Anyone tried linkwitz/transform w/their PPSL?
My PPSL is tuned to 40hz as lowest appropriate for my JBL drivers. I'm wondering if a linkwitz transform would let me drop to 25 or 30hz w/o the risk of high distortion or damage to the drivers? Just starting to learn about this potential. Thanks.
My PPSL is tuned to 40hz as lowest appropriate for my JBL drivers. I'm wondering if a linkwitz transform would let me drop to 25 or 30hz w/o the risk of high distortion or damage to the drivers? Just starting to learn about this potential. Thanks.
"My PPSL is tuned to 40hz as lowest appropriate for my JBL drivers. I'm wondering if a linkwitz transform would let me drop to 25 or 30hz w/o the risk of high distortion or damage to the drivers? "
Probably not.
The LT can work with a vented system, but it must be designed that way from the ground up.
In general, I prefer 6th order vented alignments.
A 2 cu ft 2nd order sealed box with an F3 of 30hz can only be 0.18% efficient (84.55dB).
A 2 cu ft 4th order vented box with an F3 of 30hz can only be 0.36% efficient (87.56dB).
A 2 cu ft 6th order vented box with an F3 of 30hz can only be 0.90% efficient (91.54dB).
Probably not.
The LT can work with a vented system, but it must be designed that way from the ground up.
In general, I prefer 6th order vented alignments.
A 2 cu ft 2nd order sealed box with an F3 of 30hz can only be 0.18% efficient (84.55dB).
A 2 cu ft 4th order vented box with an F3 of 30hz can only be 0.36% efficient (87.56dB).
A 2 cu ft 6th order vented box with an F3 of 30hz can only be 0.90% efficient (91.54dB).
Linkwitz transform is specifically for sealed boxes. If box is not sealed it is simply called EQ boosting your bass
Are you not just EQ boosting your bass in sealed boxes as well..
It you are introducing gain/attenuation at certain frequencies, is it not equalization? I don't see a difference.
Oh - and aren't a lot of LT users OB users as well?
LT is equalization but a specific case with a closed analytic solution called the Linkwitz Transform. It is mathematically prescribed based on a sealed response natural frequency. As far as I know, the LT closed form solution is only valid for a sealed system. Apply it to a non sealed alignment and it is not a Linkwitz Transform anymore. Look at section 9 of SL's description of the LT - it is for a closed box system.
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"Apply it to a non sealed alignment and it is not a Linkwitz Transform anymore. "
Certain undersized vented systems have the same response as the high Qtc sealed designs normally used with the LT. In this case the LT works just as well, but the vented system has less excursion than the sealed does at the vent Fb.
I suggest using a program like BassBox Pro v6.0 to model it and see for yourself (as I have done).
The LT is just EQ, and if you have a good PEQ you can get the same result.
Certain undersized vented systems have the same response as the high Qtc sealed designs normally used with the LT. In this case the LT works just as well, but the vented system has less excursion than the sealed does at the vent Fb.
I suggest using a program like BassBox Pro v6.0 to model it and see for yourself (as I have done).
The LT is just EQ, and if you have a good PEQ you can get the same result.
i am considering building a ppsl with 4 dayton st305-8 and am crunching numbers in winisd , comparing 10 cu ft to 12 cu ft box volume , tuned to 27hz and trying to decide if 2 drivers per box might be sufficient?
one thing i really struggle with is figuring out the wiring for the drivers.
do you wire through the cabinet ,or the port?
how would the wiring look like for 4 drivers in one box connected in series parallel?
the additional reverse in polarity for the opposing driver throws me for a loop and it seems that i have a hard time figuring that one out, perhaps someone can help?
thanks
one thing i really struggle with is figuring out the wiring for the drivers.
do you wire through the cabinet ,or the port?
how would the wiring look like for 4 drivers in one box connected in series parallel?
the additional reverse in polarity for the opposing driver throws me for a loop and it seems that i have a hard time figuring that one out, perhaps someone can help?
thanks
~12.566 ft^3 seems the 'sweet spot'. Dunno, you don't give us any performance goals.
