Infinite Baffle in 1100 cubic foot room - AVS Forum
Forum Jump: 
 
Thread Tools
post #1 of 12 Old 03-03-2014, 07:55 AM - Thread Starter
AVS Special Member
 
armystud0911's Avatar
 
Join Date: Jul 2006
Location: Cincinnati
Posts: 4,423
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
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.
armystud0911 is offline  
Sponsored Links
Advertisement
 
post #2 of 12 Old 03-03-2014, 08:11 AM
AVS Special Member
 
bass addict's Avatar
 
Join Date: Dec 2003
Location: A padded room
Posts: 3,774
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Liked: 210
Quote:
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?

Achievement Unlocked

Psychotic Episode Averted

bass addict is offline  
post #3 of 12 Old 03-03-2014, 08:20 AM
AVS Special Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 9,269
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1192
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.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #4 of 12 Old 03-03-2014, 08:21 AM - Thread Starter
AVS Special Member
 
armystud0911's Avatar
 
Join Date: Jul 2006
Location: Cincinnati
Posts: 4,423
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
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
armystud0911 is offline  
post #5 of 12 Old 03-03-2014, 08:25 AM
AVS Addicted Member
 
MKtheater's Avatar
 
Join Date: Jul 2006
Location: New Hartford, NY
Posts: 14,202
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 92 Post(s)
Liked: 403
How loud do you listen? Proper location of drivers for smooth response is very important.
MKtheater is offline  
post #6 of 12 Old 03-03-2014, 08:27 AM - Thread Starter
AVS Special Member
 
armystud0911's Avatar
 
Join Date: Jul 2006
Location: Cincinnati
Posts: 4,423
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
Quote:
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?
armystud0911 is offline  
post #7 of 12 Old 03-03-2014, 08:29 AM - Thread Starter
AVS Special Member
 
armystud0911's Avatar
 
Join Date: Jul 2006
Location: Cincinnati
Posts: 4,423
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 14
Quote:
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.
armystud0911 is offline  
post #8 of 12 Old 03-03-2014, 08:42 AM
AVS Addicted Member
 
MKtheater's Avatar
 
Join Date: Jul 2006
Location: New Hartford, NY
Posts: 14,202
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 92 Post(s)
Liked: 403
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.
MKtheater is offline  
post #9 of 12 Old 03-03-2014, 08:46 AM
AVS Addicted Member
 
MKtheater's Avatar
 
Join Date: Jul 2006
Location: New Hartford, NY
Posts: 14,202
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 92 Post(s)
Liked: 403
Quote:
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.
MKtheater is offline  
post #10 of 12 Old 03-03-2014, 08:48 AM
AVS Club Gold
 
AV Science Sales 5's Avatar
 
Join Date: Sep 2011
Location: A beautiful view of a lake
Posts: 7,168
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 115 Post(s)
Liked: 339
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

Mike Garrett, AV Science Sales
Call Me: 585-671-2968
Email Me: Mike@AVScience.com

Brands we sell: http://avscience.com/brands/

 

Call for B-stock projectors

Stewart, Seymour, SE, SI & many more.
Klipsch, RBH, Martin Logan, Triad, Atlantic Technology, MK Sound, BG Radia, SVS & Def Tech.

AV Science Sales 5 is offline  
post #11 of 12 Old 03-03-2014, 08:57 AM
AVS Addicted Member
 
MKtheater's Avatar
 
Join Date: Jul 2006
Location: New Hartford, NY
Posts: 14,202
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 92 Post(s)
Liked: 403
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.
MKtheater is offline  
post #12 of 12 Old 03-03-2014, 09:18 AM
AVS Special Member
 
bass addict's Avatar
 
Join Date: Dec 2003
Location: A padded room
Posts: 3,774
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Liked: 210
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.

Achievement Unlocked

Psychotic Episode Averted

bass addict is offline  
Reply DIY Speakers and Subs

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off