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Old 11-24-2004, 09:21 PM   #1
emxracer
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Help free air subs NEWB

hey guys i wanted to know if i did 2 free air sub on a 2004 m3 coupe 6in subs will it hit at all or am i wasting time and money
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Old 11-24-2004, 11:55 PM   #2
rcurley55
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Two 6" free-air subs?

Well, keep two things in mind, a 6" sub has just over 1/3rd the cone area of a 10", and generall the 10" would have more excursion as well, so you are fighting a battle by selecting two really small drivers.

Adding to your issue is that a free-air alignment will generally have less output then a sealed or ported system.

So will it hit? Depends on how you define it - generally, I'd say no.....you just won't be able to move that much air. b/c of the way that an E46 is setup, it's fairly easy to add a larger free-air driver if you wanted to...
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Old 11-25-2004, 02:05 AM   #3
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Quote:
Originally Posted by rcurley55
Two 6" free-air subs?

Don't mean to hijack this thread, but I have a related question. What are your thoughts on the following free-air/IB setup:

2 x 8" JL Audio 8IB4's
Free-air subs under rear shelf (HK sub location).
Running ~80hz and below in MONO.

2 x 6.5" JL Audio XR650C's
Component Woofers in rear shelf (factory cut-outs).
Running say: ~80hz to 160hz in stereo.

2 x 6.5" JL Audio TR650CSi's
Component 2-ways set in front doors (factory cut-outs).
Running ~160hz +
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Old 11-25-2004, 03:41 AM   #4
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Originally Posted by stewey
Don't mean to hijack this thread, but I have a related question. What are your thoughts on the following free-air/IB setup:

2 x 8" JL Audio 8IB4's
Free-air subs under rear shelf (HK sub location).
Running ~80hz and below in MONO.

2 x 6.5" JL Audio XR650C's
Component Woofers in rear shelf (factory cut-outs).
Running say: ~80hz to 160hz in stereo.

2 x 6.5" JL Audio TR650CSi's
Component 2-ways set in front doors (factory cut-outs).
Running ~160hz +
Should work fine - if you are using the 8IB4's without the stealthboxes, I see no reason why that wouldn't work - presonally, I hate rear fill and don't use it in any of my cars, but if you like it, go for it.

I don't know why you want to run the front speaks from 160 and up.....I'd lower that crossover point as much as you can....maybe between 80 and 60...but then again, that depends on how good your door install is.
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Old 11-25-2004, 04:50 AM   #5
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That's a good question. Basically, I'm scared that if I cross the door speaks too low, it will rattle like crazy. I don't plan on doing any MDF rings or other door mods. I'll probably stick some dynamat behind the drivers in the door, but that's about it. I had rear fill in my previous system and didn't mind it. There's definitely the concern of pulling the soundstage too far back though.

Knowing that I'm not planning on doing much with the door install, how low do you think I could cross the front speakers and still avoid rattles? I know that 80 is right around the point where imaging comes in, but I'm afraid that it would buzz and rattle like a *****! I'm going to need to tune it anyway, so I guess I don't have to decide now.

The important question is whether or not this is a work-able plan. I want to avoid a sub in a box; I went that route last time and really got tired of the eye-sore. I think that 4 drivers with sufficient power (150w to the 8IB4's, 75wx2 to the XR650C's) should give me a decent bottom end. I don't like my music excessively bassy, maybe 3db+ centered around 100hz, and a little tweak around 10khz (general loudness curve).

What do you think? My other plan was to use stealthboxes only, but that seems boring.


Quote:
Originally Posted by rcurley55
I don't know why you want to run the front speaks from 160 and up.....I'd lower that crossover point as much as you can....maybe between 80 and 60...but then again, that depends on how good your door install is.
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Old 11-27-2004, 02:04 AM   #6
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Jeez... I posted about free air setup a while ago and no one responded.

I was curious about going with two 10inch Alumapro Alchemy FA's which are specific for free air setup. A local audio shop in the area with multiple car audio install awards recommended this setup to me. They just did one in a Benz that they said bumped really nice and accurate. I never heard it tho. They would remove my HK sub which will give it room to port through and mount it to a board underneath the rear deck and isolate the front of the woofer from the back portion in the trunk. Then I can run rear fill as well.

The other option I am thinking of going with is stealth subs... and Focals up front, but I am worried that it will not stage correctly without rearfill.
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Old 11-27-2004, 03:29 AM   #7
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I am worried that it will not stage correctly without rearfill.
The opposite is true - these kinds of things always turn into long arguements, but generally, rear speakers do nothing but pull your stage back, rather then help you out. I have not run front speakers in my cars for years now, and I wouldn't have it any other way....

two 10's free-air should be nice.
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Old 11-27-2004, 03:31 AM   #8
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Originally Posted by stewey
That's a good question. Basically, I'm scared that if I cross the door speaks too low, it will rattle like crazy. I don't plan on doing any MDF rings or other door mods. I'll probably stick some dynamat behind the drivers in the door, but that's about it. I had rear fill in my previous system and didn't mind it. There's definitely the concern of pulling the soundstage too far back though.

