Having recently seen @tubelectron's micro and miniripole designs, it inspired me to play around with different variations to pair with my son's future bookshelf speakers, which are expected to be Zaph ZA5.2s (thanks for the midwoofers, @mordikai!) that could benefit from support below 80 Hz. I'm not looking for high SPL or shaking the whole house, but playing down (to ideally below 30 Hz) at modest volumes would be pretty sweet.
I'm swinging from cheap and cheerful to slightly better but still inexpensive drivers arranged in different ways. It seems that a downside is that it's hard to compete with a pair of inexpensive 12" drivers for one of these things. But, a fun form factor might make it worth not being the highest impact for the dollar. 🙂
I know very little about driver selection, so please take these ideas with a grain of salt!
Version 1: Quadripole... super cheap e.g. GRS 8SW-4 8" Poly Cone Subwoofer 4 Ohm drivers (currently $14 USD) arranged like a plus with 2 opposing pairs firing into a common chamber. The outer profile could be an octagon, perhaps with the "45 degree" sides curved inward a bit for visual cheekiness. Or maybe the outline is almost a pure circle. Not sure these would play that low with such high Fs drivers, though.
Version 2: Version 1 but with a better driver, e.g. GRS 8SW-4HE 8" High Excursion Subwoofer 4 Ohm. . Currently on sale for $40 USD. 10.5 mm xmax driver with 25 Hz Fs. Kind of expensive for a kid's ripole that still needs an amp, though, with 4 of them.
Versions 3 and 4: Trioripole... same notion as above, but with 3 drivers firing equilaterally into a common chamber. Could look pretty cute. Assumes an amp that's stable to 2 ohms or so, I'd imagine. Version 3 is cheap drivers, version 4 is the slightly better ones.
Version 5: fairly straightforward ripole using something like the GRS 8SW-4HE.
Version 6: fairly straightforward ripole using an inexpensive 12" driver like the GRS 12SW-4 12" Poly Cone Subwoofer 4 Ohm, currently 27 USD.
Thoughts? Other suggestions?
I'm swinging from cheap and cheerful to slightly better but still inexpensive drivers arranged in different ways. It seems that a downside is that it's hard to compete with a pair of inexpensive 12" drivers for one of these things. But, a fun form factor might make it worth not being the highest impact for the dollar. 🙂
I know very little about driver selection, so please take these ideas with a grain of salt!
Version 1: Quadripole... super cheap e.g. GRS 8SW-4 8" Poly Cone Subwoofer 4 Ohm drivers (currently $14 USD) arranged like a plus with 2 opposing pairs firing into a common chamber. The outer profile could be an octagon, perhaps with the "45 degree" sides curved inward a bit for visual cheekiness. Or maybe the outline is almost a pure circle. Not sure these would play that low with such high Fs drivers, though.
Version 2: Version 1 but with a better driver, e.g. GRS 8SW-4HE 8" High Excursion Subwoofer 4 Ohm. . Currently on sale for $40 USD. 10.5 mm xmax driver with 25 Hz Fs. Kind of expensive for a kid's ripole that still needs an amp, though, with 4 of them.
Versions 3 and 4: Trioripole... same notion as above, but with 3 drivers firing equilaterally into a common chamber. Could look pretty cute. Assumes an amp that's stable to 2 ohms or so, I'd imagine. Version 3 is cheap drivers, version 4 is the slightly better ones.
Version 5: fairly straightforward ripole using something like the GRS 8SW-4HE.
Version 6: fairly straightforward ripole using an inexpensive 12" driver like the GRS 12SW-4 12" Poly Cone Subwoofer 4 Ohm, currently 27 USD.
Thoughts? Other suggestions?
30hz response?…..forget any variation of OB designs…….between the expense and footprint displacement , it’s a losing game. A single 12” driver tuned to 30hz will get you there.
That's certainly a very cost-effective option. Thanks for the suggestion.
I find it very puzzling... some contributors say that it's more or less impossible, and some love the less boomy deep bass (if not high SPL) in their systems? Is it a nearfield vs standard listening difference thing?
I find it very puzzling... some contributors say that it's more or less impossible, and some love the less boomy deep bass (if not high SPL) in their systems? Is it a nearfield vs standard listening difference thing?
That's quite a lineup of variations! I've never (knowingly) seen a few of those.
I'm sure this isn't anything particularly new, but I've considered making a modified H-frame with a taper on the front, either with wedges/slanted front sides, or as a cone if starting from a cylinder. My interest in doing so was actually driven more by partially hiding the fronts of the drivers from view in order to better make large drivers integrate with my wife's preferences! 🙂
Here is a cross-section showing the H on the left and the tapered H on the right.
For this particular example I was trying to make the GR Research OB servosubs have a front baffle width that would also match their Oticas (and their "wings").
Would the tapered H-frame have the same cavity resonance limitations as with a ripole? Or how would one model this? I think the above image on the right, which was a rounded slot, was reducing the Sd to about 1/3 Sd.
I'm sure this isn't anything particularly new, but I've considered making a modified H-frame with a taper on the front, either with wedges/slanted front sides, or as a cone if starting from a cylinder. My interest in doing so was actually driven more by partially hiding the fronts of the drivers from view in order to better make large drivers integrate with my wife's preferences! 🙂
Here is a cross-section showing the H on the left and the tapered H on the right.
For this particular example I was trying to make the GR Research OB servosubs have a front baffle width that would also match their Oticas (and their "wings").
Would the tapered H-frame have the same cavity resonance limitations as with a ripole? Or how would one model this? I think the above image on the right, which was a rounded slot, was reducing the Sd to about 1/3 Sd.
That seems similar to the slot loaded open baffle just a different shape restriction. The resonant peak may be hard to model; I think Linkwitz just measured it.
These may be of interest:
https://www.linkwitzlab.com/models.htm#C
https://www.firstwatt.com/wp-content/uploads/2023/12/art_slob.pdf
These may be of interest:
https://www.linkwitzlab.com/models.htm#C
https://www.firstwatt.com/wp-content/uploads/2023/12/art_slob.pdf
Hi,
Does anyone have the specs of this OB from Papa?
[Report] Burning Amp 2012 [English]
Baffle dimensions and slot details would be great.
Thanks,
C.
Does anyone have the specs of this OB from Papa?
[Report] Burning Amp 2012 [English]
Baffle dimensions and slot details would be great.
Thanks,
C.
Linkwitz does have the formula of how to calculate the cavity resonance of the standard H frame ob.
"The PHOENIX woofer has D=19" (0.48 m) separation between its openings. The peak should be at f = 0.5*v/D = 357 Hz,but the cabinet layout is too complicated for such simple calculation to apply exactly."
"The PHOENIX woofer has D=19" (0.48 m) separation between its openings. The peak should be at f = 0.5*v/D = 357 Hz,but the cabinet layout is too complicated for such simple calculation to apply exactly."