Why you need a Rta to correctly install car audio equipment

Make sure you pick the right shop to work on your car. 

This 2012 Acura TL is a perfect example of why any shop the does audio needs some sort of Rta ( real time analyzer . 

We have 4 of them here at Nvs audio ). 

The shop that attempted to do the install before us used a nice line level converter made by PAC ( a part we also use made by a great company but not on this car ) 

The PAC oem 2 is a great piece but not the correct piece to use on this vehicle and I will explain why. 

After the other shop competed the install , they could not get to car to sound good no matter how hard they tried . They adjusted the gains one the oem 2 , gains on the amps , crossover settings on the amps but to no avail . So the customer gave up and brought the car to us to look at. 

First this we did is hook up the audio control Rta to all the output of the factory amplifier and started to take notes . 

We were actually surprised at what we found . We expected the outputs of the factory amp to need summing to create full range output channels , that was not the case. ( most luxury cars need summing of the factory amplifier channels to create a usable full range signal ) The front and rear output channels of the factory amplifier were full range 20 hz to 20000 hz . While that is a very good thing it does not mean that the output signal was usable .

The car had a very heavy built in factory eq curve with as much as + 12 Db at certain frequencies while cutting as much as -12 certain frequencies while at the same volume !!!

In this picture you can see a +12 Db boost at 12.5k hz while at the same time a cut of 12 Db at 200 - 400 hz. 

What that means in simple terms is that with a completely flat input signal with the customers new amplifiers and speakers the tweeters would be screaming at 12.k  while the mid range between 200 and 400 hz would be almost non existent.  The factory subwoofer channel acts the same way while being flat at 80 hz it boost 30 hz +8 Db. It would be really easy to blow a subwoofer if this is left uncorrected . 

This is exactly why cars like this need a dsp ( digital signal processor ) like the Audison bit one and the bit ten . 

The DSP will take the signal from the factory amp and sum it if needed ( not needed on this car ) and it will take the factory eq curve and de equalize it or flatten it out to give us a nice near flat signal to work with  like in the picture below . 

Now that we are done using the Rta for electrical measurements we now switch the input of the Rta and plug in the microphone and place it on the drivers seat. We now take acoustic measurements of the speaker outputs