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Discussion Starter · #1 ·
I'm getting flustered, Just when I think I have it dialed in, I'll listen to a song that I know has bass, but i can barely hear it. I'll turn up the level....and it doesnt get any louder, just sounds like crap.
The 4 6.5" flutes almost do it for me on their own, but some songs just need the extra hit of subs. Especially when i have the windows rolled down. I have some ideas on what i want to try, but wanted to see what you guys think would be my better choice...

(equipment is pioneer 1500nex headunit, punch 4x100 and 1x750 amps, dayton DSP-LP for the subs, (2) 8" audiophile subs, (4) 6.5" silverflutes, Whispers in the dash along with some dayton AMT tweets, 2004 GTO)

SO heres my thoughts.... I could order a set of cerwin vega 8's and a set of kicker comp C 8's and see what sounds better, hate to do it but amazon has a great return policy so i could test both. Maybe I'll get lucky. I was also planning on trying the tangband w6 6.5" subs i have since i added that LP dsp AND trying the blaupunkt 8's I had in there also. Since then i've sealed and deadened the trunk much better and the dsp-LP helps too. OR>>>>>>>>>>>>>

I could get a set of 8" flutes for the back deck and add those on the rear channels with the rear 6.5" flutes in the side panels and then just bite the bullet and put my sub in the box back in the trunk. Or I could do the same with the tangband 6.5's or even the blaupunkts. That will give me a little more accurate "kick" inside the car and use the box sub for like 80hz and below.
Or...I could use the factory amp on the rear deck speakers and still add my sub back in. I'm just more or less brain storming. I may get a wild hair this evening and pull the back seat and deck out and start swapping speakers. I dunno...I'm just getting aggravated because its just not what I want yet.
 

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How well is the front and back wave separated? Do you have the rear seats, and the rear deck baffled?

Swapping 8" subs will most likely just add to your frustration, similar sized subs will have similar output, you shouldn't expect a different pair of the same sized subs to have drastically different output. Sure, there may be a pair that out perform the others, but I wouldn't expect it to be by much, and the trial and error that it will take to find out may leave you even more frustrated.

Do you know anybody close by that can come check it out, maybe someone with a microphone and REW? It's tough to suggest fixes without knowing where the problem is, but as I said before I wouldn't expect drastically different results unless you step up to much more displacement. Most people would say that a pair of 8's IB won't cut it, I ran a pair of 15's and although I didn't need to push them very hard, I can't imagine 8's being satisfying.
 

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My output increased with a third of the power when I went IB. Don't get me wrong the high end cut had to be lowered considerably but the low end increased noticably.

I'm with Gijoe. You may have cancellation or lost output at certain frequencies do to a flexing baffle or the front and rear waves interacting.
 

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Where are your IB subs located, in the rear deck?

I have a 2005 GTO, and am having a hard time visualizing where you have subs mounted in an IB config with the fuel tank in the way.

BTW: I'm finally getting my car to sound great, just with front components and a sub box in the trunk. No rear side speakers, and no rear deck speakers. I did do a LOT of sound treatment though.
 
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Discussion Starter · #5 ·
How well is the front and back wave separated? Do you have the rear seats, and the rear deck baffled?

Swapping 8" subs will most likely just add to your frustration, similar sized subs will have similar output, you shouldn't expect a different pair of the same sized subs to have drastically different output. Sure, there may be a pair that out perform the others, but I wouldn't expect it to be by much, and the trial and error that it will take to find out may leave you even more frustrated.

Do you know anybody close by that can come check it out, maybe someone with a microphone and REW? It's tough to suggest fixes without knowing where the problem is, but as I said before I wouldn't expect drastically different results unless you step up to much more displacement. Most people would say that a pair of 8's IB won't cut it, I ran a pair of 15's and although I didn't need to push them very hard, I can't imagine 8's being satisfying.
Well the car has a metal fire wall separating the seat and the trunk because of a gas tank. Then I used dynamat all over to seal off the holes. Most holes have dynamat on the cabin side and truck side to serve as double thickness on the holes.
the 8’s have enough output for me. The problem is the current 8’s I have get silent below 30hz, peak by about 15db more at 40hz then get quiet again around 100hz with dips in volume around 50-60hz. I used the dsp to compensate but I just think these subs aren’t doing it. The Blaupunkts propped lower, cleaner and went higher. But the 40hz peak (cabin gain?) caused them to bottom badly before I had the dsp to control that. I’ve yet to try them again, but I need to.
 

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Discussion Starter · #6 ·
Where are your IB subs located, in the rear deck?

I have a 2005 GTO, and am having a hard time visualizing where you have subs mounted in an IB config with the fuel tank in the way.