Knowing that I'm not planning on doing much with the door install, how low do you think I could cross the front speakers and still avoid rattles? I know that 80 is right around the point where imaging comes in, but I'm afraid that it would buzz and rattle like a *****! I'm going to need to tune it anyway, so I guess I don't have to decide now.

The important question is whether or not this is a work-able plan. I want to avoid a sub in a box; I went that route last time and really got tired of the eye-sore. I think that 4 drivers with sufficient power (150w to the 8IB4's, 75wx2 to the XR650C's) should give me a decent bottom end. I don't like my music excessively bassy, maybe 3db+ centered around 100hz, and a little tweak around 10khz (general loudness curve).

What do you think? My other plan was to use stealthboxes only, but that seems boring.

Either plan seems viable - the stealths are obviously the "plug-and-play" option there. As far as your door install, there's really no way to tell how it will sound w/o hooking it all up - you are going to have to experiment with the x-over point....
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Old 11-27-2004, 07:15 AM   #9
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Ok rcurley, I'll argue with you a little bit.

Rear fill playing lower frequencies will not necessarily pull the soundstage towards the rear. Most midrange drivers rolloff around 2-4khz, which will pull your soundstage rearward. If cutoff at a steep slope around 300-400hz, the rear fill speakers can augment the bass and midbass region. Which in the case where they are using IB8's, would be a waste of money IMO because you are using 4 speakers that have similar freq response characteristics (play midbass well, suck at 100hz and lower). I think putting the 6's in the rear to augment midbass makes sense if you have a 15" sub for example.

Rcurley is correct, once your rear fills start playing above 500 hz (the lower range of the human voice), your soundstage will be basically destroyed. For audio purists, not too many people listen to live music with their back turned to the stage.

I disconnected my rear fill BTW.
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Old 11-27-2004, 12:48 PM   #10
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It's an interesting point, but anything above 150Hz is localizable, so really, you want everything playing frequencies above 150 in front of you.

Second, you are creating multiple point sources - generally a bad thing in an audio system.

I'm certain that rears work for some people, but taking a look at IASCA's most winning cars....I think you'd notice a trend about rear speakers (or lack there of). I guess I adhere to the KISS principle and keep things simple (sort of )
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Old 11-27-2004, 03:35 PM   #11
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Agree that you can locate where 150hz and over is coming from. But the dead giveaway is the human voice. You can get away with the midbass freqs with most people.

But rcurley, since you know what to listen for, its tough to fool you.

I am against rear fill since you have to buy another amp in an active system or use up power in a passive system. Yes, the KISS method is the best way to build a system.

I tried some rear fill speakers for the hell of it because my DA Xovers have the rear fill output. Can't say that it made much of a difference so I disconnected them.
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Old 11-27-2004, 05:52 PM   #12
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Originally Posted by bigjae1976
Agree that you can locate where 150hz and over is coming from. But the dead giveaway is the human voice. You can get away with the midbass freqs with most people.

But rcurley, since you know what to listen for, its tough to fool you.

I am against rear fill since you have to buy another amp in an active system or use up power in a passive system. Yes, the KISS method is the best way to build a system.

I tried some rear fill speakers for the hell of it because my DA Xovers have the rear fill output. Can't say that it made much of a difference so I disconnected them.

I totally see where you are coming from, and I have used some rear fill with my factory H/K, but since I'm working on the trunk, I pulled out the "sub" and was driving around with just the cabin speakers.

Faded all the way to the front, it sounded soo much better!

And my second biggest gripe is wasting power and $$$ on rears. Typically, deck power (if I have it) and the factory rears or a cheap ass pair - read "wizzer" cones go in the rear so that if I have additional passengers, I can give them some sounds - I refuse to spend good money on expensive speaks back there and expecially an amp - I only run matching amps - I'm anal like that, so I just don't want to spend the money on what doesn't sound better to me.

I used to have the Diamond S600s, and I always wanted to try that RAF option....
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Old 11-27-2004, 09:28 PM   #13
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Quote:
Originally Posted by rcurley55
I used to have the Diamond S600s, and I always wanted to try that RAF option....
You're not missing much.
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Old 11-28-2004, 12:35 AM   #14
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Quote:
Originally Posted by bigjae1976
Rear fill playing lower frequencies will not necessarily pull the soundstage towards the rear.
Ya, this is what I'm thinking. If I keep the rears playing down beneath ~150, then they should be able to prop-up whatever components I install in the front and cross high-ish.

Quote:
Originally Posted by bigjae1976
If cutoff at a steep slope around 300-400hz, the rear fill speakers can augment the bass and midbass region. Which in the case where they are using IB8's, would be a waste of money IMO because you are using 4 speakers that have similar freq response characteristics (play midbass well, suck at 100hz and lower).
I think 300hz would be too high, but I agree they should work well for mid-bass.

