Coupe build. Preliminary questions. Noob but quality expert advice sought.

[ladysmanfelpz 10+ year member]

Hey guys. I just picked up a 2007 Honda accord LX and being an audiophile have already thought about what I am going to do to it. It gets me excited, but I'll try to keep it short.

So Big 3 will be a first and definite upgrade. Maybe battery too, but prolly just stick with stock alt. Then next will be the deck. You have to buy a whole new dash kit to fit an aftermarket stereo and they run about $300 which kind of *****, but it keeps you stereo up high where you can see it. This is what I want because I want a double din thats ipad compatible and video capable so I can play music videos while jamming.

Next will be sound dampening. I just got into it on my last car and threw 40 sq ft of hushmat on my doors and trunk and the difference was insane. I really want to quiet this car up tho and get it smoother than a lexus. I've read a little about sound dampening and now understand you need soft dense material to absorb sound. I also saw that hushmat extreme has a layer of MLV or some foam type material in it and is capable of quieting your ride 10 db on the highway. So my question is is this going to be the most simple and cost effective way of sound dampening or should I do the resonance tiles, MLV, and whatever layer type gig?

So my initial thought on the car was to bring in my old CVX on 500 watts and build a nice SQ sealed box and build the system around that. After driving it for a while tho, I like the lightweight and quickness of the car and don't think I want a big sub in the back. Plus the small cabin of the car gives it a real "coupey" sound and I don't think a sub would sound all that great in it really. So now my thought is to just run a four channel amp have nice components and maybe even a crossover set up. It has 6x9's in the back and 5 and 1/4's up front and two tweets on the dash. My thought is to get good mids and maybe even create a baffle and put some polyfill behind them to get some good 'pop' out of the mids and then some nice inverted dome tweeters. Now I am new to component set ups so if you can explain some of the differences in these and especially with the tweeters because I've heard soft dome and whatever they all have now can sound completely different. I think the inverted dome firing up into the windshield will give a really nice sound stage.

So now since I am thinking of going subless it will be a challenge to fill out the lows. It is not useless tho and I find myself enjoying mids more so I can go without super boomy bass. I do however need my lows and need them clear. I'm thinking the 6x9's on decent power can do the job and get it sounding nice at least to 30 hz. So I would sound dampen the flimsy aluminum rear deck of course before install. I've heard some issues with powerful speakers firing up into the rear window sounding really distorted so if someone can explain this to me and say my design is completely flawed please let me know. I think with a properly sound dampened vehicle this shouldn't be an issue tho and instead the rear window will act as a box for the 'subs' and give pretty good bass response. I see they don't make many 6x9 subs or even components nowadays so I may have to go old school but I don't mind. I've been reading into infinite baffle set ups but still a little confused on those as well so if anyone has some good knowledge or links on these give me a shout. 6x9's have the cone area of an 8" sub so it would be like having two 8's in the rear deck and if I can completely seal off the trunk (if thats possible) and then have each sub on 125-150 watts I think I could have some real boom out of a subless system. If you can't seal a trunk and the infinite baffle set up firing straight up into the rear windshield will sound like trash I thought about if you could put those little 6x9 boxes filled with polyfill right below, or even better custom fabricate a box out of mdf and mount it below the rear deck. Has this and can this be done?

Thanks for all your info. And remember I am open to opinions, but this is my build and have certain expectations, and don't really want to hear some "why don't you just throw 3 sundown sa-12's in it and a sony amp" stupid ****. Thanks again.

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[trumpet 5,000+ posts]

The Big 3 alone isn't going to do anything to improve your sound. It's very good to do it, but I'm telling you this so you don't expect anything to change on a factory sound system.

For the dash kit I strongly recommend Metra 99-7803G with the 88-00-7803 optional pocket. This includes the wire harness, and the pocket is recommended because the original pocket won't close properly with the new dash.

You've got some ideas that don't really translate well to real life, such as a "coupey" sound, which I have no idea what that could mean. The inverted dome tweeter thing is a bit confusing as well. Yes, tweeters come in different designs and materials and they can sound quite different. I wouldn't focus so much on how they're made, but rather how they can sound. Most people prefer a silk tweeter because they tend to be smoother sounding. I prefer a metal dome tweeter to make my music sound more realistic, which is a lot of metal and rock bands. If you can listen to a few speaker sets of different levels of quality it may give you some idea of a sound like prefer.

