Just throwing it out there. This is old school way of doing it. In the 80's it was perforating the panels, then in 90's you cut the hole all the way and replaced the hole with nice speaker cloth panel. I have ADS components in here which I am sure many of the young pros never heard of. When I installed it was ADS, Nakamichi, EV, and Zapco were the high end stuff. There was some mild mod inside the door, but not much.

 

Zapco.. LOL. I used to have one of their under dash amplifier-equlizers it was like a booster for the weak stereo wattage and it worked great!

 

I'm running a USA-66 with the MP3 player in the glovebox on my coupe. I've got a JL Audio amp in the trunk powering a pair of Focal 6x9s in back, a JL Sub in the trunk, and a pair of Focal 2 way 6" diameter speakers in the kick panels. I bought a pair of Custom Autosound's bare kick panels, but these don't allow for the physical depth of the Focals.
I opted for a pair of custom made fiberglass kickpanels that are covered in vinyl. All the Focals have adjustable tweeters, so the sound is top-notch.
I think you could use a similar setup with the 6x9s on the trap door with appropriate damping.

 

Just don't see myself cutting the rear interior trim for speakers. I'd rather buy repo after market panels and cut those saving the originals. JMO

I bought a set of Kicker KS600 for our front kicks. These are 2" deep speakers and they JUST fit! I'd suggest something thats not quite that deep though.

 

I just installed a stereo in my 66 this past summer. Alpine 5.25" speakers in the kick panels, Alpine 6.5" in the rear (fastback trap door), 6.5 Kicker subwoofer behind passenger side trim panel, Alpine 5 channel digital amp in the trunk and an Alpine media player head unit in a custom steel underdash pod. With sound deadener throughout this car sounds better than most new car stereos. The only thing that I would consider changing is putting 6.5 speakers in the kicks because I find I have the fader leaning way towards the front for proper balance.

 

I just got back from CES and most of the companies mentioned probably will not be around by the end of the year.The new thing is "micro" sized amps.Less weight and the size is about 8X5X2 with anywhere from 600 watt 4 channel to a 1000 watt d class.The price isnt bad either and speakers are going to the slim basket now.

In a properly set up system, you should be able to close your eyes and not tell where the sound is coming from, so most upper end deck, you can add a delay to the rear to compensate for speaker imaging.

 

Thank you all.
In other words: I should look into placing rear speakers and for front speakers 2" is possible, but not recommended.

 

on another note ... let's say you have 2" in there and it doesn't fit, couldn't you just fabricate a wooden ring as a spacer for between the panel and speaker?

 

That's actually a great idea! Thanks! Indeed, why not?

Edit: the ones i found with the adjustable tweeters are from Infinity (Kappa series). I found them in a store where you could listen to them. They sounded actually really good, as well as the pioneers and further some JBL's. In that case I'm aiming at 50mm. Thursday is the day we're going to buy them.

 

i had infinity (kappa) a good few years back and I'm well impressed. My brother snatched them off me at some stage. really good speakers they are (at least I think so)