car subs outside - horn loaded?

I'm looking for subwoofers for my big 7200W system. It will be outdoors, and apparently car subs and home stereo subs too suffer from lousy freq. response whe used outside. But no PA subs have the low freq. response and Xmax that I need for my system. I'd like to use ALUM12X's, with their 31mm Xmax and deep bass response. Each one needs to handle only about 112.5W RMS, but I want to go LOW, like 10Hz or lower. I'm trying to combat the problems car subs face when outside the cabin without using so much EQ. Maybe I could try horn loading them, bass reflex or bandpass encolsures or something. Or maybe I could install them in boxes built into the side of a large partly open enclosure the size of a small vehicle cabin, simulating running them in a pickup with a door open. Any thoughts or ideas?
Hi Kilo

Lost track of which thread I told you about the Turbosound boxes on, but here are the details:

I think you need to think about the laws of physics a little, Kilowatt, the amount of cone area needed to give a decent output at 10Hz would be in square metres, and probably need amps providing tens of Kw! ( especially outdoors).

Remember, measured performance isn't everything...



p.s. what is this system for????
It's not really the frequency response of SUBS that suffers when used out of doors, it's a lack of SPL. Because there are no room boundaries involved the bass just rides off into the sunset.

Horn loading would help increase SPL if it was practical but with a goal of 10Hz you're looking at one mother of a horn. Installing the sub enclosure in a larger enclosure, like a car, is not going to give you what you are looking for.

You could parallel woofers until you reach the lowest impedance your amp can handle. If that isn't enough, add another amp and bank of paralleled subs. This, theoretically, could go on forever but remember that the number of sub/amp banks needed will grow faster the the SPL.
Horn loading is the only way to go if you want serious SPL outdoors. The problem is of course the size of the LF horn as mensioned. If you cut the horn flare too early (to reduce size) you will get ripple on the frequency response curve.

But maybe the ripple can be used;
You could theoretically get the last peak of the ripple, before fall off, to extend high enough in frequency to let another (smaller and shorter) horn take over. This means that you only use a narrow frequency band of the lowest horn before filtering over to the next horn. Then you can hopfully get a rather flat response in that band.

This of course means that another set of amps and filters are needed.

Just a thought. I don't know if it will work in practice.

It looks like I'll have to make some monster horns (like LAB horns) just for really low freq. and let some Eminence 18" PA woofers take over from maybe 40Hz on up to 200Hz or so huh? Maybe I'll have to settle for 25Hz too if 10 is a little unrealistic out there. I've only got 3600W to work with for all bass. The rest is for 5" Vifa midwoofers and tweeters.

P.S. Q- "What are you going to reproduce out doors that goes to 10Hz, or even 20Hz ?." A- music.
Q- "What sort of venue, etc ." A- as big as anyone could ever need :D Actually though, I may end up having to sell it if I can't find anything to do with it myself but it may come in handy. I'm sure I'll be critisized by some for not having a definite and important purpose.
LAB Horn Project. It's going to be big, it might be a bitch to sell and the performance of the whole thing is questionable in terms of ripple and cut-off frequency.

Just think how easier it would be to do the multiple sub/amp thing I recommended - better sounding, easier to transport and much easier to sell; a lot of people are looking for subs and amps. Almost no one is looking for a horn the size of a truck.
I applaud the vision Kilowatt, but reality is a little different...

Outdoor sound is a major problem, and one that PA companies with massive r&d budgets and vast investment in kit are only coming close to solving. Problems such as lack of room reinforcement, temperature, humidity, wind speed and direction will all contribute to damage the perceived sound of your system, let alone the problems of enviromentally proofing your enclosures and drivers, ( ever thought how high humidity could effect paper cones and surrounds?).

For outdoor use you will probably end up driving the system a lot harder than you would indoors, and so then you will have problems with burnout, as most hi-fi and low end pro audio drivers, such as fane, are not designed for this.

You also mention using multiple drivers in arrays... why?

Why not just use fewer numbers of pro audio drivers that are designed to take the load reliably, then you have less problems with comb filtering, phasing and lobing, ( yes I know it's different aspects of the same thing!)

Now I'm not knocking innovation but I think your idea of a system would need far too much in the way of heavy maths, constructional technique, and systems design to be a practical project for someone new to the hobby, and you would end up spending too much money chasing an idealised dream system that would never quite work the way you want it to.

But if you want to go for it I think all of us here wish you the best, and we want running reports on your progress...