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7 x RE Audio XXX 18" subs, Infinite Baffle Sub, Ultimate IB build - Page 3

post #61 of 540
Thread Starter 
Quote:
Originally Posted by beastaudio View Post

Pretty much you will have so much headroom you can shape your response to look like pretty much anything you want. Smiley face, Christmas tree, that naked woman you see on people's truck tire flaps, etc etc. you'll be able to shape it anyway you want if you get something capable to do so. pay particular attention to phase/delay to get them all to play well together...

Dirac live does phase delay pretty well, so I will leave it to that to set the delay. It will certainly be interesting as to how low I can go at reference. Just to be safe, I will be putting 8 x 2" x 10" ribs on the baffle wall to make absolutely sure the wall won't flex.
post #62 of 540
no consideration of a dual manifold-type install where the subs are opposite each other? Would help with box vibrations
post #63 of 540
Thread Starter 
I will be going with something similar with this, only horizontally mounted, so opposed subs is not really an option.

post #64 of 540
Just be aware that the xxx has an absurd amount of moving mass and tons of excursion, would be hard to keep that wall from flexing. Im sure you are considering those things though.
post #65 of 540
Quote:
Originally Posted by JapanDave View Post

LOL.
Now, the big question, what will the in room response be with infinitely baffled 4 x RE XXX 18"s + 4 sealed LMS ultra 18" s in a 3000cf solid concrete bunker be like?

Dave,

A couple things.

1. What are your plans for implementing the IB itself? I don't know anyone with a "concrete bunker" (i.e. - 6 concrete walls) that has implemented an IB. Unless your concrete bunker is sectioned off into multiple chambers?

2. Being in a "concrete bunker," others can attest that there is a difference in tacticle feel one can accomplish on a solid concrete floor vs. suspended wooden floor (or other than concrete). Might have a few differing opinions in the group, but just keep that in mind as being a possibility.

3. Remember that most people are very limited when it comes to room placement of their IB. And in most cases it's simply a roll of the dice as what the end result will produce.
post #66 of 540
Quote:
Originally Posted by keager View Post

Just be aware that the xxx has an absurd amount of moving mass and tons of excursion, would be hard to keep that wall from flexing. Im sure you are considering those things though.

+1. four of these all firing one way will produce a lot of force.








As far as what you can expect in a 3,000 cube room...Probably something similar to this. Note that I am amp limited. There's another 3 dB peak output that could be extracted from the drivers before they run into excursion trouble. I'm not in any hurry to upgrade for that.





You won't be using those types of output levels except for a random let's see what she'll do type demo to scare the occasional friend or yourself. You will be repairing some things around the place when you do. redface.gif.
Edited by Ricci - 10/12/12 at 1:28pm
post #67 of 540
Quote:
Originally Posted by Ricci View Post

As far as what you can expect in a 3,000 cube room...Probably something similar to this.


You won't be using those types of output levels except for a random let's see what she'll do type demo to scare the occasional friend or yourself. You will be repairing some things when you do redface.gif.

^^^^^^^^^
I want to know a LOT more about this. cool.gif
post #68 of 540
Ricci is that only 4 or all 8 of yours?
post #69 of 540
Quote:
Originally Posted by JapanDave View Post

I will be going with something similar with this, only horizontally mounted, so opposed subs is not really an option.

I would re-think the way you are going to mount those subs. I had 4 IXL 18's built into my wall just like that pic. It was a disaster. I used 3" of ply, triple braced with 4x8's and beefed up as much as humanly possible and it still flexed the entire wall. It shook the entire house and rattled everything. You could actually see the entire wall flex. I used it like that for about a month and tore it all down and did a opposed box....... only about a million times better! the difference was beyond belief. The only way I do an array like that is if it was concreted.
post #70 of 540
Beast,
That's all 8 on 2 K10's on a 240v 50a line. I quit the burst testing after 31.5Hz because I'd already broken a few things like a big picture that is one of the missus favorites in the upstairs living room and my back door to the patio. I have a big peak near 45Hz which means that 40-50Hz would have been well over 140dB and my mic systems starts clipping the soundcard input at about 137-138dB anyway. It kind of irritates me that my electronics fall off of a cliff after 6Hz but hey I guess 5 to 6Hz extension with 120dB+ at the seats capability will have to suffice.

