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?
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?
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.
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.
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.
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!
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!
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.
A lot of car subs depend on the cabin gain to fill in the low end. A pro sub tuned like a JBL SR4719 still has floor-shuddering output at 40 Hz; the 10 dB down point is 25 Hz. I don't think there's much content below 40 Hz in most music, but I haven't checked out dubstep using an RTA.
Building a couple of subs into a trailer might make more sense. You could have large flap doors that fold out to create a larger mouth.
Building a couple of subs into a trailer might make more sense. You could have large flap doors that fold out to create a larger mouth.
+1
Car subs are designed for the smallest possible box size and sacrifice efficiency to do so.
But then why not make a horn that you can just barely squeeze in and out of the van. That way you don't NEED the van as a sub. You can easily remove a PA horn and use Dolly's/casters to get the sub around outside the van after transport.
I think the only way this would make sense is if you had a system in your car with a subwoofer, and were tight on space and HAD to use the car as an "enclosure"
Just a thought
Are cars really more efficient than purpose built horns?
Lets think of yourself (or the measurement mic) inside the cabin, driver seat.
Technically you're inside the "throat" of the horn, no?
Using inverse distance law, what is the SPL inside the throat of an efficient tapped horn....125db at one meter from the mouth for a PAL12 with around 500watts. Inside the throat 145+ is possible.
Or is my thinking totally off..?
Are cars really more efficient than purpose built horns?
Lets think of yourself (or the measurement mic) inside the cabin, driver seat.
Technically you're inside the "throat" of the horn, no?
Using inverse distance law, what is the SPL inside the throat of an efficient tapped horn....125db at one meter from the mouth for a PAL12 with around 500watts. Inside the throat 145+ is possible.
Or is my thinking totally off..?
1)No.
2)Technically, in a car you're generally inside a sealed enclosure, or inside a bass reflex enclosure when the windows are rolled down.
3)Throat pressures in a horn can easily exceed 145 dB.
4)Not totally
.Yes, that is the reason for this thread.
I'm not a DJ or anything,(although after hearing what passes for sound systems at the last few weddings I've been to, I've been tempted...) but it would be nice to have something that would work for a block party or something occasionally.
A few years ago, I had 3 LABhorns in my living room for my HT system. I sold them, and replaced them with tapped horns, so making horns wouldn't be a problem, but at 64, I'm getting too old to be lugging big cabinets around, and have no room to store them when not in use.
Seems a shame to not take advantage of the cabin gain of a car to get some extra bass without big, heavy cabinets.
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