the running it especially below 100db (like a loudness button). It adds a lot to movies (adding tension) compared to my double 15 running wide open (down low).
"Turn down for what" makes your belly message from across the room. It's impressive. Adding in the x-over cleans up the mids of my double 15's at mid volume. I've yet to try LOTR or SW.
And I'm not in a hurry to add the boost box. Anechoically mine would be F9 around 25hz (I suspect), but sitting on a slab, they seem like they arn't missing anything.
Overall, a great project.
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Let's see.............
6th order (lower qts drivers, tuning to F9, then adding 6db boost @ tuning).
Seems to be best compromise balancing output, extension, and box size.
See here under djk.
Audio Asylum Thread Printer
"The optimum Qts for an equalized 6th order Butterworth design (not to be confused with a bandpass design) is .312. The formula for box size is Qts*Qts*4.1*Vas=Vb.The formula for Fb is (Fs/Qts)*.312. For a Qts of .312 the Faux (eq frequency)=Fb with a Q of 2 ."
Over there, aren't dayton subs pricey?
Over here, b&c are expensive !!!!!
There original driver has a qts of .35, Vas 4.5ft3, and Fs of 29.6hz .
Dayton st305 series 2. The 8mm xmax helps also.
I see more 18's with qts around .312 with Fs under 30hz, even some 15's.
I haven't seen many 12's that fit the bill.
But I'm sure they are out there.
Norman
6th order (lower qts drivers, tuning to F9, then adding 6db boost @ tuning).
Seems to be best compromise balancing output, extension, and box size.
See here under djk.
Audio Asylum Thread Printer
"The optimum Qts for an equalized 6th order Butterworth design (not to be confused with a bandpass design) is .312. The formula for box size is Qts*Qts*4.1*Vas=Vb.The formula for Fb is (Fs/Qts)*.312. For a Qts of .312 the Faux (eq frequency)=Fb with a Q of 2 ."
Over there, aren't dayton subs pricey?
Over here, b&c are expensive !!!!!
There original driver has a qts of .35, Vas 4.5ft3, and Fs of 29.6hz .
Dayton st305 series 2. The 8mm xmax helps also.
I see more 18's with qts around .312 with Fs under 30hz, even some 15's.
I haven't seen many 12's that fit the bill.
But I'm sure they are out there.
Norman
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