PDA

View Full Version : Replacing rear 6x9s - should I use components instead?



Umbra
04-20-2014, 03:12 AM
I have a pair of aftermarket component speakers in the front on a 35W x 4 @ 4 ohm amp. I also have a pair of subs. The sedan in question also has two 6x9s in the rear deck, but they sounded like crap with the rest of the system, so I disconnected them. I know most people don't bother with the rear deck, but there are often backseat passengers. If I could get a pair of speakers for $50 - $100 to better immerse the cabin, that'd be great.

My question is this: should I replace the stock 6x9s with another pair of 6x9s, or should I use a different form factor, like 6.5s or 6.5 components? I could make an adapter out of MDF if necessary.

I have the components and subs crossed over at 80hz. The highs are nice and crisp and the lows are powerful, but I feel like the midbass is lacking currently. What would be an ideal speaker type for this situation?

Cliff459
04-20-2014, 03:35 AM
I think most factory speakers will sound like "crap" when paired to aftermarket ones. Factory systems have a complete system design paradigm to maximize the balance between cost vs sound quality and SPL. This is decided by a group of engineers at the auto factory, and many things swing the balance one way or the other towards each factor being considered. That's why aftermarket systems sound so different, a totally different set of criteria are used to design them. "Better" or "Worse" are really just subjective judgements, in the end. So, there you go on that... ;)

You should give the forum more info on your individual system components if you want more helpful suggestions, like maybe what aftermarket components, what amp, what sub and how it's mounted (box type, amp power driving it) and the kind of sedan this is all going in. Also, maybe a good cross section of your normal listening music might help as well...

keep_hope_alive
04-20-2014, 04:26 AM
ideally you match the fronts so tonality is maintained. if your sub stage is large enough, the sub will pressurize the trunk and force the rear deck cones to move - distorting them. yes, factory sounds terrible and aftermarket will sound better.

match the fronts and you're in good shape.

is the amp bridged to the fronts so the rears will be off the HU?

Umbra
04-21-2014, 03:38 AM
Cliff's got a good point; it couldn't hurt to list what I've got so far.

4ch Amp: Kenwood KAC-748 (http://www.crutchfield.com/S-XQNMOfwDaBE/p_113KAC748/Kenwood-KAC-748.html)
4x35W RMS @4ohms

Front speakers: Kenwood KFC-P709PS (http://www.crutchfield.com/S-A2Cd2tGSNbW/p_113KFCP709/Kenwood-KFC-P709PS.html)
6.75" components, 5-80W power range

Mono Class D Amp: Kenwood KAC-9103D (http://www.crutchfield.com/p_113KAC9103/Kenwood-KAC-9103D.html?search=kac+9103d&osp=kac-9103d&tp=115)
500W RMS @4ohms

Pair of subs: Rockford Fosgate Punch HE2 RFP3212 (http://www.crutchfield.com/p_575RFP3212/Rockford-Fosgate-Punch-HE2-RFP3212.html?search=rfp3212&osp=rfp3212&tp=111)
4ohm, DVC, 400W RMS ea., in a sealed box - 2.5 cubic ft after displacement

The sedan in question is an '02 Hyundai Elantra. Stock electrical, 90A alt.



is the amp bridged to the fronts so the rears will be off the HU?
The amp is not bridged. I tried it once, but it appears that I can only run the pair both mono left ch.

It's not a high end system, but the Kenwood stuff actually sounds pretty good. I didn't plan for it to be all Kenwood, it just worked out that way. The two amps and the pair of subs came from three seperate Craigslist transactions. The component speakers I bought new because they were well reviewed. The box I built.

You would of course know much more about the acoustic and physical properties of any trunk pressurization that might be going on. I can tell you I didn't do anything special, like add deadener to it. That may be added later on.

If the sub pressure is interacting with the cone, is there anything I can do to prevent or lessen that? The basket of the 6x9s drop right into the trunk - nothing special - so if there's pressure it would definitely move them. I still have the stock speakers in, but unplugged. I should see if they move.

If I end up going with components in the back, where could I mount the tweeters?

keep_hope_alive
04-21-2014, 08:49 AM
if you want a rear coax then the KFC-1795PS is a good match, but the same components in the rear would be great. mount the tweeters on the door similar to where they are in the front doors.

Umbra
04-22-2014, 02:49 AM
Unlike the front that had component 6.5s originally, there's no immediate way to mount tweeters in the back. In the front there's a spot in the door for them and the area is molded in such a way so the tweeter would better face the driver and passenger.

The KFC-P709PS tweeter can be angled natively after mounting, so I could probably get away with putting them in the same relative spot like you suggested by cutting a hole into the plastic. I could then tilt them, but where? Towards where ear level would be for a person sitting in the back?

Is the general consensus 6.5s are better than 6x9s and 6.5 components are better than coaxials in terms of SQ if the specs and prices are similar? To what degree would the pressure created by the subs affect the SQ and longevity of speakers mounted in the rear deck? Does it matter if the woofer is behind the person and the tweeter is in front?

