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Discussion Starter #1
Hello, everyone. I'm a newbie on this forum.

I'm considering trying IB in my Lexus LS430.
3-way SQ setup. At the moment the sub is Sinfoni C320 in a sealed box, but it has to be rebuilt to fit correctly and to direct the sub upwards.
Love the sound, a very fast, deep response. But it will take a lot of work to rebuild the box.

I've attached the photos on my trunk. The rear seats do not fall down, there's a refrigerator and there's rear AC system. + there's a sound insulation behind the seats and I installed.

So the only way the air from the sub is coming - is throughout the factory 8 (increased to 10) inch hole in the rear deck.

I wanted to try 1x15 or 1x18 FI ib318 v2 pointing to the trunk so the air will come throughout the rear deck. (4-th picture attached).
Reasons:
- Easier to build the baffle than to build a custom sealed box.
- Takes less space / less weight.
- To play very low with ease.

Can you please advice - is it worth it to build an IB in this trunk and the best way to do it?
Will the 18-inch sub match the speed of my 6 inch midbass?

Thank you very much!
 

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I too would like to hear opinions on this, and/or ideas.

I also have an LS430, a 2001 with just over 198k miles on it.
 

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Discussion Starter #3
Update: bought an IB sub. FI IB3 18inch.
Will be installing it.

Question: Is it necessary to build the rear wall of the manifold as shown on this image? (behind the magnet). Or is the front wall enough?
 

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No if you can get a good seal to the deck only thing I'm worried about is some weird quasi Bandpass behavior. The front is going to be a regular baffle right?
 

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Discussion Starter #5
No if you can get a good seal to the deck only thing I'm worried about is some weird quasi Bandpass behavior. The front is going to be a regular baffle right?
Thanks!
Yes, I planed a regular baffle.
 

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Any updates on this?
 

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Discussion Starter #8
Not yet. My sub is held at the customs, I have to wait a little before installing.
 

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Discussion Starter #9
Update:

I will be installing FI IB3 18 (first gen) soon. Choosing the location at the moment.

Thinking about building the baffle at the angle. (ATTACHMENT 2) Like the guy on this forum did, but I plan to aim the magnet inside the cabin.
This way I could save a little bit more space of the trunk.
 

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Discussion Starter #10
Started building the baffle.

This is just 1 layer of 3/4 plywood. Will be gluing 2 of them, and probably the third one of 10mm (already done) to make it solid.
The next layer will cover the holes that are clearly visible.

I also cut the back OEM cover behind the sub to allow the air move thought the rear deck hole.
Will be increasing the hole from 8in to 10+ inches.


I plan to secure the baffle to the top of the rear deck and to the floor with solid metal corners.
 

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Started building the baffle.

This is just 1 layer of 3/4 plywood. Will be gluing 2 of them, and probably the third one of 10mm (already done) to make it solid.
The next layer will cover the holes that are clearly visible.

I also cut the back OEM cover behind the sub to allow the air move thought the rear deck hole.
Will be increasing the hole from 8in to 10+ inches.



I plan to secure the baffle to the top of the rear deck and to the floor with solid metal corners.
Nice start!

Regarding your statement (bold and underlined above):

Just make sure you have good separation (airtight is the goal) between the front and rear of the speaker. Sounds like you’re trying to get more air to the rear of the speaker (facing the front of the car) by enlarging the hole in the rear deck - most just allow the sound waves to pass right through the rear seats, which they do with ease. ;)
 

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Discussion Starter #13
Hello, thank you for your response!

The "problem" with my car is that the seats can't be folded + there's a solid baffle after the seat + there's rear AC after that baffle (with a refrigerator in the ski pass) + I sound deadened heavily the rear seats inside the cabin.

So, my main goal is to allow the air from the sub to move through the rear deck hole and rear deck as a whole. Of course, some of it will also come from behind the seats.

I will be secure the baffle at the beginning of the rear deck (and I will insulate every hole so that air is separated from the trunk, but the other part of the deck (2/3 of the deck) will allow the air to move into the cabin.

Hope it will work well.



Nice start!

Regarding your statement (bold and underlined above):

Just make sure you have good separation (airtight is the goal) between the front and rear of the speaker. Sounds like you’re trying to get more air to the rear of the speaker (facing the front of the car) by enlarging the hole in the rear deck - most just allow the sound waves to pass right through the rear seats, which they do with ease. ;)
 

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Discussion Starter #14
Thank you!