I don't see why 6.5" speakers would be a waste if they're playing a different frequency range then the 8IB4's. Where did you hear that the 8IB4's suck below 100hz? Everything I've read says they're the best 8" free air subs around (well not really around anymore). If you check my first post you'll see that I'm planning on low-passing these at ~80hz. If they suck below 100, then my plan is screwed!!!
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Old 11-28-2004, 10:14 AM   #15
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Quote:
Originally Posted by stewey
I don't see why 6.5" speakers would be a waste if they're playing a different frequency range then the 8IB4's. Where did you hear that the 8IB4's suck below 100hz? Everything I've read says they're the best 8" free air subs around (well not really around anymore). If you check my first post you'll see that I'm planning on low-passing these at ~80hz. If they suck below 100, then my plan is screwed!!!
I would say go for the 6.5s if you have bigger subs to augment the midbass region. But, the 8IB4 are going to play strong in the midbass range because of their cone size and IB setup. You'll just get a ton of midbass.

Think about this...mount the 8's in the rear deck (will require some extra effort) and put a single small box 12 or 15 in the trunk above the battery or something. Something like an Image Dynamics IDQ12 or a JL W6 will work great. Then you'll get a more even frequency response.
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Old 11-28-2004, 01:40 PM   #16
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Originally Posted by bigjae1976
I would say go for the 6.5s if you have bigger subs to augment the midbass region. But, the 8IB4 are going to play strong in the midbass range because of their cone size and IB setup. You'll just get a ton of midbass.
I'm still not following this logic.

Why would the 8IB4's put out midbass if they're low-passed from 80hz down? That doesn't make any sense. JL sold the 8IB4 as a subwoofer.

In my proposed setup, its the 6.5" speakers will be delivering the mid-bass.

I see a few problems with my setup: 1. too many drivers, 2. probably weak below 40hz. However, I don't see anyway around this without using a box which is exactly what I want to avoid.
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Old 11-28-2004, 02:01 PM   #17
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Originally Posted by stewey
I'm still not following this logic.

Why would the 8IB4's put out midbass if they're low-passed from 80hz down? That doesn't make any sense. JL sold the 8IB4 as a subwoofer.

In my proposed setup, its the 6.5" speakers will be delivering the mid-bass.

I see a few problems with my setup: 1. too many drivers, 2. probably weak below 40hz. However, I don't see anyway around this without using a box which is exactly what I want to avoid.

I don't follow the logic either. A good 6.5" driver in a good installation should be adequate for midbass duties - sure we all want 8" or even larger drivers up front, but without a total door rebuild (and I've seen it done on an E46) it's just not in the cards.

I also run all my midbass frequencies up front, personally, I wouldn't ever run anything in the rear unless it's faded in only for times when I have passengers in the rear for an extended period.

The JL's should be fine at reproducing bass and subbass duties - you just can't expect too much outout from a pair of 8" drivers in an IB alignment. IB should allow them to play as low as those drivers are capable.

Run the comps up front, stealths in the rear on a very capable amp (more power the better) and I'd see how that goes for you. If you want more bass output from there, you are going to have to look at other options then the stealths.....regardless of you sub choice, in this instance, you really can't change your choice up front (you want factory speaker locations, so you are sorta stuck there).

That's what I would do if it was me....
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Old 11-28-2004, 04:39 PM   #18
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The logic is that you are not gaining much in cone area or excursion from a 6.5" to an 8" midbass driver. Worse yet, an IB setup is not good for deep bass. Even if you cross the 8IB4 over at 80hz, its doesn't affect the driver's FS which probably in the high 30's or low 40's...which is probably about the same number as your 6" drivers.

Why even put the 6.5s in the back? If you are bent on filling the rear deck speaker slots, then just put 4 8IB4s.

ID Max is designed for IB setups...I have yet to hear one. Low will tell you all about them.
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Old 11-28-2004, 05:17 PM   #19
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3 Alpine 10 type R's woud give you a lot more bang...lol
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Old 11-28-2004, 08:41 PM   #20
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Originally Posted by bigjae1976
The logic is that you are not gaining much in cone area or excursion from a 6.5" to an 8" midbass driver. Worse yet, an IB setup is not good for deep bass. Even if you cross the 8IB4 over at 80hz, its doesn't affect the driver's FS which probably in the high 30's or low 40's...which is probably about the same number as your 6" drivers.

Why even put the 6.5s in the back? If you are bent on filling the rear deck speaker slots, then just put 4 8IB4s.

ID Max is designed for IB setups...I have yet to hear one. Low will tell you all about them.
The question is not what to use in the back - 6.5 or 8" and then add sub....the idea is to use the 8IB4's as subs.....

An IB alignment will reinforce low bass more then a sealed setup would --- remember, an IB setup is essentially a very large sealed enclosure....According to Hoffman's law, keeping power the same, as box size increases, so does low end response.

Ask anyone who has IB IDMAX's - they get WICKED low....
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