I'm doing my cardomain site, and when it asks to specify my sound system, I get these choices:

stock
SPL
SQ
SQ/SPL

Then it asks for:

SPL: ___ dB

What does this all mean?

 

Decibels. You have to have this measured by an audio store, unless you have the tool. (which since you are asking what it is, I assume you don't.)

 

ok but i have an afermarket head unit and aftermarket speakers, so im not gonna choose stock, which of the other 3 do i choose?

 

I guess I would just choose SQ. (sound quality)

 

can you tell me what all those other ones mean?

 

stock = obviously, the OEM (stock) system
SPL = Sound Pressure Level. Simply put, BASS!
SQ = Sound Quality. Less a measure of bass, and more a measure of how 'crisp' and unmuffled the music sounds
SQ/SPL = a combo of the previous two

 

Thanks nubiannupe. I was trying to find him the best defintion, and this is all I could come up with.

SPL is for sound pressure level and is similar to dB. SPL measurements are also ratios, but are always measured relative to a constant. This constant is 0dB which is defined as the smallest level of sound pressure that the human ear can detect. 0dB is equal to 10^-12 (ten to the negative twelfth power) W/m^2 (watts per square meter). As such, when a speaker is rated to produce 92dB at 1m when given 1W (92dB/Wm), you know that they mean that it is 92dB louder than 10^-12W/m^2. You also know than if you double the power (from 1W to 2W), you add 3dB, so it will produce 95dB at 1m with 2W, 98dB at 1m with 4W, 101dB at 1m with 8W, etc.

 

Grant, you're gonna give someone an aneurism with THAT explanation, bro!

 

I feel ya. That sucker was straight out www.caraudioforum.com. I don't even fully understand that bad boy.


Better be glad I didn't post this one along with it.

dB is for decibel, and is a measurement for power ratios. To measure dB, you must always measure with respect to something else. The formula for determining these ratios is P=10^(dB/10), which can be rewritten as dB=10log(P). For example, to gain 3dB of output compared to your current output, you must change your current power by a factor of 10^(3/10) = 10^0.3 = 2.00 (that is, double your power). The other way around, if you triple your power (say, from 20W to 60W) and want to know the corresponding change in dB, it is dB=10log(60/20)=4.77 (that is, an increase of 4.77dB). If you know your logarithms, you know that a negative number simply inverts your answer, so that 3dB corresponding to double power is the same as -3dB corresponding to half power. There are several other dB formulas; for instance, the voltage measurement is dB=20log(V). For example, a doubling of voltage produces 20log2 = 6.0dB more output, which makes sense since power is proportional to the square of voltage, so a doubling in voltage produces a quadrupling in power.

 

oh dam, that reminds me of my physics class in junior year. well just a little more deatiled, makes me feel like my head is gona burst