Deaf bonce Apocalypse DB-3012R D2 Box

[MarcoPT]

hey,in the past every thing i build was with the recomended box specs now im getting this sub (Deaf bonce Apocalypse DB-3012R D2) but i want to do something diferente, the recomended specs are 1.94 cf tuned to 35hz with 31 square inchs of port area, they even tell me the port length of 27 inch, that with my targetted box height would give me 2.1 inch width port.

acording to win SD i would have 34 meters/secund air speed at 34 hertz. (possible port noise rigth?)

in the past i used aero ports and liked a lot and im kind of thinking at going back to those again.

i have 3 questions:

how much biggeg can i go over the recomended 1.9cf?

if i go with aero port, how much can i reduce in port area?

regarding port air speed, how much is aceptable using aero port? 

i was thinking of something betwin 2 and 2.5cf with two 3.5" aero port tune to 34/35hz giving me 19sq inch of port area but the air speed is up there (60m/s at 34hz 3.5") 

is 60m/s to much for two aero ports?

[Joe X]

1) larger enclosure plays peakier with better low end but with a loss of sound quality. You need to watch out for over excursion at lower power levels with a bigger box, you can check that with WinISD, keep maximum excursion below Xmax at all costs.

 

2) port area is judged by airspeed, lower airspeed is better, for slot ports I would keep around 26 m/s or less, for aero ports if its just round pipe would keep within 30 m/s, if it has professionally designed flares 35 m/s or a little more. If the form factor of the port is high or you have turns in the port its better to go for lower airspeed.

 

3) with WinISD add a linkwitz transform filter to simulate cabin gain frequency response, bear in mind that you need to disable it when looking at all the other plots.

[MarcoPT]

the ideia is to have the sub facing the seats, is a sedan a mercedes w211 but i cant have a deeper box because i must have usable trunk space thats one of the reason for the sub to be face this way, so i can use the trunk without wory about something damaging the sub. 

ports wil be professionally done.

i was thinking of having sub front, port front (facing seats) but this way i have to have a 90º on the ports, is there any advantage of having side ports? (side ports could be straigth)

regarding box size im working out a middle ground betwin peakier and sound quality, and yes i have excursion and atencion.

so port area is not that important besides air speed? thats good to know....

yes i use WinISD and i did add a linkwitz transform to see how the box that im working on would perform and it would have a nice low end without lossing up there
 

[Joe X]

One important thing here is that many european cars need the rear deck opened so that sound waves get into the cabin so you may need to do that.

 

You can have port to the side, many SPL designs go that way, digital designs enclosure suggestions use port to the side, you just need abundant clearance for the port to work well.

 

Also bear in mind that WinISD is a basic program and the plots obtained are really coarse representation of what you will get, you need to experiment where to aim sub and port, what location is best for the box, better aesthetics and functionality in car audio many times mean worse performance, my recommendation is setup the way is best for sound, for example fire back the sub and since it is exposed use a grille to protect it if that's better than firing forward.

[MarcoPT]

exacly my mercedes is basicly close deck, one of the main reasons that i have to think sub and port facing seats, let me explain, my car was imported from Germany so it has a "snow pack" is a ski bag that come into the car by the rear seat arm rest, i have removed that, now with my rear seat arm rest down i have +/- a 8inch by 13inch hole from the trunk to the cabin

yeah winsd is more or less of "you get something like this" program but i think is a good base to work on, dont you agree?

i was thinking about sub location but i thing this one (facing seats) is maybe the one that would give better sound quality, im not aiming to SPL, i want more of SQL sistem, nice quality but a big bass too, want to find a nice middle ground betwin them, thats why i have the mosconi and hertz amp and 6 audison speakers to put in there, nice quality amps and speakers, i have a db sa2712 and is a nice sub for the money but want more power and deafbonce sub can be nice musical subs but still gives you big bass.

ports facing side, was an option but after checking some stuf is no longer, the max clearance i can have is like 8 inch but the port will unload to the trunk because with seats up that side 8 inch space would be allmost close the back of the seats so air from the port would go the easy way to the trunk

[Joe X]

The ski hole is not going to be enough for a ported setup and you would need to open up the rear deck, sure enough it's a mercedes and probably you won't be inclined to cut holes on it so you may have to live with whatever you get or do a 4th BP blowthrough  which the sub seems not ideal for it.