Newbie question

[Bob_99]

I tried to login into one of the IB website to get basic information but was not able to get a key code so I'm hoping not to test the patience of this group with a really simplistic question. When considering an IB project, how do you determine the location in the ceiling that will give you the best results? And should multiple locations be considered?

Thanks.

Bob

[Sonnie]

This is actually a very good question.

If you have the means to do so... place a sub in your listening chair and start taking measurements with REW about 6"-12" from the ceiling locations that would be available to you for an IB driver. These will very close to the responses you will have to deal with if you install your drivers in those locations.

This is what I did when I was considering installing an IB.

Here's what I did (these are edited excerpts copied from my post at IB Cult):


First off I scoped out the potential mounting locations and did some measurements. ALL BY MYSELF I lifted one of my PB12-Plus/2's up into the recliner and let it relax for a few minutes...




Then with the sub reclining and me with one hand holding the mic taped to a broom stick and my other hand working the computer I took some measurements.

I basically checked all across that front ceiling and got the same response down lower all the way across about every two feet. I did not go all the way in the corner because there was no way I could have mounted it on the outside wall with the roof being so low in the attic. I was going to have to stay close to center if I followed through. I noticed that I was getting the same measurements with the SVS subs in their locations as I was getting at the location above them at the ceiling with an SVS in the recliner.


Here are the five different response measurements from the five spots across the ceiling...




Since I was getting those same measurements at the ceiling as I was getting with the subs on the floor in their respective locations, I decided to try placing one sub in the back of the room and leaving the other in the front and taking some measurements. I ended up having to crossover the rear sub at 60hz to get the area above 60hz looking better (I suppose there were some cancellation issues) but this is the unfiltered response I got...




Since the measured responses from the locations near the ceiling were almost identical to the measured responses of where were subs were located on the floor, I could deduce that I would get the same measured response from installing the IB drivers in the ceiling above the floor locations of my subs in the front and rear.

This is actually where I first got the idea of building an LLT for the rear of the room... after discovering it would be easier than tackling the attic installation, not to mention less expense and better low end response from the LLT.

So... if you have the means, I would definitely try to measure several potential locations to see what you would be dealing with response wise.

[Bob_99]

Sonnie,

First of all, thank you for responding to my question and providing a really excellent answer (as usual).



Secondly: I am totally in awe of anyone who can get that sub into a chair.



Bob

[Sonnie]

You are quite welcome... and I did find a few muscles I had no idea I still had.