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Post by chopshop1 on Apr 12, 2012 10:43:39 GMT -7
Hey All,
First of, a big thank you to Thomasw and all the members here for the readily available info. With weeks of reading, couple of threads started on various forums, I think IB is going to be the way to go for me. My house is still being fromaed, so no build thread yet, but I will start one once I can.
My questions are with regard to placement. I have read an incredible amount and have gotten some recs on AVS, etc, but since this is the home for IB, I wanted to ask some here.
My room is 19'6" fornt to back and 25'8" long. The ceiling start at 9' and vault to 16' at their highest point(change ceiling height from original plan). My limitations for the IB will be as follows: It must be a floor IB, which will work out fine seeing as the room below is about 3600ft3. The bigger limiting factor is the actual placement on the floor. I really need to keep manifolds on the front, 25'8" long wall. My plan is that 8 18" fi IBs will fit the bill for output. I could do four manifolds with 2 in each, or like some I have seen lately, do two manifolds with 4 drivers in each. I can place them anywhere along the front wall, but thats it. Am I playing with fire here??
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Post by ThomasW on Apr 12, 2012 11:38:07 GMT -7
Hi,
That's a bit of a bizarre room configuration. From an acoustic standpoint long and narrow rooms are better than shortish and wide.
And you'd get more even in-room response with drivers scattered in the room.
That said.
If front wall is the only option, divide the front wall into 1/3rds and put the manifolds there...
There's no price break after buying 4 drivers. My suggestion is build 2 manifolds each designed and sized for 4 drivers but only put 2 drivers in them. Cap off the holes for the other drivers.
Now build the entire room including all acoustic traps and start listening. If you really think you need the other 4 drivers go for it. You may find 4 drivers is plenty provided the room isn't to loosy
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Post by chopshop1 on Apr 12, 2012 13:35:48 GMT -7
Thank you very much for the suggestion! I guess I should have mentioned that it is a family room with vaulted ceilings. What about it is odd?? I think I understand what you mean....the reason it is configured this way is due to the fact that it is the main family room. It just makes for a much more "spacious" feel to the room. In a room that is over 6000ft3, I would love to think that 4 would be enough, its just such a large room.
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Post by ThomasW on Apr 12, 2012 19:30:32 GMT -7
In a room that is over 6000ft3, I would love to think that 4 would be enough, its just such a large room. The number of drivers needed depends upon the desired output levels and the distance from the listening position to the subs. |
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Post by chrisbee on Apr 12, 2012 23:08:03 GMT -7
Thomas, could you expand on your doubts about this room? It would, on the face of it, seem ideal: Large, but not vast. With no simple factors between the room dimensions. Offering an essentially neutral character with a good, even spread of eigentones. A high, variable height, vaulted ceiling will avoid the usual problems associated with the two largest parallel surfaces. Which are usually closest together in most domestic rooms. Your average audio punter would say that you couldn't ask for a better room. So, what's not to like?  |
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Post by chopshop1 on Apr 13, 2012 6:27:07 GMT -7
I like the sound of that. I am still learning much, so please bare with me on this, but that is what I thought about room demensions as well, but also don't know much about the other factors. I just knew not to have numbers that were multiples of each other.
On a side note, the manifold openings are going to be quiet big for these. Does anyone have good info on some classy covers, at fabric, etc. that could dress these up??
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Post by ThomasW on Apr 13, 2012 6:39:38 GMT -7
Thomas, could you expand on your doubts about this room? Nothing is a deal breaker. If the priority is getting the best sonics, the main speakers should fire the longest dimension in the room. Vaulted ceilings can be problematic depending on their location and whether or not they're symmetrical, or asymmetrical. As an example the vaulting in my family room causes a 40Hz null at the listening position |
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Post by ThomasW on Apr 13, 2012 6:41:44 GMT -7
On a side note, the manifold openings are going to be quiet big for these. Does anyone have good info on some classy covers, at fabric, etc. that could dress these up?? Look in the generic design/build/install FAQ section. |
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Post by chopshop1 on Apr 13, 2012 6:43:09 GMT -7
Thanks Thomas, i have. I was just sort of wondering if anyone had anything additional that has not been posted.
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Post by chrisbee on Apr 13, 2012 7:29:06 GMT -7
Vaulted ceilings can be problematic depending on their location and whether or not they're symmetrical, or asymmetrical. As an example the vaulting in my family room causes a 40Hz null at the listening position I'm a martyr to sloping ceilings myself. I have a sink hole at 14Hz in which you could lose an aircraft carrier. Oh wait, it's the stairwell. ;D I always recommend listening across long rooms. Listening along the greater length always forces the speakers into the corners. Unless, of course, the room is the size of a ballroom. |
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Post by chopshop1 on Apr 13, 2012 8:03:43 GMT -7
The problem with that is that the intended layout for the room(furniture, etc.) does not lend itself to placing my viewing wall on one of the shorter dimesions and listening down the legnth of the room. I would love to, but with the furniture, it then makes a rather large room start to feel narrow.
