Hi guys

I have vw polo hatch and will be building it for street B.

i have notice alot of guys on beginning an installation - the first the thing they do is dynamat the entire boot/trunk area?

does dynamat not change the frequency of the car?

is it best to do this first or to dynamat a small piece at a time with regualr testing to see if the car drops or picks up?

 

It changes the resonation/vibration of any panels it's attached to by adding mass. It helps to 'dynomat' the panels for sure, but mainly the path lengths of the inside (X/Y/Z) and the interior (dash/seats etc) is what majorly dictates the frequency of the car. If you want to test, along with dynomating make any large panel flex resistant by also adding strength to the panel (wood/steel etc). And stop any air leaks that occur from your doors/windows/hatch etc. Think of your vehicle as a subwoofer enclosure, if the walls move your output is less.

Hope this helps!

 

My understanding is that it usually lowers the vehicles resonant frequency. It also stiffens the metal, causing less flex, which in turn yields a small gain in db's.

Damn I type slow... ya, what tubeamp said. lol

 

thanks guys... this is most helpful

i have placed one of my old boxes in the car and tested the same figure from 52hz to 59hz. after covering two holes in the hatch - the car is only playing between 50hz and 52hz.

the reason i posted this topic is i know the higher frequency the better so am just worried if i go dynamating everything - how low will the car play at?

the polo hatch resonant frequency is 54hz. i would like to play 59-60hz

is that possible?

 

Thats out of my league .... my van has a low tuning frequency, I've got no idea how to raise it. Always thought I just had to live with it.

 

You can change the resonant frequency by changing the path lengths. It is possible, one way would be to shorten or make smaller the interior of your vehicle. Either by it's length, width or height (all three perhaps)... this will be trial and error on your behalf. Note: the enclosure you are using to test the RF should have a very flat response curve or it will add to your calculations.

...check to see if your class allows this type of vehicle modification, if not you will be disqualified. If they catch you that is

 

if u resin your enclosure or shorten port length it will also change resonant frequency

 

Dont worry about the frequency. Look at your score. Do you win because of what frequency you play???? No. You win by the score posted. Take your time and take notes when you are lying down the dynomat. Just look at the score and see your gains.

 

gains also depend on the quality of the dampener used as well

 

true try getting your hands on vibraflex. You heat it up and then when it cools it is rock hard. Guys is europe use it because it keeps the cars frequency the same. Once you find all your gain from your deadener then you start messing around with box designs. You were right saying that higher frequencies are generally better for spl.