Anyway Dave you should be looking at headroom similar to this. REF level playback and most anything else really, will be a walk in the park. Please give serious thought to Nate's post as well. I've never done an IB but he has direct experience with it and I know how bad these drivers can shake something. I would strongly suggest mounting them dual opposed to help cancel out vibration.
post #71 of 540
Quote:
Originally Posted by popalock View Post


1. What are your plans for implementing the IB itself? I don't know anyone with a "concrete bunker" (i.e. - 6 concrete walls) that has implemented an IB. Unless your concrete bunker is sectioned off into multiple chambers?

I'm pretty sure there was some discussion on this fairly recently over at the cult. Dave, you might be interested in looking for it if you haven't already. It was within the last few months in the project section if I recall.
post #72 of 540
Dave. Is building an external manifold a viable option?

I can't remember where I saw it but one guy had an IB system that looked just like a cube shaped sealed sub but the bottom of it was attached to a large airspace and it was indeed a real IB system. It just looked like a regular subwoofer.
post #73 of 540
Quote:
Originally Posted by Scott Simonian View Post

Dave. Is building an external manifold a viable option?
I can't remember where I saw it but one guy had an IB system that looked just like a cube shaped sealed sub but the bottom of it was attached to a large airspace and it was indeed a real IB system. It just looked like a regular subwoofer.

Its called an outie! I contemplated that before going under my house with mine. There are benefits to that design.
post #74 of 540
Ah... if JapanDave can fit an external box like that where he wanted to vent out for IB anyway, then that would definitely cure the problem he would get with 4x XXX18's. Yikes I totally would not even try that!
post #75 of 540
Thread Starter 
@popalock. Even with next to not much tactile sensation through the floor, 1 x LMS 18" in a sealed box gives quite a bit pressure. Other than that I have no idea how this will sound.

Ricci, that is a bad ass system!
Quote:
Originally Posted by Scott Simonian View Post

Dave. Is building an external manifold a viable option?
I can't remember where I saw it but one guy had an IB system that looked just like a cube shaped sealed sub but the bottom of it was attached to a large airspace and it was indeed a real IB system. It just looked like a regular subwoofer.

To give you an idea, the subs will be placed like this,



@N8DOGG, I don't quite understand the oppossed idea? Could you explain?

My subs will have the bottom of the manifold bolted to concrete, but that will still not stop wall flex I guess. The wall is made out of 2" x 4" studs at 4" spacing with cross bracing at about every 6" (wall size is 2.8m wide by 1.9m). The wall itself is 1" MDF. I don't know if that is enough, if not I will think of something else.
post #76 of 540
"Like this"

Eh? You mean where the Teraform XL's would be? If so... you totally have room..... I think. Looks like it to me.
post #77 of 540
Quote:
Originally Posted by Scott Simonian View Post

Dave. Is building an external manifold a viable option?
I can't remember where I saw it but one guy had an IB system that looked just like a cube shaped sealed sub but the bottom of it was attached to a large airspace and it was indeed a real IB system. It just looked like a regular subwoofer.

I remember the picture. From looking at the sub, you would think that you could just go over and pick it up and move it, but it was fastened down to the floor and the crawl space was the back chamber.
Reply
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post #78 of 540
I think this is the idea you guys are referring to:

http://www.jonathanfoulkes.com/Home_Theater/Speakers/IBSub.htm

Chris
post #79 of 540
A couple of steel I-beams would really take care of business for this install... Rigidity is key, for IB or for a box.
post #80 of 540
Quote:
Originally Posted by filtor1 View Post

I think this is the idea you guys are referring to:
http://www.jonathanfoulkes.com/Home_Theater/Speakers/IBSub.htm
Chris

Here is a link to a thread based on that IB setup on "Whats Best Forum"

http://www.whatsbestforum.com/showthread.php?5402-Infinite-Baffle-and-the-Audiophile

I thought those pictures looked familiar.



Forin
post #81 of 540
Thread Starter 
Quote:
Originally Posted by Scott Simonian View Post

"Like this"
Eh? You mean where the Teraform XL's would be? If so... you totally have room..... I think. Looks like it to me.
The problem is that with these drivers VAS, I will need all that space behind the baffle wall and the screen is about 1 foot away from the baffle wall in the center at its closest point. So my only option is to mount them in a line array formation I think.

