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Discussion Starter #1
Hey,

I need help designing a custom 6x9 enclosure for each separate 6x9 in my car's rear deck.

The problem: My 6x9's are currently housed in baffles in the rear deck that cup the speaker (protecting it from the violent bass air from the sub), giving it no space to push air of it's own and thus creating a vaccum and as a result giving me no midbass (60Hz-130Hz). As a result the over all system mid-bass response is about 10db below the deep bass response (20Hz-50Hz).

The goal: Design an enclosure for each 6x9 for the rear deck that gives it enough breathing room to create it's own midbass and boost the big dip in the frequency range from 60Hz to 100Hz.

Now. What size of cabinet would be ideal for Infinity Reference 9613i 6x9's? Should I put egg crate foam in back of the 6x9's just like I did in the front doors to help reduce backwaves?

I need ideas. I will email Infinity with the question and have them recommend a sealed enclosure volume.
 

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Discussion Starter #5

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Will those secure to the rear deck? I'm thinking about screwing the wood to the rear deck and then using some puddy like stuff that will harden and seal the wood to the rear deck to hold in the air and make a real sealed enclosure. The thing that worries me is that it might not make a difference after all the work.
yes with a couple screws and some 'putty' or 'caulk' it will protect the 6x9s from the sub output.

it will make a good difference, your sub is harming the 6x9s, if you protect them with an enclosure they will sound much better.
 

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I think it's a great idea.
so his sub is crossed at let say 80hz, his 6x9s will pick up from 80-20,000

if the 6x9s are out of phase with each other

wheres his midbass going to come from?

there wont be any, because the 6x9s are out of phase.
 

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Discussion Starter #10
Um,

Maybe you guys missed something. The 6x9's right now are indeed sealed with baffles. The baffles aren't providing enough volume to allow for decent bass production from the 6x9s. The 6x9s sound muffled and muted by the baffles. It's not logical to try switching polarity when the obvious problem is the baffles and the lack of a proper sized enclosure.

I'm just worried I'll go through a ton of trouble for little to no gain when the project is done.
 

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Um,

Maybe you guys missed something. The 6x9's right now are indeed sealed with baffles. The baffles aren't providing enough volume to allow for decent bass production from the 6x9s. The 6x9s sound muffled and muted by the baffles. It's not logical to try switching polarity when the obvious problem is the baffles and the lack of a proper sized enclosure.

I'm just worried I'll go through a ton of trouble for little to no gain when the project is done.
you sure the mids and tweets are working?
 

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Discussion Starter #12
you sure the mids and tweets are working?
Yeah, the speakers are producing what sounds like 200Hz - 20KHz even though the cross over is down at 80-100Hz range. I've tested the output already and nothing is wrong with the amp. The baffles I put on the back of the 6x9s are logically the issue. Free up those and my midbass should be helped a great deal.
 

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How much sub do you have? I've run a lot of IB systems like that without 6x9 enclosures. Did you verify the subs are moving the 6x9 without? Sounds like they just need to be larger if you do need enclosures, might get an idea by modeling a similar IB 8" but I rarely find T&S on 6x9s. I assume the manual says nothing? I would guess 1cf to get more midbass, maybe a little less as I think most 6x9 are high Q. I just tested them by ear.

I think the most I ran that way were four 10s and they were not huge xmax, car had a smallish trunk. 6x9 did not move over say 1/4 of xmax at full tilt, it was hard to see exactly but they moved much more from their own power when playing. I never detected a SQ issue with this, though some say there is one. When it is going that loud I'm not sure if SQ is really that relevant, or it sure is not to me long as I can't hear a problem. I think the only issue would be damage to the 6x9 or excess movement interfering with its ability to play properly of course. A friend had the same car with higher xmax 10" and had six of them, he did get movement and made sheet metal boxes. He lined the bottom with wood and not sure what else he did. I have a poor photo I'll post of those boxes.

Baffle = the flat plane the driver (6x9) is mounted to in IB use, if you mean one of those foam/plastic dishes that go over the back of speaker they tighten up response but don't really protect from subs. They are more aperiodic and reduce bass. If you need to protect you must have a rigid sealed box/enclosure behind them.