One 3/4 plywood piece is soooo not enough :)

Update:
I glued a second 10mm piece of the baffle that's behind the main one.

Tomorrow - I will add a third 3/4 piece that will be covering the areas that are not tight.

I also sound deaned half of the rear deck with a 4mm heavy material that is very solid. The part of the rear deck that I will secure the baffle.

I will post more photos tomorrow.


18" Fi looks sweeeet Make sure to triple up
 

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Discussion Starter #15
Installed the sub. Not perfectly, of course. There are still some small gaps left.
The baffle is 4 layers at the moment (very heavy. I think 4 layers is overused, but I have to add them because I've cut the hole larger than it needs to be 2 times!!!!)

Running it from a small 2channel Steg that gives 400w bridged. Think it could handle 500w.

Comparing FI IB3 to my previous Sinfoni 12 in sealed...It can play low easily and you feel the bass. The response is smooth, with no "hearable" peaks (will be measuring with REW soon).

As I expected - this sub can't play high, but it can play up to 45-50 with a drop after from what I hear.
So there's a lot ot work left with the midbass be able to play at least to 63 with 12db.
If I won't be able to make the midbass play that low - I will think about 2*15 AE subs that can play higher.

I love the sound and I think I will stick with IB for now.

- I have to sound deaden the whole trunk.
- Cover small gaps that are left.
- Build an amp rack.
- Work on the midbass.


Can anyone recommend amplifiers for this FI IB3? I have a powerful Steg K2.03 which lies on the shelf (gives up to 1000w in 4 ohms bridged), but it think I don't need that much power. + it's quite large.

What about D-class amplifiers?

P.S. Thinking of getting 2x15 AE SBP subs (I've heard a lot of great reviews about them). How they would compare to 1xFI IB3 18 that I have now?
 

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Installed the sub. Not perfectly, of course. There are still some small gaps left.
The baffle is 4 layers at the moment (very heavy. I think 4 layers is overused, but I have to add them because I've cut the hole larger than it needs to be 2 times!!!!)

Running it from a small 2channel Steg that gives 400w bridged. Think it could handle 500w.

Comparing FI IB3 to my previous Sinfoni 12 in sealed...It can play low easily and you feel the bass. The response is smooth, with no "hearable" peaks (will be measuring with REW soon).

As I expected - this sub can't play high, but it can play up to 45-50 with a drop after from what I hear.
So there's a lot ot work left with the midbass be able to play at least to 63 with 12db.
If I won't be able to make the midbass play that low - I will think about 2*15 AE subs that can play higher.

I love the sound and I think I will stick with IB for now.

- I have to sound deaden the whole trunk.
- Cover small gaps that are left.
- Build an amp rack.
- Work on the midbass.


Can anyone recommend amplifiers for this FI IB3? I have a powerful Steg K2.03 which lies on the shelf (gives up to 1000w in 4 ohms bridged), but it think I don't need that much power. + it's quite large.

What about D-class amplifiers?

P.S. Thinking of getting 2x15 AE SBP subs (I've heard a lot of great reviews about them). How they would compare to 1xFI IB3 18 that I have now?
If that sub can only play up to 40-50hz it's complete junk. There's no reason to believe it won't easily play well into the midbass range. A 80 or 100hz LPF should not be a problem for any subwoofer.
 

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Discussion Starter #17
There are lots of FR graphs of these FI's. It doesn't play higher.

I will take a REW measurement tomorrow to get more idea.



If that sub can only play up to 40-50hz it's complete junk. There's no reason to believe it won't easily play well into the midbass range. A 80 or 100hz LPF should not be a problem for any subwoofer.
 

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There are lots of FR graphs of these FI's. It doesn't play higher.



I will take a REW measurement tomorrow to get more idea.
Can you post a link to these graphs? Curious as to what the response looks like for a sub that can't play higher than 50hz. Inductance would have to be pretty dang high for a sub not to reach 100hz, but more importantly, I'm guessing there's some nasty peaking that needs to be dealt with EQ which probably throws most for a loop. Add cabin gain to a sub peaking in the it's midband and that's a recipe for audio disaster.

Man & Machine... Power Extreme!
 

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Anymore updates and/or pictures of this install? I've obviously very interested still.
 

