Homebrew acoustic measurements of your Room Characteristics.
This thread is totally spot-on regarding the problems of room resonances and how they wreak havoc on faithful sound reproduction (especially the bass regions).
Perhaps i would share some home-brew methods on how to measure the severity of room colouration in one's listening space. Keep in mind that this is not a professional rig, but purely an enthusiast's attempt into further demystifying the boundaries between black-arts and acoustic sciences.
The rig is as follows:
1) A good condenser measurement mike. These usually require phantom power (48VDC) from a powered mike preamp. Good example would be a Behringer ECM8000 or Dayton EMM-6. If one's really nitpicky, one may buy a calibrated version from 3rd party companies such as Cross-Spectrum Labs (with calibration file & all).
2) Mike preamp that supplies phantom power to the condenser mikes. (Example, Behringer MIC200) (Would recommend to feed the mike preamp's line level output into the computer for lower noise floor signals).
3) Mike stand. (or a generic camera tripod stand would do fine)
4) a SPL meter. ( for input-level referencing, typical Radioshack is fine)
5) Mac or PC computer with line level input. (don't use the mic-inputs , coz they're terribly noisy)
6) If on MacOS, get (buy) this software called FuzzMeasure. If on PC, get Room EQ Wizard (available Freeware from HomeTheaterShack website). Familiarise oneself with these software.
7) Misc. cabling and connectors to hook everything up nicely.
Once the above rig is put up and the mike position as the listening position, one can then proceed to execute some interesting measurements:
A) Overall room response (dB vs. Freq). This would give an overall response at the listener's position. Typically most people stop at this graph but it is not even revealing close to the true picture of the room colourations. Avoid 1/3 Octave resolution as its too coarse. Use at least 1/12 Octave to really see the problem spots.
B) Waterfall Plot. Now we're getting somewhere.... this would be a 3D "aka waterfall" plot of how the frequencies DECAY in the room. x-axis: Freq, Y-axis: dB, Z-axis:time(ms)
(Those "mountains" that lunge forward are bad news.... best to keep them pushed back.)
C) Decay times. Depending on what software, you might be able to generate a RT-60 Spectrum graph. Very useful in revealing overly long bass decay notes especially in small room setups.
Once this has been comfortably achieved, one can then proceed to experiment with speaker placement, listening spot location, and hanging temporary drapes and whatnots to get the best compromise in sound reproduction.
One last note, since' we're only concerned with how its going to sound at where we're seated at, we would just focus on taking measurements at our listening positions in the room unlike a THX engineer who is trying to get the best sonic experience for a wide audience in a THX certified Cineplex hall.
Anyone trying this out over the Xmas holidays ? Do share your findings!
"Losing half the music": why musicians hate hi-fi
In an intriguing guest editorial in the April 2012 issue of The Absolute Sound, Robert E. Greene claims that most real musicians hate hi-fi because of a massive hole in the frequency below middle C in reproduced music. That hole, somewhere between 100 and 300 Hz, he suggests, is caused by the fact that most speakers have not been designed to interact with floors correctly, leading to a loss of response that is "massively destructive to music".
I seem to recall that Alan has already written about floor reflections, but I can't find the thread. I don't want to waste anyone's time by repeating a discussion that might already have been covered extensively. If this is as destructive to one's enjoyment of music as Greene suggests, then I'm surprised that all loudspeaker manufacturers don't bear it in mind as one of their primary design issues. Greene doesn't say how one might correct for this. Can anyone (Alan, if you have the time?) comment on this.
here's a link to the editoralhttp://www.enjoythemusic.com/tas/ in question.
Site about sound
It would be very worthwhile also to visit Robert's site at http://www.regonaudio.com/ as there are lots of great articles relating to Audio there.