I'm not reading to much into these models but here they are anyway.
Green = 4x XLS10 in 130ltr sealed enclosure with LT(Q=0.5, Fp=20hz)
Orange = 4x XLS10 in 130ltr vented enclosure tuned to 14hz
MaxSPL:
Phase:
GD:
Excursion at 20hz/105dB:
Port Velocity at 20hz/105dB:
Green = 4x XLS10 in 130ltr sealed enclosure with LT(Q=0.5, Fp=20hz)
Orange = 4x XLS10 in 130ltr vented enclosure tuned to 14hz
MaxSPL:
An externally hosted image should be here but it was not working when we last tested it.
Phase:
An externally hosted image should be here but it was not working when we last tested it.
GD:
An externally hosted image should be here but it was not working when we last tested it.
Excursion at 20hz/105dB:
An externally hosted image should be here but it was not working when we last tested it.
Port Velocity at 20hz/105dB:
An externally hosted image should be here but it was not working when we last tested it.
And the design:
I was bored once again so decided to play in CorelDraw. Check the sig, how cool is that 😀 The sub is shown to scale against the Perceives. I was thinking it would be cool to have a TV stand come subwoofer. Maybe with a recessed smoked glass top, there's a good glazier near me that could cut that sort of thing to size
View from side showing port detail:
Bottom of the enclosure showing driver layout:
I was bored once again so decided to play in CorelDraw. Check the sig, how cool is that 😀 The sub is shown to scale against the Perceives. I was thinking it would be cool to have a TV stand come subwoofer. Maybe with a recessed smoked glass top, there's a good glazier near me that could cut that sort of thing to size
An externally hosted image should be here but it was not working when we last tested it.
View from side showing port detail:
An externally hosted image should be here but it was not working when we last tested it.
Bottom of the enclosure showing driver layout:
An externally hosted image should be here but it was not working when we last tested it.
Looks cool, definitely, though port length and shape as pointed out before... umm. Also if TV stand, consider driver shielding issues!! I have two unshielded 2" computer speakers that will warp my CRT if within 10" from the screen.
EDIT: The sims still don't look realistic for the sealed figure. Using the SL worksheet numbers that would give you 87 dB@20Hz/1 XLS10 would give you 93 dB for 2 and 99 dB for 4 drivers. You'd need 4 B&C 12" in fact for your specs.
The worksheet is here btw:
Pluto sealed subwoofer with Peerless 10" SLS driver
This worksheet does any sim for sealed (standard), infinite baffle and open baffle (set box volume to >> Vas) SPL, power and excursion calculations.
Another worksheet to just calculate excursion limits:
excursion limited SPL
and the formulas used to calculate them:
excursion limits theory
Doubling drivers will give you an additional 6 dB Xmax limited output while increasing power demands by 3 dB only (you gain 3 dB in efficiency) as outlined here:
3 or 6 dB?
EDIT: The sims still don't look realistic for the sealed figure. Using the SL worksheet numbers that would give you 87 dB@20Hz/1 XLS10 would give you 93 dB for 2 and 99 dB for 4 drivers. You'd need 4 B&C 12" in fact for your specs.
The worksheet is here btw:
Pluto sealed subwoofer with Peerless 10" SLS driver
This worksheet does any sim for sealed (standard), infinite baffle and open baffle (set box volume to >> Vas) SPL, power and excursion calculations.
Another worksheet to just calculate excursion limits:
excursion limited SPL
and the formulas used to calculate them:
excursion limits theory
Doubling drivers will give you an additional 6 dB Xmax limited output while increasing power demands by 3 dB only (you gain 3 dB in efficiency) as outlined here:
3 or 6 dB?
MBK said:
OK, I've tried Bassbox, Unibox and WinISD, all have the same predictions give or take.
SL's spreadsheets seem to estimate the output at a staggering 10dB less than these models (99 vs. 109dB for sealed)! That's over 8 times less power output, a third of the SPL and, very roughly, half as loud. How can these models be soooo different in their hypotheses?
Thanks for the links BTW.
SL's calculations use only Sd and excursion to calculate SPL, one should be able to obtain the formulas in his worksheets from the "theory" gif he presents (I have not tried to derive them).
