6000 cuft HT (27L x 22W x 10H) BassTrap Question - AVS Forum
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post #1 of 37 Old 09-22-2012, 09:12 AM - Thread Starter
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Hi All !

We are having a new home built. Once the home is completed I will begin finishing the basement. One portion of this basement is under one of the garages (the 3 car) so it will have a SpanCrete ceiling. The whole theater will be a sarcophagus of concrete making for some great isolation. I have been planning this new build for the last 12 months or so. I have attached a link to the most current incarnation thus far. My question revolves around the basstraps I am planning. I have two in the rear corners which will be 2ft x 2ft column from the floor to the first soffit. They will be filled with fiberglass insulation. The traps will be a simple frame with a few wire mesh "shelves" on the inside supporting the fiberglass so it doesn't crush itself due to weight. The whole frame will be covered by a dark colored fabric.

In the front of the room you can see I have planned for a 1ft x 1ft column (floor to 1st soffit). In between these front columns will be a shelf of sorts which extends in front of the screen wall. The face of this shelf will be the baffle for EIGHT 18" IB318 subs.

Anyone see any cons with these basstraps?

th_Basement_revised_NEWest.jpg


## DIY Rustic ConcreteBunker HT Build w/8 x 18" IB subs & 25KW ##

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post #2 of 37 Old 09-22-2012, 10:40 AM
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I'm just concerned they're not enough. The IB will drive the length modes of the room strongly. The first mode, near 21 Hz will lead to a broad null near the center of the room. That may be low enough in frequency to not be too troublesome, and if all the seating is near the center and you have adequate headroom, you may get some improvement from EQ. The second order length mode, around 42 Hz, will be harder to deal with since the distance from peak to null will be within your likely seating zone. Seat to seat variation could be very high and can't be fixed through EQ. You should expect 42Hz nulls around 1/4 and 3/4 room length, with a peak at 1/2. The tertiary length mode will be clustered near some other modes, and hopefully get swamped, but maybe not (63Hz). Near that frequency you may start to see meaningful interaction from your LCR as well - hopefully mitigating the effects.

http://www.hunecke.de/en/calculators/room-eigenmodes.html

I'm not very well versed in IB, but you should check out what Digital Chris has been going through in his "Shhh! No Talking" Build.

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post #3 of 37 Old 09-22-2012, 03:04 PM - Thread Starter
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Quote:
Originally Posted by HopefulFred View Post

I'm just concerned they're not enough.


I'm not very well versed in IB, but you should check out what Digital Chris has been going through in his "Shhh! No Talking" Build.

What else would you suggest? I have plenty of time! Also, I was unable to find the thread you mentioned.frown.gif


## DIY Rustic ConcreteBunker HT Build w/8 x 18" IB subs & 25KW ##

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post #4 of 37 Old 09-22-2012, 04:06 PM
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I suspect you'll just need more trapping. It's too soon (for me) to know what type, or where exactly. I'm just concerned (especially given what I've seen Chris deal with) that the length mode will be basically undamped. Velocity-based absorption in areas where the longitudinal standing wave has high velocity (nulls, I think) or pressure-based absorption where the pressure is highest. I've tried to leave myself options for both types in my build - but I'm too much of a novice to know what I'll need before I measure. Apart from the rudimentary analysis I described earlier, I'd have to wait and measure. Read through Chris's build here: http://www.avsforum.com/t/1290765/shh-no-talking-home-theater (especially the last few pages)
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post #5 of 37 Old 09-23-2012, 07:39 AM - Thread Starter
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Wow.

That thread is a major downer. Is it too difficult to say why he ran into so many bass issues (room dimensions, IB Line array, poor EQ...) ??

I'm looking to see if my ideas for bass traps are way off base (no pun intended wink.gif ), or are they a really good start. Are they too big/small? Would I gain the same benefit by just building a wedge shape column in the corners vs. the 2 x 2 box column?

THANKS!


