Smallest box with passive radiator for 25Hz F3.
We now know that in case of multi sub setup the individual sub's alignment doesn't matter, reasonably speaking. As long as the sub can reach the intended extension within its excursion and power handling limit, the alignment does not matter. So, lets not discuss driver parameters and alignments, from the plethora of drivers available from either home audio or car audio, just about any decent one could work fine.
Now, for the same tuning (Fb) a smaller box means increased added mass on the PR. It means that the added mass and size of the enclosure are the limiting factors. Because we cant add more mass, we cant make the box any smaller.
So, how small can a box get and how much mass can be added to 10"/12" PRs for 25Hz, F3? Pls note that for 25Hz, F3, a much lower Fb will be needed.
Related: Bose:Small enclosure, long port, how?
We now know that in case of multi sub setup the individual sub's alignment doesn't matter, reasonably speaking. As long as the sub can reach the intended extension within its excursion and power handling limit, the alignment does not matter. So, lets not discuss driver parameters and alignments, from the plethora of drivers available from either home audio or car audio, just about any decent one could work fine.
Now, for the same tuning (Fb) a smaller box means increased added mass on the PR. It means that the added mass and size of the enclosure are the limiting factors. Because we cant add more mass, we cant make the box any smaller.
So, how small can a box get and how much mass can be added to 10"/12" PRs for 25Hz, F3? Pls note that for 25Hz, F3, a much lower Fb will be needed.
Related: Bose:Small enclosure, long port, how?
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When you make the box small, the -3dB point rises regardless of the actual tuning frequency.
If you're planning on using EQ, then f3=Fb=25Hz is a reasonable target.
I'd be more worried about the spider and suspension of the PR holding a 1kg+ mass, so down to individual PRs I suppose.
In the case of extremely small cabinets, the power handling of the main driver will become the limiting factor: small cabinets mean very low efficiency at the bottom end, to a point where you'll need to exceed the driver's thermal rating to get it to Xmax.
Chris
If you're planning on using EQ, then f3=Fb=25Hz is a reasonable target.
I'd be more worried about the spider and suspension of the PR holding a 1kg+ mass, so down to individual PRs I suppose.
In the case of extremely small cabinets, the power handling of the main driver will become the limiting factor: small cabinets mean very low efficiency at the bottom end, to a point where you'll need to exceed the driver's thermal rating to get it to Xmax.
Chris
1.5cuft with a 12" Earthquake Magma X and 12" slaps (1st gen with the recommended mod) and 250 odd grams added mass using a bolt, lock nut and lead.
Tuning was 16hz ish
Tuning was 16hz ish
What qualifies as small? I built a 1 cubic foot sealed subwoofer enclosure with the ScanSpeak 23W/4557T-02, 9" Aluminum Cone Subwoofer and ScanSpeak 23W/0-00-02, 9″ Subwoofer, Passive Radiator.
From the distributor’s web page at the time; "The Scan-speak 23W/4557T is a very high end subwoofer, designed to be used with a passive radiator in a small enclosure. This sub has a very rigid aluminum cone, low loss rubber surround and cast frame. The passive radiator is similar, but with a weight attached to the bass of the cone. The 23W/4557T is using the SD-1 motor system. There are gold plated binding posts and the woofer is covered by a decorative rubber cap.
Frequency response with the passive is down to 25Hz. One cubic foot sealed has an F3 of 33Hz."
“This is the passive radiator intended for use with the 23W/4557T active woofer. We recommend putting both in a 1.0 cubic foot enclosure. This should yield a bass response down to 25Hz. The woofer should still be linear at 180 watts and have an output of about 104dB.”
Not the loudest and can’t take as much power as some but it does sound great and plays low.
From the distributor’s web page at the time; "The Scan-speak 23W/4557T is a very high end subwoofer, designed to be used with a passive radiator in a small enclosure. This sub has a very rigid aluminum cone, low loss rubber surround and cast frame. The passive radiator is similar, but with a weight attached to the bass of the cone. The 23W/4557T is using the SD-1 motor system. There are gold plated binding posts and the woofer is covered by a decorative rubber cap.
Frequency response with the passive is down to 25Hz. One cubic foot sealed has an F3 of 33Hz."
“This is the passive radiator intended for use with the 23W/4557T active woofer. We recommend putting both in a 1.0 cubic foot enclosure. This should yield a bass response down to 25Hz. The woofer should still be linear at 180 watts and have an output of about 104dB.”
Not the loudest and can’t take as much power as some but it does sound great and plays low.
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One of the fellows who attends our informal car audio get togethers has a 23W/4557T-02 in a 30 litre (circa 1 cubic foot) sealed box in the boot of his Toyota Avalon and it goes deep, loud and sounds very musical in a classic case of quality over quantity.
Sorry I can't help with what kind of passive radiator might be able to handle it; I just wondered if this car audio driver is interesting to you, since at my level of knowledge it appears to be build for for this application: The EBP recommends vented, but it only needs tiny tiny boxes even for very low tunings, so I'm not sure what it would be useful for beside PR use!
WinISD suggests that it might have a quite loud -3db point at 25hz, in 0.75ft3 ported, which is completely unbuildable as a vented box (it would 12 feet of 6" pipe for a port to keep velocities under control, haha).
WinISD suggests that it might have a quite loud -3db point at 25hz, in 0.75ft3 ported, which is completely unbuildable as a vented box (it would 12 feet of 6" pipe for a port to keep velocities under control, haha).
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Since F3 is relative to nominal output, you can get as low an F3 as you want in as small a box as you want. Practically speaking though, with available drivers, probably about 1 cu ft. I currently run a CSS SDX12 with 2 of their APR12s (990g on each) in the smallest box you can actually cram all 3 drivers in. In this scenario, the box is 1.25 cu ft with a 30Hz F3, but the rolloff emulates a sealed enclosure, dropping off at only 12dB/octave down to about 15Hz.
While it's in the gray area of both types, it's specs bias it towards best suited for sealed as the motor's too weak to properly energize the PR as your sim proves, ditto the vent length proves best vented is a 2:1 CR 1/4 WL resonator [pipe] tuned to Fs/Qts.
GM