From the bottom of the front windshield to the trunk opening there is 90". From the top of the front windshield to the trunk opening there is 65".

1130'/15' = 75.33hz

Is that correct?

 

a^2+b^2=c^2

 

I don't understand. I thought you took the longest length from the front windshield to the trunk opening, multiply it by two, divide into feet, then divide 1130 by the feet.

I'm not making a triangle here.

 

Metric is louder

 

Best tested for with a meter.

Wave length calculations will only get you into the ball park.

 

The seats, panels, etc will change it a lot, so just burp every frequency with 10-20% of the power and pay attention, normally you can find it just hearing the noise from outside. BAck in days people would throw a coin on the roof and find it.

 

Shouldn't it be 40hz not 75hz?

 

Just tune between 47-52hz and you'll be good
the deeper you make the box the lower you'll need to tune it. Also make sure you seal the box around the opening into the cabin if you are facing forward