## DIY Rustic ConcreteBunker HT Build w/8 x 18" IB subs & 25KW ##

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post #6 of 37 Old 09-23-2012, 09:16 AM
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Are you completely committed to an IB sub? WIth a theater that large and complex I think it would be prudent to hire a pro to design it. They'll have the expertise and software to do a proper analysis and make recommendations based on science. Multiple subs in the space will go a long way to correct room modes. You just can't predict what's going on without the tools.

Also, concrete is an excellent conductor of sound. It will not give much isolation. That should be addressed too.

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post #7 of 37 Old 09-23-2012, 12:24 PM - Thread Starter
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Quote:
Originally Posted by petew View Post

Are you completely committed to an IB sub? WIth a theater that large and complex I think it would be prudent to hire a pro to design it. They'll have the expertise and software to do a proper analysis and make recommendations based on science. Multiple subs in the space will go a long way to correct room modes. You just can't predict what's going on without the tools.
Also, concrete is an excellent conductor of sound. It will not give much isolation. That should be addressed too.
Awesome car, by the way!


I am pretty committed to the IB concept. I have already purchased the drivers and amp. Of course nothing has been built yet (including the house), but I prefer not to have multiple sub-boxes all over the room. If it was absolutely necessary I could build two subs using the pair of 15" Titanic MkIII's I am using in my existing HT.

The HT will be framed with in the concrete structure. The only contact will be the base plates of the framed walls to the concrete floor. The floor of the HT is 2ft deeper than the rest of the basement (12' pour vs. 10' pour) and is completely under a garage, not living space. The side walls will be ~ 2" from the concrete walls behind them. The screen wall will be framed as 2x6 due to the IB subs. Also, the screen wall will be covered front AND rear with 1/2" OSB. The front of the screen wall will also have 1/2" drywall as well. The framed cavities will be insulated.
The side and rear walls will be constructed in a similar fashion except there will only be 1/2" OSB on the inside of the side/rear walls (not both). The soffits will have thicker OSB/plywood for the mounting arms for the side & rear surrounds.

Given the above, do you still think it will be a problem from a sound isolation standpoint?

I was hoping the bass traps I was thinking about would be a good start.

PS: Thanks for the prosp ! smile.gif


## DIY Rustic ConcreteBunker HT Build w/8 x 18" IB subs & 25KW ##

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post #8 of 37 Old 09-23-2012, 01:27 PM
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So here's some ways to think about it. A 42Hz sound wave, the one I project will be a problem, has a wavelength equal to the length of your room - around 27 feet. A rule of thumb is that to attenuate a wave, the porous absorber should be 10% of the wavelength (even though the theoretical optimum is at 1/4 wavelength). The suggests 2.7ft should be appropriate, given enough coverage. I'd be looking for ways to cover area below and/or above the screen. You've got a 10x22ft wall (front - 220sqft) for the wave to reflect on, and you have planned to use absorbant (of sub-optimal depth) over less than 10% of it. I don't know where the gains should kick in, but I think 10% is too little for a wave of that power and influence.

I could be totally wrong here, but I'd be nervous.
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post #9 of 37 Old 09-23-2012, 05:19 PM
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Hey RMS, I'm sure you skimmed through my thread but I just wanted to reiterate something... The 36" faced corner superchunk bass traps I did in the rear of the room had almost no effect regarding the two peak problems I was having. They helped very little at my 60hz and 30hz problems. The traps did help with the LF ringing a bit but that's about it, in my case anyway. I'm sure some of the big wigs will chime in or you can PM Dennis directly, he might be able to give you a much better insight.

Also, since you haven't built the theater yet, were you planning on putting all 8 drivers up front? If so, I HIGHLY recommend you don't do that. I would at least split them between the front and rear of the room somehow. Multiple subs (whether it be IB or box) spread around your room (luckily your room will be large enough) will be your best setup. The thing about IB is that once you build the baffle, you can't play with placement. I was in the same predicament earlier until I added a couple of 15's behind the back row. So, with those implemented along with the correct subwoofer distance setting in the AVR, I was able to get much flatter LF graph.

