Audio Systems: Background fill speakers, 1968 ford torino, speaker holes

Question
Hi Jerry,  Under the top middle of my dash is room for two 4" speakers.  I thought of putting two-way speakers of mid-range with tweeters there.  I read that is a good place for sound imaging the vocals of the music.  In each kick panel area are three speaker holes-- a 2" circle hole, a 3-3/8"x5" hole, and a 6" round hole.  I want to add bass and stereo background to the music to add to the sound imaging.  Would woofer/mid-range speakers for the 6" diameter speaker holes in the kick panel area accomplish that, or would you have another recommendation?  1968 Ford Torino

Answer
Hi Carl.
The short answer is that the 6" holes could provide added bass. The real issue is: Will it add enough bass for your tastes?
A lot of that depends how much power you use and which speakers you use and how the doors and the vehicle will resonate to/with them.
How much power or system do you need?
I use a Decibel meter, ride in a car under acceleration with the windows down and take an averaged reading. I call that our 'noise floor'. Then you generally need enough speaker/power to over come that reading by about 10Db..
A pair of the free-air speakers shown below should hit about 110Db with 125 watts of power each applied. That is quite a bit of bass. Of course with the windows up and the vehicle parked you are going to be 30 DB above the noise floor but that just means you have great system headroom in those conditions.
So...Using a decent free air speaker design, what you are trying to do can be done IF you are not looking for a real trunk thumper system.

I would suggest a free-air type 6 or 6.5"
http://www.crutchfield.com/p_2060CVT654/Kicker-10CVT654.html
100.00 but you really get what you pay for with a set of those in this situation.

A good center channel may be desirable, but I would wait and see how well the door speakers fill the center, first (I would avoid cutting or digging in more than is needed to get good sound until you have to). How the mids and highs are 'aimed' has a lot to do with this staging, front fill and separation stuff. IF ya decide you cannot live without a CH later, you will have to do it. I suggest a dedicated mono amplifier channel for CH's though there are other ways of doing it.

It might be better to build a pod to cover the kick panels and it will allow you to aim the mounting locations back and up. You can have a shop build a pair or try it yourself if you are handy with materials and tools. They are generally from materials like fiberboard, particleboard, ABS plastic and fiberglass.
http://bbkworks.blogspot.com/2012/04/fiberglass-for-bignners.html
You may also be able to find pre-made custom ones but be prepared to pay heavily.

A wealth of knowledge is at your fingertips right here:
http://www.crutchfield.com/App/Learn/Article/Menu.aspx?g=182850&tp=404

cheers,
JM