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Originally Posted by jkdas Whats subsonic filters for? |
Ok, I don't want to scare you or anything so I'm keeping things simple. I wonder why Navin has to say that of me whenever I'm feeling a bit diligent, which is anyway rare.
Typical power amplifiers have a frequency response of about 5Hz to 100000 Hz, and sometimes beyond. This is not a very intended feature, but a result of the charachteristics of the components used to build one. Subsonic frequencies are defined as those frequencies that lie below the human audible frequency range, so typicaly below 20Hz. So if the music you play has some subsonic frequencies, which you can't hear, there is no point tiring your amplifier by getting it to amplifying those frequencies and thus running short of steam in the audible band. So you can engage the subsonic filter switch to filter out this part. This makes things easy on the amp. I would think that it is a very essential feature for a subwoofer amplifier.
Additionally, when you are driving a subwoofer in a vented enclosure, the sub could ruin itself with overexcursion when fed with signals below the tuning frequency. A variable frequency subsonic filter can be employed to cut out these frequencies and prevent damage to the driver.
In both cases, the subsonic filter acts like a high-pass filter.
Some may argue that they can hear frequencies lower than 20 Hz, and above 20kHz and so you shouldn't shut out the subsonics and blah blah blah. I have heard reputed individuals from the field make innumerous arguments about claims that they have felt 5 Hz and so on. 5 Hz is also the wave that runs through a 747 when the aircraft door is slammed shut. Well, you sure can hear that due to the high frequency content comprising that sound, and if you're lucky, you would probably feel it too, but there's a a one in a zillion chance that you'll miss it because it takes a really powerful 5 Hz wave to pressurize a cabin the size of a 747! Most individuals I know, and who claimed to have beyond perfect hearing have failed miserably when put to a blind test, not knowing what's playing and usually haven't been able to even distinguish vastly different drivers playing in the same environment. You can't blame them, they have also always insisted that clipping distortion kills speakers, without knowing exactly why! |