If you place your bass cab the wrong distance from the walls or floor you will make getting a good tone impossible. Here's a great excerpt about this:
“Boundary Cancellation throws another wrench into the cogs. If the bass cab is not in a corner, there will be a notch in the frequency response that is related to the distance from the cab to the wall:
2 feet will notch at ~140Hz 2.5' at ~112Hz 3' at ~95 Hz 3.5' at ~ 80Hz 4' at ~ 70Hz 5' at ~ 57Hz 6' at ~ 47Hz 7' at ~ 40Hz 8' at ~ 35Hz
So, no matter where you put the bass cab, try to place it within 2 feet of a room boundary (wall, floor, ceiling), or at least 8 feet from a boundary.”
If you're trying to fill a venue with bass you need to take advantage of boundary reinforcement - each boundary gives you another 3dB - brute force will not get you there (which is why outdoors gigs need much more PA support).
Boomy stages can be help by isolation pads to reduce coupling between cab and stage. The GRAMMA is the standard. A cheaper and more portable solution is a length of Auralex PlatFoam, cut into two lengths the width of your cab. Use one for tilt, two for full isolation. Available from Studiospares. The GRAMMA is a piece of carpeted plywood supported by two lengths of PlatFoam.
Just to recap the room acoustics thing, bear this in mind: A typical 2×10” will have sensitivity of 96dB and power handling of 200W (this are real world specs, not manufacturer's bs). This will give a max SPL of 119dB. A matching 4×10” will have 3dB more sensitivity and twice the power handling, giving another 6dB of max SPL - i.e. 125dB.
Take the 2×10” from just sitting on the floor and move it into the corner and you gain 3dB from the back wall and 3dB from the side wall. Max SPL is now 125dB - equal to the 4×10” when away from the walls. Now take the 4×10” and position it 4' from the back wall and 5' from the side wall - it now loses over 3dB from ~70Hz to ~57Hz, so it now has less max SPL than the correctly positioned 2×10”.
This isn't just techy geeky theory - it matters in the real world!
