Rear Speakers in a 240

[bazan]

I recently put some Infinity 4"x6" plate speaker in the rear of my 240 Fastback. I didn't think of it at the time, but isn't it bad to be running an amplified signal off of my HU (Alpine CDA-7873) into the stock rear speaker amplifier? I pulled the front amps when I replaced those a few months ago.

Isn't it kind of bad to basically amplify and amp'd signal? I haven't been able to find the rear amp to pull it. Can anyone confirm if this is indeed very bad, or tell me where the amp is to disable it and pull it. I would just run new wire, but i'm at school living in the dorms. Next summer I'll probably do that while I'm at home. Thanks guys

[itsRaine]

It's definitely bad to run an amplified signal into a line-level input. You're probably better off running new wire to take advantage of the aftermarket head unit's power output... or you can get some of those line-level converters for like $5 each.

I put a post up about the stock amp locations too. Check that for answers =)

[LT_Z]

I was just just trying to figure out if the "plates' fit the stock 4x6 location in a 249sx hatchback. is that what you have ?

[itsRaine]

Actually I have an S14 but I know the S13 hatchbacks run 4x6 all around, so they should fit.

[bazan]

Yes the infinities fit perfectly. The position of the rear spekers in relation to the glass makes them a pain the put in, but otherwise they fit great. And as far as clarity I haven't heard anything better. But I need to remove that amp before I'm willing to turn them back on.

[180fan]

Yes, the infinity plates will fit the fastback with no problems. If you're running an amplified signal to the amplifier, you'll blow your amp in no time. Use your RCA connects in the back of your reciever to send the signal to your amplifer. In my fastback, I put my alpine mrv-f340 between the rear strut towers, under my strut tower bar and secured it via large velcro pads on the underside of my amp. If you're interested, I'm currently in the process of working out a method to install 6x9 infinity kappa 693.5i's in the location of the 4x6, I'll let you know what ideas come up and how I'm going to do the mod (if you're interested).

[bazan]

I'm definitly interested in wether it can be done or not. I'm not going to worry about switching what i've got in there. I'm putting the car away for the winter this weekend. Snow is really bad here in Houghton and I'm not able to pay insurance on it without a job right now. I'm not worrying about that amp or the speakers etc. until spring when I pull it out. I don't have a good place to work on the car here at school so my times are rather limited.

I don't care about the factory amp anyways. All i care about is the speakers and the headunit, neither of which should be affected by this.

[dorifkin]

Dont worry about putting 4x6's in the back; its a waste of time. If you take out the plate in the front doors you can make a wood baffle and fit upto 8 inch speakers into it. I've got 7" Crystal mids in the front. They get plenty loud.

And dont worry about running line level like that. The speakers will be fine, just dont crank it up too high. You'll clip them to death.

[LT_Z]

Crystal, what is crystal ? **** i used to have some rockford 8's too but i sold them. I have the infinity plates in the back already, and i have Infinity Kappa component 5.25 in the fronts. But im definintely missing alot of mid bass. My amp will throw 75 watts rms to the fronts any suggestions ?

[dorifkin]

The biggest thing that kills midbass is how you have the mid installed. If you have area of spaces around the mid then you will get cancellation, so it is important for you to make a plate that will totally seal off the back of the speaker from the front.

Then check to make sure everything is in phase. In other words two speakers will produce the same waves. If they match then each will overlap and create one sound. If they are firing one after another then they will cancel each other out. This makes a huge difference in the midrange area since that is the most directional of frequencies.

To test the phase disconnect the tweeters from the crossovers, you dont want to blow them. Get a AA battery and go to your amp. Then hook the positive end to one wire and the neg to the other. Your speaker should either pop in or out. If it pops out then it is in phase and you hook the wire that is touching the pos end of the battery into the positive terminal of amp. And do the same for the other side, and then the back speakers also. Most people overlook this step and get huge cancellation and wonder where the hell all the mid bass went.

