This is what I get in Vituix...It appears that there is a bit of directivity with the front to back configuration. Not what I expected
am I doing it right?
am I doing it right?
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Looks like I could run both subs up to 300hz its a matter of will I like the sound or not. This is with time alignment though...
Feeling confident, about 2 designs of the PPSL that I believe fit this category. I've contemplated them for little bit now.
Both PPSL woofers are the face to face type variety. Both are to have a top and bottom baffle on the slot. The slot height is approximately 1.5x the diameter of the woofers used. The slots depth is only deep enough to house woofer, unless otherwise specified. The slots width is 1/4th-1/3rd the diameter of woofer used.
The first one below, is the type of response that you get from starting the slots rear wall, mid woofer, thus covering one half of the woofers. I think this would result in a response that could be fine tuned with EQ. and lacking the usual slot null.
The second design is a more typical slot and requires the rear half of the slot be filled with a potent damping material like Rock Wool. This approach results in response that has all the slot resonances dampened out, but still leaves the low end un attenuated.
Rockwool requires a significant depth to create significant attenuation, so unfortunately, according to my HR sims, the shorter slot of top design doesn't allow enough damping material to mute the resonance. For this reason I rate the lower design, one notch above. There are several resonances creates in these slots. With EQ/DSP the response can be evened out but you will end up some delay on the signal and multiple arrivals will still prevail. With the successfully dampened slot, one could argue that technically this is the more accurate solution, even if both somehow, ended up virtually indistinguishable perceptually.
The resulting enclosure shape can easily be configured into a tapped horn. With Damping material used similar to how described above, there is potential for a decent FR. I think the key is to design with approximately 10" of straight like filled with Damping material. This seems to provide enough attenuation to clear up the harmonic cancellations and peaking issues. The results in the simd, damped ppsl above, look promising. If successfully implemented, it creates a very dynamically capable loudspeaker capable of handling subwoofer and lower midrange duties.
Both PPSL woofers are the face to face type variety. Both are to have a top and bottom baffle on the slot. The slot height is approximately 1.5x the diameter of the woofers used. The slots depth is only deep enough to house woofer, unless otherwise specified. The slots width is 1/4th-1/3rd the diameter of woofer used.
The first one below, is the type of response that you get from starting the slots rear wall, mid woofer, thus covering one half of the woofers. I think this would result in a response that could be fine tuned with EQ. and lacking the usual slot null.
The second design is a more typical slot and requires the rear half of the slot be filled with a potent damping material like Rock Wool. This approach results in response that has all the slot resonances dampened out, but still leaves the low end un attenuated.
Rockwool requires a significant depth to create significant attenuation, so unfortunately, according to my HR sims, the shorter slot of top design doesn't allow enough damping material to mute the resonance. For this reason I rate the lower design, one notch above. There are several resonances creates in these slots. With EQ/DSP the response can be evened out but you will end up some delay on the signal and multiple arrivals will still prevail. With the successfully dampened slot, one could argue that technically this is the more accurate solution, even if both somehow, ended up virtually indistinguishable perceptually.
The resulting enclosure shape can easily be configured into a tapped horn. With Damping material used similar to how described above, there is potential for a decent FR. I think the key is to design with approximately 10" of straight like filled with Damping material. This seems to provide enough attenuation to clear up the harmonic cancellations and peaking issues. The results in the simd, damped ppsl above, look promising. If successfully implemented, it creates a very dynamically capable loudspeaker capable of handling subwoofer and lower midrange duties.
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The excursion vs spl of a stereo set, sealed, shows potential to be the subwoofer/midrange of a Dynamic 2 way.
Just a quick messing around in Horn Resp, I am not sure of the potential of a Tapped Horn to Fulfill the Thread Title. I would have to take some finesse otherwise it doesn't really appear worth the trouble. On the other hand, a BR is easy money with predictable results. From what I see... Sealed/BR enclosure with dual woofers, vibration cancellation, improved headroom room and efficiency, single woofer front baffle foot print, singular source, capable of midrange and subwoofer. Best part, easy building with a strong shape that is easily braced.
Just a quick messing around in Horn Resp, I am not sure of the potential of a Tapped Horn to Fulfill the Thread Title. I would have to take some finesse otherwise it doesn't really appear worth the trouble. On the other hand, a BR is easy money with predictable results. From what I see... Sealed/BR enclosure with dual woofers, vibration cancellation, improved headroom room and efficiency, single woofer front baffle foot print, singular source, capable of midrange and subwoofer. Best part, easy building with a strong shape that is easily braced.
