Sorry Guys, I've been neglecting my thread
I'll get more pics of the rest of the room posted soon, back included
RT.. Wow! thanks for the kind words. I sincerely enjoyed your visit and our conversations, it was refreshing to show the theater to someone who appreciates all the various aspects of what goes into a room.
Jeff C.. Ah.. proof of life.. been waiting on your star ceiling update. Curious about your impressions of the light engine you chose. I've been contemplating a small star ceiling that I can implement with out having to run fibers back to a large illuminator.
Originally Posted by J_P_A
I'm considering an IB for my space, so this comment caught my attention. Seems like conventional wisdom on the other forums is to put it front and center. Where would you recommend putting an IB?
BTW, this is an awesome theater!
JPA.. Please dont base any of your design desicions on my incoherant ramblings.. my earlier post was more of an overall refrence to having only a single sub on the front wall (like most) and the need to add the triads to smooth the response. Additionally at that time I was thinking that my manifold height was causing a frequency notch at my previous seating position because it was equidistant to both the ceiling and the side walls.
Regardless of the placement of the IB (or any sub), I think the important thing to take away from the Welti paper Moggie posted is that Multible subs, with locations other than just the front wall, will be required to reduce the total variation across the seating area.
Using the Harmon paper to illustrate my overly simplistic, less technical, understanding of the "multiple subs" concept:
Configurations 1-5, 8 & 9 in investigation 4 from the paper where all subs are located on the front wall only, the results are similar for the MIN-Max variation regardless of the number of subs used. Although we can increase the number of subs or increase the SPL (think IB) at these locations, it wont necessairly (and most likely will not) improve the overall response across all seating positions becasue we are just adding more energy to any existing modal issues, additionally we end up needing to add more treatments to suck this excess energy back out of the room.
Another important behavior from the various placements can be observed in configurations 21 and 23 from investigation 6. (disregard SBIR issues with this placement for now) Note that although only a single sub is used, they have been moved away from the boundries more towards the center of the room and this configuration exhibits less min-max variation than configurations 22,24,25 where the subs are located "on" the front wall.
When the sub is moved away from boundries towards the center of the room the less energy we are feeding the room modes, so we get less variation in the SPL across a larger area, Although it's not practical in most situations to have a sub in the middle of your seating area, this general concept becomes important when considering the behavior of multible subs.
When two subs are located, say in opposing locations, such as in configuration 6, the resulting interaction of the 2 subs is very similar to the result you would get by placing a single sub in the center of the room.
These opposing subs create a single "imaginary sub" at a point between them, and through interfearence and reinforcement we in essence have moved thier combined output to the center of the room, thus realizing a similar reduction in the SPL variation that is seen with a sub actually placed away from the boundries.
And lastly as Adam pointed this consistancy does not necessairly translate into good but once the variation has been minimized, then parametric Eq can be used to flatten the response.
Also note that although the harmon paper emphasizes an even number subs at symetric locations there are other approaches that can be used to create this imaginary sub and a consistant response at your seating locations that may offer more flexibility in meeting specific needs/constraints of a room
I've not had any alcohal yet today, so hopefully this was somewhat coherant, I realize this is an extremely overly simplistic view of a complex subject, but this is how I got the need for "multiple subs" to fit into my
box. Maybe others can correct any my misconceptions.
Originally Posted by Moggie
This research paper is quite easy reading.Harman Kardon Paper
According to this center wall placement is not necessarily bad; actually two subs center of two opposing walls is one of the recommended solutions.
Thanks Moggie.. Heres another refrence from cedia that has some cool depictions of the spatial deviation from various sub configurations.http://www.cediacrosspoint.com/conte...r-optimization
This one was eaiser for me to try to grasp ... because of the pictures