IB is the ish - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 4 Old 07-27-06, 10:29 AM
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IB is the ish

After poking around on the cults forum. I decided to take a swing at IB. I made numerous sealed and ported enclosures prior to this, but never thought of IB in the home before. My IB is up and running and now in need of being dialed in. I am ecstatic at the preliminary results so far. It has lived up to my expectations. This is just a copy and paste of the adventure I logged on the cults site.

This n00b is jumping in head first. The first of many pictures to come. This is delivery day. Look at all those pretty woofs in a row. Looks intimidating already.

OK, here comes the head scratchin. I originally just thought I would do a 2stage manifold, but I also have enough room to do a line array above and across the screen area. I know there isn't a definitve answer on this, but is either application a safer bet generally speaking than the other? Is one design more susceptible to cancellation issues?

Here is my room.

Floor plan

Sketch of proposed Line array

Sketch of manifold placement.

Any tips and recomendation are appreciated

[quote author=lhreeves board=projects thread=1143731406 post=1143732947]Is the back wave of the drivers venting into an attic space? [/quote]
Yes. They will be mounted on the ceiling with the back wave in a large attic space. Sorry I didn't explain that part. This leads me to yet another question then. If I go with a line array, then they will be mounted upside down and I don't know how to determine by specs whether a sub is suitable for facing upside down. here are the specs(the 4815).

[quote author=admin board=projects thread=1143731406 post=1143738754]My recommendation is to make a long narrow manifold running the same direction as the proposed line array. Mount 4 drivers on each side. [/quote] this was another thought I had lol.

OH my the decision are overwhelming ;D

Here is a picture of the beginning of the manifold. I hate stopping midwork to take progress pix, so you will have to bare with me on no play by play detailed log. I got the meat of the manifold pounded out. It is 72" x 16.5". Tomorrow I work on cutting out the speaker baffles and bracing the inside with dowels. Next weekend I move to the attic and start pounding out the install.

As promised, I got the baffles cut and bracing put in. I will probably brace the outside with 2X4 framing once it is situated on the joists. So here is where I sit for now.

Update time. This update brings many changes thanks to an oversight. When I first went into the attic before starting this project I mapped out and measured where I wanted this and how I could get it there. The original manifold I made would have gone there no problem, however I never bothered to pull back the insualtion when I was measuring and planning. When I got ready to huff this monster up there I scooped away insulation from the area. It just so happens that this spot has every wire in the house intersecting there going to my OnQ panel(Lan, Alarm, romex, cable, surround sound, and something that I have no clue to) in the master closet. There wasn't enough slack to reposition them either. I wasn't rewiring 20 different wires for numerous reasons. So a revision and modification to the manifold was necessary. So that is where I am at now. A new manifold ready to go in tomorrow.

OK. It is all finished, but unfortunately I had the digicam out. For some reason it is making weird lines across. You will all have to be happy with pictures of progress from last weekend when I got it installed in the attic. When I get a new camera, I will post the finished pictures and the grill I made.

Preliminary thoughts are that this thing goes very low. Its presence is not obnoxious like most peaky sealed and ported enclosures. It blends well with the other speakers. I will need to play with it and fine tune it by figuring out the best settings for the para=eq and crossover. I put in a few select movies and tested it out. This subwoofer setup isn't heard as much as it is felt. walls shake and a heavy feeling comes across. On music it is just absolutely flat. Not one note comes across much louder than the rest. I will get more in depth when I can put up the finished pictures. By then I should have it dialed in all the way and tested a lot of material. I should probably invest in an EQ instead of relying only on the para built in to the amp. I'll see after I figure out how to graph the response. I have never done that. Does anyone maybe have an ecel file that I only have to plug numbers into and it produces the graph?

OK, that is it for now. I will update here with finished pics when a new cam arrives. Being ready to figure out what I need to tame the beast has lead me to this forum, home of the room eq wizard
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post #2 of 4 Old 07-27-06, 11:38 AM
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Re: IB is the ish

Nice work DeMan... impressive!

I like the way you did the manifold design.

Are those Rockford Fosgate subs?

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post #3 of 4 Old 07-27-06, 01:55 PM
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Re: IB is the ish

I'll see after I figure out how to graph the response. I have never done that. Does anyone maybe have an excel file that I only have to plug numbers into and it produces the graph?
Sonnie provides an Excel graph for use with any one of the three Radio Shack SPL meters and provides the correction files HERE. Test Tones may be found HERE

Or, you can use Room EQ Wizard and do it much more accurately - also found HERE.

Answers to all questions regarding a BFD parametric equalizer (a must in your case) or carrying out a frequency response with tones (or the superior method of using REW) are found HERE.

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post #4 of 4 Old 07-27-06, 02:29 PM
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Re: IB is the ish

Sonnie wrote:
Nice work DeMan... impressive!

I like the way you did the manifold design.

Are those Rockford Fosgate subs?
Yes the are the original HE models 200RMS each. I got them for 70 each and then shipping was like 26 for all. That was my main decision maker. For the price they do the trick admirably. It was a sale woofersetc was running. Right now they have them at 80 which still isn't bad IMO.


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