Removing sub frequencies ("steep" filter?)

Counterparts · Post by **Counterparts** » Thu Jul 01, 2004 5:15 am

I've been trying to remove the low frequencies (i.e. below 30-50 hz roughly) from various tracks / instruments in a mix I'm working on, but without effecting the tonal balance upwards of 100-120 hz but find that it's difficult to do this.

Even using a 48db/Oct filter, if you want to chop out the really low stuff, you're also eating into more useful frequencies.

I've been trying to use a high-pass filter for this purpose...perhaps a low-shelf filter is more suitable? Or...is there a 'brick-wall' type of filter (96db/Oct?) which would do the job?

I'm interested in any ideas regarding precise EQ-ing in this low frequency area.

Royston

Plato · Post by **Plato** » Thu Jul 01, 2004 6:19 am

Maybe completely removing them is not the way to go - rather taming them to an acceptable level ?......just a thought

Counterparts · Post by **Counterparts** » Thu Jul 01, 2004 6:28 am

True...I need to tame them a little more though!

Royston

Ricardo · Post by **Ricardo** » Thu Jul 01, 2004 10:23 am

May be using Optimaster or Finaliza and set the crossover to 100Hz, or wherever you want. Thinking about it, Finaliza is good for this sort of thing in conjunction with EQ module.

Micha · Post by **Micha** » Thu Jul 01, 2004 10:51 am

In Audition 1.5 is a function called Frequency Space Editor. Inside it you can mark the desired frequencies(!) and mute them. Maybe you check it out with the now available trial version?

alfonso · Post by **alfonso** » Thu Jul 01, 2004 11:34 am

On 2004-07-01 06:15, Counterparts wrote:
I've been trying to remove the low frequencies (i.e. below 30-50 hz roughly) from various tracks / instruments in a mix I'm working on, but without effecting the tonal balance upwards of 100-120 hz but find that it's difficult to do this.

Royston

Obviously it is...near higher frequencies sound totally different if those you want to remove are there or not...

There is a setting on Sound Forge "paragraphic equalizer" (if I remember well) that was the removal of everything in the file below 20hz. Well, the result of this was a considerable boost of the low end perception...

The psycological interpretation of sound is someting tricky....your brain can create unexistent frequencies by the perception of some harmonics that naturally are present only together with those frequencies you "create from nothing"...

blazesboylan · Post by **blazesboylan** » Thu Jul 01, 2004 12:25 pm

Royston there is a 1/3 octave EQ plugin. I don't remember how low it goes frequency-wise though, and CreamWare seems to have dropped it from the shop.

A multi-band compressor is another option. Maybe this is what Ricardo was suggesting? Optimaster (and Finaliza?) has a crossover + limiter. Compress the hell out of the signal below 50 Hz.

You can't get much reduction from the shelf filters (-12dB I think?), so I wouldn't bother with them for this task.

There's also the notch filter.

And even the peak filter would probably be narrow enough, at such low frequencies, to reduce the 30-50 without affecting other frequencies too heavily.

And finally, there's the wacky approach. Take a compressor and feed the signal into it. Mult the signal out into a low shelf filter. The output of the filter should have nothing above 50 Hz. Feed the filter into the side chain of the compressor.

The output of the compressor will give you a pumping action which could sound horrible. But if the ultra-low bass is rhythmic it might just work. Not what you asked for, but still...

Cheers,

Johann

Plato · Post by **Plato** » Thu Jul 01, 2004 1:15 pm

Here's Early First 24db/octave eq....might help (and it's free - whoopee!)

http://www.planetz.com/forums/viewtopic ... forum=16&0

astroman · Post by **astroman** » Thu Jul 01, 2004 4:57 pm

steep filters have the habit to 'ring' (as before self-oscillation sets in).
Since octave bands are pretty narrow in low frequency range this influence also reaches the neighbour band - at least im my humble understanding.

cheers, Tom

Counterparts · Post by **Counterparts** » Fri Jul 02, 2004 2:52 am

Thanks for all the replies and suggestions!

Some food for thought there...

Royston

dbmac · Post by **dbmac** » Fri Jul 02, 2004 10:59 am

On 2004-07-01 11:51, Micha wrote:
In Audition 1.5 is a function called Frequency Space Editor. Inside it you can mark the desired frequencies(!) and mute them. Maybe you check it out with the now available trial version?

Micha - I can't find a Frequency Space Editor in Audition 1.5. There's a Fequency Band Splitter, FFT Filter, Notch Filter - these don't seem to be the tool you describe. Is "Frequency Space Editor" the actual name? Is it in the filters section? It sounds interesting, I'd like to try it out.

