As could I....
I ask, because you can calculate an awful lot of clever stuff if you know how... and including the acoustic response field of the environment (in this case a car) and it's modal properties, can help you achieve higher measurement numbers through precise placement relationships...
for example, in a simple model, of an average domestic living room, it's common to have modal response variations of the space itself, of as much as ±40dB, at assorted frequencies.... .
this is caused by a phenomenon commonly called (in english, not in geeklish) Standing Waves.
(more properly called modal room response )
these can be calculated quite accurately....
what they effectively do is vary the measured SPL at different frequencies, and different spatial points around the space, by interfering with it , either destructively ( causing a low point, ) or constructively, (causing a high point) ,
it's the reason bass sounds different when you're sat in different seats in a room.... or moving around the room....
careful measurement of the acoustic of the environment to be used (in this case a specific car) , can give a clue as to how best to arrange tthe driver arrays to make most use of this phenomenon, to give pressure maxima at the required measurement points...
THEN there's the issue of inter-driver phase coherence.
if you have an array of drivers spread out over a distance, moving away from you... , say at n+ zero, 1 foot, 2foot, 3 foot,.... and you feed them all a signal at the same moment (either as a simple parallel feed to multiple amplifiers, or parallel load across one amplifier, ) then the spl at the rest point will not be as high and even spread as it could be.....
because the pressure waves from the drivers are arriving spread across time, and so interfering with each other.... , in the stated example, they'd arrive at approximately 1 millisecond intervals....
this spreads transient arrival, reducing the maximum SPL of the transient, as well as causing phase cancellation...
in that instance, the highest SPL reading would be achieved by feeding the furthest driver first, and then inserting a 1 millisecond delay before the next nearest driver, and then a 2 millisecond delay to the next one, and so on....
this way, the pressure wave maxima is constructively added to as it approaches the measurement point.
this technique is commonly used in Large venue PA systems for example, where there are satellite arrays of speakers , say halfway down the length of the hall.... to which the feed is delayed , so that they make their output propagate in sync with the arrival of sound coming from the front of the venue.... thus reinforcing it.... and not making it sound like an echo....
it is however, direction specific.... so, it can be calculated and implemented to make the system measure louder ONLY in one direction....
the point being, such an arrangement would give a higher measured SPL in the front of the vehicle.... ... from drivers arranged in the rear of the vehicle... (but conversely, would somewhat reduce the level and screw with the quality of sound at the rear of the vehicle)
then there's the questions of axial response , and wave interactions between drivers....
but i'll leave those for another time...
here's my latest set of toys.... the room at mix position has a flat frequency response from 18Hz, to 18KHz, and is only 5dB down at 5 Hz and 22KHz.
(the lower ones are about £13k, the upper ones about £2.7K (with their subs, which you can;t see in the picture) ... so not for the faint hearted.....
)
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Topic: Lozzys Omega- The Sentinal Sound System Build (Read 32725 times)