I’ve simulated in WinISD a 11 liter speaker box with a SB acoustics sb15sfcr39-4 and a passive radiator similar to the woofer but without the magnet, it has exactly the same Sd and Xmax.
I’ve readed in many sites that for a 8” woofer do you need two 8” passive radiator but in my simulation i get better result with only one passive radiator, is this possible?
I’ve readed in many sites that for a 8” woofer do you need two 8” passive radiator but in my simulation i get better result with only one passive radiator, is this possible?
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Joined 2003
It is also dependent on the size of the cabinet. A much larger cabinet requires less passive radiator excursion.
I have used several combination. With like size a 2 X increase in box size and a same size or HE (high excursion)
radiator may work better. Unless you are maxing the PR. Then one size larger is "a choice", but it may not be
"the choice". The smaller the driver weather active or not usually has less total mass. That equates to centering
the cone quicker. Usually smaller = FASTER.
An example is a 12" HE active like a Ultimax 12" and using an 18" HE passive. If I add cabinet volume to the mix
there would be little control over the 18" passive. If I dropped the volume I still have to accommodate the size of
the 18" passive to mount it. Then the 18" can't re-center or a 15 for that matter as fast.
The rule is 2 X the active driver. WHO made the rule? I didn't and in all fairness I've tried every combination under the
sun with Passive Radiators. It is best to match the size of the largest driver and then the volume of the cabinet.
IF you're after BIG BASS in a small box the 2 X rule works great, but it is NOT my rule and never has been for
most music applications. Another feature to add to a PR is add a soft mass like Mortite. "Pinch putty", fine tune?
I've used 4 active 12" drivers and ONE passive 15". I've seen 4 active 12s, one active 15" and ONE 15" PR.
They are large cabinets. 16 and 16.75cf. Mine are 16.75cf. 1-6 active drivers or PRs.
VMPS made the 72" 16cf model it used a 1000 watt plate amp from PE I think. Been a while. ONE 15" PR. for
5 active and one 15" PR. It was one of the best analog bass cabinets I ever heard.
For the money it was a super deal.
RIP VMPS.:-(
VLA, 180 cm (6 ft.) tall powered woofer column ($4950ea 2007 or 12), the VLA (Very Large Array) with four 30 cm drivers plus one side-firing 38 cm (15") and one down-firing 30 cm (12") PR. <--------ONE. He really didn't pay attention to the rule did he? LOL
http://pointillistic.com/vmps-audio/subwoofers.htm
I have used several combination. With like size a 2 X increase in box size and a same size or HE (high excursion)
radiator may work better. Unless you are maxing the PR. Then one size larger is "a choice", but it may not be
"the choice". The smaller the driver weather active or not usually has less total mass. That equates to centering
the cone quicker. Usually smaller = FASTER.
An example is a 12" HE active like a Ultimax 12" and using an 18" HE passive. If I add cabinet volume to the mix
there would be little control over the 18" passive. If I dropped the volume I still have to accommodate the size of
the 18" passive to mount it. Then the 18" can't re-center or a 15 for that matter as fast.
The rule is 2 X the active driver. WHO made the rule? I didn't and in all fairness I've tried every combination under the
sun with Passive Radiators. It is best to match the size of the largest driver and then the volume of the cabinet.
IF you're after BIG BASS in a small box the 2 X rule works great, but it is NOT my rule and never has been for
most music applications. Another feature to add to a PR is add a soft mass like Mortite. "Pinch putty", fine tune?
I've used 4 active 12" drivers and ONE passive 15". I've seen 4 active 12s, one active 15" and ONE 15" PR.
They are large cabinets. 16 and 16.75cf. Mine are 16.75cf. 1-6 active drivers or PRs.
VMPS made the 72" 16cf model it used a 1000 watt plate amp from PE I think. Been a while. ONE 15" PR. for
5 active and one 15" PR. It was one of the best analog bass cabinets I ever heard.
For the money it was a super deal.
RIP VMPS.:-(
VLA, 180 cm (6 ft.) tall powered woofer column ($4950ea 2007 or 12), the VLA (Very Large Array) with four 30 cm drivers plus one side-firing 38 cm (15") and one down-firing 30 cm (12") PR. <--------ONE. He really didn't pay attention to the rule did he? LOL
http://pointillistic.com/vmps-audio/subwoofers.htm