BTW: I'm finally getting my car to sound great, just with front components and a sub box in the trunk. No rear side speakers, and no rear deck speakers. I did do a LOT of sound treatment though.
in the rear deck. I did a lot of deadening too. The interior speakers sound great, it’s just the subs don’t sound right. Not enough frequency spread to them. (Note, this isn’t the deadening I have now. I pulled that out and used better stuff and did a better job).

Motor vehicle Car Hood Automotive tire Automotive lighting
 

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I really don't think you're going to get anything below 30hz from a pair of 8's. Low frequencies require big displacement. We aren't very sensitive to frequencies that low so they need to be loud in order to be perceived as the same volume as the higher frequencies.

Cabin gain will not cause the subs to bottom out, cabin gain is "free" output. The vehicles interior reinforces certain frequencies, so the speaker actually works less to produce those frequencies.
 

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Well the car has a metal fire wall separating the seat and the trunk because of a gas tank. Then I used dynamat all over to seal off the holes. Most holes have dynamat on the cabin side and truck side to serve as double thickness on the holes.
the 8’s have enough output for me. The problem is the current 8’s I have get silent below 30hz, peak by about 15db more at 40hz then get quiet again around 100hz with dips in volume around 50-60hz. I used the dsp to compensate but I just think these subs aren’t doing it. The Blaupunkts propped lower, cleaner and went higher. But the 40hz peak (cabin gain?) caused them to bottom badly before I had the dsp to control that. I’ve yet to try them again, but I need to.
I've been following your post... IB 8" is no bueno! Dude if Ida didn't have my balls in a sling I'd bring my laptop and mic over and see what's what. I live in Metairie and just got back in my house with power Monday. Bet you're glad that bad b!tch took a last minute turn to the right! My project has moved to the back burner temporarily! Stay in touch and let's try and get together sooner than later. Dave
 

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I tried 6.5" Tang Band subs in that location, and was never satisfied with them. When I treated the interior, I put CLD tiles on the rear wall, and then hung MLV over it as well. I left the 6.5" holes in the rear deck open, but put a 6.5" round, 4" thick piece of OCF in there, along with a 1/4" piece of CCF on top. So the high frequency noise of the fuel pump is blocked, but low frequencies can pass.

Then I just dropped in the Rockford P300-12 unit, and it's been great! I have it crossed over at 63hHz, and my door speakers (Hertz 6.5" mids) crossed over at 80Hz. The sound is very well balanced, and imaged out onto the hood ... and the bass is perfect. My trunk space is significantly compromised though ... which I assume you are trying to avoid?


If you happen to be somewhere near Central Texas, I'd be happy to let you listen?

These cars are definitely a pain to figure out, and I'm doubtful you'll ever be satisfied with an IB setup in the rear deck.

For those who don't know, here is what it looks like under the rear deck. This pic was taken when I still had the 6.5" Tang Band woofers in place ... and I had to trim the fuel tank strap a bit for them to clear. Yes, that large black plastic thing is the cover over the fuel tank.

Motor vehicle Automotive exterior Automotive design Auto part Gas


Here's what it looks like on the inside, with the seat cushions removed

Automotive tire Motor vehicle Vehicle Bumper Asphalt


I did CLD:

Hood Motor vehicle Trunk Automotive exterior Vehicle


And MLV:

Automotive tire Hood Black Automotive design Motor vehicle


And I'm still not sure an IB setup would work ... there are more holes on the sides, where the wheel wells are, which extend into the trunk area. I used these to pass signal and power cables through.

But for an IB setup, they would all have to be damped and air sealed. I don't think CLD alone (ie: Dynamat) is enough to seal it off completely.
 

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Discussion Starter · #10 ·
I really don't think you're going to get anything below 30hz from a pair of 8's. Low frequencies require big displacement. We aren't very sensitive to frequencies that low so they need to be loud in order to be perceived as the same volume as the higher frequencies.

Cabin gain will not cause the subs to bottom out, cabin gain is "free" output. The vehicles interior reinforces certain frequencies, so the speaker actually works less to produce those frequencies.
I misunderstood what "cabin gain" meant. At 40hz, with all subs i've tried so far, the output if far greater than other frequencies and without a way to pull some volume from that particular frequency, all the subs i tried will rattle and bottom out. The blau's actually sounded good below 30hz but the 40hz rattle ould be unbearable if I turned it up. Now that i can control that, they may work out better.
 

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Discussion Starter · #11 ·
I've been following your post... IB 8" is no bueno! Dude if Ida didn't have my balls in a sling I'd bring my laptop and mic over and see what's what. I live in Metairie and just got back in my house with power Monday. Bet you're glad that bad b!tch took a last minute turn to the right! My project has moved to the back burner temporarily! Stay in touch and let's try and get together sooner than later. Dave
Yea maybe one day I can ride out your way. Ive been looking at mic setups today, just contemplating. Then I think to myself, just throw the dang sub box back in the trunk and be done with it! But i hate giving up the little room i have.
Yea we actually got hammered pretty hard in my area. We were lucky though, i only lost power for 8-9 days. We just got it back.
 