Regarding the surrounds and how I wired them, I just ran them in parallel mode, no separate delay box or anything... I didn't know they made such a gadget.
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post #10 of 37 Old 09-24-2012, 12:02 PM
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1. Bass traps as shown and placed are too small to do anything other than help the guy out who is selling the fiberglass;
2. Eight 18" woofers in an IB design? Why? What engineering specification did you follow to determine you needed that much low frequency energy ... and what engineering specification did you use to determine what your bass response might be like in those frequency ranges where 18" woofers are very inefficient? What will you be using for HF and MF drivers that will be sufficient enough to not be over powered by the subwoofers?
3. What method will you use to relocate the drivers when you discover they need to be relocated to improve in room response?
4. Since the drivers are facing the listening positions, what technique are you thinking of using so those in the listening area will not hear the higher frequency artifacts created by those drivers?

Just asking.

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post #11 of 37 Old 09-25-2012, 07:33 AM - Thread Starter
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Quote:
Originally Posted by Dennis Erskine View Post

1. Bass traps as shown and placed are too small to do anything other than help the guy out who is selling the fiberglass;
Therefore the reason creating a thread. To get input/advice/alternatives.

2. Eight 18" woofers in an IB design? Why? The room will be large (8x 18"ers) and I do not want a lot of boxes (IB) taking up floor space. IB's are extremely efficient. What engineering specification did you follow to determine you needed that much low frequency energy ... and what engineering specification did you use to determine what your bass response might be like in those frequency ranges where 18" woofers are very inefficient? Considering I'm an electrical engineer and not an acoustical engineer, None & None. What will you be using for HF and MF drivers that will be sufficient enough to not be over powered by the subwoofers? If each speaker has it's level properly matched/set then it would all work cohesively. I will take advantage of the 11.1 channel capability of my receiver as well. Current speakers are Phase Tech's (Premier Collection) and Niles (Stage Front Pro series). Future will incorporate additional Niles for the new channels. Speakers could change though.

3. What method will you use to relocate the drivers when you discover they need to be relocated to improve in room response?
Is it guaranteed to be that bad? There are so many IB setups with the drivers arrayed in the front (be it via manifold or direct radiating). If it were really that unworkable, would people still praise it for it's virtues?

4. Since the drivers are facing the listening positions, what technique are you thinking of using so those in the listening area will not hear the higher frequency artifacts created by those drivers?
Are you saying those drivers in particular (FiCar IB318) create higher frequency artifacts? If in general, then I would do what ever anyone would do to correct this, although, at the moment, I am unfamiliar with higher frequency artifacts created by a subwoofer.

Just asking.


As I stated earlier I am looking for advice on setting up DIY Bass traps. I want to take advantage of using the seating platform as a bass trap as well. It seems there are many types of bass traps out there. Coming to a forum such as this and seeking the experience of 100's if not 1000's seems like the most logical thing to do.

Should this be posted in a different sub-forum perhaps?


## DIY Rustic ConcreteBunker HT Build w/8 x 18" IB subs & 25KW ##

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post #12 of 37 Old 09-25-2012, 07:46 AM
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I'm going to take a stab at this, and I may be wrong. However, when I was considering an IB, one of the "rules" is to put them at the front of the room. It's generally frowned upon to locate your IB elsewhere due to localization. In an ideal world, you would not be able to localize sound below 80 Hz, and it wouldn't matter where you put your IB. However, the speakers create harmonics above 80 Hz. So a 60 Hz note might create harmonics at 120 Hz, 180 Hz, etc. Those are the sounds that you can localize. To address that, the IB is placed at the front of the room near your mains. That way, you localize those harmonics near the speakers generating the higher frequency content anyway, and the sound is coming from the same location as the image, so it's not objectionable in most cases.

It's my understanding that all subs create harmonics. You can either point them away from the listening position, or perhaps put some absorption in front of them to attenuate the high frequency content.