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You will need a reflex or a TL for this. A reflex will be the easiest. Horns (tapped or not), transflex and bandpass all don't go high enough in frequency response for your wishes.
I designed a similar goal box for a guy (he build it last summer) with a Beyma 18PWB1000Fe/S 18" driver. The owner crosses it to a B&C464 horn/coaxial compression driver at 300Hz without issue. It's a big cabinet altough, 250L internal space with 4 slot ports of 10x10cm and 47cm deep. that box is 50cm wide, 150cm high and 60cm deep (bigger also for extensive bracing, it's needed) and gets an 20Hz at 108dB max) and an F3 of 24Hz (at max 122dB) without any eq. The owner eq's a lot with the lake processing of the Labs Gruppen amps he use for it, it's his partyroom system (he is a techno dj). The exact plans i can't give you (paying job) but you could do something similar and cross lower than that guy.
I designed a similar goal box for a guy (he build it last summer) with a Beyma 18PWB1000Fe/S 18" driver. The owner crosses it to a B&C464 horn/coaxial compression driver at 300Hz without issue. It's a big cabinet altough, 250L internal space with 4 slot ports of 10x10cm and 47cm deep. that box is 50cm wide, 150cm high and 60cm deep (bigger also for extensive bracing, it's needed) and gets an 20Hz at 108dB max) and an F3 of 24Hz (at max 122dB) without any eq. The owner eq's a lot with the lake processing of the Labs Gruppen amps he use for it, it's his partyroom system (he is a techno dj). The exact plans i can't give you (paying job) but you could do something similar and cross lower than that guy.
I suspect this project is more of an engineering exercise and personal challenge? I agree that a multi-way design using reflex enclosure for the low frequencies is the most straight forward approach, if difficulty is a consideration. Not to say that reflex designs are "easy". I succeeded in over-complicating mine!
The only TL speaker I know of in production is by Kerr Acoustic. (Interview with designer:
)
I built an 8 cubic foot/ 218 liter 4 way cabinet that roughly matches Waxx's results for frequency range and SPL. I followed Genelec's recipe--use 2 drivers! My current configuration has the ported sub (12") covering ~17hz to 50hz, the sealed woofer (12") is 50hz to 120hz, and then I have a 12" B&C coaxial above 120hz. This design is capable of ~110dB @ 20hz. It will exceed 110dB at higher frequencies, but I don't know how loud it will actually play!
I've been tempted by the B&C large format horn more than once, contemplating using it instead of coaxials...but it is a lot wider than my current baffle! I'm still tempted to try the Ciare PR614 horn with the new DCX 354 CD.
The only TL speaker I know of in production is by Kerr Acoustic. (Interview with designer:
I built an 8 cubic foot/ 218 liter 4 way cabinet that roughly matches Waxx's results for frequency range and SPL. I followed Genelec's recipe--use 2 drivers! My current configuration has the ported sub (12") covering ~17hz to 50hz, the sealed woofer (12") is 50hz to 120hz, and then I have a 12" B&C coaxial above 120hz. This design is capable of ~110dB @ 20hz. It will exceed 110dB at higher frequencies, but I don't know how loud it will actually play!
I've been tempted by the B&C large format horn more than once, contemplating using it instead of coaxials...but it is a lot wider than my current baffle! I'm still tempted to try the Ciare PR614 horn with the new DCX 354 CD.
Hmm, thought I posted this back at the beginning......
Qts' = 2*20 (Fs)/200 (Fhm) = 0.2, so not that you can't have high SQ over 3+ octaves; it's just a matter of having a powerful enough driver and a sufficient number of them (or huge Vas) to get the desired efficiency........ now you know one reason why the pioneers built adjustable field coil woofers that went down to ~ 0.1 Qt.
Qts' = 2*20 (Fs)/200 (Fhm) = 0.2, so not that you can't have high SQ over 3+ octaves; it's just a matter of having a powerful enough driver and a sufficient number of them (or huge Vas) to get the desired efficiency........ now you know one reason why the pioneers built adjustable field coil woofers that went down to ~ 0.1 Qt.
Considering you want 20Hz to ≥200Hz, I'm sure TH are not going to work- haven't seen any with more than a three-octave usable range.
I dub thee PPMSL. Push/Pull or Push/Push Muted Slot Load. I always wanted to have my "create a character" enclosure, to add to the culture. Right now it seems that a Rear Half, Fully Dampened Slot, is a key aspect.
Second iteration, I dub thee, Truncated PPSL. This version ask for the rear wall of the slot to be moved forward until the slot null is ≥1000hz or simply no longer exist.
