Digital Room Correction
From DRC
Contents |
What is DRC
DRC is the principle of playing test "tones" through your hifi system to measure its frequency response and character using a microphone placed in the listening position (and possibly other locations as well). We know what the tones were supposed to be, we know what we recorded, and so to some extent we can construct an inverse filter to improve the subjective audio quality which arrives at the listening positions.
But I already have an £X,000 system - is this stuff necessary?
Perhaps. However, remember how that system you bought sounded different when you were demoing it in the shop?
I will tentatively suggest that the effect your room has on the sound of your system is far greater than that of the amp, cables or CD player - in fact it is second only to that of different speakers. Even where you place the speakers in the room has a tremendous effect on the sound of your system - getting a tape measure out and optimising the position of your speakers will likely give far bigger improvements than a new and more expensive set...
DRC attempts to correct quite a lot of the effects caused by your room (echos, reflections, etc), and leave you with a near theoretically perfect speaker. A side effect of the calculations are that any frequency lumps and bumps in your speaker response can also be dialed out.
Is it worth it?
Oh yes!!
Doesn't it degrade the sound quality?
Consider that for a typical fast convolution operation with single precision arithmetic (32 bit IEEE floating points) Brutefir is able to achieve something like -160 dB THD+N with about 1500 dB of dynamic range, and with doubles probably it gets figures around -300 dB THD+N with more than 12000 dB of dynamic range.
This should be compared with the typical 120 dB of THD+N and dynamic range of the best DACs and ADCs available. Degradation caused by the digital signal processing needed to perform digital room correction is inaudible when properly done, whereas the benefits could be huge.
Links
- http://en.wikipedia.org/wiki/Digital_room_correction - Wikipedia Digital Room Correction page
- http://www.roomcorrection.com/ - Tact sponsored link talking about room correction in general
- "Room Correction is Impossible!"
- Success Stories
- DRC links