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post #13 of 37 Old 09-25-2012, 08:01 AM - Thread Starter
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Quote:
Originally Posted by J_P_A View Post

I'm going to take a stab at this, and I may be wrong. However, when I was considering an IB, one of the "rules" is to put them at the front of the room. It's generally frowned upon to locate your IB elsewhere due to localization. In an ideal world, you would not be able to localize sound below 80 Hz, and it wouldn't matter where you put your IB. However, the speakers create harmonics above 80 Hz. So a 60 Hz note might create harmonics at 120 Hz, 180 Hz, etc. Those are the sounds that you can localize. To address that, the IB is placed at the front of the room near your mains. That way, you localize those harmonics near the speakers generating the higher frequency content anyway, and the sound is coming from the same location as the image, so it's not objectionable in most cases.
It's my understanding that all subs create harmonics. You can either point them away from the listening position, or perhaps put some absorption in front of them to attenuate the high frequency content.

Ah. I kinda thought that, but wasn't sure.

Also, your comment regarding ideal placement of an IB setup is precisely what I thought as well. (lots of great info over at THE CULT). I'm all DIY so was seeking the experience of those who have done the bass traps already. Especially the seating platform. Plenty of time though for advice and modifications.


## DIY Rustic ConcreteBunker HT Build w/8 x 18" IB subs & 25KW ##

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post #14 of 37 Old 09-25-2012, 04:02 PM
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There are two people on planet earth who have developed methods of using the seating platform to deal with in room LF response ... they are Dennis Erskine and Tony Grimani. Anyone else is make a copy and stab at it and, if they are lucky, might hit the mark hit the mark. Both individuals us different techniques.

IB subs are efficient. Given that, there is no way in this universe you need or require that many drivers (all of which will create HF artifacts as will *any* sub of any design). Amps and speakers tend to be best when operating between 1/3 and 2/3 of their rated power. Looking at "reference" level in the seating location for that many 18" drivers, your amps and subs will be operating at way, way below the 1/3 mark. Subs mounted in the front boundry will exacerbate all length modes and no mechanism is available in your current design to address width modal response without about 8' of fuzzy stuff.

Your proposed LCR speakers will not be able to provide 20kHz at -20dBFS at the seating locations (or anything near that). I suggest other speakers, fewer better placed subs if only because no amount of acoustic treatments will fix the problems you are about to create. BTW "efficient" does not equate to good for the intended purpose.

"Cult" is very descriptive.

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post #15 of 37 Old 09-25-2012, 05:47 PM
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Quote:
Originally Posted by HopefulFred View Post

II'm not very well versed in IB, but you should check out what Digital Chris has been going through in his "Shhh! No Talking" Build.
Fred

Digital Chris was the sole designer for his IB, he didn't ask for help until his IB was completed. He failed to follow the fundamental idea of testing location BEFORE building the sub. And he's ignored posted solutions to his problems

Quote:
Originally Posted by Dennis Erskine View Post

"Cult" is very descriptive.

No need to be nasty Dennis, the word 'cult' is of course a tongue in cheek play on words.......

BTW the OP of this thread created his design and posted it on the IB forum. This is not a design created by the 'Cult' nor would we advocate 8-18"s drivers in one location, BUT that appears to be what the OP wants....
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post #16 of 37 Old 09-25-2012, 07:14 PM
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My room isn't much smaller than yours. Maybe a few feet each way and a foot less height but with a hallway and equipment room that gets the volume up over 4000 ft^3. I was seriously considering doing an IB setup myself. I could have easily dumped the back-wave into my adjacent garage. The likelihood of exciting room modes, with no possibility of moving subs is what put me off the idea of going IB. Plus I got really crappy results placing my anemic B&W ASW100 in the likely spot for the IB manifold.

Instead I bought cheap close-out 15" drivers and built four sealed boxes. I'm powering them with 145 watts per box (145 watts, not 1400). I tried about a half dozen placement options to get decent frequency response. It's damn near flat and the overall system sound is simply remarkable with the addition of a "dialed in" subwoofer system. My simple sub system can completely overpower my mains. I've got less than $500 in it (amp was free).

