I am planning to build an open baffle "subwoofer" to complement my existing electrostatic speakers. The goal is to cover 30Hz to 100 Hz. Sensitivity can be as low as 86dB/1m. Each unit could have four drivers (space limit, one driver could be 6" diameter at most, they will be in line).
That means fs should be around 30Hz and Qts should be 0.7 to 1.2 or so. I think long throw is the most important requirement for an open baffle subwoofer.
What products shall I consider? (EU source preferred). Could any car audio drivers usable for the purpose?
That means fs should be around 30Hz and Qts should be 0.7 to 1.2 or so. I think long throw is the most important requirement for an open baffle subwoofer.
What products shall I consider? (EU source preferred). Could any car audio drivers usable for the purpose?
I think you run into the Hoffman iron law. Small, low going and efficient or loud is not possible, so you need to choose 2 factors of those...
I don't know any who can do that, and certainly for open baffle, you need big woofers to get any bass that low.
I don't know any who can do that, and certainly for open baffle, you need big woofers to get any bass that low.
If you lower your requirements a bit, probably these are viable options:
- Peerless SBS-160F35CP01-04
- Tang Band W6-1721
- SB Acoustics SB17NAC35
- Peerless SBS-160F35CP01-04
- Tang Band W6-1721
- SB Acoustics SB17NAC35
Within these constraints (open baffle, limited size), this is what I'd do:
- use eq (e.g. mini DSP) to make the response do whatever I want.
This would make Qts and Fs irrelevant, so driver selection would be much easier.
- use a SLOB (Slot loaded Open Baffle) rather than a flat baffle.
This would mean you could fit twice as many drivers into the same frontal area.
...then I'd shop for whatever drivers gave me the greatest displacement, within my budget and space limitations.
Note that throw isn't really what you are after - it is total displacement.
Drivers like this
Test Bench: Exodus Audio W06-017R “Anarchy” | audioXpress
...have a lot of throw, but they are too chunky to use on a SLOB, and the round frames won't pack very closely together.
Using a SLOB, you might be able to pack 10 truncated frame 6" into the same space as four Anarchy woofers on a flat baffle.
- use eq (e.g. mini DSP) to make the response do whatever I want.
This would make Qts and Fs irrelevant, so driver selection would be much easier.
- use a SLOB (Slot loaded Open Baffle) rather than a flat baffle.
This would mean you could fit twice as many drivers into the same frontal area.
...then I'd shop for whatever drivers gave me the greatest displacement, within my budget and space limitations.
Note that throw isn't really what you are after - it is total displacement.
Drivers like this
Test Bench: Exodus Audio W06-017R “Anarchy” | audioXpress
...have a lot of throw, but they are too chunky to use on a SLOB, and the round frames won't pack very closely together.
Using a SLOB, you might be able to pack 10 truncated frame 6" into the same space as four Anarchy woofers on a flat baffle.
Just an idea: have you considered horizontal mounting of the woofers? That way the sub must not be that high.
Used in eg.
Gramophone Dreams #26: Nelson Pass & Harmonic Distortion Page 2 | Stereophile.com
6moons audio reviews: Daudio W1
Gainphile: S19 4-Way Dipole Radiator
Used in eg.
Gramophone Dreams #26: Nelson Pass & Harmonic Distortion Page 2 | Stereophile.com
6moons audio reviews: Daudio W1
Gainphile: S19 4-Way Dipole Radiator
Thanks for all. I checked the specs of SEAS L16RN family (X3 and SL). They have Xmax=22mm, fs 32 and 37 Hz, resp. The only issue is the price for 8 pcs :-(
Compared to the Seas, this one has similar Xmax but twice the surface area (so they displace about twice as much air) for the same $.
Visaton GF 200 8" DVC Woofer 4 Ohm
Eight of the Seas in a SLOB would make two lines 584mm long. For $800
Four of the Visaton in a SLOB would make two "lines" only 444mm long. For $400
Visaton GF 200 8" DVC Woofer 4 Ohm
Eight of the Seas in a SLOB would make two lines 584mm long. For $800
Four of the Visaton in a SLOB would make two "lines" only 444mm long. For $400
'Aint no replacement for displacement. Pretty much a law of physics.
Yes, you can add a huge amount of mass to a 6 inch driver to get the Fs and VAS to go low enough, use enough of them to move enough air, eq enough to get the response, but far better to start with a 12 having 3 times the displacement to start with. USE physics, don't fight it.
X-max is at very high distortion. One spec suggests 10%, others suggest calculation based on coil to gap ( as I am learning) Plotting HD for the drivers I have on hand, suggests I want to keep excursion to 1/4 x-max at best for 90 dB. Pretty loud and louder does mask somewhat. In a BP4 or PB6 alignment, it could be the harmonics are blocked to an extent one can get away with higher excursion, but alas, as my morning calculations have shown, a 30 to 100 BP-4 is about impossible. Not the double hump response, but impractical ports. 20 to 60, beautiful, 80, nope. 100? Not even close. So stuck first or second order. Better drivers? I am all ears!
Yes, you can add a huge amount of mass to a 6 inch driver to get the Fs and VAS to go low enough, use enough of them to move enough air, eq enough to get the response, but far better to start with a 12 having 3 times the displacement to start with. USE physics, don't fight it.
X-max is at very high distortion. One spec suggests 10%, others suggest calculation based on coil to gap ( as I am learning) Plotting HD for the drivers I have on hand, suggests I want to keep excursion to 1/4 x-max at best for 90 dB. Pretty loud and louder does mask somewhat. In a BP4 or PB6 alignment, it could be the harmonics are blocked to an extent one can get away with higher excursion, but alas, as my morning calculations have shown, a 30 to 100 BP-4 is about impossible. Not the double hump response, but impractical ports. 20 to 60, beautiful, 80, nope. 100? Not even close. So stuck first or second order. Better drivers? I am all ears!
BTW, have you read the Linkwitz site about open baffle and bass? Why he went critical Q sealed for the sub? Might also check out the IB forums. Far better than trying to do an OB. An H-frame helps, but you still have to deal with the wavelength. Really, OB for a sub is not a very clever idea.