Can someone advise on the optimal diameter of a tube for a 10ft El Pipe-O driven by 2 12 inch woofers?
TIA
TIA
Stick the drivers TS parameters in horn response and use the ‘Nd’ to search for a generic ‘pipe’ size that’ll create a not so ‘spike/peaky’ result in 304.8cm?
Then connect the drivers to it with a small box/coupling chamber and observe anything you might want to change as it tunes slightly lower as a result
Then connect the drivers to it with a small box/coupling chamber and observe anything you might want to change as it tunes slightly lower as a result
A TL requires modeing,just like any other system. Except in how it relates generally to Fs and Vas
So the first thing” what woofers?
dave
So the first thing” what woofers?
dave
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I have four of these to play with
PEERLESS 830669 12" ; PAPER CONE SLS SUBWOOFER
I could put them all on one tube, or two on a stereo pair. As always enlightenment is sought and appreciated.
PEERLESS 830669 12" ; PAPER CONE SLS SUBWOOFER
I could put them all on one tube, or two on a stereo pair. As always enlightenment is sought and appreciated.
https://www.parts-express.com/pedocs/specs/264-1118--tymphany-sls-p830669-spec-sheet.pdf
Needs gigantic pipe to compliment the ‘loose/soft’ suspension.
a single ‘in a box’ connected to two 48” pieces of 12” sonotube from Home Depot
Needs gigantic pipe to compliment the ‘loose/soft’ suspension.
a single ‘in a box’ connected to two 48” pieces of 12” sonotube from Home Depot
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Please confirm my understanding which is you want a pipe length that corresponds to the resonant frequency of the driver so as to load up the driver and prevent uncontrolled resonance..? So optimal tube length is set by the choice of driver? And system volume plays a role...
What are the pros and cons of putting 2 or 4 drivers on the same tube?
and thanks
What are the pros and cons of putting 2 or 4 drivers on the same tube?
and thanks
Hmm, ~2*522.8 cm^2 = 1045.6 cm^2 = ((1045.6*4)/pi)^0.5 = 36.49 cm/14.37" eff. dia, so at a glance 14 - 16" seems big enough to the 1st approximation..........
142.32 L*2 = 284.64 L Vas
14^2*pi/4 = 153.94"^2/993.16 cm^2
153.94*120 = 18472.56"^3/10.69 ft^3
993.16*304.8 = 302715 cm^3/302.715 L.........ditto factoring in Vas if I did the math right 😒
BUT....... dual max flat vented = 2*(20*142.32*0.54^3.3) = 693.29 L tuned to 0.42*31.48*0.54^-0.96 = 23.89 Hz !!!
10 ft/120"/304.8 cm
Fb = (~1128.6 ft-sec/4/10) = ~28.22 Hz, so while slightly lower with its pipe end correction it's still too high for a max flat alignment. 😳
693.29 L/693290 cm^3
693290 cm^3/304.8 = 2274.57 cm^2
pipe dia = (2274.57*4/pi)^0.5 = 53.82 cm/21.19", so 20 - 24" and damp to ~24 Hz Fb or to 'taste' 😉
142.32 L*2 = 284.64 L Vas
14^2*pi/4 = 153.94"^2/993.16 cm^2
153.94*120 = 18472.56"^3/10.69 ft^3
993.16*304.8 = 302715 cm^3/302.715 L.........ditto factoring in Vas if I did the math right 😒
BUT....... dual max flat vented = 2*(20*142.32*0.54^3.3) = 693.29 L tuned to 0.42*31.48*0.54^-0.96 = 23.89 Hz !!!
10 ft/120"/304.8 cm
Fb = (~1128.6 ft-sec/4/10) = ~28.22 Hz, so while slightly lower with its pipe end correction it's still too high for a max flat alignment. 😳
693.29 L/693290 cm^3
693290 cm^3/304.8 = 2274.57 cm^2
pipe dia = (2274.57*4/pi)^0.5 = 53.82 cm/21.19", so 20 - 24" and damp to ~24 Hz Fb or to 'taste' 😉
Please can you translate that into something for the hard of thinking?
I think I understood 14-16" diameter for dual drivers, 20-24" diameter if using all four on a single pipe. Haven't got the rest yet, but thanks
I think I understood 14-16" diameter for dual drivers, 20-24" diameter if using all four on a single pipe. Haven't got the rest yet, but thanks
Math isn't my forte', so have to work through it one little piece at a time for myself and those folks that are willing to correct it if need be.......
