I noticed some rattle in the back of my car so i investigated. I found the grills for the rear speakers were rattling around 50-ish Hz. At first glance i was just going to take them off, then i noticed something: the rear deck speakers (6.5's) were trying to play the 50Hz! Bad.

If i remember correct, the device that fixes this is a crossover. At the moment here's how my car is setup:

Alpine deck
--> Front Speakers
--> Rear Speakers
--> Rockford 1000W amp --> (2) Eclipse 12" subs

The in-cabin speakers are being powered directly off of the deck's built in 25-ish watt amp.

If i was to go crossover would i need to externally amp the in-cabin speakers? Should i even be using a crossover or are the settings on my deck sufficient enough?

Thoughts? -- Thanks.


Oh, one more thing. What frequency should the 6.5's stop playing at the sub kick in? Anyone have similar expirience in a GC8 4dr sedan?

 

you should be able to put an inline filter (forget what they are called exactly, look kinda like capacitors) to pass thru just the frequencies that you want.

what you really need to do is take a dremel to that rear deck and throw in some 6x9's, get rid of that sub box. dead weight, car goes faster without it

 

lol @ sub box.

6x9's.... It's crossed my mind in the past.

I think i know the passive filter you're talking about. I've heard some mixed reactions about those, something about them stealing power to the speakers. Anyways, that's an idea and i had actually forgot about those so maybe i'll check 'em out.

 

6x9's with an amp (doesn't even need to be a big one), with the right settings will give you mroe than enough bass

 

now that comes down to personal opinion.

a good set of 6x9's are enough for you and me, but there is someone out there who always wants more hp/bass/crack/etc.

wastingtape, its not hard to do. took me about an hour of cutting to do. it also nice for listening to something that doesnt need alot of bass ie classical. ill see if i can dig up some pics of mine

 

Well yeah, but for street purposes it's more than adequate, unless you're going to SPL competitions, you dont need subs

 

1. how do you know it is 50 hz?

2. forget rear speakers.

3. you can go passive or active crossovers.

a passive one is one used AFTER the amp. but since it uses coils and caps, some of the power going to speaker is wasted. and unless you have a very well designed crossover network, you might be "cutting off" the frequency incorrectly.

an active crossover goes BEFORE the amp. granted some amps have them built-in. but the signal is being "filter" before the amplification stages. these are all electrically powered and of course it adds costs to the system.

but they give you WAYYYY better control.

FWIW, normally, i cross the front speakers around 120-150hz. i then cross the subs, depending on the vehicle, around 60-120 hz.

the smaller the speakers up front, the higher the cut off is...

 

1. A: I have a "db drag" test CD which i can play specific frequencies.

2. haha...

3. Yes, and so I've found. The passive crossovers are a group of capacitors/coils (sometimes resistors) which you can actually assemble yourself based on formulas (formulas which happen to have convinient calculators availble online). I read somewhere that the loss of power is about -0.5 dB.

I also found, as you mentioned the active passovers go before the amp. This would probably end up requireing me to externally amp the in-cabin speakers which i should do anyways.


Thanks for the info about which frequencies you cut off on.

I've still got a bunch to think about and i'm sorta taking my time and readin about all this. One other thing i've been looking at is i drive the sedan, which, on the rear deck, the speakers hang down into the trunk. At the moment i have no baffle on them at all. I've been wondering if the sound pressure from the subs in the trunk pushes on the cones of the rear speakers while they're also trying to play something completely screwing whatever they're trying to do.

 

I don't race my car so i can afford to burn the extra weight. I only wish i had more trunk space... :-/

I go diving with my friends often. A little bit of gear goes in the trunk, but 90% ends up filling the back seats up (which makes it difficult if 3+ people are going). I didn't really think anything of it until one weekend when my friend drive. Almost all of the dive gear fit into this trunk. It was then i noticed how much the subs eat up. I've since been thinking about designing a box which makes me efficient space of the trunk...

 

Did you have to recarpet or anything after that? I was looking at how it was assembled and thinking i could probably do it, with some good planning and patience.

 

exactly why I would never get a sub box, I need the trunk space, and a well designed and powered system w/ decent 6x9's hits just as hard

 

exactly. the sound pressure in the trunk, while NOT REALLY air tight, can be enough to be bad for the smaller speakers in the deck.

one thing to lessen this is to make sure that the speakers are in phase. i.e., the sub is wired correctly. if they are out of phase, as the sub pushes forward, the rear deck speakers must be pushing forward too.

cause if at the same instance, if the sub is pushing forward and the rear deck ones are pushing backwards, well, you get the idea.

best thing though is to loose the rear deck speakers and just get the biggest and baddest speakers for the front doors. power them with a kick *** amp.

then adjust the sub to "cooperate" and you will end up with a sweet sounding system...

 

sorry for bumping an old thread... yea i recarpeted the rear deck. pulled the 3rd brake light and found some carpet that was just barely off, colorwise. my server died so i'll have to grab new pics... then rebuild the server. maybe tomorrow if i get time.

 

You may need to baffle the rear deck speakers so they don't get pushed by the air that the subs are pushing out.