Originally Posted by Bill Fitzmaurice
Well, if you're only using the sub with music there's little to be gained from having one that goes lower than 35Hz. But otherwise, yes, accurate reproduction is accurate reproduction.
That is not quite true. A lot of techno sound goes below that. But there is more to it. Reverberation from the surrounding changes the frequency bandwdith. For instance, let us say we have an impulse response at time t=0. If there is an echo at time 50ms and this reflection occurs with the same phase as the orginal impulse, there will be an emphasis at 20hz on FFT (Fast Fourier Transform) result. If, in addition to that, there is also an echo at 25ms, but with inverse phase of the original impulse, that will further enhance the frequency component at 20hz (as the impulse has made it more like a waveform resembling a sine wave). We all know the sound of the announcer in a large heavy reverberate stadium sound like it has a lot of bass. Now in the movie, how do you create that type of effect? We first record the announcer voice in the studio and put it through DSP with an impulse response that injects many of these tiny time delayed echoes and out comes the special effect. In the early days of room EQ, it was a tough sell because engineers quickly realize this type of reverberation (similar to what happen in room) is not same as just manipulating the frequency domain response.
Now most of the musically recording is still done naturally. For instance, in the 1980's, labels like Proprius started recording in huge churches. The sound effect is just amazing. When you have a sub with good extension, it makes you feel you are actually in there. On the other hand, once it is played in the elevator with limited low end extension, all the sense of being in the church is gone. So one can argue it is easier to demonstrate the sound quality with music that is naturally recorded than with HT riddled a lot of DSP processing. Personally I feel there is a push from movie studios to dismiss sound quality difference ever exists in good amps vs bad amps so that they can continue to feed us artificial sounds.
BTW, I started working on these servo subwoofers when I started really enjoy those recordings. "Jazz at the Pawnshop" is just one example. I found the "hall effect" is greatly enhanced when I set the extension filter to 14hz.
-Edited by Rythmik - 1/26/13 at 8:51am