Partly right, the 20-24" is for dual drivers that are tuned based on an optimized (max flat) vented box alignment, which due to the driver's relatively soft suspension (high Vas) combined with a high Qts (weak motor) = huge box (weak air mass 'spring').
Partly right, the 20-24" is for dual drivers that are tuned based on an optimized (max flat) vented box alignment, which due to the driver's relatively soft suspension (high Vas) combined with a high Qts (weak motor) = huge box (weak air mass 'spring').
so first approximation is that cone area is similar to tube diameter.
the more involved modelling relates the optimal volume for the Vas and Qts of the driver and then `divide by length' to get a more optimal choice for diameter
Is that a reasonable interpretation?
So if I use four motors, can i use a smaller diameter pipe more optimally?
the more involved modelling relates the optimal volume for the Vas and Qts of the driver and then `divide by length' to get a more optimal choice for diameter
Is that a reasonable interpretation?
So if I use four motors, can i use a smaller diameter pipe more optimally?
I was referring to
"Hmm, ~2*522.8 cm^2 = 1045.6 cm^2 = ((1045.6*4)/pi)^0.5 = 36.49 cm/14.37" eff. dia, so at a glance 14 - 16" seems big enough to the 1st approximation.........."
"Hmm, ~2*522.8 cm^2 = 1045.6 cm^2 = ((1045.6*4)/pi)^0.5 = 36.49 cm/14.37" eff. dia, so at a glance 14 - 16" seems big enough to the 1st approximation.........."
Correct.
Correct.
??? Well, you could use four pipes sized for just one driver, but it's acoustically inefficient, i.e. think in terms of it being a reflex (BR) vent, so the bigger it is, the more acoustically efficient and vice versa, ergo (4) motors would ideally require a truly huge pipe for max efficiency.
That said, just like a BR it will likely need some in room EQ for best overall performance, so might as well be tuned to an under damped alignment (smaller pipe(s)) and use DSP, pipe damping to correct it in room if the drivers can still produce the desired peak SPL at low distortion.
Thanks for the confirmation!
And sorry let me rephrase... If a high Qts (weak motor) -> large volume, then would using four drivers on a single pipe effectively quaduple the drive available, hence enable a smaller pipe ?
And sorry let me rephrase... If a high Qts (weak motor) -> large volume, then would using four drivers on a single pipe effectively quaduple the drive available, hence enable a smaller pipe ?
You're welcome!
Would you perform your driving duties as well if three more people were crammed into your solo seat speedster? IOW Vas sums, not divides.
Would you perform your driving duties as well if three more people were crammed into your solo seat speedster? IOW Vas sums, not divides.
My favorite woofer... I keep thinking of building the 7 footers but my wife might not like them... unless they look like Corinthian Columns.
Back in '80 I built the Chili Con Carne Can Speakers. Take a large ( 1 gallon? ) can of chili (*)... EMPTY!, make sure both ends have been opened clearly. Then using a bit of plywood, use it as a "ring" to mount a 6 inch speaker at one end of the cylinder. I used a Pioneer coax car speaker. Loosely fill the cavity... making sure it has been clearly washed of chili con carne and beans... keep the back open.
Mount it in your car... Vega Hatchbacks are the best for this but first gen Honda Civic wagons got honorable mention, in a metric sort of way... And just crank some Pink Floyd on the cassette.
It sounded great...
(*) I was working at Sambo's then... I didn't have to eat that much chili.... phew.
Back in '80 I built the Chili Con Carne Can Speakers. Take a large ( 1 gallon? ) can of chili (*)... EMPTY!, make sure both ends have been opened clearly. Then using a bit of plywood, use it as a "ring" to mount a 6 inch speaker at one end of the cylinder. I used a Pioneer coax car speaker. Loosely fill the cavity... making sure it has been clearly washed of chili con carne and beans... keep the back open.
Mount it in your car... Vega Hatchbacks are the best for this but first gen Honda Civic wagons got honorable mention, in a metric sort of way... And just crank some Pink Floyd on the cassette.
It sounded great...
(*) I was working at Sambo's then... I didn't have to eat that much chili.... phew.
Are you sure it's not just a `good reason' to buy multiple gallons of chilli?
My wife said corinthian columns would be acceptable too - women with illusions of grandeur
My wife said corinthian columns would be acceptable too - women with illusions of grandeur
Your post made me recall disguising speakers as columns to satisfy corporate aesthetics.
I found getting a good paint finish using Sonotube was very difficult, as the spirals show through unless primed and sanded (multiple times..).
Covering them with Spandex is easy. Anyone that can operate a sewing machine can make covers in minutes. Your wife could pick the color.
Beautiful AND Functional 😎