The value in being able to move things around cannot be overstated. If you aren't going to do a full system design based on engineering and science you at least need to have the flexibility to measure - tweak - measure.

Here's my first run, subs placed where they were convenient:


Then after a bunch of move-measure-move cycles, we got here:


IB and massive bass seems cool, but so does a Cadillac Escalade with the license plate rattling from all the one-note bass.

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post #17 of 37 Old 09-26-2012, 07:50 AM - Thread Starter
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*** Some Clarification on my Expectations of this room ***


Here are the items I do Not want to change :
- Do not want a stage in front of room
- Do not want a seating platform that stretches wall-to-wall
- Do not want to change the general look of the front of the design. I want my equipment rack located in the front in one of the "rooms" jutting out of the front corner. The other "room" is simply for symmetry and will not have a door on the side (despite what the drawing currently shows). The size and shape of these "rooms" is not set in stone. May even consider putting the inside walls of these "rooms" at an angle???

Here are my ideas for the room aesthetics :
- Rustic
- The side & rear walls will have faux dry-stacked stone panels along the bottom capped with a pseudo chair rail which will hide a rope light to cast light down the wall.
- The side walls will have two faux wood beam pillars jutting out (15"W x 13"D) from the wall from floor to soffit.
- The ceiling will be reclaimed barnwood panels
- The ceiling will have two faux wood beams (smaller than the side beams) stretching from side to side (actually soffit-to-soffit). These beams will not be flush mounted with ceiling but be dropped by ~ 8" or so.

I could mount a few of the drivers in the rear of the room on the right side of the drawing up to the wet bar location. Of course this is all guess work since it appears there is no software to predict where the problem areas might be and at what frequencies. But building an IB type sub does not afford one to move drivers around if the guess-timated loactions are bad since the baffle walls need to be reinforced during framing and the cavity behind needs to be accounted for, unless someone has some good suggestions.

Ideas/comments please!


## DIY Rustic ConcreteBunker HT Build w/8 x 18" IB subs & 25KW ##

Denon AVR-4520 11.2 | Sony VPL-HW55ES | Elite Screens 11' screen | Sanway FP-14000 | Sherbourn PA 7-350 | Buttkicker BKA-1000(3x) | Behringer iNuke NU1000DSP | GR Research LS-9 + LS-C | 8x IB318's | Buttkicker Original(2x), LFE(2x), MiniLFE(8x) | MinDSP 2x4 | 21'W x 27'L x 10'H | MiniSplit
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post #18 of 37 Old 09-26-2012, 12:29 PM - Thread Starter
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Okay,

I have modified the plan to move 4 of the drivers to the rear of the room.

Better?

th_Szewczyk-BasementPlan_9-18-2012HT-only_Printat100revised.jpg


## DIY Rustic ConcreteBunker HT Build w/8 x 18" IB subs & 25KW ##

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post #19 of 37 Old 09-26-2012, 02:04 PM
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Quote:
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Better?
Yes, better - but not a complete solution. You're setting up to more-or-less have subs in each of the four corners. This is a common way to get close to a smooth in-room response.

Instead of driving only one room mode (the length mode) you're driving all (most) of them, as well as their odd-number opposites (that's a not a real phrase - let me explain). The 1st, 3rd, 5th (and so on) axial modes generate areas of high pressure at walls and a null in the middle of the room (as well as other nulls and peaks). The high pressure peaks near each wall are 180 degrees out of phase. By driving the mode from both ends, you can get good cancellation of those out-of-phase, odd-number modes. This happens, of course, for any axial mode - not just length. This approach still does not address even number modes.

The bigger concern to me is not exciting each mode from the design phase,but having the flexibility to adjust to what you find when you actually start making noise in the space. Small variations in wall construction (like having a door) will change the way the wall reflects sound - in ways and to extents that are not readily predictable. For instance, you might calculate the center of an out-of-phase standing wave, and plan to place a driver there. If the opposite wall introduces a few degrees phase shift to the reflected wave at that frequency, the position of the peak could move several feet - obliterating the desired effect.