Quote:
Originally Posted by imagic View Post

A couple of steel I-beams would really take care of business for this install... Rigidity is key, for IB or for a box.

That is probably the best thing I could do, I think I will do that as it would be easy to bolt a beam to the floor and ceilling.

How much force are we looking at here? I have about 10mm gaps around my LCR's which have been sealed with about an inch of silicon. I wonder if it will blow the silicon out?

Here is a pic of the silcon bead around the speaker, it is about 1" deep worth of silicon.
Close up.


post #82 of 540
Quote:
Originally Posted by JapanDave View Post

@popalock. Even with next to not much tactile sensation through the floor, 1 x LMS 18" in a sealed box gives quite a bit pressure. Other than that I have no idea how this will sound.
Ricci, that is a bad ass system!
To give you an idea, the subs will be placed like this,

@N8DOGG, I don't quite understand the oppossed idea? Could you explain?
My subs will have the bottom of the manifold bolted to concrete, but that will still not stop wall flex I guess. The wall is made out of 2" x 4" studs at 4" spacing with cross bracing at about every 6" (wall size is 2.8m wide by 1.9m). The wall itself is 1" MDF. I don't know if that is enough, if not I will think of something else.

Now that I see you pic and you plan, you should be good to go. I though it was going to be built into a wall.
post #83 of 540
Dave forget about the whole VAS thing. Seriously. If the IB guys want to say that it's not a true IB because it doesn't meet some prescribed vas multiplied by how much amount of air volume who cares. It's not like you will hear some huge audible difference between 15 cubes per driver and 150 cubes per driver.

How much space you got anyway?
post #84 of 540
Quote:
Originally Posted by Ricci View Post

Dave forget about the whole VAS thing. Seriously. If the IB guys want to say that it's not a true IB because it doesn't meet some prescribed vas multiplied by how much amount of air volume who cares.
+1. IB means Infinite Baffle, which is defined as a speaker where the front and rear waves do not meet. Said definition applies equally to a 1/2 cu ft sealed box and a 10,000 cu ft attic. Vas only enters the equation in determining the minimum rear chamber size required for a desired F3, the same as with any alignment.
post #85 of 540
+2

While I acknowledge there is a difference between the technical definition of IB and the commonly used meaning, I don't find it necessary to meet a certain volume requirement before the attempt becomes worthwhile. If you have the space, bigger is better. If you have the money, shoving more drivers into that space even if falling well short of some IB guideline may be beneficial. In any case, my personal definition of IB is a sealed box big enough to substantially reduce power requirements and minimize effects of box on final q. A couple or so times VAS is a big danced box, and the difference between small sealed and that point is much greater than between 3x VAS and 300x VAS.
post #86 of 540
+3

Ignore the 10x Vas requirement.
post #87 of 540
Wow, great discussion, great thread. I haven't had a chance to keep up with this thread.

I've followed Japan Dave's room/system build, and the complex and perplexing hearing issues he's encountered upon first firing up his previous rig. So it's great seeing things moving along again. I really dig the room specifics and details on choices made thus far in his build.

Regarding VAS guidelines, there are none.

I'm not sure if Josh, Bill, Bigus or Scott have built an IB for HT use, but they do offer good advice. Typically, there's other factors to consider when discussing the theoretical standards for IB construction. Yes, the VAS question seems to come up first, and the answer would be typically about 4-10 is the goal when pursuing those theoretical benefits. More importantly would be the overall implementation of the build, and subsequent optimization with the mains and room.

This case, it is what it is, the backspace is predetermined (and maximized via fluffy stuff too IIRC). The theoretical ideal VAS element to IBs is really a design from ground up question. In builds with less than theoretical ideal, I'd only be concerned with IB only drivers, like Dave's fist choice the Fi IB3-18, and it's modest motor. So driver choice is a factor to how significant the backspace characteristics are.

It's also been empirically determined the space immediately around the drivers is impactful, and ideally can benefit from being free from acoustic obstruction. Again that doesn't apply here (can't be altered significantly), just like the VAS parameter.

The use of the RE XXX 18" drivers is fantastic. Robust bottoming tolerance is hugely important for IB use, sounds like it's the ideal driver for such. I wish I didn't have to be concerned with amp power with my quad 18 IB. I've been considering a retrofit,...another conversation.


