why do filters only reach 16khz? Why not 20khz?

[Brian Oblivion]

...filters and eq's work by lowering volume. If you lower a frequency by 200db, it will still be there, only it will be 200db lower. There's no such thing as it hitting 0 and being completely gone

if you look at a wav there is a centre line that is absolute zero, if your sound doesnt raise any points off that line it is absolute silence.

Correct, but you cant remove a frequency. If it is at 0, then it was never there. All you cn do is lower the volume of the frequency until u cant hear it anymore, but it will still be there

no you can test it yourself, pack 5 high pass filters at 20k followed by 5 low pass filters as low as they go and render them on audio over and over, you will quickly get to the point where you can look at the file in something like soundforge and it registers -inf through the entire file the same way it does if you create a new file that is pure silence. When you work in digital there is an absolute zero and you can get there through filtering.

[drake89]

FFS ppl have you never seen -infinity gain on an eq? I'm pretty sure I have on a waves eq in PT.

[jrisreal]

When you bring digital into the equation, you're right brian...but that would such an insane amount of filtering that it isnt even relevant anymore

[Brian Oblivion]

When you bring digital into the equation, you're right brian...but that would such an insane amount of filtering that it isnt even televant anymore

possibly true in most cases but you might have for example a hat and if you play it through a freq analyser you find its got some really low noise going all the way down to 20hz sitting at -110db where you cant even hear it, if you nuke it with 4 steep hp filters around 300hz you can completely kill that 20hz zone dead, which is removing a frequency that was there. The eq I tend to use is Gliss and it has 6 individual points you can swap between hp/lp/peak/shelf etc, its not unheard of for me to throw up to all 6 on as filters to nuke top end/low end noise. I dont really care if its actually getting those areas to zero, as long as its virtually gone thats fine for practical use, but technically it is possible to reach zero on a computer as far as I am aware, and I have tested it. Im not trying to piss on anyones shoes, its just the convo came up and thats the facts as far as I am aware.

[jrisreal]

If the freq is hitting at -110 dB and you cant hear it, theres no point in removing it. And messing with eq's when you dont need to isnt a good thing to try imo.

[Brian Oblivion]

I think you'll find it can be worth removing it, you may not notice it in that one sound but when you start stacking 30+ sounds together all with low levels of noise running to either end of the spectrum it can muddy things, when in doubt nuke from orbit, standard.

I don't try to mess with eqs, I use them when and where I want them, Ive done that thing where you read what 'people who know stuff' say in forums and follow the rules like don't boost and don't play with the eq when you don't need to because it might 'phase' something etc. It's all nonsense, I've known how to use an eq and its consequences for long enough to just get on with it. Imo if a sound has frequencies in an area that you cant hear in the mix thats one of the best reasons to cut it with eq, if you dont need it amputate it, presuming you know how to use an eq theres not a lot that can go wrong.

Not that any of this has a baring on the point in hand, which is the ability of a filter/eq to completely remove a frequency that was once there, it was a flat statement of technical fact which I responded to with another, in analog hes probably right, in digital I dont believe he is. I don't see where the relevance of extreme filtering in every day music production bares any relevance in that discussion, and I didn't come here to argue with people for the sake of it.

[jrisreal]

If you want to cut it, go ahead and cut it. I'd prefer not to, but it's my opinion. I don't know why I made my previous post...I'm tired, I guess...it's irrelevant to the discussion.

PS: I'm worrying about phase issues...I just don't like my mixes to sound too pristine. I mix with linear-phase eq's anyway, so phase isn't an issue for me.

[Augment]

You are right that the freq will be removed once bounced to audio, but that is the fault of the audio, not that the signal was gone

[AxeD]

This is all missing the point on so many levels.. it's crazy

[Artie_Fufkin]

Please enlighten us then.

[drake89]

Please enlighten us then.

none of this shit matters when it comes to making music. and we should be making music and not talking about this stupid esoteric minutiae.

[jrisreal]

none of this shit matters when it comes to making music. and we should be making music and not talking about this stupid esoteric minutiae.

that's irrelevant

Production, Hardware & Technical

Technical...I'm pretty sure this is a technical discussion, here.

[Artie_Fufkin]

lol I was just about to say that and bold technical
I mean this is interesting to me. I had an idea kinda related to what's come up in this discussion. What about a multiband gate?

[Augment]

Explaining how things work and having discussions is what this forum is about

[JTMMusicuk]

Explaining how things work and having discussions is what this forum is about

for the most part...

[Artie_Fufkin]

Can someone explain this phase stuff?

[JTMMusicuk]

Can someone explain this phase stuff?

Its probably best to google as it can be quite complicated to explain but its basically when you get two things playing at the same frequency and the sound cancels itself out so say it you have your sub playing over a kick drum both hitting around 100hz, you kick may just sound very treble-..y.....basically why you have to EQ things to fit the mix
Its especillay a problem if your recording a band because you will probably have spill from other drums into each mic, the instruments can even start to seem like theyre changing the pan and floating around the spectrum

http://www.uaudio.com/blog/understanding-audio-phase/

[staticcast]

jesus christ you lot are fucking hopeless. anyone who argues that no filter can completely remove a certain frequency is (a) wrong, and (b) an insufferable pedant

EDIT:

EDIT EDIT: maybe i should explain

very technically speaking, you're basically correct that a minimum phase (analog or "analog style digital") LPF or HPF never reaches zero*, since they just slope downwards towards -inf dB... but there are other types of analog filter (e.g. notch) that DO attenuate to zero at the cutoff frequency, and if you use an FFT filter then you can surgically remove frequency content to your heart's content.

in practice, you're limited by the noise floor and distortion characteristics (analog) or bit accuracy (digital). if you make some drastic filter cuts then your original signal (0.749573) gets much smaller (0.000034) and loses precision, i.e. starts sounding grainy and bitcrushed.

the real question is, why the hell does it matter?

[jrisreal]

^ thanks, bro

[Artie_Fufkin]

Its probably best to google as it can be quite complicated to explain but its basically when you get two things playing at the same frequency and the sound cancels itself out so say it you have your sub playing over a kick drum both hitting around 100hz, you kick may just sound very treble-..y.....basically why you have to EQ things to fit the mix
Its especillay a problem if your recording a band because you will probably have spill from other drums into each mic, the instruments can even start to seem like theyre changing the pan and floating around the spectrum

http://www.uaudio.com/blog/understanding-audio-phase/

I don't mean like that. I meant like...well I found a few things that explain it so nevermind.
http://www.homestudiocorner.com/linear- ... egular-eq/
http://theproaudiofiles.com/linear-phas ... -phase-eq/
http://www.gearslutz.com/board/masterin ... e-eqs.html

I've just been curious as to why this stuff happens and how digital filters are made.
I tried filtering out some sine waves with steep slopes on different filters and then boosting a lot (84dB) to try and get the original tones back. With some, depending on the cutoff of the filter and slope, all I got was little blips of noise and none of the original signal. With others (slopes less steep), I'd get back the original signal pretty much. And I didn't use notch filters but high pass and low pass and so maybe some of the different slope options do filter out stuff straight to negative infinity? I'm also wondering why I was getting this extra noise, and why I get this nasty crackling when I move the cutoff frequency around?

**Also to the OP, I found a filter that supposedly goes up to 44.1hz. It's filterONE by buzzroom, and it's free.