No, Man, The slot itself is the vent. If you have a ported rear chamber, PPSL, then wouldn't that make it a 6th order bandpass? What did you tune the vent to?
Uh, that's not the way folks talk about slot loaded.....the slot is a "slot".
Vented is a synonym of ported. So vents are ports. Like the bass reflex-ports i was pointing out, in the speakers you were posting.
So your PPSL is sealed after all...of course....that's why it has such drooping low end response.
My PPSL slot is 20"x11.5"
For them to be the same thing they need to let air go from inside the box to outside and vice versa.
List those things
No different than other bandpass designs...except instead of the vent owning the lf roll off, and the sealed portion owning the hf roll off (average bandpass sub), its reversed.... ie, the dynamic driver is dominate beneath the horns cut off....just like any other horn I guess.
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The design that Camplo has is a bandpass, but one whose front chamber is likely tuned very high. This will create the rough FR that is shown. I don't see any positives from this kind of usage. It is sometimes used in Pro sound reinforcement situations where it does have a high power handling capacity at the sake of smooth response. The SPL advantage won't ever be used in a home situation, but the smoother response would be.
A bass reflex, ported/vented speaker has positive reinforcement of the low bass frequencies
So just another pointless semantic discussion where what you say is not actually what you mean
+1 for the intended purpose of this project
https://www.attackmagazine.com/wp-content/uploads/2014/05/7-Attack-800x460.jpg
Reflexion Arts uses TAD TD-2001 or TAD TD-2002 (depends what is available) and crosses at 500Hz.
Unforntunately TAD TD-2001 is out of production and we only have 2 pairs on stock. We also have several DP-2001 on stock.
If you know what you do you can crossover at 500Hz on a large 2" or 1" horn.
Reflexion Arts uses TAD TD-2001 or TAD TD-2002 (depends what is available) and crosses at 500Hz.
Unforntunately TAD TD-2001 is out of production and we only have 2 pairs on stock. We also have several DP-2001 on stock.
If you know what you do you can crossover at 500Hz on a large 2" or 1" horn.
I've used it....sounds pretty good too. Not so much the SPl advatange. but the LF extensions advantage which is all tied into the same attributes (xmax/sd/powerhandling). I want a system that is uninhibited in expression of amplitude, keeping excursion low is the only way.
its like telling someone they are reaching for too high of SQ. I have had listening sessions (just one mid and one bass section -- 85 to maybe mid 90s average spl) where I can see the woofers move. See it move see it distort...Even more SQ can be had, hopefully i'll make it there with the system as a whole.
The FR is smooth within confines of the slot null... use accordingly. The lower 18's pick up right where the roll off of the mid woofer is limited to 2mm at max designed volume. Genius, or practical, one of the two or both. PPSL is the best subwoofer in my opinion, but its my personal opinion. I'd say so, in particular, if your situation is one like mine, where you have other woofers to handle mid bass deep enough to avoid the slot null.
Multi subs are still apart of the design.
Further more, the bass quality, as good as it can be in a untreated room, and a little bit of eq....is exactly what I was aiming for. I stated that if I had of aimed for max spl using 2 channels I would of been disappointed. I can tell that from the experience I am having now, in real life, no longer, hypothesizing and theorizing.
I also am having thoughts that wonder if 30hz is really enough extension for music....I feel that there is content under 30hz, and with the monitoring system I am putting together there's no reason why the information my ears are receiving should be very distorted. I haven't tried a high roll off just yet but....theres something to this extremely well covered low end approach. It just seems more revealing as the excursion goes down. I think the lack of distortion is the technically correct expression.
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List all the alternatives that you have built and compared in your room to base that opinion on.
My experience from studying and building PPSL's is that the only advantage they offer, is a dramatic reduction in cabinet vibration, and all the associated vibrations/resonances the cabinet makes in contact with floor and other speaker sections, if attached.
No SPL gain to be had...if anything a very slight loss. They are not seen in the pro world very often, a simple double 18" dominates maybe 1000:1 in terms of occurrence.
The 1/4 WL slot resonance shuts down the upper end of use. But who cares, it is meant to be used as a sub, aka for use 100Hz or such and below. No higher.
Personally, i'll never have another sub that doesn't use opposed drivers, simply for the cabinet vibration reduction.
I won't build any more PPSL's though, probably just use double drivers opposed on opposite sides of the box.
No SPL gain to be had...if anything a very slight loss. They are not seen in the pro world very often, a simple double 18" dominates maybe 1000:1 in terms of occurrence.
The 1/4 WL slot resonance shuts down the upper end of use. But who cares, it is meant to be used as a sub, aka for use 100Hz or such and below. No higher.
Personally, i'll never have another sub that doesn't use opposed drivers, simply for the cabinet vibration reduction.
I won't build any more PPSL's though, probably just use double drivers opposed on opposite sides of the box.
With a steep enough slope like you use it wouldn't matter, but at 24dB /oct it was still interfering in the response with an 80Hz crossover.
You completely unappreciated doubling SD and power handling while halving front baffle foot print
Any vent, whether a 3/4" thick baffle cutout, long pipe, etc.: http://hyperphysics.phy-astr.gsu.edu/hbase/Waves/opecol.html#c1
You made me pull up a raw measurement and check a shallow (for me) slope
My slot, which is wider than camplo's gives a notch at about 370Hz. And a boost in response as shown.
A 24 dB/oct low pass at 100Hz, (above the 80 Hz you mentioned)....needs but a little attenuation to bring the peak down to curve.
And the notch is entirely inconsequential.
So imo, a PPSL or any dual opposed sub, is very viable and desirable, steep xovers or not.
When I say PPSL, I'm not speaking to sealed vs vented. Im referring to the sideways orientation allowing halving of excursion, dbl power handling, while keeping a foot print thats much less than another orientation with the same 2 woofers. Vibration cancellation is cool bonus.