ok here , lets take a typical example, since most of us live in HDB. Letâs assume the room is 4m x 4m x 2.4m
Lets just take a simple example above and assume the speakers run full range down to 30hz and you dont use a subwoofer.
The left/Right speakers are placed symmetrically in the room as you can see they form the triangle at 60 degrees at MLP. We cannot move these speakers, else we lose the stereo image. So to maintain that balance, we can only either move our MLP forward or backwards. But note that no matter how one moves the MLP, we cannot escape the standing waves. this is a typical example in any HDB room with concrete walls, we now have a big smiley face from 43hz down to 72hz, midbass is Non-Existent in this full range set up!
Note that ultimate goal for a good sounding system, does not lie just in the amplitude response alone, there are many other factors that i will cover later. But note that we want a smooth response in the bass region, so various content when played back, sounds smooth across the bass region. So for the sake of this discussion, we want to achieve a âperceivedâ flat target. Perceived doesnt mean ruler flat response, but rather one that has equal loudness at MLP from the range of the given frequencies.
Lets dive in deeperâŚ
Like it or not, the room is part of the equation, what we hear, depends a lot on the room as well. The above shows
Axial â standing waves between two walls, can be front back left right
Tangential â standing waves between 4 walls, left right front back
Oblique â standing waves between 6 walls, left right front back top bottom.
Now we all know, Killing the Axial Mode, takes care of the Tangential and Oblique modes at the same time in some way.
Running the speakers full range, you cannot move the speakers. You are now at the mercy of the room modes. Like it or not, you are stuck with these modes (see above sample). This is where you stop and go, ok nothing i can do, its the room. Heng Sway my room is like that. Suddenly one is demotivated.
WAIT⌠Hang onâŚ
How about we use the speakers as small, and we send that bass frequencies below 100hz to the subwoofers. We can then play around with subwoofer placement. We are no longer restricted to that location where i need to maintain the stereo image
See what happens now,
Using a dual sub approach, lets say the subs dig down to 10hz, i place them at diagonal corners. Notice the Dip is still there at 100hz? But now i have the option to use my speakers in another position / move MLP forward backwards so that it doesnt have a dip at 100hz, but hey, i am getting very smooth response across from 20hz to 100hz. What looks like a bass suckout problem, is now resolved with utilising the subs. You are no longer at the mercy of the room.
Did it solve the problem? Yes it did! A suckout is a problem, and we need to fix it, else there is no bass at MLP
Do i need to dive in further? with Headroom, distortion ? i can break it down further. I back what i say with a scientific calculated approach. This is what the top guys are doing, be it the UK Integrators, the US Integrators, they are professionals, and i like to follow what they have done.
Of course we cannot stop someone to do anything they want to do, as we know, it is their equipment, their money, their effort. As much as i would like to say nobody can tell you how you should dial in the system, i personally, prefer to take the path where i have less problems to deal with, or to even begin with.
Yes we have helmhotz, tuned traps etc. Those are not cheap really. we can use pressure devices , as the square area goes up, the cost goes up as well. Why not use the subs to solve these pressure issues in the room? its already proven.
