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<blockquote data-quote="mustangowner" data-source="post: 1243642" data-attributes="member: 559693"><p>first off chill out, here is the formula i got. i believe it was posted on this forum. i may have found it on another forum (not sure). but it was said it was tested and it came within +/- 3 dB.</p><p></p><p>This formula gives a rough estimate +/- 3 dbs.</p><p></p><p>-This formula is assuming that all things are perfect. It is a Logical "Guessimate" that is always within 3 db of actual!</p><p></p><p>-That voltage is near 14 volts/plenty of</p><p></p><p>battery/alternator</p><p></p><p>-Using at least 1/0 Ot guage wire</p><p></p><p>-Some kind of Line Driver is being used</p><p></p><p>1st Things first</p><p></p><p>Start off with sensitivity of the "raw" driver</p><p></p><p>Then total power of the amplifier (peak AC</p><p></p><p>volts measured with a volt meter)</p><p></p><p>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)</p><p></p><p>2nd Thing</p><p></p><p>Calculate the toal efficiency of the woofers</p><p></p><p>Add each woofer as +3, doubling of cone area</p><p></p><p>equals output</p><p></p><p>The concept SS-12" subs are 87 db 1W/1M (typical of all small box woofers"</p><p></p><p>Lets do the dB Log:</p><p></p><p>1 woofer = 87 dB</p><p></p><p>2 woofers = 90 dB</p><p></p><p>4 woofers = 93 dB</p><p></p><p>3rd Thing</p><p></p><p>Do the "dB log" starting with the total subwoofer(s) efficiently (which is 93 in this instance)</p><p></p><p>93 dB = 1 watt</p><p></p><p>96 dB = 2 watt</p><p></p><p>99 dB = 4 watt</p><p></p><p>102 dB = 8 watt</p><p></p><p>105 dB = 16 watt</p><p></p><p>108 dB = 32 watt</p><p></p><p>111 dB = 64 watt</p><p></p><p>114 dB = 128 watt</p><p></p><p>117 dB = 256 watt</p><p></p><p>120 dB = 512 watt</p><p></p><p>123 dB = 1024 watt</p><p></p><p>(for the example, we have 1764 watts, (comtemplate... 125 dB)</p><p></p><p>126 dB = 2048 watt</p><p></p><p>4th Thing</p><p></p><p>Add up the special "side deals" Like is the box sealed (no extra dB), hatchback or coupe? Etc.</p><p></p><p>Use the following to get "close to the REAL DEAL in SPL.</p><p></p><p>-Transfer Function (sedan) = 12 dB</p><p></p><p>-Transfer Function (hatchback with woofers aiming towards the rear glass) = 16 dB</p><p></p><p>-Sealed Box = no extra dB</p><p></p><p>-Vented box = 3 dB (UNLESS you have an odd order alignment)</p><p></p><p>-Vented box = 6-9 dB (If an odd order alignment - Big A$$ box)</p><p></p><p>-BandPass Box = 6-10 dB (depending on how small the enclosure is)</p><p></p><p>-Mic Placement = 6 dB for DB drag dash/window mic placement</p><p></p><p>Example: let's total it all up</p><p></p><p>124 dB (basic "dB log") + 12 dB (standard cab car with a direct facing woofer box) = 137</p><p></p><p>Woofer box is vented in something other than optimum or flat + 6 dB = 143 dB</p><p></p><p>+6 dB (DB drag dash/window mic placement)</p><p></p><p>So...this car will play</p><p></p><p>= 149 db (total) (+/- 3 dB)</p></blockquote><p></p>
[QUOTE="mustangowner, post: 1243642, member: 559693"] first off chill out, here is the formula i got. i believe it was posted on this forum. i may have found it on another forum (not sure). but it was said it was tested and it came within +/- 3 dB. This formula gives a rough estimate +/- 3 dbs. -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) [/QUOTE]
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