Of course infinity is'nt known for excellent midbass, but it can still do some. If you can, try upgrading to some cdt's, cdtaudio.com. Actually I'm running Vifa 7" mids in the fronts, these are the same drivers used in $700+ per speaker systems. I got them for 43 shipped off of partsexpress.com. But, I would recommend the cdt cl-61's that are running for 150 right here http://www.thezeb.com/caraudio....html.

The cdt's put out crazy midbass and are good if your unwilling to put a sub in. email me at [email protected]. I can point you to some other suggestions and you may not even need new speakers.

[dorifkin]

Also, if you use 1/4" mdf or whatever for you baffle you should'nt have any problems with deep speakers hitting the windows on their way down.

[flipittothewall]

Let's here something about how anyone has fabbed in non-factory speakers in their front S13 doors...I had to severely mod mine just to get Infinity 4x6's in, and intend to push Kappa 6.5 seperates in soon.

[dorifkin]

Well let me see if attaching a pic works

[dorifkin]

Sorry for those with dial up:

In case anyone wants to know these are 7" mids that are max depth of 3 1/8". Also I used a .5 inch baffle made of plywood, though its pretty $hitty lookin. And my windows roll down without a hitch, so you should'nt have any problems.

The black mid is a Vifa PL and the Aluminized one is a Crystal Csc60s mid. There was no room inside the door so I put the crossover in the lower right pocket of the door with the tweeter right below the sail panel.

[dorifkin]

O yeah, I had to trim away some of the door panel right where the speaker grill is. It was hitting the cone when the speaker was at higher excursions.

Next thing I'm going to do is put eight inch midbass speakers in the doors with the crystals in the kicks.

[flipittothewall]

Cool Dorifkin....I didn't think spkrs that big would fit! I plan on making a fully boxed pod to fit in the door, mebbe....might sound better than just having them use the door as a chamber.

[Simmsled]

dorifkin... sound deadening!!! Before I sound deadened my front doors, I would run my Infinity Kappa Perfect 6.1 system with a low freq cutoff at about 90hz with a 12dB rolloff. It would distort and not reproduce the sweet midbass that those speaks are known to do. After I sound deadened the doors, I was able to turn it up louder and lower the cutoff to 70hz with a progressive 12dB rolloff. I turned off the sub pre-out to see how low she'd go. I was really impressed, and better yet.. NO RATTLES! One word of advice... the wood plate is a great idea, but make sure that you dont go for a couple years without checking the wood for rot. Moisture can get down in there and soften the wood. It is always good to throw a layer of some kind of sealant on there. Even if it is a buck twenty-five can of spraypaint from Home Depot. I have heard those Crystal speakers. They are really sweet.

[dorifkin]

Simmsled, you should try the Vifa Pl's. I was able to cross them down to 50 hz no sweat. And what you said about the sound deadening makes sense. With a door that is'nt sealed you would have an infinite baffle situation. The speaker will hit its peak faster and bottom out. But, with sealing the door, your making it work more and thus keeping it from bottoming out. And I'll have to check up on that wood as you said.

Flip, your gonna have a helluva time putting a box in the door. I would use fiberglass instead. The doors are very thin from the speaker back and assembling it from inside is pretty much impossible. Or better yet make some fiberglass kicks, that would be nice.

[flipittothewall]

Dorifkin, yeah, gonna have to fiber them, I figured as much. Just hard to come up with the design while I'm away from my car for so long. Space IS tight with those doors, but I'll figure a way to make it work. Kicks? Nah.....footroom is already small, I'd be all over the pod with my clodhoppers. Anyhow, think I could use the original plastic pods as part of the mold for depth, maybe alter the door if they stick out too much.

[dorifkin]

I think you could use the original pods, you could trim them and set them back a little into the door. Actually thats a pretty good idea, its too bad I through mine away:( .

[flipittothewall]

Ha, pretty much destroyed mine cutting in the Infinity K 4x6's; depth was too shallow for them, damn factory ****e. Still have a little of the backsides left as a template for depth, and the entire front which is what one really needs. You'd have to completely re-fab anyhow for enough cubic space for the larger mids anyhow.