Thanks for the Sims and explanations!
I decided to go with a slightly smaller box (70 liters) with the assumptions that The drivers would measure somewhere between the posted specs and Patrick’s, and that stuffing would somewhat offset the volume of the braces. It seemed the worst case is a slightly higher Q, but not by a whole lot.
I’ve read stuffing increases the apparent box size by 5-15% depending on the type and how much is used, which is similar to the volume occupied by the bracing. Is it reasonable to assume they sort of cancel?
Boxes are in the planning stage but are not built yet.
Happy to help and yes I think box stuffing does effectively increase the box volume.
I think its worth reading up a bit on different internal wall dampening and box stuffing materials.
After years of experimenting with sheeps wool, fibreglass, eco loft insulation, denim based materials etc, I have settled on this:
(1) "Twaron" or Angel Hair - Mundorf MSilence TWARON Angel Hair, 200g
Esp good if you combine with 1mm or 2mm thick bitumen adhesive panels stuck on the inside walls.
One other important point re the internal shape of a cabinet-
Asymmetry is better than symmetry and non parallel walls are better than parallel walls. Obviously aesthetics and practicality / ease of construction come int play but you can "cheat" ie on the outside its just a rectangular box (or trapezoid if possible) but on the inside... You can glue different shapes of wedges (balsa wood is great) and or acoustic foam wedges on one side wall and either top or bottom of the cabinet to avoid parallel walls.
Also using different types and density will have slightly different energy absorption characteristics ie different wavelengths.
There are many interesting articles on the web on this subject.
Cheers
A.
I think its worth reading up a bit on different internal wall dampening and box stuffing materials.
After years of experimenting with sheeps wool, fibreglass, eco loft insulation, denim based materials etc, I have settled on this:
(1) "Twaron" or Angel Hair - Mundorf MSilence TWARON Angel Hair, 200g
Esp good if you combine with 1mm or 2mm thick bitumen adhesive panels stuck on the inside walls.
One other important point re the internal shape of a cabinet-
Asymmetry is better than symmetry and non parallel walls are better than parallel walls. Obviously aesthetics and practicality / ease of construction come int play but you can "cheat" ie on the outside its just a rectangular box (or trapezoid if possible) but on the inside... You can glue different shapes of wedges (balsa wood is great) and or acoustic foam wedges on one side wall and either top or bottom of the cabinet to avoid parallel walls.
Also using different types and density will have slightly different energy absorption characteristics ie different wavelengths.
There are many interesting articles on the web on this subject.
Cheers
A.
Thanks for the sims, Alex. I was recently able to purchase a third driver for the center channel of an LCR setup; for the center I would like to go sealed so this info is very helpful.
Finally!
OK........ in review realized width will be < the max 40" as it makes the cab too shallow for a duplex, so best overall to completely ignore the original post/design and will redo based only on 40" ear height.
Did a T/S max flat, but way too big [~540 L!] with no real wide band bass advantage peak power wise other than it can have a wider baffle, so went with the pioneer's Vb = Vas/1.44 = ~143 L, Fb = Fs as it has the most extended low-frequency, transient response with subjectively unnoticeable hangover/'boom' with less internal damping required and of course can always add 'wings' to make a wide baffle for acoustic BSC.
All dims inside [i.d.] and approximate, damp to 'taste' ;):
H = 60.3"
W x D = 144.75"^2
driver offset = 39.25"
vent offset = 9.15"
vent = 8" dia. x 7.92" L
If too 'lean' a LF power band and can tolerate/move a bigger cab, then upping it to a ~[143*540]^0.5 = ~278 L yields a worthwhile EQ'd LF power increase around Fb.
OK........ in review realized width will be < the max 40" as it makes the cab too shallow for a duplex, so best overall to completely ignore the original post/design and will redo based only on 40" ear height.
Did a T/S max flat, but way too big [~540 L!] with no real wide band bass advantage peak power wise other than it can have a wider baffle, so went with the pioneer's Vb = Vas/1.44 = ~143 L, Fb = Fs as it has the most extended low-frequency, transient response with subjectively unnoticeable hangover/'boom' with less internal damping required and of course can always add 'wings' to make a wide baffle for acoustic BSC.
All dims inside [i.d.] and approximate, damp to 'taste' ;):
H = 60.3"
W x D = 144.75"^2
driver offset = 39.25"
vent offset = 9.15"
vent = 8" dia. x 7.92" L
If too 'lean' a LF power band and can tolerate/move a bigger cab, then upping it to a ~[143*540]^0.5 = ~278 L yields a worthwhile EQ'd LF power increase around Fb.
