Advanced SPL for Street Competitors
Thread Starter
1000 Watt CAFz'r
Joined: Jan 2005
Posts: 1,149
Advanced SPL for Street Competitors
Gone are the days of trial and error method of testing spl. This testing is good but only up to a certain point or if your lucky.
Through my own testing, there is a direct relation with power (amp power) and overall spl. As power increases, so does spl.
Now for street competitors, power is limited so you want to achieve the most spl with the least amount of power. This is when efficiency testing is the better way to test for spl.
Efficiency is simply input over output. Input being power and output being spl. This method requires an spl meter (termlab), an amp clap (ac) and mulitmeter (ac).
Anytime testing a new box or changing tuning it is best to record how much power is produced along with the spl. This will give you better idea if the box or tuning is right.
Example:
Box 1 - does 150.2 db with 2000 watts
Box 2 - does 150.2 db with 2700 watts
Box 1 is more efficient than Box 2
Box 1 is also gonna be louder with the same power as Box 2. If Box 1 was given 2700 watts, the gain could be 0.8 - 1 db.
(Note: through testing I have found that doubling amplifier output power equals 2.7-2.9 db)
Also, Box 1 will most likely have a higher impedance rise and therefor can be lowered by changing to lower resistance coils.
Say in both boxes, the same dual 2 ohm sub was used in testing wired to 1 ohm and the first box had a 3x impedance rise, while the second box had 2x rise. (impedance=VoltsAc/AmpsAc)
Now changing the sub to a dual 1 ohm coil wired to 0.5 ohms, the amp will see 1.5 ohms in Box 1 and produce 3200 watts, with Box 2 the amp might clip, or protect cause it will be see under 1 ohm load. Box 2 could be fatal to the amp and/or the sub.
Now if Box 1 did indeed get 3200 watts, that would end up in being approx. 1.5 to 1.8 db gain. So that will be between 151.7 - 152 db!
Here is a tip, the most a single battery in Street A will produce is 5500-6000 watts rms of amplifier output
In Street B with a bigger battery around 6500-7000 watts of amplifier output
Hope this helps
Happy testing
Through my own testing, there is a direct relation with power (amp power) and overall spl. As power increases, so does spl.
Now for street competitors, power is limited so you want to achieve the most spl with the least amount of power. This is when efficiency testing is the better way to test for spl.
Efficiency is simply input over output. Input being power and output being spl. This method requires an spl meter (termlab), an amp clap (ac) and mulitmeter (ac).
Anytime testing a new box or changing tuning it is best to record how much power is produced along with the spl. This will give you better idea if the box or tuning is right.
Example:
Box 1 - does 150.2 db with 2000 watts
Box 2 - does 150.2 db with 2700 watts
Box 1 is more efficient than Box 2
Box 1 is also gonna be louder with the same power as Box 2. If Box 1 was given 2700 watts, the gain could be 0.8 - 1 db.
(Note: through testing I have found that doubling amplifier output power equals 2.7-2.9 db)
Also, Box 1 will most likely have a higher impedance rise and therefor can be lowered by changing to lower resistance coils.
Say in both boxes, the same dual 2 ohm sub was used in testing wired to 1 ohm and the first box had a 3x impedance rise, while the second box had 2x rise. (impedance=VoltsAc/AmpsAc)
Now changing the sub to a dual 1 ohm coil wired to 0.5 ohms, the amp will see 1.5 ohms in Box 1 and produce 3200 watts, with Box 2 the amp might clip, or protect cause it will be see under 1 ohm load. Box 2 could be fatal to the amp and/or the sub.
Now if Box 1 did indeed get 3200 watts, that would end up in being approx. 1.5 to 1.8 db gain. So that will be between 151.7 - 152 db!
Here is a tip, the most a single battery in Street A will produce is 5500-6000 watts rms of amplifier output
In Street B with a bigger battery around 6500-7000 watts of amplifier output
Hope this helps
Happy testing
Thread Starter
1000 Watt CAFz'r
Joined: Jan 2005
Posts: 1,149
Tuning and loading will also effect impedance, can go up or down. This is why power testing can help make the box(s) more efficient. If 2 different port lengths hit the same score, how else can you tell which one is better?