I've never run anything but tweeters out of phase with each other. You can run the mids out of phase with subs if you have excess midbass at xover point.

This car hammered pretty good, is an old school setup. It is not in use and he was messing with things thus the wires hanging and its pretty dusty. I think most of the time he had a 300wrms 12v rated 2ch on each pair of subs.

 

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I'd disconnect the sub...

and play some midbass heavy music ;)

Once you get some seperate mids in there you'll be fine !

If the midbass is weak, I'd switch out the Infinity's.
 

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I like infinity but all the ones I have used tended to not be strong in midbass if that is what you need, but they do make it so if you have none I'd look for other issues. Check phase, try taking those covers off them, etc. Right, play it without subs and see what you can come up with.
 

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Discussion Starter #16
I like infinity but all the ones I have used tended to not be strong in midbass if that is what you need, but they do make it so if you have none I'd look for other issues. Check phase, try taking those covers off them, etc. Right, play it without subs and see what you can come up with.
It's not the speakers. It's the baffle. The car's oem paper 6x9s gave more mid-bass with the factory stereo than these 6x9s with a 60-watt RMS amp and no crossover set while in the baffles. It's pretty obvious the 6x9's require some kind of decent volume space to operate in.

I got my email back from Infinity. They said the 6x9s are made for an infinite baffle, which means, "free-air". They said that if I cannot use the trunk to at least use a .5 cuft enclosure minimum to improve the bass response.
 

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It's not the speakers. It's the baffle. The car's oem paper 6x9s gave more mid-bass with the factory stereo than these 6x9s with a 60-watt RMS amp and no crossover set while in the baffles. It's pretty obvious the 6x9's require some kind of decent volume space to operate in.

I got my email back from Infinity. They said the 6x9s are made for an infinite baffle, which means, "free-air". They said that if I cannot use the trunk to at least use a .5 cuft enclosure minimum to improve the bass response.
Sounds right. I'd take those covers off and see what happens. See if the subs move them or not and what sound you get. They should have good bass IB running full range, for what they are.
 

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Discussion Starter #19 (Edited)
orly !


try adjusting the crossover up or down.
I did try that. I can hear the difference when i lower the crossover frequency but it's not enough output in the midbass region due to the baffle. When the sub is played, the really low frequencies like 20-50Hz can hit 115db on my SPL meter using 0db test tones then right at 60Hz the SPL drops drastically down to 102-105db and stays that way until i get the tones that reach 110Hz, which is basically the crossover frequency of my front door comps. I also checked and there is no bass boost engaged on the HU or the sub amp. I've tried to increase the sub's crossover and it doesn't effect the low 60Hz-100Hz output. There seems to be an acoustic absorption issue at those frequencies, so I need all the help I can get in that range.

My front door comps (6.5") really don't do too well at 60-90Hz when pushing the SPL in the car to 110db average. So, I had to cross the front door comps to around 100-110Hz to reduce breakup and panel vibrations. The 6x9's are much more likely to hit 60Hz-100Hz with less distortion.
 

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I did try that. I can hear the difference when i lower the crossover frequency but it's not enough output in the midbass region due to the baffle. When the sub is played, the really low frequencies like 20-50Hz can hit 115db on my SPL meter using 0db test tones then right at 60Hz the SPL drops drastically down to 102-105db and stays that way until i get the tones that reach 110Hz, which is basically the crossover frequency of my front door comps. I also checked and there is no bass boost engaged on the HU or the sub amp. I've tried to increase the sub's crossover and it doesn't effect the low 60Hz-100Hz output. There seems to be an acoustic absorption issue at those frequencies, so I need all the help I can get in that range.

My front door comps (6.5") really don't do too well at 60-90Hz when pushing the SPL in the car to 110db average. So, I had to cross the front door comps to around 100-110Hz to reduce breakup and panel vibrations. The 6x9's are much more likely to hit 60Hz-100Hz with less distortion.
get rid of the baffles, get rid of the fronts, get rid of the 6X9's and put in front comps capable of crossing lower. done. taken care of.
 
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