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So I just got through taking it all apart again. I yanked one of the audiophile subs out and replaced it with a Blaupunkt. Did some swapping back and forth testing. Now I see why I took the Blaupunkts out. No matter what, they bottom too easy. Even with all the deadening and sealing I did. And the dsp. Dont matter. The audiophile subs pretty much trounce them. I’m leaving my interior apart and order a few other subs to try. No point in trying the 6.5’s I have because I remember the Blaupunkts beat those. I think I’m gonna order some cerwin Vega Vegas to try and some kicker comp c’s. I may order one of each. Skar has an 8” sub so I may order that too. I’m determined to make this work. I dunno why. I guess I’m seeing it as a challenge at this point.
Man....stop wasting your money. All of the subs you just mentioned have about the same SD and xmax. So just physically speaking they will all sound the same.
Except for the kicker comp. That might be the worst sub kicker has ever sold.
If printed a better bracket and used 10 inch subs it would be much better suited.
You said you might cut the back deck to open it up a little? Cut it. Print better adapters and problems solved.
 

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So you either need to be more realistic about the amount of bass that 2 typical 8in subs are capable of, or you need drivers that have massive amounts of travel and a high cone area. Something like 2 JL w7 8in.
I've been saying all this since like 3 threads ago.
He believes he just needs a sub that was designed for infinite baffle. That is 8 inches. And also doesn't cost a lot.
I was called pretentious I think. Lol.
 

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Discussion Starter · #43 ·
Think of it in terms of displacement alone. You have four 6.5in mids, each of them has a cone area of 132cm each. Then you have two 8 in subs with a cone area of roughly 216cm each. You have 18% more cone area with your mids than you do with your subs. So it's not a surprise your mids are giving you nearly what you want and the subs are underwhelming.
132 x 4 = 528cm vs 216 x 2 = 432cm

That doesn't take into account linear travel, but even if your subs have 2x the xmax of your mids, that's still only 60% more air moved at xmax.
With have the same SPL level at one octave lower, you need to move 4x the amount of air.
So if you wanted to be able to match the spl capability of your mids running at 80hz @ xmax w/ 528cm, you would need to be displacing 2112cm. Drop that down to 30hz and you need 4224cm displaced. That also doesn't take into account the rise in the lower octave that is typically wanted.
Moral of the story, if you want to keep up with the 4 6.5in mids, you need to displace much more air than two 8in subs will provide when running in IB without a SS filter in place.
Maybe you are right when you are talking about just the total air displacement, considering just spl, but one larger speaker with more cone area than two smaller speakers with drop lower. For example, two 8” subs displace 50.24 square inches of cone area whereas a single 15” sub has 47.1” of cone area but we all know that the 15” is going to catch a lower note much easier. This isn’t about just overall spl. I want good sound over a wider range of frequencies. I know two 8’s can do what I want, I just haven’t found the right driver yet. I’ve only tried two anyways. The bad thing about this is I can’t change the volume of the trunk (think changing box design or size) to change the sound, so I’m having to try different drivers. I keep seeing you guys keep harping on bigger subs, bigger subs....I get it. But it’s not an option. I don’t have the room in the deck for it. Or the depth. I wish I did because this would be much easier.
 

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Discussion Starter · #44 ·
Man....stop wasting your money. All of the subs you just mentioned have about the same SD and xmax. So just physically speaking they will all sound the same.
Except for the kicker comp. That might be the worst sub kicker has ever sold.
If printed a better bracket and used 10 inch subs it would be much better suited.
You said you might cut the back deck to open it up a little? Cut it. Print better adapters and problems solved.
Car is apart right now. I’m going measure. Be right back.
 

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Maybe you are right when you are talking about just the total air displacement, considering just spl, but one larger speaker with more cone area than two smaller speakers with drop lower. For example, two 8” subs displace 50.24 square inches of cone area whereas a single 15” sub has 47.1” of cone area but we all know that the 15” is going to catch a lower note much easier. This isn’t about just overall spl. I want good sound over a wider range of frequencies. I know two 8’s can do what I want, I just haven’t found the right driver yet. I’ve only tried two anyways. The bad thing about this is I can’t change the volume of the trunk (think changing box design or size) to change the sound, so I’m having to try different drivers. I keep seeing you guys keep harping on bigger subs, bigger subs....I get it. But it’s not an option. I don’t have the room in the deck for it. Or the depth. I wish I did because this would be much easier.
Yes and no. It all has to do with displacement in the lowest octaves.
Will a larger sub tend to play lower? Yes. But is it ALWAYS the truthful? No.
But that is because of 2 main things. Displacement potential, and driver resonance. Larger drivers tend to have a lower resonant frequency due to the extra mass of the larger cone, spider, coil, and surround.

