As MTA said, it will be dependent on the transfer functions of the system. Each element of the system will have a transfer function with its own unique shape; the sub will have a transfer function peaking at the sub's Fs, the car will have one peaking at the cars resonant frequency (even different areas of the car can have different transfer functions such as if the dash resonates differently than the frame), the box will have one peaking at the box's tuning frequency, etc.

None of these transfer functions will be symmetrical, and each will affect the overall output of the system.

To further complicate things, we also have impedence rise, which, due to the influence of the total Q of the system, will tend to peak approximately where the convolution of all the time-domain transfer functions peak. This means that where you have the most efficient system possible, you will also have the least power going to the subs, meaning the total system might be louder at a frequency other than where it is most efficient.

Impedence rise itself is even composed of two factors: the simple electrical self-inductance of the voice-coil (which will increase relatively linearly with frequency since it is jwL in the frequency domain, where L is the inductance of the coil) as well as the impedence rise due to the affect of the magnetic field of the woofer itself, which will be highest at the tuning frequency of the box and will be relatively symmetrical. Take the frequency domain transform of each of these functions and multiply them (or convolve in the time-domain) and you will find the impedence will rise faster after your box peaks. If you were to measure your total power at 55hz, I would guarantee it would be less than the power you are getting at 49hz.

This phenomenon is most likely to be the cause of what you observed, but unless you were to take the Fourier transform (or LaPlace transform if you prefer s-domain calculations) of every one of the transfer functions h(t) in the system, and multiply all the results to find the actual overall transfer function H(jw) of the system (which is nearly impossible to do accurately I might add), there is no way of knowing exactly what caused your results.

 

This is exactly what I had in mind. I'm too lazy and stupid to type all that out.

But the part at the end is wacky, I dunno what the fawk he's talking about.

 

someone pass me a dictionary and a physics text book.....

 

Blaaaaa????????

 

Yuli

i got some info for you that i would like to pass along to you. seeing as how you are using a term lab and you are in tl and ac country over there. I understand that you are very well versed in spl but i just want to help where i can. please contact me at westcoastextremepl@hotmail.com or msn me online for my 2 cents if you require them. it would take too long to type it out and then have to discuss and explain my opinion. id rather do it one on one......if you need it.

Pato

 

i think that it is cause your maker designed the laws of physics in a maner that none of us pee-ons can fathom!

 

hahaha