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-   -   Car subwoofer for outdoor PA use (http://www.diyaudio.com/forums/pa-systems/241288-car-subwoofer-outdoor-pa-use.html)

Don Bunce 23rd August 2013 12:17 PM

Car subwoofer for outdoor PA use
 
The title of this thread may be a bit misleading... Yesterday as a car went thumping past my house it occurred to me that instead of lugging huge subs around, why not use the car as the enclosure for an outdoor PA system subwoofer.

The rest of the system could be set up next to the car.

I suppose a car would act as a 4th order bandpass with a sealed box placed inside. You could tune it by rolling the windows down to adjust vent size.

Would this work, or is it a completely stupid idea?

weltersys 23rd August 2013 03:52 PM

It would work, but a sub the size of a car could be a lot louder, not having most of it's space wasted in the engine compartment, wheels, seats etc.

Speedskater 23rd August 2013 04:51 PM

Also notice that those cars are good at 'thumping' but not so good at playing different musical bass notes.

weltersys 23rd August 2013 05:09 PM

Quote:

Originally Posted by Speedskater (Post 3606336)
Also notice that those cars are good at 'thumping' but not so good at playing different musical bass notes.

Depends on the system inside, some can be quite good, but as Don Bunce noted in the OP, "You could tune it by rolling the windows down to adjust vent size."

Often we hear the "port" (window) output rather than any full range signal from the car.
Even with the windows up, the car body is a band pass filter, what ever frequency tends to resonate loudest becomes the "thumping" frequency.

At any rate, a sub designed to radiate sound to the outside will work a lot better for PA use than one designed for the inside of a car.

Speedskater 23rd August 2013 06:31 PM

The ones that are good are not the ones that are thumping.

Arty 23rd August 2013 10:24 PM

PA speakers are high efficiency ones.
car subs sometimes fail to even make 85 dBL, for PA 93+ is not an uncommon figure.
if You would take a car sub out of the car, and place it on an open field, You would notice that it would actualy be.. quite not loud at all.

But, to give a twist, isobaric boxes with PA speaker do work pretty well in cars.

sine143 23rd August 2013 10:41 PM

arty, he's talking about turning the entire car into a bandpass box. sealed sub inside car, firing into car that is ported via window height

m R g S r 24th August 2013 02:49 AM

I've always thought about this because the SPL which my single 15" Dayton HO reaches in my car with a 500w amp is unreal compared To the amount of speakers / amps needed to produce that kind of sound outdoors.

Honestly, I don't think you'll get a very musical subwoofer from this situation. But give it a shot, this is what DIY is all about!

OscarS 24th August 2013 04:29 AM

Quote:

Originally Posted by Arty (Post 3606717)
PA speakers are high efficiency ones.
car subs sometimes fail to even make 85 dBL, for PA 93+ is not an uncommon figure.
if You would take a car sub out of the car, and place it on an open field, You would notice that it would actualy be.. quite not loud at all.

But, to give a twist, isobaric boxes with PA speaker do work pretty well in cars.


It's all relative, because most car subwoofers can play lower than PA subwoofers. The sensitivity rating of a speaker on the low-end does not match the sensitivity "rating" on paper. It is dictated by enclosure specifics. Get a good car sub and a good PA sub and measure the sub-40Hz output, and see who wins. Again, it's all about compromise.

epa 24th August 2013 07:54 AM

if you would use a van/truck with enough volume, you can make a serious horn in the back.


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