in a 91 EF sedan, will 6 Rockford fosgate 10s and a RF 18 All XLC all 4 ohm . I am willing to give up my whole trunk

 

I can tell you right now, NO! The 18" alone would need almost 4 cu/ft. of airspace or more. Probably more. Then, each ten would need 1-1.5" cu/ft. per sub. At least to sound decent. You'd need to lose your back seat, or a portion of it, too.

 

If you give up the sealed enclosure and go with an composite isobaric or aperiodic enclosure, you could maybe squeeze all 6 10's in the trunk. 18 could fit in spare tire well. Another option is a 4th order triple chamber isobaric bandpass that would take up the lower half of your trunk and use 4 subs.

 

Well, your Isobaric idea just sounds like a waste of money. For those with the attitude that more is better. He would be spending LOTS of money just to say he's got more subs rather than actually hitting harder or sounding better than others.

The aperiodic enclosure you were mentioning may be a better option. Never heard an aperiodic enclosure though, so I can't say for certain. I'm more inclined to take a sealed enclosure or a bandpass design as they will actually use the sound produced by his subs more efficiently. The bandpass being more efficient than the sealed of course. Like I said though, that aperiodic design sounds interesting and I'd like to hear what one sounds like.

 

The aperiodic enclosure is a bitch to design and install properly, last time someone wanted me to install one it ran $800 just for the install, including making ducts for the membrane to breathe.

They sound extremely clear though, no boominess at all. Good for classical and jazz. SQ over SPL.

Requires a lot of amp juice just to get decent volume and subs with low Qt's- I don't know if the RF 10's qualify.

Unlike subs in more normal enclosures AP's don't make the car vibrate.

In addition to the isobaric he could go free air too, just a piece of MDF with seven holes and subs, that'd be interesting.

 

hahaha Yeah, I'm WAY past my boom phase. I've lost too much of my hearing to stay in the SPL category. Now I really want to go with SQ. I'm looking for the best separates I can find. I want something that isn't really power hungry though. Got any suggestions?