One possibility is that SL calculates using true peak Xmax and maybe other programs use the peak Xmax as if it was an RMS value. That would account for 3 dB SPL. And, maybe other programs assume 2 speakers, adding another 6 dB. So here we'd have 9 dB accounted for. But honestly, that's just speculation.
In general through experience with his design models I have come to trust SL's formulas more than a lot of other stuff I've seen around, he definitely knows his subject... and may I add, SL's numbers sound a lot more like what you actually measured and heard
😀
One possibility is that SL calculates using true peak Xmax and maybe other programs use the peak Xmax as if it was an RMS value. That would account for 3 dB SPL. And, maybe other programs assume 2 speakers, adding another 6 dB. So here we'd have 9 dB accounted for. But honestly, that's just speculation.
In general through experience with his design models I have come to trust SL's formulas more than a lot of other stuff I've seen around, he definitely knows his subject... and may I add, SL's numbers sound a lot more like what you actually measured and heard
😀
You have a small room.
Have you explored the attic or building a monster subwoofer outside and port the bass into your room.
Have you explored the attic or building a monster subwoofer outside and port the bass into your room.
Finished design:
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Hi Josh,
I'm not 100% sure just yet.
I was considering mounting a pair of UcD400's in there and wiring each to a pair of drivers in parallel. But it means providing access to the amps which should be fairly simple with hinged door that could also double as ventilation with some creative routing. I also realised I could use one of those blue LED push buttons again!
(I nicked these pics off Jase)
If I go this way things will look a fair amount smarter because of the integration.
If not then I'll likely fill them with sand.
I'm not 100% sure just yet.
I was considering mounting a pair of UcD400's in there and wiring each to a pair of drivers in parallel. But it means providing access to the amps which should be fairly simple with hinged door that could also double as ventilation with some creative routing. I also realised I could use one of those blue LED push buttons again!
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
(I nicked these pics off Jase)
If I go this way things will look a fair amount smarter because of the integration.
If not then I'll likely fill them with sand.
Drivers have all arrived now:
An externally hosted image should be here but it was not working when we last tested it.
Why not stack the four woofers in a tall column so you can
place the box in the corner of the room - out of the way -
then, later, when you get the itch again, you can make another
for the other corner of the room? Having a big square box in
the room takes up space 😎
place the box in the corner of the room - out of the way -
then, later, when you get the itch again, you can make another
for the other corner of the room? Having a big square box in
the room takes up space
😎 
m0tion said:
Yes but only when you sit at ear height level between the mid and treble and from a dstances over 2m.
Sloping the baffle isn't really ideal though because your then listening off-axis all the time - in my case upto 16degrees off axis for the treble! This isn't a problem with the bass driver and the wide dispersion mid, overall the power response of the speakers is good though, which let you get away with doing that. A better solution would be a staggered baffle but then you're looking at reflection/diffraction/comb filtering issues if your not careful.
Not really much progress because the port turned into something of an excercise in frustration. It seemed so simple when I sketched the idea out, Looks like I got the toughest part out of the way anyway.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
ShinOBIWAN said:
Ola!
I've thought about this for a while now and I think the problem is with the port size (diameter). Increased non-linear resistance to air movement (aka port "compression"). In other words you get to a certain sp-level and the port's contribution "flatten's out at a ceiling" in a somewhat similar manner to a driver with thermal "power" compression.
Unfortunetly that puts us back with an unacceptable cabinet volume and shape for something like a 5 inch diameter port (..and all the volume it "eats-up").
Its a guess though.. 🙄
ScottG said:
Could well be, port noise certainly doesn't seem to be a problem though unless your running sines, on music and normally content I haven't heard anything.
Ahem, the discrepancy between SL's spreadsheets and the popular box calculators is still unsolved. It may have been the port alright... But, if SL's stuff is right and all else is too optimistic, then there may be more surprises in store for other designs as well, proportional to the discrepancies noted for the B&C sub.
ScottG said:
Ah, but Shin's a clever fellow. He could find a way to put that port on the outside of the box and make it look like a designer feature. Homage to the industrial age?
Sheldon
Neat idea... which immediately suggests a name for the box: "Le Boom-pidou" 😀 😀 😀
[am I showing my age here?]
[am I showing my age here?]
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