I'd suggest to use top and bottom baffles on the slot. The slot height is approximately ≤1.5x the diameter of the woofers used. The slots depth is only deep enough to house woofer or smaller in which the woofer becomes buried... The slots width is ≤1/4th the diameter of woofer used. You are going to want the woofers to stay within 1/4lambda throughout their passband, for sure but not surpass detrimental particle velocity at the mouth at max spl.
There are other ways to get the PPSL response to play nice but I have not figured them all out. You basically need a type of phase plug, I believe. This Alpha bass horn has an interesting solution. I think there is likely still null in the response but an expanding line and half the woofer exposed, likely pushed the null high enough to properly cross at 350hz as the design suggest.
Nowadays its hard to justify building a TL instead of a BR.
The Sealed PPSL is hitting this or higher with 15"/18"s and enough xmax. That is why I think they are the best choice, when done in an optimal way, like my two iterations above. Below is output placing 20hz at the 14mm xmax of my drivers. Adding a BR slot, is very simple if thats what the designer wanted.
Force cancellation, Efficiency of 2 woofers coupled, doubled power handling performing as a single point source, to a much higher frequency than normal side by side woofers, no worry of comb filtering in the off axis or beaming.
Single woofer baffle footprint, lowering CTC for use in 2way, allowing better vertical dispersion, instead of the null created by TMM, no need to for 2.5way.
High output, low distortion covering subwoofer and midrange when used with the right woofers. Can be used in a MTM as well. Sounds like a lot of win.
PPMSL & Truncated PPSL!
Now I just need to finish my PPMSL and measure it for all it see...
Second iteration, I dub thee, Truncated PPSL. This version ask for the rear wall of the slot to be moved forward until the slot null is ≥1000hz or simply no longer exist.
I'd suggest to use top and bottom baffles on the slot. The slot height is approximately ≤1.5x the diameter of the woofers used. The slots depth is only deep enough to house woofer or smaller in which the woofer becomes buried... The slots width is ≤1/4th the diameter of woofer used. You are going to want the woofers to stay within 1/4lambda throughout their passband, for sure but not surpass detrimental particle velocity at the mouth at max spl.
There are other ways to get the PPSL response to play nice but I have not figured them all out. You basically need a type of phase plug, I believe. This Alpha bass horn has an interesting solution. I think there is likely still null in the response but an expanding line and half the woofer exposed, likely pushed the null high enough to properly cross at 350hz as the design suggest.
Nowadays its hard to justify building a TL instead of a BR.
The Sealed PPSL is hitting this or higher with 15"/18"s and enough xmax. That is why I think they are the best choice, when done in an optimal way, like my two iterations above. Below is output placing 20hz at the 14mm xmax of my drivers. Adding a BR slot, is very simple if thats what the designer wanted.
Force cancellation, Efficiency of 2 woofers coupled, doubled power handling performing as a single point source, to a much higher frequency than normal side by side woofers, no worry of comb filtering in the off axis or beaming.
Single woofer baffle footprint, lowering CTC for use in 2way, allowing better vertical dispersion, instead of the null created by TMM, no need to for 2.5way.
High output, low distortion covering subwoofer and midrange when used with the right woofers. Can be used in a MTM as well. Sounds like a lot of win.
PPMSL & Truncated PPSL!
Now I just need to finish my PPMSL and measure it for all it see...
Near enough for me without you Exporting yours........
@Booger weldz you showed me a nicely dampened Tapped horn once, It must of been tapered
@weltersys I am just a guy with a mouse and HornResp. I think this flies but no experience with dampened tapped horns in real life.
Given the complexity versus the results I don't think a build this this is worth it.
@weltersys I am just a guy with a mouse and HornResp. I think this flies but no experience with dampened tapped horns in real life.
Given the complexity versus the results I don't think a build this this is worth it.
I would agree that it makes little sense to build a resonant design, then "mute" it's response with lossy damping to achieve a response that could be achieved in a smaller enclosure.
kinda like the older versions of paraflex? A huge box that’s like the kitchen sink version of resonance that needs all kinds of damping material and offset stubs or anything to fix it?
Waste of time and money and wood. Like the big ‘roar’ thing I keep stubbing my toe on recently 😝. Stuffed to the gills and lots of tweaking the exit, etc.
approximately 14025.10cm2 to hit 20hz/115db/1m or 7550cm2 to hit 20hz/110db/1m with 2mm excursion in 0.5xPI in a sealed enclosure.
About 6 18"s or 8 15's to hit the 110db metric.....