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If that sub can only play up to 40-50hz it's complete junk. There's no reason to believe it won't easily play well into the midbass range. A 80 or 100hz LPF should not be a problem for any subwoofer.
The sub-woofer is fine. Its not junk. There is a Problem with this design acoustically. If you model the woofer, this is going to be a lot more like a BAND pass box. Not a TRUE I/B.

The woofer IMO, is the wrong woofer to use for this application as the specs don't model correctly. Those small holes are acting like a Very badly built Band-pass box that the Ports got taken out off.

The idea with I/B is to SMOOTHLY transition the air into the cabin.


That's why the lower notes come through, but the lack of Information in the 100- 60 hz band is missing its magic quality that an I/B is known for.


Cox talked about this in his book on how to deal with I/B and how to make something like what we have here work.
267766


If you have not read this BOOK? You should. In it he talks about QRD baffles, and what we have here as of right now is a problem where the energy of the woofer is being transmuted into the cabin, but as soon as it does, its doing a Band-pass effect. That's my assumption and those that have experience troubleshooting I/B room response.

Since we can't fire right into the cabin, (METAL IN THE WAY/ FUEL PUMP A/C etc COMPUTERS etc) We need to smooth the air path so that it does not cause reflections and cancellation.

E.G. We need to SMOOTH the air flow.


There is a calculation of how to do this, and Its been YEARS since I did the math for it. But in Laymans terms, You are going to either have to use a FIBERGLASS, (Yes dude, I'm talking to you) horn like way to concentrate the output of the driver into the cabin SMOOTHLY without causing turbulence at the throat exit. Or in this case, the rear parcel shelf.


I take NO joy in telling you all this, And I am VERY sorry, but as it is set up? There is going to have to be a severe amount of Custom fabrication to get the IDEAL I/B response characteristics of in cabin response with the current design.

The other issue is that of space behind the driver. As mounted, the driver is coupling to the enclosure. If you calculate the angles & Radius that the sound waves travel, there will be a NULL that you might be experiencing as described to its output. This is not a bad thing, and it can work, and if your target tuning for that response, you hit gold, then great.


I just hate to see all that work and money spent when folks don't get the desired results.


The reason why drivers made for I/B work so well, is that they are from the get go made to work as so:
267767


Please see here and response graphs per baffle used and how to model its output with a closer response chartarstics of what actual installation of driver performance would be with LEAP.


Imagine water being pushed through that space into the cabin.

Instead of Laminar flow? You got this.
267772




These things even small do matter as AIR is working fluid. THe problem here is that we are using it not on a pressure basis, but to transmit sound waves. What its called in Physics is Wave interference is the phenomenon



TO explain this simply, lets use water as anyone can get this. even though we have a single driver, we are not dealing with test tones here. But music. And we have a NON uniform radiation pattern. Visually, this sound waves are canceling each other.
267774



This is what is looks like if we have music and we have multiple surface wave interference
267775



This was actually the reason why this guy and his book was such a good read all those years ago. He talked about the problems with speaker cancellation in his books and articles over the years and papers.
Joseph D'Appolito
267776


I emailed him YEARS ago, and I still have the email, and I cherish it and printed it out years ago and it was about the very same problem. But with 6x9's in my Volvo and response that I was getting. (thank you Joe)

The reason for the shit response was the way they were mounted on the rear deck. What we have here is the same issues but magnified.


We are not just "cupping " the response of the the sub woofer, but it is now loading it like we would in a leaky box with, and changing the Fs of the woofer at the same time as well as its defined electrical properties in a true open baffle if that makes sense.

In order to make this work, a smooth transition needs to happen to the cabin space. That can be achieved via a Tuned flare inside of the cabin.

Something like this is not really a TRUE I/B This is more of a Large sealed box pressurizing another. And its a HORRIBLE way to get output if you want that natural roll off and speed of the transients & detail that you get with a Sudo I/B used in cars. To test this, do this with all doors and truck open, and you will hear what I'm alluding too.

267777




I hope this helps the rest of you with your I/B setups. Always remember, that when doing an I/B, ANY AMOUNT OF Loading is going to change the drivers response. An the key to that AMAZING set up is make the front and the back of the woofer to be loaded EQUALLY. Otherwise? Its not going to give you that Magic that you got when you modeled it.
 
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