Basement studio?

  On 2/6/2013 at 11:18 PM, elusive4 said:

any small acoustical space is going to suffer from modal issues of which must be addressed if one is to make accurate mixing decisions with respect to the low end response. dimensions yield poor/overlapping modal distribution. boundary material (highly resistive) will compound these issues and allow resonances (modal ringing) to persist much longer (LF decay times).

 

and this is irrespective of the high-gain early arriving destructive indirect specular energies that must also be addressed to maintain a semblance of accurate localization, imaging, and intelligibility with respect to the direct signal.

  On 2/6/2013 at 11:52 PM, elusive4 said:

 

  On 2/6/2013 at 11:16 AM, Squee said:

Yeah, put up some sheets (thick ones or multiple layers), put some big foam bricks in the bottom corner of the room (behind your speakers), and do some sweeps to see what frequencies bounce around the room.

a recommendation for objects insufficient in design to achieve a set goal.

 

any porous material to be used as a broadband absorber needs to be sufficiently thick as to be placed (spaced away from rigid boundary) into areas of high particle velocity for the lower (longer) wavelengths. the erroneous recommendation and application of thin porous absorbers ("sheets", "carpets", "rugs", "foam") is far too common a theme. pressure maximizes at a rigid boundary as particle velocity goes to zero (the components are inversely proportional). porous absorbers rely on high (relative) particle velocity in order to convert kinetic energy into heat via friction as the soundwave traverses through the porous structure - attenuating the signal such that the interference caused by superposition/summation is less destructive.

 

a porous absorber designed and applied to attenuate a broadband indirect specular reflection must be sufficiently thick (and large, with respect to wavelength) to be effective to the lower schroeder cut-off; typically 250-300hz dependent upon boundary dimensions. a thin porous absorber will attenuate the mid-HF band of the indirect specular reflection, but allow the lower band to persist - essentially turning the absorber into a low-pass filter (coloring/filtering/eq'ing the reflection).

  On 2/6/2013 at 11:16 AM, Squee said:

>and do some sweeps to see what frequencies bounce around the room.

what is important is the time-arrival and gain of the indirect energies with respect to the direct signal. small rooms deal with local areas of variable pressure with respect to the ambient noise floor: modal resonances, non-resonance interference (SBIR), and focused specular reflections.

 

  On 2/7/2013 at 12:33 AM, elusive4 said:

once you know the total time of flight for the indirect energy (as measured with respect to the direct signal), one can then work backwards to calculate the total flight path distance of the indirect energy and identify the incident boundary or source (since the speed of sound will be a constant within your room's medium). you can then manage the energy as required to achieve the desired response (eg, absorption, diffusion, reflection(redirection - to attenuate the signal)