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Post by chopshop1 on Apr 13, 2012 11:33:07 GMT -7
So I have been reading a lot... The latest question I have developed from my reading is for Thomas. The 12 shiva install you did utilizes a long manifold(top to bottom) and a relatively small looking opening in comparison to the numebr and size of the drivers. I remember reading that the mianfold should be kept as "short" as possible and also warned of making the mouth too small. My goals are to keep my manifold openings as small as possible without giving up the optimum install. What drawbacks and work arounds were there to that install of yours?? thanks in advance
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Post by ThomasW on Apr 13, 2012 13:20:47 GMT -7
My 12 driver IB was built in 1999. There were no reasonably priced 15" or 18" drivers at that time. So I went with 12"s in as compact a manifold as possible.
It's 42" tall, so in theory given the 'pipe' length there is cancellation around 140Hz as a result of the distance between the top and bottom drivers. Of course it's never run that high so it's not an issue.
It was limited to a 14.5" square opening due to H2O, the natural gas line, electricity and phone line all being way to close for comfort....
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Post by chopshop1 on Apr 13, 2012 19:38:34 GMT -7
My 12 driver IB was built in 1999. There were no reasonably priced 15" or 18" drivers at that time. So I went with 12"s in as compact a manifold as possible. It's 42" tall, so in theory given the 'pipe' length there is cancellation around 140Hz as a result of the distance between the top and bottom drivers. Of course it's never run that high so it's not an issue. It was limited to a 14.5" square opening due to H2O, the natural gas line, electricity and phone line all being way to close for comfort.... So I guess my question is: could I build a manifold that is 42" tall with a mouth that is 14.5" x 22" with 4 18" fi drivers and expect it to perform at 90% or better than one with half the height and a bigger mouth, in the 80hz and down region?? |
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Post by severianb on Apr 13, 2012 20:03:53 GMT -7
Thanks Thomas, i have. I was just sort of wondering if anyone had anything additional that has not been posted. Check out my build thread, the place I list (Atlanta Supply) has floor grills (in stock) in any size you want. There are lots of places that build custom floor grills if you don't mind paying a little more and waiting. |
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Post by ThomasW on Apr 13, 2012 21:16:08 GMT -7
You ask for history and info, that's what was provided, it's not something to emulate.
Post pictures and dimensions of the crawl space, along with a copy of the listening room floorplan.
Then we'll design your subs.
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Post by ThomasW on Apr 15, 2012 8:49:39 GMT -7
Do to misspelling "fromaed" instead of framed, I didn't realize this house is a long way from being completed. So forget about my request for pics, I know what stud-walls look like.
Do post a copy of the main floor elevation from the floor plans
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Post by chopshop1 on Apr 17, 2012 7:09:55 GMT -7
Do to misspelling "fromaed" instead of framed, I didn't realize this house is a long way from being completed. So forget about my request for pics, I know what stud-walls look like. Do post a copy of the main floor elevation from the floor plans I will do my best to get some pics up today...what do you mean by the main floor elevation?? |
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Post by FOH on Apr 17, 2012 8:25:00 GMT -7
Do to misspelling "fromaed" instead of framed, I didn't realize this house is a long way from being completed. So forget about my request for pics, I know what stud-walls look like. Do post a copy of the main floor elevation from the floor plans I will do my best to get some pics up today...what do you mean by the main floor elevation?? Ah,...been reading blueprints for thirty years. Perhaps a bit rusty but..... .....An elevation drawing is one showing the space as viewed from the front, rear or side,...not down as one would include as a floor-plan. Oftentimes there will be a section elevation also, whereby one views the room as if it were "sliced" open, and all the vertical elements of the space are detailed. For our purpose here you would see the flooring, the floor-joist height, clearances etc. A front elevation of the house would show the front door, windows, and every vertical detail as seen from a one dimensional frontal view. A sectioned view of the main floor front elevation would strip away the entire front face of the structure, allowing every vertical detail inside to be seen at any given cut point. Details, that all. Attempting to describe something in typewritten form just doesn't cut it. Pic, details,....etc. Hope this helps |
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Post by chrisbee on Apr 17, 2012 8:25:20 GMT -7
I will do my best to get some pics up today...what do you mean by the main floor elevation?? I think He means "floor plan." As seen from above. Thomas' usual viewpoint. ;D |
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