If you do stick with installed LF drivers (not movable), invest in DSP that allows for individual phase, delay, and level adjustment (four channels should be sufficient for this arrangement, IMO). Still bass trapping of some kind is likely necessary.
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Yes, better - but not a complete solution. You're setting up to more-or-less have subs in each of the four corners. This is a common way to get close to a smooth in-room response.
Instead of driving only one room mode (the length mode) you're driving all (most) of them, as well as their odd-number opposites (that's a not a real phrase - let me explain). The 1st, 3rd, 5th (and so on) axial modes generate areas of high pressure at walls and a null in the middle of the room (as well as other nulls and peaks). The high pressure peaks near each wall are 180 degrees out of phase. By driving the mode from both ends, you can get good cancellation of those out-of-phase, odd-number modes. This happens, of course, for any axial mode - not just length. This approach still does not address even number modes.
The bigger concern to me is not exciting each mode from the design phase,but having the flexibility to adjust to what you find when you actually start making noise in the space. Small variations in wall construction (like having a door) will change the way the wall reflects sound - in ways and to extents that are not readily predictable. For instance, you might calculate the center of an out-of-phase standing wave, and plan to place a driver there. If the opposite wall introduces a few degrees phase shift to the reflected wave at that frequency, the position of the peak could move several feet - obliterating the desired effect.
If you do stick with installed LF drivers (not movable), invest in DSP that allows for individual phase, delay, and level adjustment (four channels should be sufficient for this arrangement, IMO). Still bass trapping of some kind is likely necessary.
Thanks for the informative post !!!!

Yes, I already have several tools in my current HT for equalizing bass (Anti-Mode 8033, Behringer FBD, Audessey...) which will go into the new HT. I'll also get a minDSP to use as a highpass.


## DIY Rustic ConcreteBunker HT Build w/8 x 18" IB subs & 25KW ##

Denon AVR-4520 11.2 | Sony VPL-HW55ES | Elite Screens 11' screen | Sanway FP-14000 | Sherbourn PA 7-350 | Buttkicker BKA-1000(3x) | Behringer iNuke NU1000DSP | GR Research LS-9 + LS-C | 8x IB318's | Buttkicker Original(2x), LFE(2x), MiniLFE(8x) | MinDSP 2x4 | 21'W x 27'L x 10'H | MiniSplit
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post #21 of 37 Old 09-26-2012, 10:41 PM
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Rule of thumb, do not use multiple methods or pieces of equipment to EQ the same channel. Pick one and stick with it. smile.gif.

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Rule of thumb, do not use multiple methods or pieces of equipment to EQ the same channel. Pick one and stick with it. smile.gif.
One cannot bypass the sub portion during the Audessey setup. The AntiMode is for my dual 15" DIY sub and the FBD is for my 12" HSU clone.


## DIY Rustic ConcreteBunker HT Build w/8 x 18" IB subs & 25KW ##

Denon AVR-4520 11.2 | Sony VPL-HW55ES | Elite Screens 11' screen | Sanway FP-14000 | Sherbourn PA 7-350 | Buttkicker BKA-1000(3x) | Behringer iNuke NU1000DSP | GR Research LS-9 + LS-C | 8x IB318's | Buttkicker Original(2x), LFE(2x), MiniLFE(8x) | MinDSP 2x4 | 21'W x 27'L x 10'H | MiniSplit
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New plan...

Question :

Will I have to worry about any phase issues due to drivers on opposite ends of the room? All 8 of the drivers are wired to the same amp. The only flexibility I would have would be to wire one set 180 out if it came to that.

th_Szewczyk-BasementPlan_9-18-2012HT-only_Printat100revised2.jpg


## DIY Rustic ConcreteBunker HT Build w/8 x 18" IB subs & 25KW ##

Denon AVR-4520 11.2 | Sony VPL-HW55ES | Elite Screens 11' screen | Sanway FP-14000 | Sherbourn PA 7-350 | Buttkicker BKA-1000(3x) | Behringer iNuke NU1000DSP | GR Research LS-9 + LS-C | 8x IB318's | Buttkicker Original(2x), LFE(2x), MiniLFE(8x) | MinDSP 2x4 | 21'W x 27'L x 10'H | MiniSplit
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post #24 of 37 Old 09-28-2012, 05:18 PM - Thread Starter
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Anyone with experience with having subs front & back? Do they ever work out not needing any phase changes between the front and back drivers?

