Room Treatment Question, lost the lowest bass notes.


This is what I have:
25 x 40 ft room 12 to 15 ft tall ceilings

The stereo is on the narrow wall on one end of the room. (I can move it 90 degrees if needed).
I have a pretty good system, Wilsons, Audio Research, VPI, I do not think I have to give what components are. They are considered high end.
Here is my problem.  My seating position is about 15 ft away from the speakers.  The lowest notes that I know that are on the recording are NOT being presented. For example: Lyle Lovett - She has already made up her mind.  There are a few super low notes on the song. I have heard them before when I had a lesser stereo.

I did find that when I stood near the open door at the far end of the room, I can hear them. But when I move towards the center of the room near the far wall, They go away. It is very easy to hear the drop off.

I spoke to a couple of HiFI shops in the LA area. One mentioned a Node Cancellation. I do not know what that is.
I added (2) 2 x 4 section of sound absorption material high on the back wall. The only conclusion I came up with is the low notes are being cancelled once they bounce off the back wall and head back to the front wall. Stop the bounce and the low note have a place to go.

I am thinking correctly here or am I just reaching for straws, and I am. 

I am no scientist. Please answer in non scientific terms.

Thank you. 
Bill 


128x128bill_peloquin

Showing 2 responses by rego

Also you may want to contact Wilson for some insight and / or helpful info ... you already have insight into what why and how to best correct.
@bill_peloquin, The 'Wilson' setup is demonstrated (somewhat) in a video by Wilson.
https://www.youtube.com/watch?v=UOI8py0DAC8&t=358s
The process described begins with finding a 'neutral zone' and this can be best demonstrated with an assistant vocalizing a sentence / tone (an octave or  two). First against the wall and then moving into the room five inches at a time (or less). Until voicing (literally) sounds normal (like outdoors).
One note: Vocals is only one third of the audio spectrum.
Highs and lows also need to be addressed separately.
Also finding the correct distance between L/R (mains) is significant.
I would suggest that the distance should be one that gives the best perceived power for a given volume (same).
Set up the Mains first without the Center Channel.
Integrating the Center Channel afterword should be easy especially if you are able to adjust in the time domain.
Also notice that there is no 'room treatment' shown in the video!
The Wilson line would be a baffle less type design (generally) with a more uniform radiation pattern.
Once a zone (for placement) is located fine adjustments (inches / cm) can be made. Toe in as well (a further discussion).