A subwoofer is a very good idea, and today there are some very strong options for a loaded and vented box that don't take up much space. JL Audio, Alpine, and Rockford Fosgate all come to mind. Your idea of putting subwoofers in the rear deck lid can work quite well, although I personally have not tried it. Some will say to put them in the deck lid reinforced with a board, others will say to put the subs on a baffle behind the rear seats. Playing through the seat will change the sound of the bass. Playing off the glass is not going to distort the sound.

 

[ladysmanfelpz 10+ year member]

Playing through the seat will change the sound of the bass. Playing off the glass is not going to distort the sound.

Thats exactly it! See I love subs and know they can make the heart of the system and thats why my original design was based around a well powered quality sub. But I thought the car had a center fold to open up for a good port to bring the sound into the cabin, but it doesn't. So that means I would have to drive around with the 40 split down like I did in my subaru. That just brings in extra road noise from the trunk and I'm an adult now and don't want to be driving around with my car all modded out and since its a coupe I really can't give up any more seats and space just for my system. So if I kept a sleeper look like I am after, that means having the sub in the trunk but blocked off from the cabin and I really don't see much of a gain with that compared to nice 6x9's that will provide accurate bass and where you can feel the air moving instead of it being locked in the trunk.

So now to the infinite baffle set up. I do want my bass to have some boom and my understanding is if I can seal off the trunk completely then the whole trunk will act as a box and provide a good sound. I do not know if this is possible though. So what is this board you are talking about on the rear deck? Like I said if I could have two of those lil 6x9 boxes with polyfill and mount them flush on the rear deck (which would be difficult since the design is a lil whack) and screw into them from the top when mounting the speakers, I think that would provide a decent sound and be a nice box size for an 8" cone area. Now if I could mount the board below the rear deck and fab up a box of 1/2 or 3/4 MDF to not strain the rear deck too much, then that would be like having a sealed box with two 8's in it firing at the rear window to reverberate the sound and give some nice bass.

 

[winkychevelle 10+ year member]

Good 6x9 sub on a reinforced back deck can sound quite good but picking the sub is critical kicker comp 8s work well infinite baffle and actually sound really good in that configuration. And the back glass wont affect the subs sound much it will however direct the sound to the front of the car

you seem to have a good idea on sound deadening but I would suggedt looking into keephopealive's accord build log its a different car but he explain hoe he does deadening and other treatments quite well

component sets are sometimes iffy. You can usually get a set with a good tweeter or a good mid most of the time its a compromise between the two. Really good set cost a high premium so I suggest listening to alot of sets before buying

ok silk dome and aluminum domes

silk tends to sound smoother due to generally being less peaky in the 4-6k hz range but generally runs out of steam around 12khz resulting on loss of detail at high frequencies.

aluminum is typically the reverse it extends high into the frequency range and brings out an "airiness" to the music but due to the peakiness in the 4-6khz range they may tend to "eat your ears up" andbsound horrible to you

both disadvantages can be overcome with proper install and eq adjustments

Dome\ring radiator vs inverted dome

dome and ring radiator tweeters have one disadvantage to inverted dome tweeters. They like to be aimed at the listeners ears to get the most detail. They work off-axis but are generally better when aimed correctly

inverted on the otherhand disperses the sound better and there for usually can retain more detail when pointed away from the listener. But when pointed at the listener they may seem harsh or distorted.

all these statements are install dependent but are true from my research and experience

a good set of components imo is the jbl ms line or the pioneer d-series when on a budget

I also recommend placing the tweeters in various positions and choosing the best sounding before mounting. Making tweeters soundbgoodnin a horrible position can be a nightmare. The dash may or may not work well for you it served me well in my trucks but I mounted my tweets in other locations for final install on every vehicle I have personally owned

 

[winkychevelle 10+ year member]

