sub acoustics by design....question

[bent77]

first of all, happy thanksgiving to all!! it has been a while since my last visit here.

My theatre room leaves a lot to be desired acoustically...dont they all..... I have found the best placement for my RSW 15 but it is all the way across the room ( a combined living/dining space or great room if you will ) by the dining room table. This is not the best location acording to my wife, and the idea of any room treatment is out. If I move the sub anywhere else in the room it creates a node right where my listening position is. I lose all audible frequency tone but keep the impact----I can feel the inital strike of a concert bass drum but I cannot hear the ring.

I realize that the acoustics of the room are determined by the size, construction, and design of the room but do different designs of subs "act" differently? Would I experience the same nodes with a sealed rear firing sub versus a ported front firing one? How about the new triangular klipsch subs.

I have no experience with this so I am asking some of you experts out there!! thanks for the help!!

[TheEAR]

I would position the sub (in a safe maner)elevated on a small table,play a 40Hz tone.Even at lower volume.

Crawl around the room and listen and take notes where the bass is the most to YOUR liking.Then position the sub in the best spot and listen at listening position.Do not worry how it soundsin spots you do not sit.

For bass to be even around the room(more or less)you need to presurise the room,and in normal homes using one sub this is next to impossible(the exception being a tiny room and a potent sub).

Good luck

[DrWho]

The only variable that could possibly affect the way a speaker interacts with the room is its directivity. Basically what magnitude and what angles the sound eminates from the speaker. The problem with subwoofers is they are very small relative to the wavelengths they are reproducing - meaning they have no choice but to spray sound in every direction. This basically means you have no hope (how reassuring) []

I don't know how the new RT subs work, but there might be some hope with the new adaptive room correction stuff...I would put more faith in that than trying to go with different subwoofer topologies - especially considering acoustical treatment doesn't seem to be an option.

Maybe a few more alternatives you might consider...

1) Move the listening position

2) Play with the phase control on the subwoofer. Chances are you're noticing issues in the upper passband of the speaker's response. I would start by setting the mains to large (to introduce as much overlap as possible) and then tweak the phase on the sub until you fill the holes. If this doesn't work, or you don't have continuous phase adjustment capability, then you might look into changing the subwoofer distance in the reciever's setup menu (assuming that your reciever allows you to set this independant of the mains).

3) Moving furniture around - I know this sounds crazy at first, but the furniture in the room is certainly going to affect the way the sound moves around in the room. Sometimes moving a couch or chair is enough to change things for the better. This is when it's good to have kids - let them have a sleepover and encourage them to rearrange the furniture in the night. I doubt your wife will want to move everything back by herself []