Thanks for answering my questions so far. Sorry there are so many new ones, it just seems like you'd be the one to ask.

calebkhill
04-22-2014, 06:39 PM
Just go with a pair of 6x9 coax.
You'll get better midbass with the added cone area and don't have to worry with locating a separate tweeter.

Umbra
04-23-2014, 03:42 AM
I've done some more reading and now I'm even more indecisive than before. It seems coaxials would be sufficient for rear fill, but if I have backseat passengers often (which I do), then components would offer the passengers better SQ.

I think either way adding speakers in the back should help keep my sound stage forward and away from the subs.

If I built enclosures for the woofers in the rear deck, that would protect it from pressurization, right? Might it also help with midbass? There's enough room in the trunk above the sub box for me to surround the speakers in mdf. I could just turn the adapter I'd make into a box and secure the deck, woofer, and box with some screws and tee nuts.

One last question, the frequency response for the components goes down to 63 Hz. Right now the front speakers and subs are crossed over at 80hz. If I brought this down, would that help or hurt midbass response?

calebkhill
04-23-2014, 07:18 AM
I've done some more reading and now I'm even more indecisive than before. It seems coaxials would be sufficient for rear fill, but if I have backseat passengers often (which I do), then components would offer the passengers better SQ.

I think either way adding speakers in the back should help keep my sound stage forward and away from the subs.

If I built enclosures for the woofers in the rear deck, that would protect it from pressurization, right? Might it also help with midbass? There's enough room in the trunk above the sub box for me to surround the speakers in mdf. I could just turn the adapter I'd make into a box and secure the deck, woofer, and box with some screws and tee nuts.

One last question, the frequency response for the components goes down to 63 Hz. Right now the front speakers and subs are crossed over at 80hz. If I brought this down, would that help or hurt midbass response?

For backseat passengers, the best way to keep SQ is to keep most of the sound coming from in front of them, and to keep the volume from the rear speakers relatively low.
A speaker playing behind your head isn't going to sound that great.

shauncox26
04-23-2014, 09:37 AM
a good pair of 6x9's is more then enough. i have a set of polk momos and they come with a crossover that's plug and play. this makes the sq better as the woofer only plays what it was designed for as well as the tweets. this will eliminate the need to mount tweets elsewhere.

Umbra
04-23-2014, 07:31 PM
I took a couple pics. Let me know if you guys think components are even feasible. You can click the images to make them bigger.

Here's the rear deck area. You can see where the 6x9 is mounted. I've also highlighted a plastic covering (on the D pillar?) where I thought a tweeter could go, but there might be just metal beneath it.

https://24.media.tumblr.com/342e16d482da6fb1fe6c00dc429eeb5c/tumblr_n4i8ayAxLE1r153evo1_500.jpg (https://24.media.tumblr.com/342e16d482da6fb1fe6c00dc429eeb5c/tumblr_n4i8ayAxLE1r153evo1_1280.jpg)

Here you can see the front and rear doors. I don't know if I could stick a tweeter in the back door similar to where it is in the front without running into just metal. There's also a plastic covering on the B pillar where it could probably go.

https://24.media.tumblr.com/469fc25930e1d2de446daaf037eecb8e/tumblr_n4i8ayAxLE1r153evo2_500.jpg (https://24.media.tumblr.com/469fc25930e1d2de446daaf037eecb8e/tumblr_n4i8ayAxLE1r153evo2_1280.jpg)

Would these locations work? Are they too much work with too little benefit?

Umbra
04-25-2014, 03:30 AM
I think I'm going to go with a second set of components.

I need to check tomorrow, but I feel as if there should be enough room before hitting metal to flush mount it in the circled location in the back door.

Thanks everyone for all the input so far. If anyone else would like to toss in their two cents, please do.

Freeman
04-25-2014, 03:36 AM
Ok i am to lazy to read all thus it late but don't bother with rear deck speakers they will just get raped by your sub or subs. and then the money you spent on them is down the drain.

:wave:

Umbra
04-25-2014, 06:06 PM
Raped as in the subs will drown them out, or raped as in I'll have to buy another pair shortly thereafter?

Umbra
04-28-2014, 04:16 AM
Nevermind, I found out the answer earlier today. I removed the rear deck cover and (with the speakers unplugged) turned my subs all the way up and watched the cones bounce all over the place.

I'd still like to add another pair of speakers in the back, but they don't have to be in the rear deck. I don't think there's room for the woofers in the door, but I'm pretty sure I could stick tweeters in there. As for the woofers, it looks like I need to build them enclosures, then put them in the rear deck (so the subs can't "rape" them), or put them on the floor. I was thinking of bolting under the front seats so they face the back passengers, but move with the front seats if they're adjusted.

I had another set of components, same as the front, in my virtual shopping cart, but I worry there's not enough midbass. I bet it'd be ideal to match the speakers perfectly, but if I find another brand with better midbass and put those in the back, would that end the world?