Hey, No there probably isn't anything wrong with the 4's.

I run a set of the reference series 4's in my big Mitsu Box Truck. They won't reproduce any frequency below 250 hz at any significant volume level. If you try, they over extend the excursion (or travel) of the cone and start breaking up. I run them on a 4 channel old school (late 80's) Lanzar amp at 150 watts per channel. They will flat hurt you!

But to make up on the bass end, I was forced to build a fiberglass enclosure and put two old school Pheonix Gold 10's behind the seats. You should see the reactions I get on the job and in traffic when this old guy (29ish) in a box truck is bassing or blasting some Underoath or As I Lay Dying.....

Even when you finish the boxes for the 6x9's I would recommend either turning the bass down on the head if you aren't running an amp, or Fading the volume to the rear just slightly so you don't damage the front speakers.

They sound amazingly better with some power to them though....

 

Once you have the 6x9's back in, if the head is a four channel (FBLR), fade the sound slightly to the rear channels so that they are louder. Chances are that if they are behind the seat, they will be slightly muffled anyway and you can make up for that by turning the volume down slightly to the fronts.

 

Yeah, that's talking about the RCA outputs on the back of the unit. You'll use those if you ever get an amp, but I don't think you're using them now.

BTW check ebay every once in a while for amps. You can pick up a used Lanzar vibe 4 x 150 watts per channel for less than $50.

 

Did you seal the corners with any adhesive caulk? I can't really tell.

 

Any air leaks can greatly effect the bass output of your speakers. Usually the only time you want "air leaks" would be through a port in a ported enclosure for subwoofers.

 

The best thing to do is to take the box back apart and use liquid nails or another construction adhesive. This does two things, One it seals all air leaks, and two it helps keep the panels from vibrating.
With a speaker, there are two sound waves coming from the cone. One from the front of the cone and the opposite from the rear. Any part of the sound wave from*the rear of the speaker that mixes with the sound wave from the front will cause some cancellation of the wave. This is much more noticeable with lower frequencies in the bass or midbass classification.
There are however times when you do want to port or vent the enclosure. Usually this techique is used to tune or load a box with a certain subwoofer/ enclosure combination. Porting a box can make the combo much more efficient at a certain frequency, but you must know all the speaker parameters and also know how to use them. There are computer programs that can help with this, I use Bassbox Pro from Harristech.

So anyways, don't worry about porting this box, we'll talk more about it when you get your subs.......

 

If you are worried about getting the wire out again, use silicone. It isn't as strong, but is removable. If not, use the liquid nails.