How To Set Subsonic Filter
Whether yous're a serious basshead, audiophile, car audio fanatic, or only someone who appreciates well-balanced sound, properly setting up your subsonic filter is of paramount importance.
A subsonic filter is simply applied and functional equally long as you prepare it upwardly correctly. It won't only make your music sound ameliorate, merely it will also make your amp'south ability supply and output devices, and the speakers, more than efficient.
That said, what is subsonic filter? What does it do exactly? How do you set it upward correctly and how does one use information technology effectively? Allow's find out…
What is Subsonic Filter?
As well known as an infrasonic filter, a subsonic filter is a feature that attenuates the intensity of depression frequency notes. It cuts off (to a certain caste) extremely low bass notes (often below the range of homo hearing) that many speakers and subwoofers cannot effectively reproduce, thereby making the amplifier and the speaker, more efficient. That said, it's safe to say that a subsonic filter is nothing more than a high-pass filter with really low crossover points.
Subsonic filter is a very of import feature for vented enclosures, as information technology can significantly reduce the loud booming notes around the box's resonant frequency. I mean, think near information technology, if you have a custom built ported enclosure tuned to 31Hz, you don't want to play frequencies that are manner lower than that, otherwise you gamble blowing your subs.
The man hearing ranges roughly from twenty Hz to 20000 Hz. So, if yous send low frequencies below 20Hz to your subwoofers, you won't exist able to hear them anyway (you'll more often than not feel them). Most music doesn't contain these frequencies for that very reason merely sometimes fifty-fifty 30Hz can exist hard on your subwoofer if it isn't designed to dig down that low.
How Does a Subsonic Filter Work?
If you accept an amplifier with a subsonic filter set at twoscore Hz, this doesn't mean, past any means, that everything below this is completely expressionless and gone.
In fact, it's safe to say that when a subsonic filter is set to twoscore Hz, a frequency like 25 Hz notes will yet get through and be quite audible, albeit much quieter than it would be if the filter was non fix at all. Call up of the filter as a slope, not an on-off switch.
Speaking of "slope", when talking virtually subsonic filters, you lot may hear that term thrown effectually quite ofttimes. It refers to the rate at which music notes will be attenuated to below the specified subsonic filter frequency.
Slope is expressed as decibels (dB) per octave, and the dB numbers (18dB, 24dB…) refer to the rolloff of the subsonic filter.
Taking into consideration that one octave corresponds to a doubling of frequency, if yous set up an 18 dB/octave subsonic filter to 40Hz, and so at 20Hz it will sound 18dB quieter, and the 24 dB/oct would exist 24dB quieter.
In other terms, if your subsonic filter has a gradient of 18db/octave, then it will attenuate (brand quieter) all the frequencies below the selected frequency at 18 decibels per octave. If it has a 12db/octave slope, then information technology will attenuate all the frequencies below the selected frequency at 12 decibels per octave.
That said, if you're looking for extreme protection of your subwoofer, and then a higher slope is better. Still, if you want a fiddling less rolloff, you lot can opt for a lower gradient such as 18dB, or 12dB.
Is Subsonic Filter a Must?
A subsonic frequency is very depression, and then low the human ear is incapable of hearing it, notwithstanding your body can feel it. Because of that and because these frequencies are decumbent to damaging woofers, filtering them out is a desirable characteristic in subwoofer amplifiers.
So, a subsonic filter isn't mandatory, but it'southward highly recommendable in some situations, specially when your sub is mounted in a vented box, or if you listen to heavy-bass music for extended periods of fourth dimension.
How to Set Subsonic Filter on Automobile Amp
A subsonic filter is used differently in sealed enclosures than in ported. If you frequent any of the popular automobile sound forums, y'all'll notice that at that place are many opinions near where to set a subsonic filter. 5Hz beneath what the box is tuned for… half (½) an octave below what the box is tuned for…etc.
In a Sealed Box:
Because lower frequencies are harder to re-produce, the lower yous fix them, the more circuit a woofer is forced to take in order to play them loudly and accurately.
Subsonic frequencies can potentially damage your subwoofer because they push it past its mechanical limit and brand it play below the enclosure tuning. This is the reason why you want to cut those frequencies out.
As a general rule of thumb, if your sub is mounted in a sealed enclosure, suit the subsonic filter to 25-35 Hz, to filter the extremely depression bass frequencies your subwoofer is unable to play.
In a Ported Box:
Ported enclosures are tuned to a sure frequency range which is determined by a combination of port area, port length, and cyberspace volume of the subwoofer box.
When a vented box is tuned to a certain frequency, it will be capable of playing all frequencies higher up that tuning without an issue. Information technology tin besides play below that frequency, simply merely half an octave, before the cone of the subwoofer is at take chances of damage considering of over-excursion.
And then for prophylactic reasons, we prepare the subsonic filter to half an octave below the frequency the box is tuned to.
To effigy out how much half an octave is, allow'due south do some math.
Call up that 1 octave up is double the frequency, Ane octave down is half the frequency.
So, lets say you lot subwoofer box is tuned to 40Hz:
- 40Hz / 2 = 20 Hz (one octave lower)
- 20Hz /2 = x Hz (half an octave lower)
So we take 40 – 10 = thirty Hz
In other words, y'all gear up your subsonic filter to thirty Hz. And so that way, if at that place's music below the ports frequency, it gets filtered out protecting your woofer.
An easy fashion to this is to take your box tuning frequency and multiply information technology by .75
Then it would be 40Hz ten 0.75 = 30Hz
If the end issue is a decimal number and so you'll need to round it upward to the nearest whole number.
Keep in mind
Keep in listen that setting upwardly your subsonic filter the fashion we described above isn't past any means a bad thing, all the same, nosotros exercise believe that this is one of those "dominion of thumb" type things as every setup (box, subs, vehicle, …etc) is quite different.
And then, information technology's prophylactic to say that no ane tin can just tell you what the subsonic filter on your amp should exist ready to, therefore, the nearly important matter to exercise is to keep adjusting your system until you hear something you like.
More often than not speaking, where you set the subsonic filter should be decided past how stressed the sub is. And so, essentially, what you need to do is to start with the subsonic filter set up a fleck high and play a vocal that hits the lowest frequency, or find a test tone disc that has a diverseness of low frequency tracks, then gradually drop the subsonic filter until the tones cause the subwoofer to exist stressed.
As you lower the subsonic filter, the woofer will motion more and more until it gets to a point where the sound becomes less clear and/or just sounds off. You lot'll notice the subwoofer is struggling (because its cone movement isn't as linear and smooth) to retain its crisp clean bass, and starts to take over circuit. You want set the filter to right before that point where the subs play as low equally possible without bottoming out.
Bottom Line
At the end, you should ever keep in mind that the subsonic filter is Non a cut-off filter. Information technology isn't a brick wall. It has a roll off "slope" where whatever frequency information technology'due south set to will be attenuated, and the attenuation event increases significantly as the frequencies become lower. Thus the power to the woofer decreases at filtered frequencies, which prevents over-excursion and chance of damage
Source: https://crystalstereo.com/how-to-set-subsonic-filter-on-car-amp/
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