I'm not sure if this is true or not but if it is I'm sure going to try it.. Basically it shows a way to find the resonance frequency for the location of the mic.. pretty interesting
"its not only the box... its the positioning and physics involved. sound travels at 1130 ft. per sec... so lets change that to inches since it will easily be used in vehicles. 1130 X 12=13,560. so a standard sine wave lets say 50" from the mic will hit the mic at 271 hz (13560/50). well 271 hz isnt very spl like... plus you cant play over 80 hz in most organizations and why waste the time and power. so take the wave and cut it into pieces (phases). front wave will be 0 degrees where the mic is 90 degrees. so i cut them into 90/180/270/360 intervals. so i take a 1/4 (90 degrees) of 271 and get roughly 68 hz. thats more like it. now comes the enclosure. the goal is to build the enclosure where the 0 degrees waves from the front of the subwoofer and the 180 degrees waves from the rear of the subwoofer meet at 90 degrees or in other words they meet at the microphone. which will give you peak resonance. and yes the box does sound like *** but meters extremely high! pics will be up soon"
In a competition, you don't place the mic wherever you want. Rules specify where the mic is placed. It would also be nearly impossible to calculate all the distances and angles required so the wave hits exactly at the mic. Sound bounces off everything, it's not like it follows a single trajectory and you can pinpoint the angles so it hits the mic perfectly.
All the local comps I go to we place the mic under the dash.. you can choose either drivers side or passenger side. Just found is interesting.. was trying to think of an alternate way besides metering my car inside and out.. don't feel like driving to a shop with a TL lol.
Also, you do realize that when a subwoofer is in a sealed enclosure, or installed on a baffle of any sort, the front and rear waves are meant not to meet. You do realize what happens when the rear wave meets the front wave, right? The enclosure keeps the rear wave from radiating into the room.
If you want to get max. spl out of a proted box, for competing scrictly, you'll want to find your car's resonant frequency first. Tune your ported box to that.
If you want to get max. spl out of a ported box, for competing strictly, you'll want to find your car's resonant frequency first. Tune your ported box to that.