Need Help from IB people (1 Viewer)

[Rick Guynn]

OK, with my recent sub/amp problems I have been considering replacing/upgrading my sub. Somehow, I came across this infinite baffle concept and began reading up on it. The more I read, the more I like it.
In particular I like the setup done by Rich Kraus, http://home.tampabay.rr.com/kraushome/IB.html especially in light of the comments from Mike Knapp.
My problem thus far is this: My current HT room already has some holes in the ceiling from an ancient (35+years) distributed music system in the house. They had ceiling-mounted full-range speakers in many of the rooms. This would be great except that these holes are situated over my current listening position rather than near the mains (other end of the room).
Question 1: would mounting the IB sub at this location create way too much localization? If I could XO at 60Hz, would that alleviate the problem?
Question 2: There are 2 holes arranged in the ceiling at this location (almost a stereo-type arrangement). If I were to do a two-tempest IB, could I mount one in each hole, or would it be better to make a box like Rich's and manifold them through one?
Question 3: I read something on the IB board about reinforcing the joists if they are normal 2x4's, shed any light on that?
I really think this could be a neat project...
Thanks ahead of time.
Rick

 

[Rick Guynn]

I know there are some IB people out there!

 

[Rich Kraus]

rick, thanks for the kind thoughts
what shape is the room (LxWxH)? where are these holes, and how big are they? where is your main speaker array (what wall is it on?)
idealy the outlet to the IB should be as close to centered between the mains as possible. (yes the 60hz crossover will help, but why risk an obvious localization issue?)
if you use the "stereo" holes (assuming they are well placed with rtegards to your current mains) then youll have all the cancelation issues that come from multiple subs. AND you have to look at the drivers (harder to make look like an A/C vent or something)
me? i think id plate over the holes in some way to avoid "leakage" and start over with a fresh location using a manifold.
as for re-enforcing the 2x4's, thats why i like the opposing drivers in the manifold. helps cancel out any physical vibrations at the install point. on mine the "load" is spread between a joist, a wall cap and a wall stud. YMMV

 

[Rick Guynn]

Hi Rich!

Well, the room is probably an acoustic nightmare. It is about 15' x 23'.



..../

___/ ______________

|M......TV.......M|

|.................../

|................. /

|.................|

|.................|

|.................|

|.................|

|...o...LP...o....|

|.................|

|.................|

|s...............s|

¯¯¯...¯¯¯¯¯¯¯¯¯¯¯¯¯



M=mains

s=surrounds

LP=Listening Position

o=hole locations

The back of the room has a bar/counter area that separates it from the kithchen, so it is partially open.

Now, the wife has given me the ok to go ahead and cut another hole in a more ideal spot, but only if we get the ceiling redone in the process (fix the current speaker holes and remove the acoustic tile - bleh). I am not sure how long this might take, so I might still try the output through one of the current holes for the short-term.

Thanks,

Rick

 

[Rich Kraus]

hey- tell your wife shes letting you do the ideal thing. that is, shes letting you try the IB in more than one spot
most of us only get one crack at it.
actually since you have to re-do the celing anyway to pass SAF you could try it SEVERAL places
seriously now, i think id just go straight to a manifold right over the TV. i believe unless your crosover slope is REALLY steep, your going to locate the subs right over head.
(also kudos on getting the ASCII art to work, most screw it up. )

 

[ThomasW]

Rick G. you've got mail
ThomasW

 

[Rich Kraus]

aw thomas, copy your reply here too if im full of it in my thinking somewhere you gotta let me know

 

[ThomasW]

Rich Kraus
I agree with you post, so no, no secrets
Rich G. emailed me with some questions and I answered them. All the info in the email has been covered on the Cult Forum at one time or another

 

[Rich Kraus]

ok, just making sure i wasnt leading somone astray. my brain gets a bit fuddled from time to time and somone needs to keep me straight