Tedious, but good way to find resonant frequency...

[Bakerman]

So, from what I've been told, and what I see most people do is take a single 10" sub in a sealed enclosure of about 1cu', and play a sweep of tones from 20hz-100hz, and record it on TL, and whichever frequency tops out, thats what most use to tune their spl setup. While this is a simple way of finding a vehicles tuning, through research, and learning from others, I've discovered other methods for finding advantageous tuning.

Okay, so first make box that is 1cu'. Next, measure the decibel levels for indivdual hz tones starting at 30hz, and going to 90hz (for ex. 30 to 90hz; 30hz=140db , 31hz=140.1, 32hz=140.3 ........ 88hz=141.8, 89hz=141.6, 90hz=141.3) and write down the db levels. Note that it will be done outside of your car, with the meter approximately 2ft from the sub. Now for the car...put the sub in your car and place the box on the meter side of the car (ussually passenger, but only familiar with NSPL). Now, you can try several different placements such as firing rear, or front, and even try it on different sides of the vehicle. For instance Passenger side firing up, Drivers side firing rear, Passenger side firing forward, and Drivers side firing forward. Now, place your meter wherever it is placed at your spl competetions (ussually passenger side windshield, kickpanel, or headrest). As with the outside test, play each tone individually, and record the db level at each tone. So, once all this is done, your chart should look something like this below...

freq __ outside test ___ pas/up___ driver/back _____ foward test

35hz ---- 140 -----------138(-2)-------141(+1)-----------136(-4)

40hz ---- 141

45hz ---- 142

50hz ---- 143 -----------150(+7)--------143(0)-----------148(+5)

55hz ---- 144

60hz ---- 145

75hz ---- 148 ------------147(-1)-----151 (+3)-----------152(+4)

So, even though the loudest db measurement was @75hz with sub firing forward, it dosnt have the most db gain from the original baseline. The 50hz tone with the sub on the passenger side, firing up has the most gain of +7db from the original baseline level.

Therefore, in this particular vehicle, 50hz would be you most advantageous tuning for an SPL setup.

I use this for resonace measurement.

Do you have different ways to measure?