"With these bigger drivers, you're probably not going to want the driver firing vertical unless you want a lot of vertical vibration on the cabinet. Rubber feet will help with that, but there's also the issue of gravity pulling the motor out of its symmetrical range."
i don't think that has been a problem yet for any of the b&c horn loaded subwoofers.
"We should also run the numbers to figure out which rear volume will reactance annul the horn - doing this will balance on the pressure on each side of the driver at Fc, and reduce cone flexing which will be a bigger issue with this large diaphragm."
i'm not sure what you are referring to here. the fc of this horn is around 19hz. the driver fs is 30.5hz. how those are going to arrive at a reactance mitigated low corner isn't something that i am familiar with how to accomplish. acoustical impedance/reactance seems well matched, but i'm not sure exactly what you are suggesting.
"Also, drilling a hole in the wall means you've pretty much fixed the acoustic source of the subwoofer into your room. Room modes will dominate the perceived performance, so it's good to make sure you're picking a location that is optimal for your space. The best way to do that would be to move an existing subwoofer along that wall until you find the ideal location. Even then, the horn presents a complicated acoustic impedance to the room which will affect these simulated results."
he has tested his current sub in the location of the horn entry to the room and it appears to be fine.
"I would also recommend lining the horn with absorptive material so you don't get the cavern effect at higher frequencies - this becomes more of an issue as you make the horn mouth larger and larger."
"How high in frequency do you want the horn to go?"
i think the application is bass horn, not midrange horn.
"Bifurcating the throat of the horn can reduce the inside/outside pathlength difference which helps with high frequency extension, but that may not be an issue here. If you do it right, you might be able to reduce your bracing needs by balancing the pressure across the bifurcation panel....I'd have to sit down and run some numbers to see if that's doable with a simple build approach."
this might have application for a midrange horn, but i don't see the advantage here. the horn design employs a relatively low compression ratio as well, so differential loading on the driver is going to be relatively minimal compared with other designs.
"Also, it's a bit counter-intuitive, but the areas needing the most bracing will actually be at the mouth end. We think about higher pressures at the throat due to the compression ratio, but that is getting turned into a velocity that gradually changes to a pressure at the mouth. It's the pressure that will cause your cabinet walls to vibrate. The mouth is also the larger aperture, so the panels vibrate easier too."
a bracing plan was suggested. i think it will be more than satisfactory. do you disagree with the bracing plan?
"What about having two mouth openings?"
that could be done, but would complicate things and a big part of the idea with this one is to keep things as simple as possible even if it gives up a little bit of the room mode minimizing behavior that you are talking about.
"Btw, you should be using 1/8 space in hornresp....the room is technically smaller than that, but that's the best hornresp will do."
agree...but for the sake of comparison with winisd models, 2pi space is being modeled. pressure vessel gain is also going improve bass response and that isn't in the model either.Edited by LTD02 - 6/25/13 at 7:54pm