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Low/High Cut Filter Question
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| Blahzaay |
| Why do filters roll off at a certain DB/Octave instead of cutting out every frequency below/above the specified level completely? The exception to this was on an Andy Vax mixing video I recently came across. I can't remember the name of the filters he used, but the slope was almost straight up and down (an extremely high DB/Octave). If you want to cut ALL frequencies below a specified value shouldn't it let you? Or does this have some kind of nasty effect? |
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| Fledz |
| Actually this interests me as well. I would like a filter than cuts to 0db straight away. |
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| Eric J |
He was using the Cambridge EQ plugin that can be purchased if you have a UAD-1 card. This EQ has an Eliptical 6 filter, which does like a 96db/oct cut which is almost straight down.
To be honest, I really dont like this extreme type of a cut. It can be good for a surgical EQ type of situation, but it doesn't sound nearly as "musical" as a 12 or 24db/oct cut. Your ears are not attuned to such extreme cuts and it really adds quite an "unpleasant" quality to the sound. I'd stick with the less-steep cuts. |
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| 3F05Q |
Take a look at circuit diagram for a high-pass filter and you will see that it involves a capacitor inline with the input and a resistor in parallel to a speaker. Since the current alternates rapidly the capacitor sees changes in the potential difference. Capacitors have a charge/discharge rate and are therefore subject to the rate-of-change of the applied signal. The values of the resistor and capacitor determine where the cutoff is. That's a first order filter, and puts the output 90* out of phase of the input. (that's a slope as well)
In terms of software, the steeper the slope, the more calculations, the more processor taken up.
Waves has a low cut filter that is pretty steep. |
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| Derivative |
Thats a very good answer. The other thing is that the steeper the roll off rate of a filter, the more artifacting you will get. Many instruments will not sound natural when you roll off audible parts of the signal with a 36dB/Octave LP filter and they would sound flat out ed if the cutoff was instantaneous.
If you are rolling off a range which is almost wholley inaudible or imperceptible then you should probably ask yourself why are you doing it if you can't hear it anyway? |
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| Ry Thomas |
There are about 15 filter types on the Cambridge, you have to be weary of using severe slopes though, can sound too unnatural
A very nice eq none the less |
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| mysticalninja |
| any other filters that are like that? |
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| Jake Benson |
| What I do (that helps a little) is run two filters. For example I'll put on a high pass filter and then also cut out the low end on the EQ. So that way there's two different effects working together....I hope. |
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| lenieNt Force |
| Cambridge is a very nice eq.. wish I had it. |
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| camsr |
| google RubberFilter. 384dB butterworth filters. |
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| RichieV |
| it comes down to math. WIthout a supercomputer , you ain't getting a complete brickwall filter. Besides , why on earth would you want one. As far as the nasty effect ? ya it soudns like . |
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| 3F05Q |
| I want a notch filter that has an incredibly steep slope. A? Forget A! There'll be no 440hz in MY beats! 439 and 441 can stay, but 440 is OUT! |
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