Wiring is typically connected to a terminal cup or Neutrik or similar prosound/mil spec connector, though some folks just hard wire them to cut down on connectors where most of the signal losses are, running the wiring out the port or a sealed hole in the cab.
Wiring Diagrams | Eminence Speaker
GM
Wiring is typically connected to a terminal cup or Neutrik or similar prosound/mil spec connector, though some folks just hard wire them to cut down on connectors where most of the signal losses are, running the wiring out the port or a sealed hole in the cab.
Wiring Diagrams | Eminence Speaker
GM
i would like to cover the 350hz and down to about 30hz ideally with highest efficiency possible, i am using synergy horns from 350hz up.
re wiring that was a misunderstanding , i was not looking for posts at the speaker box but was wondering how people connect between the opposing drivers in the plenum, one being inside the other outside of the box?
and also how to wire the series parallel w/ 4 drivers w/ regard to the driver on the opposed side that has to be wired out of phase.
re wiring that was a misunderstanding , i was not looking for posts at the speaker box but was wondering how people connect between the opposing drivers in the plenum, one being inside the other outside of the box?
and also how to wire the series parallel w/ 4 drivers w/ regard to the driver on the opposed side that has to be wired out of phase.
Hum,
For the drivers with the magnets out, drill a hole through the plenum and run the wire through it to the cabinet interior, seal the hole with caulk.
The drivers should be wired just as in the diagram in 570, except the "magnet out" drivers polarity must be reversed, so positive voltage applied to the input makes all the cones push in to the plenum. Proper orientation can easily be confirmed with a 9 volt battery applied momentarily to the "+" and "-" terminals, the cones all will visibly move towards the plenum if properly wired.
Art
I used three wires on the 412 shown in #353.
The two inverted drivers were wired in series, and the wire ran through the back of the plenum through a small hole. Remember to reverse polarity on this wire when you hook it to the input connector.
Each of the normal drivers were wired as normal, the wires taken back to the input connector, and wired in series. The wire was then hooked to the input connector.
The two inverted drivers were wired in series, and the wire ran through the back of the plenum through a small hole. Remember to reverse polarity on this wire when you hook it to the input connector.
Each of the normal drivers were wired as normal, the wires taken back to the input connector, and wired in series. The wire was then hooked to the input connector.
It is tough to get a PP 6th order slot loaded sub to cover 30Hz to 350Hz - the length of the slot will typically have a resonance cancellation at about 250Hz for a typical slot length necessitated by need to fit driver.
i heard that Les apparently crossed his ppsl higher but in all the threads i read i have not seen any measurements which would confirm possible extension into the 350hz range.
would it be beneficial to open up the slot into a V shape to extend the upper range ?
but off course the question then remains what angle is necessary to get to 350hz?
Been there, done that...
http://www.diyaudio.com/forums/subwoofers/264737-pp-slot-loaded-sub-alpine-swr-12d2.html
There are some cool variants in that thread by Tb46, and all built by Lawbiding:
Sadly, still no 350Hz:
Been there, done that...
http://www.diyaudio.com/forums/subwoofers/264737-pp-slot-loaded-sub-alpine-swr-12d2.html
There are some cool variants in that thread by Tb46, and all built by Lawbiding:
Sadly, still no 350Hz:
is that response a simulation? doesn't look like a measurement.
the alpine driver does not like playing high , couldn't find any real specs, but it looks like a pure sub driver from which i wouldn't expect higher extension.
i would really like to see a measured response of the dayton ppsl that norman bates uses.
The center brace runs down the length of the port, across the back, and up to the front.
I don't need handles, the cabinet will always ride on a two-wheeled cart.
I use Penn-Elcom dual D input cups.
Nice logo work!
My latest PPSL, a 27hz quad-12 owned by Norman Bates!
that is bad news. i will have to build something else then i guess.
i might still use a push pull configuration but without the slot.
unless , there is someone out there who measured a ppsl going to 350hz ,
please let me know.
This one does 350Hz at -10 dB:
http://www.diyaudio.com/forums/subwoofers/255010-compact-2x15-ppsl-using-dayton-pa385-8-drivers.html
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