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(A) Does it matter in terms of sound dispersion or percieved volume which way the sub speaker box is pointed- ie. side, front facing or rearwards?



No. The ear cannot tell directionality with the low frequencies. The wavelengths are simply too long to establish directionality. That is why a subwoofer can be placed anywhere within the listening space, doesn't matter.

Of course, *ideally* one would want the subwoofer in the same airspace as the listener's ears, but in your automobile there are likely space constraints involved, so the tradeoff of trunk placement is often a solution. Or use of a smaller subwoofer that may fit inside the car somewhere. I've seen and heard the little tubular Bazookas used in that fashion.

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(B) Or for that matter, where in the trunk the sub is placed?



Nope. For the same reasons as above.

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The 2 candidate positions in my car, a sedan, are:

(1) As far forward as poss. and thus close to the rear seat back (in fact potentially mounted on the rear seat back, if not the floor of the trunk), or

(2) At the rear of the trunk and to one side behind a wheel well, but up off the floor, hung on brackets. I need the floor space for my v. long bass case, among other things.



Because of those long wavelengths, the sonic difference between any position possible within the entire vehicle is not enough to make the difference. So put it where it seems to be most feasible.

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I'm asking this because, unlike the situation of passengers hearing door mounted or rear deck speakers, with a sub in an enclosure sitting in the trunk there is of course a barrier to the subs sound entering the passenger compartment and thus the listeners ears, formed by the rear deck/parcel shelf and the back of the rear seat. And these barriers being formed by a thin sheet of steel plus some upholstery, surely some muffling of sound originating in the trunk must occur. At least, you would think so.



Those long wavelengths will penetrate to a great degree. While there may be a *slight* decrease in amplitude, it is likely not worth being concerned about here.

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(C) Are the frequencies subs produce sufficiently deep that these barriers don't matter much?...or is it the case that the whole trunk compartment acts as a speaker enclosure and the vibrations are felt in the passenger compartment?



You are getting closer to the actual physics with this one.

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(D) If the trunk is filled with luggage, is that going to muffle the subs output as heard inside the passenger compartment?



That depends. More than likely, soft luggage that fills most of the air environment in the trunk can dampen the sound. But how often do you have enough luggage in there able to fill all of the available airspace in the trunk?

An installation such as this has to be considered as a tradeoff condition. When there is a lot of luggage in the trunk, you will have to live with whatever the sound quality degradation may (or may not) be.

The one thing that concerns me more about filling the trunckspace would be COOLING airflow available for any amplifier(s) installed back there. On a hot day, that could be asking for thermal destruction of output devices. These kind of problems are typically solved with common sense (don't pack the trunk so full that you have to sit on the lid to close it) and perhaps also with a small 12V cooling fan installation if necessary. Stirred air will cool the amp better in an enclosed area such as your trunk no matter what. Still, there will be an ultimate temperature buildup limit. Your locale's climate has as much to do with that as anything else, too. Common sense should apply.


--Mac

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