I've found that the Type-R 12s sound best in a 1.25 - 2 ft^3/sub sealed enclosure ... Personally, I have mine in a 1.5 ft^3/sub sealed enclosure ... They sound great ... Much better than recommended box volume (0.7-1 ft^3/sub)

 

I just recently built an abc for a 12" L7. It gets excruciatingly loud, although it lacks some punch for my taste (maybe I just chose the wrong woofer or box size, oh well). It's in a 3.2 cu. ft. box tuned around 32 hz (3 x 9").

As for calculating how to build one, calculate a vented box as you would regularly, but with two ports. Then divide the internal volume 1/3-2/3. put one port in each chamber, adding an identical one in the divider wall. Put the woofer(s) in the largest part and enjoy!

[ June 05, 2003, 10:17 AM: Message edited by: 88_T-Bird ]

 

So what are the differences between say a 5 ft^3 ported box tuned to 30 Hz and a 5 ft^3 ABC box tuned to 30 Hz ?

 

Added punch and loudness with a drop in SQ sounds like a ported box that's tuned higher ...

I've never been exactly sure of the difference in results or why/if there is a difference ... Could it be that it's just harder to get the tuning right ? Or, if not, could you explain more in-depth as to how an ABC box reacts differently than a ported box ?

 

I didn't find any compromise in the sound quality at all, facing backwards in my trunk it sounds good but not great, but facing forwards the midbass transition between my mids and subs is nearly flawless and all the bass was right up front. In fact the boomy upper bass I had before with my 12 is completely gone, even with the crossover all the way up. Could be different for 12's but I know my two 8's sound great.
I do leave it facing backwards though, because it sounds a bit louder and I don't get port noise that way (I made my ports a wee bit small, oops )

Maybe Dukk's box just SUCKS (*ducking*) lol
But they are hard to design right, I spent more than a few hours with a piece of paper, pencil and calculator.

[ June 05, 2003, 04:29 PM: Message edited by: hiredgoon ]

 

Yeah, everyone around here makes the ports the same length and size, so that might be the reason why I never understood [img]tongue.gif[/img]

I got it now ...