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ok how loud will my system be if i have a 1000 wat amp with 4 12s and a 200 wat cd player how many blocks away would you here it if its on full blast

thankx
 

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A question that often comes up. This formula gives a rough estimate +/- 3 dbs. (Formula from Concept Car Audio). It's long but worth while to check out...especially if you're wondering the potential of your system design.

Concept Basic DB Formula
-This formula is assuming that all things are perfect. It is a Logical "Guessimate" that is always within 3 db of actual!
-That voltage is near 14 volts/plenty of
battery/alternator
-Using at least 1/0 Ot guage wire
-Some kind of Line Driver is being used

1st Things first
Start off with sensitivity of the "raw" driver
Then total power of the amplifier (peak AC
volts measured with a volt meter)

For example: Take a Concept CC-D1200 amp, connected to 2 SS-12( a load of 1 ohm) You've measured the AC volts out into this speaker load as 42 volts, which calculates to 1764 "peak" watts. A/C volts squared (times itself) divided by the impedance equals power. So...42 x 42 =1764 divided by the impedance, which is 1 ohm in this instance, so its still is 1764!!! We now know the real power (cause you measured it into a real load...The Concept SS-12 woofer)

2nd Thing
Calculate the toal efficiency of the woofers
Add each woofer as +3, doubling of cone area
equals output

The concept SS-12" subs are 87 db 1W/1M (typical of all small box woofers"
Lets do the dB Log:
1 woofer = 87 dB
2 woofers = 90 dB
4 woofers = 93 dB

3rd Thing
Do the "dB log" starting with the total subwoofer(s) efficiently (which is 93 in this instance)
93 dB = 1 watt
96 dB = 2 watt
99 dB = 4 watt
102 dB = 8 watt
105 dB = 16 watt
108 dB = 32 watt
111 dB = 64 watt
114 dB = 128 watt
117 dB = 256 watt
120 dB = 512 watt
123 dB = 1024 watt
(for the example, we have 1764 watts, (comtemplate... 125 dB)
126 dB = 2048 watt

4th Thing
Add up the special "side deals" Like is the box sealed (no extra dB), hatchback or coupe? Etc.
Use the following to get "close to the REAL DEAL in SPL.
-Transfer Function (sedan) = 12 dB
-Transfer Function (hatchback with woofers aiming towards the rear glass) = 16 dB
-Sealed Box = no extra dB
-Vented box = 3 dB (UNLESS you have an odd order alignment)
-Vented box = 6-9 dB (If an odd order alignment - Big A$$ box)
-BandPass Box = 6-10 dB (depending on how small the enclosure is)
-Mic Placement = 6 dB for DB drag dash/window mic placement

Example: let's total it all up

124 dB (basic "dB log") + 12 dB (standard cab car with a direct facing woofer box) = 137
Woofer box is vented in something other than optimum or flat + 6 dB = 143 dB
+6 dB (DB drag dash/window mic placement)
So...this car will play
= 149 db (total) (+/- 3 dB)
 

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and BTW. . . no way in hell does your head unit put out 200 watts. . more like 68 watts

And even with the forumla provided, there is a ton of shit to take into consideration that will effect overall performance of your system. . . Enclosure build, staging, negative or positive cab cains etc. . .

Simply put, just build the damn thing. And stop worrying about how far people will hear it. Play it respectably, thats why we have all these stupid ass car audio laws these days.
 

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Originally posted by DeAdPhLow@Aug 15 2005, 12:31 PM~3626035
Simply put, just build the damn thing. And stop worrying about how far people will hear it. Play it respectably, thats why we have all these stupid ass car audio laws these days.
unless a civic pulls up next to you thinking there bumpin harder then anything else on the planet with a set of xplore/xplods/dhd.... then you gotta throw respect out the window with the press of a button on your headunit...

-qs
 
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