Thats exactly it! See I love subs and know they can make the heart of the system and thats why my original design was based around a well powered quality sub. But I thought the car had a center fold to open up for a good port to bring the sound into the cabin, but it doesn't. So that means I would have to drive around with the 40 split down like I did in my subaru. That just brings in extra road noise from the trunk and I'm an adult now and don't want to be driving around with my car all modded out and since its a coupe I really can't give up any more seats and space just for my system. So if I kept a sleeper look like I am after, that means having the sub in the trunk but blocked off from the cabin and I really don't see much of a gain with that compared to nice 6x9's that will provide accurate bass and where you can feel the air moving instead of it being locked in the trunk.
So now to the infinite baffle set up. I do want my bass to have some boom and my understanding is if I can seal off the trunk completely then the whole trunk will act as a box and provide a good sound. I do not know if this is possible though. So what is this board you are talking about on the rear deck? Like I said if I could have two of those lil 6x9 boxes with polyfill and mount them flush on the rear deck (which would be difficult since the design is a lil whack) and screw into them from the top when mounting the speakers, I think that would provide a decent sound and be a nice box size for an 8" cone area. Now if I could mount the board below the rear deck and fab up a box of 1/2 or 3/4 MDF to not strain the rear deck too much, then that would be like having a sealed box with two 8's in it firing at the rear window to reverberate the sound and give some nice bass.

I suggest not really worrying about the integrity of the rear deck.

personally I would cut the deck to fit two 8s then a board to matchthe back deck. Screw the board to the back deck and mounting the subs to the board using sound deadening to seal the board and cabin fron the trunk. Then putting factory plastic over everything or modify to fit. Worse com to worse box carpet doesnt look bad on back decks.

8s or 6x9s sealed arent going to play 30hz very well but two 8s infinite baffle will. They just might not be super loud.

 

[ladysmanfelpz 10+ year member]

Thanks for the info winky. So where did you end up mounting your tweeters in your final installs? And you think that IB will hit lower than a sealed box? That seems odd to me.

 

[LaserRed38 10+ year member]

I have a pair of Genesis Audio 6x9 free air subs that I'd let go of for a good price. I've installed them on everything, including Bentleys, where the owner didn't want a sub to take up their trunkspace.

 

[ladysmanfelpz 10+ year member]

I have a pair of Genesis Audio 6x9 free air subs that I'd let go of for a good price. I've installed them on everything, including Bentleys, where the owner didn't want a sub to take up their trunkspace.

How'd they sound? Just want an honest opinion and not a sales pitch cuz I'm not interested in purchases quite yet, but still researching. What were your experiences with them and do they do the job for replacing a sub?

 

[ladysmanfelpz 10+ year member]

Okay so reading more on it, it looks like IB is the way I want to go. On lower power they will be able to hit lower frequencies because they don't have to overcome the pressure of the box. Also they will tend to sound a lil better since their response curve will be flatter. Now when a manufacturer says the frequency range is 30 hz- 4khz does that mean that is what the sub is actually limited to by design and or filters or can box and install design cause variations? I would love some 6x9's in IB that could maybe dip into some high 20 hz notes without damaging them.

 

[trumpet 5,000+ posts]

The CDT ES-0690 6x9 subwoofers can play down that low and they're made for use in a rear deck. CDT has 3 levels of 6x9 subwoofers, but the ES model does the best on very low notes.

 

[ladysmanfelpz 10+ year member]

K didn't want to start a new thread so I'll see how many replies I get first. So I'm looking to start purchasing my equipment for the build, but I am still debating the subs. Like I said it is a coupe and it is mainly going to be me and maybe one other person riding in it and I love bass and sound quality so I am building it for me and don't care too much for passengers in the back since I won't have much back there anyway. Now are the 6x9 subs the way to go and how do i do it? I'm thinking I will hushmat the **** out of the rear deck on the bottom and if I can take off the carpet put some MLV or more hushmat on top and just drop the 6x9's in stock location. Will the rear deck need reinforcing with a custom built baffle or do you think the stock rear deck could handle two 6x9 subs say the CDTes on 75 watts each? And would a dedicated 6x9 subwoofer give me better sound, more boom, and get lower in frequencies than just a 6x9 woofer or coax?