Originally Posted by tsloms
I'm just curious. How much larger would a ported enclosure need to be compared to this passive radiator one? I wouldn't think it would need to be much larger overall. The PR
's do eat into a lot of real estate inside the box making the enclosure larger by themselves.
The difficulty is in making the port large enough so you don't run into issues with vent noise and compression. Ideally you want to keep vent velocity to lower than 10m/s at maximum input power. In the case of the 24" external cube you have about 5cf total internal volume. To keep vent velocity low enough with 1000W input you'd need a 10" diameter vent that would be 131" long to match the tuning of the PR
's. This adds 6.48 cubic foot of volume to the enclosure.
's themselves take up virtually no box volume. They are intentionally made with flat MDF discs for the diaphragm so the "cone" takes up no volume at all. All you have taking up volume is the aluminum frame. This takes up less than .02 cubic feet.
Originally Posted by michael hurd
's on the same face... you are talking about 2.8 KG's of mass moving back and forth 20 times a second, over 2" P-P. Not a good plan.
That's 6 pounds of mass moving back and forth. If you have a 200 pound slab of rock on top of the box, you might get away with it, without rocking.
Before having 18" PR
's we were stuck with doing 3 of the 15" PR
's. This meant putting one on the back with nothing opposing it. The cabinet I sent to Tom Nousaine for testing had serious output, but if put on shag carpet the extra PR
on back with 2100G would rock the cabinet front to back a lot. You could physically see it moving 1/2" back and forth with the PR
's at full travel. The whole thing weighed about 160lbs. PR
's directly opposing on the sides completely eliminates this issue.
The only time we do PR
's on the same face with the driver is in car applications where there isn't really any other option for placement. Then we suggest rigidly mounting the box to the vehicle. This does however cause a lot of extra rattling but it also allows you to feel the bass much more.
Originally Posted by penngray
You could maybe go with the EP1500 because the AV15 may not need a ton of power?
I'd highly recommend against any of the Behringer amps for powering an AV15. While they are 4ohm nominal drivers, the AVH has a DCR of 2.7 ohm and the AVX has a DCR of 3.2ohm. Especially the AVH DCR is quite low for a 4ohm nominal driver which is great for increased sensitivity at 2.83V, but not good when amplifiers have trouble with stability into low impedances.
The Behringers do not like 4ohm bridged loads at all. We used the EP2500's in the Five Six Club install powering 4 lab subs that were thrown in "free" with the line arrays. In short time checking the EP2500's were fine. However, after an hour of use the first night, 2 of the 4 amps became extremely unstable and sent a ton of DC out to the woofers. Four of the eight woofers didn't make it past the first hour the club was open. The following day we swapped out the EP2500's for QSC PLX 3402's (more power) and there was never an issue again for over a year that the club was open.
While the EP2500's are cheap, they just are not reliable. Something like a Crown XTi1000 or Xti2000 should be a little better. The KGND52100 from madisound is also a very solid amp.