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Discussion Starter · #12 ·
I tried 6.5" Tang Band subs in that location, and was never satisfied with them. When I treated the interior, I put CLD tiles on the rear wall, and then hung MLV over it as well. I left the 6.5" holes in the rear deck open, but put a 6.5" round, 4" thick piece of OCF in there, along with a 1/4" piece of CCF on top. So the high frequency noise of the fuel pump is blocked, but low frequencies can pass.

Then I just dropped in the Rockford P300-12 unit, and it's been great! I have it crossed over at 63hHz, and my door speakers (Hertz 6.5" mids) crossed over at 80Hz. The sound is very well balanced, and imaged out onto the hood ... and the bass is perfect. My trunk space is significantly compromised though ... which I assume you are trying to avoid?


If you happen to be somewhere near Central Texas, I'd be happy to let you listen?

These cars are definitely a pain to figure out, and I'm doubtful you'll ever be satisfied with an IB setup in the rear deck.

For those who don't know, here is what it looks like under the rear deck. This pic was taken when I still had the 6.5" Tang Band woofers in place ... and I had to trim the fuel tank strap a bit for them to clear. Yes, that large black plastic thing is the cover over the fuel tank.

View attachment 310767

Here's what it looks like on the inside, with the seat cushions removed

View attachment 310768

I did CLD:

View attachment 310769

And MLV:

View attachment 310770

And I'm still not sure an IB setup would work ... there are more holes on the sides, where the wheel wells are, which extend into the trunk area. I used these to pass signal and power cables through.

But for an IB setup, they would all have to be damped and air sealed. I don't think CLD alone (ie: Dynamat) is enough to seal it off completely.


I'm glad you posted those pics! Lets everyone see what I'm dealing with. I did seal off all of the areas in the trunk including the big crevices' in the 1/4 panels that lead up behind the real panel speakers. I have more deadener on mine tho, I pretty much left no meatal surfaces uncovered. What exactly did you use to block out the fuel pump noise? I was thinking passive radiators or leave the speaker holes open and put sound deadener INSIDE the plastic casing on the fuel tank. I have two aeromotive 340's in my tank.....
 

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You will always want more from your ib 8s man.
You need more cone area for ib
For reference a popular sub on here is the sql 12.
In a sealed box with 1500 watts guys are happy.
The 2 8s have about the same amount of cone area.
Ib has limited output compared to sealed.
So you want to much man.
I have a ported 6.5 in the passenger foot well of a 19 kia rio and it sounds decent.
So maybe try that man.
 

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+1000 to what MiniSQ said.

A single 15 in IB is my favorite sub setup. What's with the rectangular sheet metal spot dead center in the rear fire wall? Can that be replaced with a 1.5" thick plywood baffle for a 12 or 15? Or is there something lurking there?

8s are for midbass, unless you're driving a tiny hatchback like a Fit or Yaris.

Bigger sub equals lower bass. Especially free air/I.B.

Two 10s might work, if you can get them to squeeze in the rear deck, but in IB setups, I'm not a fan of the cones facing up in a rear deck. They have no rear spring aside from the suspension of the woofer. They are gonna fight themselves in a rear deck. Even tiny little 8s.
 

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What exactly did you use to block out the fuel pump noise?
My wife had some 4" thick foam left over from a project she was doing, and I cut two circles out of it. It was white though, so I topped them with black second skin closed cell foam I had left over ... so when the rear deck cover is in place, you don't see anything through the speaker grills. The OCF and CCF combo blocks out the noise from my stock fuel pump. When I 1st put everything together, I just left the holes open, and the fuel pump noise was too much. The foam circles did the trick though, since the frequency of the fuel pump is so high.

What's with the rectangular sheet metal spot dead center in the rear fire wall? Can that be replaced with a 1.5" thick plywood baffle for a 12 or 15? Or is there something lurking there?
Yes, the fuel tank is lurking behind that panel ... scroll up and see my post above.

The fuel tank in these cars is located in the trunk.
 

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Scroll up and see the pictures I posted. Without the mounts, you can't fit any speaker in there at all, as the magnet will hit the fuel tank. I'm surprised he got 8" in there to begin with!
 

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Discussion Starter · #20 ·
Scroll up and see the pictures I posted. Without the mounts, you can't fit any speaker in there at all, as the magnet will hit the fuel tank. I'm surprised he got 8" in there to begin with!
This. I printed them with a lot of infill. I doubt they flex at all and the are about 1/4” thick.
 
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