In essence, by using multiple measurements you can find the optimum resolution that does not lead to overcompensation. The result is that our filter resolution is not limited by the filter structure, but by the measured properties of the acoustic environment. Dirac Live does not simply use an FIR in cascade with a number of IIR sections, but a more complicated structure. time-domain correction) and IIR’s for what they are best at. FIRs are also less cumbersome to implement than IIRs, as they are non-recursive and therefore less susceptible to round-off errors, etc.ĭirac’s solution is to use the best of the FIR filter (mixed-phase correction, i.e. On the up side, an FIR part is required in order to do correction of the phase/impulse response properties of an acoustic system. Second, they cost more to implement than IIR filters, that is, they require more CPU power. The reason is that the time-domain ringing on one channel is different from another channel, and then the sound becomes de-correlated. That may not always be easily audible, but a typical artifact of too detailed high-frequency compensation is a more diffuse sound when you are using stereo or multi-channel systems. If you do very detailed corrections in the high frequency region, you also introduce ringing in the time domain. Too high resolution seems like an oxymoron, but then don’t forget that a filter acts both in the frequency domain and in the time domain. The high-frequency resolution may instead even be too high, unless you smooth your response by other means. FIR filters, on the other hand, are also limited but in slightly different ways: First, with a finite number of filter taps (FIR = Finite Impulse Response) you lose resolution in the low-frequency region. If you don’t have sufficient word lengths, you also get problems in maintaining the resolution in the bass region. The downsides of using parametric filters (IIR) include that you are limited in resolution by the number of filters employed and they have inherent limitations in optimizing phase/impulse response properties of the loudspeaker. Mathias Johansson: Dirac Live uses a proprietary structure that is neither plain FIR nor plain IIR.
If you want to know the full scoop on Dirac Live, keep reading!Īudioholics: What kind of filters do your room correction products use, and at what resolution (i.e. Of course, Mathias isn't just a business man he's got a Ph.D. Fortunately, we know somebody that does: Mathias Johansson, CEO of Dirac. While we know Dirac's products are used on high end products like the Emotiva XMC-1 and Theta Digital Casablanca, we can't really claim to know all the fine details of how Dirac Live actually works. Like Audyssey MultEQ, Yamaha's YPAO, and Pioneer's MCACC, Dirac Live is a room correction system designed to counter the ill effects of placing loudspeakers in a real room.
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