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Old 03-03-2014, 07:55 AM - Thread Starter
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I am going to start building my first HT, a micro mini room of 10.5' x 16' x 7' and I wanted some input on an infinite baffle here. Personally, this represents two firsts for me, I have never used subs in an enclosed room anywhere near this small before and I also have never tried an IB either. I have never made a sub before that goes deeper than 10Hz and those that have, haven't had much output down there. I am curious what kind of gain I can expect from a room this small, where will it start and what how much will it chip in down around 5 Hz or so?

My second question is whether or not 2 Ficar IB318's will be enough for this room, I don't think I have ever seen someone build an IB with only 2 drivers before so I have my doubts about this. I can go up to 4x if I have to but two would be preferable from a cost standpoint if it is at all possible. Now, I have never done a system before as much total displacement as 2x IB318's so even though I am sure it has the ability to be very loud. However, with it being an IB, I won't be able to push the drivers as much as I am used to in the audible frequencies.
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Old 03-03-2014, 08:11 AM
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Originally Posted by armystud0911 View Post

However, with it being an IB, I won't be able to push the drivers as much as I am used to in the audible frequencies.

This would be my first concern. I've never seen a two driver IB either as this design requires multiple drivers to prevent over excursion. That being said, I've never seen an IB in this size room either.

Out of curiosity; what is the driving force behind going with an IB as opposed to a ported setup. I'm assuming space constraints?

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Old 03-03-2014, 08:20 AM
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You'll get cabin gain below 35Hz, 8-10dB/octave, so i don't see the need for a huge IB, a couple of sealed boxes with an f3 of 35Hz should do fine.

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Old 03-03-2014, 08:21 AM - Thread Starter
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There are a number of reasons, space really isn't one of them, I can fit all the subs I want behind the AT screen. I have a number of reasons for trying it,

1. Sound quality
2. Extension into single digits
3. Cost
4. Ease of construction
5. I have always wanted to but was never able to
6. Such a small room seems like the ideal place for one
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Old 03-03-2014, 08:25 AM
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How loud do you listen? Proper location of drivers for smooth response is very important.

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Front subs 8 SI 18ht ported SLLT powered by Peavy IPR 7500
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Old 03-03-2014, 08:27 AM - Thread Starter
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Originally Posted by Bill Fitzmaurice View Post

You'll get cabin gain below 35Hz, 8-10dB/octave, so i don't see the need for a huge IB, a couple of sealed boxes with an f3 of 35Hz should do fine.

I have seen this generalization about gain before, does it hold true as you keep going deeper? I mean, from 35Hz to 17.5Hz, there's one octave, from 17.5Hz to ~9hz, there's two, from 9Hz to 4.5Hz, there's three, from 4.5Hz to 2.25Hz, that's four, if that were true, I could expect between 32 and 40db of gain at 2.25Hz?
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Old 03-03-2014, 08:29 AM - Thread Starter
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Originally Posted by MKtheater View Post

How loud do you listen? Proper location of drivers for smooth response is very important.

Typically about 5-10db below reference but I do enjoy watching things occasionally at full reference when the wife isn't with me, and possibly over reference for a little wow demonstration if the system could handle it.
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Old 03-03-2014, 08:42 AM
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Quote:
Originally Posted by armystud0911 View Post

I have seen this generalization about gain before, does it hold true as you keep going deeper? I mean, from 35Hz to 17.5Hz, there's one octave, from 17.5Hz to ~9hz, there's two, from 9Hz to 4.5Hz, there's three, from 4.5Hz to 2.25Hz, that's four, if that were true, I could expect between 32 and 40db of gain at 2.25Hz?

Yes it is true, except as you get lower your signal chain rolls off so you see people dropping off at 3-10hz depending on equipment.

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Front subs 8 SI 18ht ported SLLT powered by Peavy IPR 7500
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Old 03-03-2014, 08:46 AM
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Originally Posted by armystud0911 View Post

Typically about 5-10db below reference but I do enjoy watching things occasionally at full reference when the wife isn't with me, and possibly over reference for a little wow demonstration if the system could handle it.

Well, you don't want me to help then as I always go over board. I have a 1510 cubic foot room with 8 of the IB3's. Adding 4 more. Why? Smooth out the response so no EQ is needed and use only a LT boost which all will need. As soon as I get my new Mic I will start posting sweeps again. You need enough drivers to keep clean at reference from 10hz and below. I am at about 1.5% THD at 10hz with a 115 dB sweep if the mic was accurate. The levels are accurate though.

Marantz 7702 Atmos
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Speakers- 7 Behringer B215XL's, 4 212xl's for ceiling speakers.
Front subs 8 SI 18ht ported SLLT powered by Peavy IPR 7500
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Old 03-03-2014, 08:48 AM
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Quote:
Originally Posted by bass addict View Post

This would be my first concern. I've never seen a two driver IB either as this design requires multiple drivers to prevent over excursion. That being said, I've never seen an IB in this size room either.

Out of curiosity; what is the driving force behind going with an IB as opposed to a ported setup. I'm assuming space constraints?

Two driver IB's are done all the time. In fact, if I was going to do an IB, I would probably do two of them with two drivers each. Of course dual opposed for both of them. Look here and you should find several 2 driver IB's.
http://ibsubwoofers.proboards.com/board/13/builders-gallery

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Old 03-03-2014, 08:57 AM
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I just plugged your room into the ULF score calculator and you would be at 4.5 stars from 10-20hz. Meaning reference level ability. So it all depends on what you want.

Marantz 7702 Atmos
3 Inuke NU4-6000 amps for all speakers.
Speakers- 7 Behringer B215XL's, 4 212xl's for ceiling speakers.
Front subs 8 SI 18ht ported SLLT powered by Peavy IPR 7500
Rear subs 4 SI 18HT ported SLLT powered by Inuke 6000.
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Old 03-03-2014, 09:18 AM
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Quote:
Originally Posted by AV Science Sales 5 View Post

Two driver IB's are done all the time. In fact, if I was going to do an IB, I would probably do two of them with two drivers each. Of course dual opposed for both of them. Look here and you should find several 2 driver IB's.
http://ibsubwoofers.proboards.com/board/13/builders-gallery

And there you have it. smile.gif

I figured only running 2 drivers you would have excursion issues. If room isn't an issue I'd prefer a multiple sealed setup, seeing as he references single digit extension.

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