There are 15 in midranges used for prosound that have a high FS, low excursion, and can't play below 100hz for anything. There are also 6in drivers like the exodus anarchy with a FS of 40hz and the 5in dayton epique with a fs of 40.

At the end of the day, in a low order enclosure (like IB and sealed), displacement is all that matters for the last octaves.
 

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I will say this one last time before I give up.
If you want to have more low end than your 4 6in speakers will provide, 2 8in subs will NOT give you what you are looking for in IB. If you want response below 40hz at a reasonable SPL, you plain and simple need more cone area or you need to go to a higher order enclosure like ported or a bandpass.
If you are fine with +45hz, than a subsonic filter at 40hz and more power MAY give you what you are after.
 

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Discussion Starter · #55 ·
Can you take those again with a tape measure and maybe a better aspect. Maybe back up a little.
2 10 inch woofers are about the same as a 15 inch.
But if those are 8 inch woofers...you have room it looks like. Unless those are 6.5 inch woofers.
I assure you, two10’s aren’t gonna fit. If they would, I’d just do that.
 

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Can you give up some trunk space? If yes, build a 4th order box and route the port through the rear deck. If done correctly it should give you a lot more bass than you have now.
 

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Well I didn’t go back and look who posted, I was just in a hurry to prove someone wrong. In which it backfired on me. Lol
Just to be clear, I don't mean to be rude. I just mean to save you a lot of time and trouble of replacing subs a bunch of times and still not getting your desired result.

If you are stuck with 8in subs in IB as the only configuration that will work, look into jl w7 subs. They have an 8in that moves a ton of air for its size.
JL Audio 8W7AE-3

It has 245cm of cone area with 19mm xmax vs the typical ~215 of an 8in sub w/ ~10mm xmax. That is 931cm3 peak to peak. Compared to a typical 8in of around 431cm3 peak to peak (taken from a 8in focal flax Evo w/ 216cm cone area and 10mm xmax). So each of those JLs will move twice the amount of air as a typical 8in sub. And you are approaching what a good 10in sub will put out (and a typical 10in sub will have much more xmax than most 8in subs)
 

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Discussion Starter · #58 ·
Just to be clear, I don't mean to be rude. I just mean to save you a lot of time and trouble of replacing subs a bunch of times and still not getting your desired result.

If you are stuck with 8in subs in IB as the only configuration that will work, look into jl w7 subs. They have an 8in that moves a ton of air for its size.
JL Audio 8W7AE-3

It has 245cm of cone area with 19mm xmax vs the typical ~215 of an 8in sub w/ ~10mm xmax. That is 931cm3 peak to peak. Compared to a typical 8in of around 431cm3 peak to peak (taken from a 8in focal flax Evo w/ 216cm cone area and 10mm xmax). So each of those JLs will move twice the amount of air as a typical 8in sub. And you are approaching what a good 10in sub will put out (and a typical 10in sub will have much more xmax than most 8in subs)
Thanks for the suggestion. That sub is way too deep to fit. What I have now hits and it’s just under 5” depth. The jl subs are 6 7/8” deep, the only thing I could do to make them fit is delete the gas tank. Wait that’s a good idea. I could convert the car to electric and then I could fit some $1200 subs too. Lol! Seriously though. I left the interior apart as I decide what I want to do.
i think this evening I’m going to get the plasma cutter out and cut the hole out correctly so the speaker can breathe. Maybe some of the distortion I’m getting is due to the lack of correct airflow.
 

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What do you mean breathe? IB is the ultimate "breather". Explain please.
He's talking about opening up the hole in the sheet metal, since it's barely large enough to allow the magnet to fit through.

Hood Automotive lighting Motor vehicle Bumper Vehicle


That's the fuel tank under the sub, and you can see where the magnet is making contact with the fuel tank strap.

I don't think opening up this hole will help the 8" subs ... now if opening up this hole, and printing new mounts to allow 10" subs to be mounted would work ... that's a good choice.

@KFXGUY ... Have you considered shallow 10" woofers and a new mount design to allow them to fit under the rear deck cover? I think a 10" woofer's magnet could fit through the rear deck sheet metal, without having to modify the base footprint of your adapters where they mount to the deck.
 
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