Autofilter

Komplex · Post by **Komplex** » Tue Jun 15, 2004 9:31 am

Hi guys, first post.

Just a question about the auto filter, is there a specific reason why it only goes up to 12khz?

I like to have a filter on each of my audio tracks but it degrades all the shiny high end detail when it is enabled (and its enabled always)...

Is there something i havent worked out yet?

yoda · Post by **yoda** » Tue Jun 15, 2004 10:47 am

12khz is nearly out of the hearing range

Komplex · Post by **Komplex** » Tue Jun 15, 2004 11:08 am

It clearly dulls the audio when the filter is on.

I have tried to compensate by putting the resonance up a bit but then it gets too sharp so I leave the reso at around 1.0

I can live with it, but I was just wondering why the range is so low.

forge · Post by **forge** » Tue Jun 15, 2004 11:27 am

yoda wrote:12khz is nearly out of the hearing range

hate to correct you there but your about 8000Hz off there mate

about 20k is the official 'hearing' range, but it's more commonly belived these days that while we cant hear above that we can 'perceive' higher - hence the existence of 96 or evn 192, the thing being that sampling rate equates to half in real terms (44.1sampling rate = 22050 hearing range)

I've wondered the same with autofilter but you can easily automate the on button

peeddrroo · Post by **peeddrroo** » Tue Jun 15, 2004 11:34 am

automate the on button?
is there a way to do it in session mode, or are you talking about arrangement only?
i think the on/off status doesn't appear in the clip's enveloppe automation, which is a shame.
correct me if i'm wrong.

Komplex · Post by **Komplex** » Tue Jun 15, 2004 11:36 am

True, you can automate it, but I prefer to have them always on because of the way I perform my music with midi controllers. (session mode)

Maybe in the future there will be an upgrade to extend the frequency range of the autofilter? It would be nice to have the option of the dull analogue style sound and perhaps a crispy 20hz-20khz range.

External filter plugins could be used buy I'm not too sure about the stability of doing that...

forge · Post by **forge** » Tue Jun 15, 2004 11:43 am

if you've got any spare you could assign keys on your computer(qwertyuiop is ten tracks) to the on buttons

Guest · Post by **Guest** » Tue Jun 15, 2004 11:58 am

Komplex wrote:It clearly dulls the audio when the filter is on.

I have tried to compensate by putting the resonance up a bit but then it gets too sharp so I leave the reso at around 1.0

I can live with it, but I was just wondering why the range is so low.

I guess its difficult to have a nice sounding high frequ. resonance with a system that runs on 44,1 k. I had the same problem with the autofilter and also would prefer a wider range. Maybe with some dynamic resonance level correlation. So that at the top range of the filter you get maybe no resonance at all, but have acoustic transparency. However ...the Autofilter is a very nice plug allready as it is.

tekkers · Post by **tekkers** » Tue Jun 15, 2004 12:01 pm

i agree with Komplex on this.... i run full mixes through the autofiter - and u can clearly hear the topend chopped somewhat when u switch it on..

i'm supprised it hasnt been mentioned before - its too convoluted a path too switch on the effect before ya can sweeep it! - i've got other things to do!!!

-i'm sure i havnt got super hearing or anything, played out over a pa i dont really think it would be noticed...but at home on ya hi-fi that extra fidelity would be appreciated-

tweakin the resonance to get it back doesnt work - just makes the sound ring more.. so ive wasted time tyin to fix it - and i rather wouldnt risk using external filter vsts to do something that should be so simple..

Guest · Post by **Guest** » Tue Jun 15, 2004 12:02 pm

Komplex wrote:It clearly dulls the audio when the filter is on.

I have tried to compensate by putting the resonance up a bit but then it gets too sharp so I leave the reso at around 1.0

I can live with it, but I was just wondering why the range is so low.