An MTM comprised of 15"s in PPMSL, in stereo, could likely get you there. You could also do TMM comprised of PPMSL.
I think Qts/Qes still needs to be low in order to deal with box resonances. Le needs to be low for transient performance. Xmax needs to be high enough to have BL stay linear at 2mm
I would definitely go this route to SQ, I currently have 6 18"s, which is about right. Adding the additional 18" to the rear of the cabinets would be the idea, for what I have already going on.
For the frugal approach Maybe this?
or
Used 8 JBL 15"s
338*4= 1352
New 6 Eminence 18's
249*6= 1494
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I agree regarding Paraflex enclosures. I don't like the low tune port firing directly into the mouth of the enclosure.
Regarding ROAR enclosures, maybe high compression ratios at S2 are k!ll!ng the performance?
Maybe try more than 2 stepped segments in the model?
Or, is the basis of a ROAR enclosure is to only use 2 stepped segments?
Im Dumb, and licked the bus windows while eating Elmer’s glue but,
I think Roar is too long and skinny upstream to not suffer from an overdamped Fb. Plus high BL/low Qes drivers are kind of rolled off inherently at the lower frequencies?
Then the second resonator is obnoxiously huge/loud/wide open and the combo is strange. But no denying it’s LOUD!!
As soon as you change the upstream section to a similar volume tapered pipe or long Helmholtz thing it sure perks up . But then you have that big open mouth resonator after that to ‘amplify’, and not filter(port) funky noises regardless of what or where they come from? You loose the ‘distortion’ removal ?
But the series tuned stuff always needs an awkwardly small port or pipe upstream. It’s weird ???
Paraflex is weird because it’s often out of phase where the resonators merge and the short pipe is in resonace or it rings and won’t shut up in that same area , etc etc .
Meanwhile a goofy Helmholtz resonator sounds like rubber or gets turbulent quickly and ….
It all sucks, use a simple ‘4th order’ tapered qw pipe and be happy it’s has the least of any of those issues 😝 lol!!
I think Roar is too long and skinny upstream to not suffer from an overdamped Fb. Plus high BL/low Qes drivers are kind of rolled off inherently at the lower frequencies?
Then the second resonator is obnoxiously huge/loud/wide open and the combo is strange. But no denying it’s LOUD!!
As soon as you change the upstream section to a similar volume tapered pipe or long Helmholtz thing it sure perks up . But then you have that big open mouth resonator after that to ‘amplify’, and not filter(port) funky noises regardless of what or where they come from? You loose the ‘distortion’ removal ?
But the series tuned stuff always needs an awkwardly small port or pipe upstream. It’s weird ???
Paraflex is weird because it’s often out of phase where the resonators merge and the short pipe is in resonace or it rings and won’t shut up in that same area , etc etc .
Meanwhile a goofy Helmholtz resonator sounds like rubber or gets turbulent quickly and ….
It all sucks, use a simple ‘4th order’ tapered qw pipe and be happy it’s has the least of any of those issues 😝 lol!!
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Haven't paid much attention to these kinds of subs, but assume they're factoring in the inherent Qt rise/thermal power distortion in the design, so low Qt drivers won't be in practice and any roll off is designed in, which historically (my time) was pounding eyeballs flat @ 80 Hz and -24 dB/40 Hz; so is this still the norm or......?
Hi Camplo, fwiw, I'm still very happy with my "half-way" compromise PPSL, where the drivers face each other perpendicularly as opposed to facing parallel.
And the slot becomes a "corner", with the depth and height just a bit larger than driver diameter. (my double 18" reflex v-twin subs posted earlier this year).
Only things I'd like better would be if it were a little smaller...its 25 cu ft.
And went a little lower ...20Hz @ 19mm xmax per hornresp is about 117Hz.
Otherwise, i think it fits the 20Hz - 200Hz bill pretty easy.
Here's with a 23Hz BW3 hpf, and no other EQs.
Just took this in-room raw response. Mic a few inches centered between port and driver slot.
185Hz IIR LR2 low-pass., no other filters.
And the slot becomes a "corner", with the depth and height just a bit larger than driver diameter. (my double 18" reflex v-twin subs posted earlier this year).
Only things I'd like better would be if it were a little smaller...its 25 cu ft.
And went a little lower ...20Hz @ 19mm xmax per hornresp is about 117Hz.
Otherwise, i think it fits the 20Hz - 200Hz bill pretty easy.
Here's with a 23Hz BW3 hpf, and no other EQs.
Just took this in-room raw response. Mic a few inches centered between port and driver slot.
185Hz IIR LR2 low-pass., no other filters.