barefoot
barefootsound.com
The recent "Studio Foam Behind Monitors" thread has prompted me share some ideas on flush mounting monitors. I posted a detailed explanation of rear wall effects in that thread, which are some reasons why I think flush mounting is such a good idea. Here I'd like to explore how best IMHO to actually do the mounting. Most likely none of these ideas are new. I just though it would be interesting to apply my experience with loudspeaker design and acoustics to this problem.
Since everyone's situation is unique, I'll just lay out my general design principles and give a schematic representation of what I'm talking about. The details of any particular implementation are left up to you and your own ingenuity.
Schematic
This schematic depicts a top cross section and front view of the system.
Design Principles
1. Create an opening in the inner wall (a) or soffit which is large enough to accommodate the monitor or any monitors you may use in the future, plus some room for sound absorption material. Building a larger space than what you presently need gives you the flexibility to upgrade. Avoid building any structures which directly couple the inner and outer walls.
2. Rigidly mount the monitor to the outer wall (b). Mounting to the outer wall isolates the cabinet vibrations from the control room. A rigid mounting also effectively increases the mass of the cabinet which can add to linearity, but this is minor. The face of the monitor should be flush with the inner wall.
3. Mount a rigid bezel (blue) flush with the monitor face and inner wall. The opening should not contact the monitor cabinet, but the gap should be no more than 3mm (1/8 inch) . The more massive and rigid the bezel the better. You might consider sealing the gap with some sort of gasket, but this is both unnecessary and detrimental. Any gasket will increase the transfer of vibrations to the bezel, therefore, effectively increasing the cabinet radiation surface area. Discontinuities less than a quarter wavelength will have little effect on wave propagation. 3mm is less than 1/5th a wavelength at 20kHz, so audible diffraction induced by the gap isn't an issue. When you upgrade your monitors you'll just need to modify the mounting brackets (green) and bezel.
4. Fill the space in the mounting cavity with sound absorbing material (pink). This will help absorb sound radiated from the monitor cabinet.
Conclusion
You might have noticed that this methodology centers around isolating the monitor cabinet energy from the control room. This is a sorely neglected subject in pro audio. Loudspeaker cabinets are almost invariably under constructed, resulting in significant coloration. This is often looked at with great skepticism, but don't underestimate the amount of sound speaker boxes can emit. Tap your knuckles on the side of your monitors and listen. Large main monitor boxes, as well as plastic, fiberglass and metal horns are particularly egregious offenders. Professional sound reinforcement speakers are absolutely abysmal (except for maybe Meyers, which I'd give a B- on this point).
If you follow these design principles, I think you'll hear a noticeable difference from a simple flush mount. It would also be worth improving the monitor cabinets directly, but that's another subject.
have fun
barefoot
Since everyone's situation is unique, I'll just lay out my general design principles and give a schematic representation of what I'm talking about. The details of any particular implementation are left up to you and your own ingenuity.
Schematic
This schematic depicts a top cross section and front view of the system.
Design Principles
1. Create an opening in the inner wall (a) or soffit which is large enough to accommodate the monitor or any monitors you may use in the future, plus some room for sound absorption material. Building a larger space than what you presently need gives you the flexibility to upgrade. Avoid building any structures which directly couple the inner and outer walls.
2. Rigidly mount the monitor to the outer wall (b). Mounting to the outer wall isolates the cabinet vibrations from the control room. A rigid mounting also effectively increases the mass of the cabinet which can add to linearity, but this is minor. The face of the monitor should be flush with the inner wall.
3. Mount a rigid bezel (blue) flush with the monitor face and inner wall. The opening should not contact the monitor cabinet, but the gap should be no more than 3mm (1/8 inch) . The more massive and rigid the bezel the better. You might consider sealing the gap with some sort of gasket, but this is both unnecessary and detrimental. Any gasket will increase the transfer of vibrations to the bezel, therefore, effectively increasing the cabinet radiation surface area. Discontinuities less than a quarter wavelength will have little effect on wave propagation. 3mm is less than 1/5th a wavelength at 20kHz, so audible diffraction induced by the gap isn't an issue. When you upgrade your monitors you'll just need to modify the mounting brackets (green) and bezel.
4. Fill the space in the mounting cavity with sound absorbing material (pink). This will help absorb sound radiated from the monitor cabinet.
Conclusion
You might have noticed that this methodology centers around isolating the monitor cabinet energy from the control room. This is a sorely neglected subject in pro audio. Loudspeaker cabinets are almost invariably under constructed, resulting in significant coloration. This is often looked at with great skepticism, but don't underestimate the amount of sound speaker boxes can emit. Tap your knuckles on the side of your monitors and listen. Large main monitor boxes, as well as plastic, fiberglass and metal horns are particularly egregious offenders. Professional sound reinforcement speakers are absolutely abysmal (except for maybe Meyers, which I'd give a B- on this point).
If you follow these design principles, I think you'll hear a noticeable difference from a simple flush mount. It would also be worth improving the monitor cabinets directly, but that's another subject.
have fun
barefoot