Thanks,

/dave

sonolive · Post by **sonolive** » Sun Jul 04, 2004 5:25 am

i have developped a 60 db/oct into a mixer ...

http://www.planetz.com/forums/viewtopic ... orum=16&32

you should try it ! and tell me if it does the job !

if not i can try to dev a 96 db/oct !!! but at these slope values, dephasage (i hope it's the good english term !) is very important !!! you have to be carrefull with these kids of filters !

Mr Arkadin · Post by **Mr Arkadin** » Sun Jul 04, 2004 7:23 am

BTW there was a big discussion here about this subject, in case you missed it, which may offer up a few more suggestions.

Me? i cut frequencies of instruments as i go. Pad sounds i almost automatically just chuck in the standard CW low cut (from the effects section, not the inbuilt mixer one - dunno if the quality is any different).

Quite often cut voices too, guitars, basses, just about anything to stop that bottom end clogging up. Also i do any freq cuts before i compress. i usually start the cut at 80Hz and then move it around for each source.

The GraphEQ is also good for notching out indivdual low frequncies (it's not in the shop anymore - is it now part of he Effects Package?)

Mr A

<font size=-1>[ This Message was edited by: Mr Arkadin on 2004-07-04 08:24 ]</font>

astroman · Post by **astroman** » Sun Jul 04, 2004 5:41 pm

On 2004-07-04 06:25, sonolive wrote:
i have developped a 60 db/oct into a mixer ...

Since I have no idea about the mathematical principles of that stuff

I'd appreciate a clarify of the text below which I cut from a document about converters.
They discuss alias filters in the high frquency range, but the application quested in this thread looks rather similiar, except the different frequency range.

[snip]
... An aliasing filter creates a pre/post ringing. As a result of this ringing the A/D and D/A converter has a delay (a little less than1 ms at 48 kS/s with a 0.45/0.55
filter). The ringing is a result of the mathematical equations whereby the filter is constructed and is as it is unavoidable, if the filter is used to minimize aliasing.
Generally a steep filter has more ringing than a less steep filter.
[snip]

is this a general charecteristic of any filter or are some 'brands' more sensitive than others ?
The frequent request of equalizers with low Q values seems to point in this direction.

Or is this only of relevance if a physical conversion process takes place ?

cheers, Tom

<font size=-1>[ This Message was edited by: astroman on 2004-07-04 18:42 ]</font>

sonolive · Post by **sonolive** » Mon Jul 05, 2004 2:55 am

hi astroman ...

the phase rotation for filtering is not only a problem of ADDA conversion ...
even in analog, any filter products a phase transformation .
it's a mathemetical law ... and the "best" the quality of the filter is (factor Q) the bigger this phase rotation is !
they are mathemetical law about "Les systemes oscillatoires" (in french that may be oscilllatories systems ??? (in english !)
in analog, globaly, the best the electronics componant an the circuit design are, the less this rotation is ...
in digital , there are other things to consider but, this phse transformation takes place too ...

my english is very poor and i hope it's clear, peharps someone could explain it better than me !

Counterparts · Post by **Counterparts** » Mon Jul 05, 2004 10:46 am

Mr Arkadin wrote:
BTW there was a big discussion here about this subject, in case you missed it, which may offer up a few more suggestions.

Thanks Mr A - I had found that and was actually going to post a link to it until I spotted your post!

Me? i cut frequencies of instruments as i go. Pad sounds i almost automatically just chuck in the standard CW low cut

My most often used effect!

The GraphEQ is also good for notching out indivdual low frequncies

I haven't tried that yet, but intend to give it a go!

Another possibility is to chain some filters in series in modular - worth a go I think, if only to find out how much 'ringing' is introduced around the cut-off frequency.

(Thx again to everyone for their postings)

Royston

decimator · Post by **decimator** » Mon Jul 05, 2004 4:26 pm

If you have Spektral Delay : the 2 first bands are 0 - 43 Hz and 43 - 86 Hz.

You can really terminate frequencies !
Not to a Hz precision but ...
For sharp bandpass a must ( among other things of course )

What I would like to know is the behaviour of a monitor near its low range : for instance I notice at time for some sounds quite nice rumble effects like a T-Rex jogging ...

Is it in the sound and / or artefacts ?

Micha · Post by **Micha** » Tue Jul 06, 2004 5:35 am

dbmac: Switch to Spectral View.(F9) Set 1024 in Options/Settings/Display for better sight. With right click and mouse wheel you can zoom in. Select the Marquee Selection tool from the toolbar. You now can select any area(!!) inside the view. Best trick is to select a noise and use Fill single click from the DeClick filter. It replaces by using frequencies from the surrounding area. Very good.

dbmac · Post by **dbmac** » Tue Jul 06, 2004 8:11 am

Much appreciated.

/dave

Post by **hubird** » Sun Jul 11, 2004 5:50 pm