cabin gain???

[Spencerk 4]

What is the average gain you would get from a mid size trunk car???? Like my car....and how do you calc. this out??

[ncacoates 104]

Wish there was a defined equation to figure it but there isnt to my knowledge. Design the box correctly and hope for the best results.

[slim2fattycake 85]

test, test... and test some more

[///M5 2,833]

Not trivial to calculate, but you can measure. Just build a small sealed box with a pretty flat response and measure it in a free air/anechoic environment and then put it in your car and remeasure. Of course positioning of the mic and driver can also affect your results.

[shizzzon 461]

it would be impossible for a universal calculation of all vehicles as the contour shapes of objects in the car and materials used to absorb and reject sound and sound vibrations will all effect cabin gain in any vehicle.

It needs to be physically tested.

Cabin gain will change upon how much air can escape out of the car as well.

I got my cabin gain graphs made for my wall sealed and outlaw.

It takes about 30 min per pass to get the info from 20hz-100hz.

Once u have cabin gain... that's when u know where your car peaks at and start playing with that info to see how easy it is to get loud in certain areas and see where other areas in your car is hard as hell to get loud.

[///M5 2,833]

it would be impossible for a universal calculation of all vehicles as the contour shapes of objects in the car and materials used to absorb and reject sound and sound vibrations will all effect cabin gain in any vehicle.

It isn't impossible, software programs like Odeon make it possible but at $30k a crack they aren't that available to the average enthusiast. And it would require some serious modeling information to do so. The automotive manufacturers themselves do it and all sorts of other measurement/modeling as well. Not trivial and is nearly impossible for someone on here without serious connections. Much easier just to measure.

[Impious 1,476]

The general "rule of thumb" is a gain of approximately 12db/octave beginning in the 60-80hz range. This is ofcourse not going to be accurate for any one particular vehicle, but is a general approximation.

As M5 said, the best thing to do is to measure it yourself if you really want to know.

[Spencerk 4]

Well then I guess I need to get a meter..... has anybody on here tried those meter you can hook up to a DMM and get a read out look it up on the lil chart thing and get a db read out ( don't know the name or make of them)

[///M5 2,833]

Even a cheap mic will give you relative readings. Out of curiosity, why do you need to know?

[shizzzon 461]

are you referring to the Hyperdynamics meter from makeitlouder? They read real close to a termlab. Mine was reading right along with a tlab until i reached 150 then then it started reading higher than a tlab.

The accuracy fo the meter compared to another is irrelovant, it just needs to be able to meter the levels of pressure you will be using it for and yes, that meter can just fine.

You will need a meter that can read millivolts to get an accurate reading.

[///M5 2,833]

are you referring to the Hyperdynamics meter from makeitlouder? They read real close to a termlab. Mine was reading right along with a tlab until i reached 150 then then it started reading higher than a tlab.

The accuracy fo the meter compared to another is irrelovant, it just needs to be able to meter the levels of pressure you will be using it for and yes, that meter can just fine.

You will need a meter that can read millivolts to get an accurate reading.

Most definitely not.

The accuracy fo the meter compared to another is irrelovant, it just needs to be able to meter the levels of pressure you will be using it for and yes, that meter can just fine.

Exactly why I said even a cheap mic will work.

You will need a meter that can read millivolts to get an accurate reading.

Not millivolts, but parts of a dB. This is an acoustic measurement, not an electrical one.

[shizzzon 461]

u misunderstood my post.

He was referencing the Hyperdynamics meter that is required to be used with a good dmm or oscilloscope.

The word METER i used means dmm or oscope in my post, not referencing db meter.

That is how their meter works. I have one and some other people around the internet do to, that's how they advertise it to work.

I'm not in the electrical field but snoopdan knows quite a bit about stuff like this and he told me how the meter works as to why it requires a dmm or oscope to get the proper reading off the meter.

The millivolt reading is converted using a formula they give you or you can use their software to do it for you to obtain the proper pressure measurement.

"has anybody on here tried those meter you can hook up to a DMM and get a read out look it up on the lil chart thing and get a db read out"

That is the Hyperdynamics meter made by makeitlouder and that is how you use it.

[///M5 2,833]

Just misunderstood who you were directing it at.

To clarify, you can hook up any microphone and power supply up to any meter. They all have a sensitivity of xmV/dB(or Pa) which means that they output a voltage which can be read by a voltage meter. Considering this you could even use a mic that has a weighted output since by default when you subtract you will be normalizing the response and measuring cabin gain.