Also, you're approaching the IB implementation to a HT spot on correct IMO. Like other approaches, an IB has some wonderful benefits otherwise unattainable in other subwoofer alignments/approaches. The planar wave launch close coupled acoustically to the mains, combined with the response smoothing effects of the additional small sealed balancing subs. I too am utilizing te IB/small sealed balancing sub approach. Dave, good lookin' out, great approach for sure.

The Datasat processor is a piece of work. I attended the private party roll-out last year while attending Cedia. The demo had issues, but none related to the processor. That thing is absolutely amazing. When optimizing, I think you'll benefit most from varying phase and low-pass settings on the small sealed 5400s. I'm guessing the automated optimizing has this covered, but some tweaks manually after the fact may help as well. That, is down the road.


Best of luck Dave
post #88 of 540
Another thing Dave,..others, are you saying the back of the mighty Quested's are fully exposed to the acoustic back-pressure of the IB?

If so, I'd contact your rep/dealer, or ever Quested themselves,... and inquire with them. Surely, with all the similar installs in baffle walls in studios, various concerns and questions has come up. I don't know if it'd be problematic or not. I know they're robust boxes, I've seen them. I'd not want any of the critical midband, HF energy being modulated by the subs back-wave, if that's possible.

Good luck
post #89 of 540
Does anyone have a link, or the actual driver before them to give me some dimensions?


I've been entertaining the idea of retrofitting my 4x18 dual opposed attic IB manifold, for more system experimentation ever since I completed it. I'm interested in the precise OD of the surround, the precise OD of the entire driver frame.

Also, what would be the general consensus on ideal maximum recommended amplification per driver, in an IB alignment, w/no high-pass? As I re-read the powering discussion, dual 2ohm XXX, and about 2kw per 4ohm (2+2) driver, .....is this it, series the coils and feed them ~2kw?

IIRC, there's been a couple IBs with these, and a small amount of small-sealed. Wrt the IBs, what have been the actual choices made, 2kw into the 4ohm load? Without the paranoia of the hard bottoming, the powering can have a lot more latitude, and I've always wanted to employ some big, robust drivers in the IB. Like Dave, I considered LMS 5400s, but I liked the re-coning capability of the Fi drivers. I strongly considered Kevin Haskin's Maelstrom 21"s, again there was some factors pulling me toward the Fi offerings.


My application was ideal for the Fi IB3-18s, with a huge attic backspace, but the inherent roll-off could be better. Believe me, the quality and bang for the buck for the Fi 18s is superb. For ~$1300, material, four of those and an EP4K,... yields 127.5dB@1m@20hz@225w/driver). I'm getting a clean 117dB@20hz at the LP. But still I was constantly re-visting the IB powering conundrum I mentioned on page one in this thread. Despite what a small minority claim, the bottom octaves add realism, .... regardless whether one hears them, feels them or a blend of the two,....high passing isn't an approach I'm interested in. As Josh mentioned, the inherent electronics roll off is bad enough. There's a bottom octave component that oftentimes accompanies percussive explosive type effects. Encountering this effect is fabulous, ...sure it's exaggerated a bit perhaps but that component of the big deep effects is something I don't want to do without. So no hi-pass for me if I can help it.

Dave, which amplification route are you taking/considering?

Also, have you examined the LF decay characteristics of the space yet? The construction method of the bunker is killer for PVG, but sharpens the Q of any modal interactions, and doesn't dissipate the LF in the time domain as well as a stick built residential room. I know you've got bass traps, etc, and I believe Dennis helped on the design to, right? Anyway, it would be of interest to see.

You're certainly going to possess some LF fire-power. cool.gif

All the best
Kevin
post #90 of 540
FOH

18"
Mounting Depth - 14.75 inch
Mounting Hole Diameter - 17.375 inch
Overall Diameter - 19 inch
Bolt Hole Circle - 18.25 inch
Motor Width - 10.5 inch
Motor Depth - 5 inch
Basket Depth - 9.75 inch
Displacement - 0.30 cu. ft.


1000-2000w per driver is fine. 1500 is probably "right". If you are worried about clanking watch the xxx excursion vid I posted in the free air driver excursion thread in the forum at Databass. Id link but Im on my phone. That is a 1400w amp channel clipping on it by the end and remember that is an 18" driver.
Edited by Ricci - 10/14/12 at 1:23pm
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