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The truth about digital EQ
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Don't know if this has been posted here but I found it an interesting read.
http://www.gearslutz.com/board/so-m...-fact-myth.html
| quote: | If you ask me...
1) All minimum phase filters (that's more than 90% of filters you see) with the same frequency curve without added distortions sound the same. There is are no magical "EQ algorithms" that would make EQs sound different without added distortion or different frequency curves.
2) Some EQs are based on some specific hardware units. If they are, it's clearly stated somewhere, like those made by Waves, which seem to usually have 2-4 first harmonics. That means added distortion, nothing magical, very easy to implement.
3) Linear phase filters sound somewhat different from minimum phase. Apart from that, phase doesn't matter because all minimum phase filters have the same phase behaviour. You can add so called all-pass filters that change the phase, but this is inaudible unless you mix the original sound with the filtered.
4) Minimum phase filters can be made to sound the same. Some EQs have different filter shapes (URS N-series comes to mind) so you may need two or more filters of different shape to approximate it. For example, you could use one shelf and one bell filter to approximate a "pultec-style" shelf. The only difference is in the frequency domain.
5) When a minimum phase filter is said to be specifically "clean" or "accurate" it probably only has to do with the usual problem of that normally digital filters have +-0 difference at half of the sampling rate (like 22050hz) and that leads to less boost or cut at e.g. >18khz.
So, if someone comes to me and says that he has a new EQ design, I would ask him which is it: new filter shapes or added distortion. Most likely it would be just a new GUI. |
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| RichieV |
| wouldn't the distortion be a pretty integral part of the actual sound. The only difference between hardware and software is that software has to devise algorythms to replicate the distortion created by Analog units |
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| Zombie0729 |
that's interesting. some are built with much different algorithms and i'd beg to differ that all slopes are the same. just because you use a logarithmic algorithm in your C++ code doesn't mean you're going to get the same result every time, that's what he's arguing. ableton and a few other daws have different setting on their EQ's, "hi-quality" or "hi-fedility" ... which right there is the host using more CPU resources to make a more precise log or ln curve. how can you say they're going to do the same thing?
my native daw doesn't have 10% of the curves my UAD Cambridge has regardless of quality or added distortion. |
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| DJ RANN |
Interesting, but as I read them they seemed pretty obvious. Once the signal is in the digital domain, the rest is just programmed "distortion" or differences in the curves. Basicially, with any fully analytic parametric eq you can replicate any digital host based eq. |
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| RichieV |
| I wonder why most EQ's avoid the sharper filter types found in the UAD Caimbridge vst. I suppose they wouldn't really be that necessary but why not include many filter types if it isn't really such a big deal. |
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| Eric J |
| quote: | Originally posted by RichieV
I wonder why most EQ's avoid the sharper filter types found in the UAD Caimbridge vst. I suppose they wouldn't really be that necessary but why not include many filter types if it isn't really such a big deal. |
I'm guessing usefullness maybe? In my experience, the more steep the slope, the less "musical" it sounds. I almost never use anything steeper than 24db/oct. |
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| RichieV |
I agree,
but if it isn't really a big deal , why not include them. At least give people the opportunity to ruin their mixes. |
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| Eric J |
| quote: | Originally posted by RichieV
I agree,
but if it isn't really a big deal , why not include them. At least give people the opportunity to ruin their mixes. |
I agree, although, people seem to be doing just fine ruining mixes without the option. :) |
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| DJ RANN |
| quote: | Originally posted by Eric J
I agree, although, people seem to be doing just fine ruining mixes without the option. :) |
Lol.
I suppose the didn't warrant the extra programming.
Basically, I just use the native logic eq's which have always seemed as good as needed. Anyone noticed a major difference by swapping to other eq's (outside of extra features or being able to use it differently) |
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| Eric J |
| quote: | Originally posted by DJ RANN
Lol.
I suppose the didn't warrant the extra programming.
Basically, I just use the native logic eq's which have always seemed as good as needed. Anyone noticed a major difference by swapping to other eq's (outside of extra features or being able to use it differently) |
Not really. I mean, I use the Logic EQ's more than anything. The only EQ that I turn to as often as the Channel EQ is the EQ section in the Neve 88RS, which is really, really good. Among its other features, I can boost with it and it still sounds great, which is not the case with other EQ's, including the channel EQ. Other EQ's tend to have a "harsh" sound if I try to boost at all. |
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| RichieV |
| quote: | Originally posted by Eric J
I agree, although, people seem to be doing just fine ruining mixes without the option. :) |
although in hindsight, i do often use the bandaxl curve for air on certain tracks. |
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| DJ RANN |
| quote: | Originally posted by Eric J
Not really. I mean, I use the Logic EQ's more than anything. The only EQ that I turn to as often as the Channel EQ is the EQ section in the Neve 88RS, which is really, really good. Among its other features, I can boost with it and it still sounds great, which is not the case with other EQ's, including the channel EQ. Other EQ's tend to have a "harsh" sound if I try to boost at all. |
Totally. I actually hardly ever boost any frequencies because I've always had the feeling that doing so is a negative to the quality of the sound - I'd prefer to go back to the synth/source if possible to change it at the route.
basically, EQ for me a nearly a purely subtractive function. |
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