I guess its difficult to have a nice sounding high frequ. resonance with a system that runs on 44,1 k. I had the same problem with the autofilter and also would prefer a wider range. Maybe with some dynamic resonance level correlation. So that at the top range of the filter you get maybe no resonance at all, but have acoustic transparency. However ...the Autofilter is a very nice plug allready as it is.

spiderprod · Post by **spiderprod** » Tue Jun 15, 2004 12:52 pm

forge wrote:
yoda wrote:12khz is nearly out of the hearing range
hate to correct you there but your about 8000Hz off there mate

about 20k is the official 'hearing' range, but it's more commonly belived these days that while we cant hear above that we can 'perceive' higher - hence the existence of 96 or evn 192, the thing being that sampling rate equates to half in real terms (44.1sampling rate = 22050 hearing range)

I've wondered the same with autofilter but you can easily automate the on button

sorry to pushing the debate but what you say is true in a silent environment as the ear in a tough hearing environement (like in a studio/club/city...)recalibrate its hearing frequency range for the brain to have a better undestanding of the signal percieved.at 20k, when the ear enter this mode ,it is nealy impossible for the brain to understand top end frequencies if it is at resonable level .
as for the sampling rate doesn't relate to a signal frequency.
44.1 sampling rate means 44.1 kilobits per seconds.it is the rate at witch the signal is transformed from analogic to digital.
96 or 192 sampling rate just give a better quality to the signal not more top end frequency

Moonburnt · Post by **Moonburnt** » Tue Jun 15, 2004 1:21 pm

96 or 192 sampling rate just give a better quality to the signal not more top end frequency

Hmm, no doubt Mr Nyquist would have something to say about that! There's plenty of extra frequency, but I guess what you're saying is that the extra frequency would not be within our hearing range, and that the only perceptible difference is that there's less aliasing?

robbmasters · Post by **robbmasters** » Tue Jun 15, 2004 3:10 pm

yodab wrote:the sampling rate doesn't relate to a signal frequency.

Er, it absolutely does! It needs to be twice the highest frequency you wish to sample (to avoid "aliasing", i.e. nasty artifacts). This is Nyquist's theorum, mentioned above. So 44.1kHz will sample up to 22.05kHz and 96KHz will sample up to 48kHz, etc.

gaspode · Post by **gaspode** » Tue Jun 15, 2004 3:45 pm

The sample rate is how many slices you take per second... frequency is how many times per second a particular sound occurs... hence, a lower sampling rate will be unable to detect and reasonably reproduce a frequency that occurs more often than your sampling frequency...

Nyquist said you actually need to sample twice as fast as the highest frequency you wish to record... and from off the top of my head this makes sense because if you sample at the same frequency as the signal you wish to produce you end up recording only one point in the frequency over time, instead of the changes that occur over time. Recording at double the frequency allows you to record the rise and fall of the sound you wish to capture.

It also seems that there is some confusion over bit/byte depth... While sample frequency determines how many samples you take per second... bit depth has to do with the amplitude of the signal. So you could record at 192khz at 8 bits per sample... but you would end up loosing subtle changes in the volume of the sound.

Think of this in terms of a graphic image... if you scan in a picture say... the resolution might be the frequency... so the higher resolution you scan the picture in, the larger you can reproduce the image (ie time stretch). The bit depth of your image controls how many colors you can pick at a time... ie, if you scan it at at a low bit depth you can pick out places where the color (ie amplitude) is wrong... you get strange artifacts that pop up because the program has to do the best it can to select the appropriate color, but it ends up averaging a great many things... with a higher bit depth it can get much closer to the correct color, and will make much fewer compromises throughout.

I don't know if that was at all useful or makes any sense... I'll post it, but maybe I'll do a follow up or think it through a bit more if it would help to clear things up.

ethios4 · Post by **ethios4** » Tue Jun 15, 2004 4:11 pm

the Autofilter's narrow frequency range has long been a problem...on the low-end as well as high-end. Try running the Autofilter into a Spectrum Analyser plugin to see the cutoff. I use the EQ4 now for filtering, as it has a wider frequency range. Its a shame to loose the "Auto" part of the Autofilter though.
Good call on the Nyquist Theorem rundown. I wish all these informative posts were collected in one place on the forum...

Autofilter

Autofilter

well...

autofilter