ABC Boxes....
 

Are people still building these boxes? I had one a while back it sounded so dam loud and so dam clear I'd like to try another one. My question is how to mock up the response in a box sim program like WinISD. Is the lower tuning frequency the total airspace of BOTH chambers with TWO ports? And is there some way of simulating the second tuning frequency if I just do another simulation and use 1/3 the total volume and 1 port? Or is it alot more complicated than this? I'm curious cause when I do it this way, I am not getting tuning frequencies that wind up 1 octave apart, it is close though if I do the lower tuning frequency with just ONE port instead of two.... Any input is appreciated. These boxes can be difficult to build so I want to get it sounding good on the first try.

Thanks,
R

Oh, the box will be for two Rockford RFR2210, power subwoofers, ya, they're old, but they pound like snot in vented enclosures! And I got em for 100bux...

where to start lol.
as far as i know there are no programs that can model the resonce curve of an abc enclosure,but you have already have the basic concept of how they work. 2 tuning points, an octave apart.great slq boxes.generaly they have to be about 2x the size of a ported box,and have really long port lengths

chose how big you want to make your box. lets say 4cf
to figure out the size of the first and second chanber chamber multily 4 by .666 and then again multily 4 by .333

first chaber=2.7 cf
second chaber =1.3
2.7+1.3=4cf
(rounded off numbers)

now you need to find a port lenth calculator

choose how much port area: use the same about as would woild if you were building a ported box with one port ( example 16sq")

next choose your tuning you only have to choose the lower tuning becasue the higher tuning will come about an above the lower tuning

now in the port length calculator type in a 4cf box @ xx hz. then select 2 ports. ( 2 ports @ 16 sq" each)

and that is how long you must make all 3 ports.

I hope that explains how to design them a bit better for ya.using the above way gives you chamber sizes and port length, that is the easy part, the hard part is actually comeing up with a design is exaclty to the specs you come up with. also the port lenths and chamber sizes used in the method above just suggestions that we can predict what the end results will be ( we know that the higher tuning will be an octave above the lower tuning), but you can change the sizeing of the chambers or lengths of the ports to get differnt results( maby makeing the smaller chamber 3/4 the size of the larger one to change the higher tuning to 1/2 octave above the lower tuning or something like that)

pm me if ya need a design

^ The method described above is mostly correct. Determine the maximum safe volume for your drivers - WinISD has an excursion graph on it - use it. Generally the design tuning is kept low, 30-35hz max.

Right on! Thanks for the great replies fellas. I think I'm going to try and get about 5-6 cubic feet total for the two drivers and tune down to 30Hz. Should sound sweet!

Thanks again,
Rrrrolla

Oh my....:hah:

Why do I feel a case of "Deja Vu" coming on??....:cheeky4:

I've never heard of an abc box, what exactly is it? anyone have photos? I'm curious :)

aperiodic bi-chamber.

should be more info here:
http://audioforum.termpro.com/cgi-bi...c;f=8;t=000451
you may recognize the name in there ;)

^^^ by the time a person reads that whole thead they should be well educated about abc boxes lol

scroudt111 :)look at my avatar, its hard to see but its a slot port abc, i cant seem to find a larger pic of it.

heres a better pic:

http://www.diysubwoofers.org/images/site/ported-dc.gif

cool...just seeing a pic helps me understand the post a heck of alot better. I might have to try on of those one day :D