See image in post above for current idea for room.....


## DIY Rustic ConcreteBunker HT Build w/8 x 18" IB subs & 25KW ##

Denon AVR-4520 11.2 | Sony VPL-HW55ES | Elite Screens 11' screen | Sanway FP-14000 | Sherbourn PA 7-350 | Buttkicker BKA-1000(3x) | Behringer iNuke NU1000DSP | GR Research LS-9 + LS-C | 8x IB318's | Buttkicker Original(2x), LFE(2x), MiniLFE(8x) | MinDSP 2x4 | 21'W x 27'L x 10'H | MiniSplit
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They may or may not require phase changes. It's difficult to say with any certainty until you actually measure the room with the subs and see what they are doing in that room.

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The way you have those drivers organized in the current plan would, in our case, require four amps and a minimum of a one x four DSP. The DSP should provide, at a minimum delays, gain, PEQ, high shelf, low shelf, dual shelf, high pass, low pass (symmetric and in-phase) and zero difference in latency between output channels. (In addition, of course, to proper acoustic treatments in the room.)

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Do they ever work out not needing any phase changes between the front and back drivers?
Once in twenty years. Luck trumps good any day.

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Hi Shawn!

The reason I ask if it's more common than not is all 8 drivers will be on the same power amp.

Since Denon has finally released the what looks like (despite the odd numbering sequence??) the successor to my current AVR-4810ci (the AVR-4520ci), I will be upgrading to that when I complete the HT. It appears to have the ability to run Audessey on two separate Sub outputs (Audyssey Sub EQ HT dual subwoofer acoustic correction). I could split the sub output to each channel on the amp. The front four could be chnl-1 and the rear four chnl-2.


## DIY Rustic ConcreteBunker HT Build w/8 x 18" IB subs & 25KW ##

Denon AVR-4520 11.2 | Sony VPL-HW55ES | Elite Screens 11' screen | Sanway FP-14000 | Sherbourn PA 7-350 | Buttkicker BKA-1000(3x) | Behringer iNuke NU1000DSP | GR Research LS-9 + LS-C | 8x IB318's | Buttkicker Original(2x), LFE(2x), MiniLFE(8x) | MinDSP 2x4 | 21'W x 27'L x 10'H | MiniSplit
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post #29 of 37 Old 09-29-2012, 06:54 AM - Thread Starter
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Quote:
Originally Posted by Dennis Erskine View Post

The way you have those drivers organized in the current plan would, in our case, require four amps and a minimum of a one x four DSP. The DSP should provide, at a minimum delays, gain, PEQ, high shelf, low shelf, dual shelf, high pass, low pass (symmetric and in-phase) and zero difference in latency between output channels. (In addition, of course, to proper acoustic treatments in the room.)

Thanks Dennis.

I was planning on getting a MiniDSP in the future if needed. Looks like that too will be on my short list!


Thanks!


## DIY Rustic ConcreteBunker HT Build w/8 x 18" IB subs & 25KW ##

Denon AVR-4520 11.2 | Sony VPL-HW55ES | Elite Screens 11' screen | Sanway FP-14000 | Sherbourn PA 7-350 | Buttkicker BKA-1000(3x) | Behringer iNuke NU1000DSP | GR Research LS-9 + LS-C | 8x IB318's | Buttkicker Original(2x), LFE(2x), MiniLFE(8x) | MinDSP 2x4 | 21'W x 27'L x 10'H | MiniSplit
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post #30 of 37 Old 09-29-2012, 08:48 AM
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The miniDSP is interesting ... it will not provide exactly the same latency per channel regardless of the number/types of filters used in each channel.

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