Hi/Low Pass filter VST?

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Junski
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RE: Hi/Low Pass filter VST? 2008/12/14 10:59:25 (permalink)
ORIGINAL: mike_mccue

...

edit to add: Ah SynthEdit. I have a license and really enjoy that program... but I sort of faded away from it when it got hung up with multicore processors... has it been updated yet?

edit to add:

Hi Junski, where did you find the Butterworth and Chebyshev HP Filter modules for Synth Edit?



It's v. 1.0170 Unicode now (does not work on 64-bit systems). Exe/dll's are complied 11/2007.

SE Filter modules (HP/LP) can be found from Christian W. Budde's home site

Junski


post edited by Junski - 2008/12/14 11:02:06


#31
The Maillard Reaction
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RE: Hi/Low Pass filter VST? 2008/12/14 12:50:53 (permalink)
Thanks I'm working with them at the moment.

I also got the latest SynthEdit upodate this morning.

Does it do multicore?


#32
Junski
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RE: Hi/Low Pass filter VST? 2008/12/14 13:23:52 (permalink)

ORIGINAL: mike_mccue

Thanks I'm working with them at the moment.

I also got the latest SynthEdit upodate this morning.

Does it do multicore?


I don't know.

Actually, I'm in Shareware mode (not registered) ... I downloaded SynthEdit yesterday (after surfing the Budde's site) and not been registered (yet) to get updates ... as I have no previous knowledge over this software, I need to examine it's potentiality 1st before registering (I'm on Delphi for VST programming ATM ... and I use these (freeware/shareware/trial/demo) VST Development Environment software just for quick testings). BTW, so far SE looks capable software ...

Junski


#33
The Maillard Reaction
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RE: Hi/Low Pass filter VST? 2008/12/14 13:42:35 (permalink)
The Frequency Analysis object is not accurate enough in the lo freq to make it worth using. I tried it and took it out and shrunk the gui:



Unfortunately it seemed to have a noticeable impact on my old laptop test system. It was fun to make in SynthEdit but I'd prefer something similar written by someone who knew how to streamline everything and keep any side effects in mind etc.

I've done several simple object patches in SynthEdit and they always seem to run the CPU more than store bought stuff.

best,
mike



post edited by mike_mccue - 2008/12/14 13:48:24


#34
Junski
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RE: Hi/Low Pass filter VST? 2008/12/15 00:51:41 (permalink)

ORIGINAL: mike_mccue

The Frequency Analysis object is not accurate enough in the lo freq to make it worth using. I tried it and took it out and shrunk the gui:

...

Unfortunately it seemed to have a noticeable impact on my old laptop test system. It was fun to make in SynthEdit but I'd prefer something similar written by someone who knew how to streamline everything and keep any side effects in mind etc.

I've done several simple object patches in SynthEdit and they always seem to run the CPU more than store bought stuff.

best,
mike



Yes, the frequency analyzer module in SE isn't suitable for what you was wanting.

Do you mean CPU usage since, I don't see anything else which would be 'harmful'?
In my surfing/testing PC (2.66GHz P4), CPU increase is 4% (max) w/ one 32-order filter though, it shouldn't be more than 0-2% as like it's w/, say, GlissEQ.

@ lower frequencies, do you need to use filter orders higher than 8-12 = 48-72dB/octave (BTW, by the graphs, stacking five filters in GlissEQ gives result of a 20th order filter = 120dB/octave, though the roll-off is for 4th order filter ... not very 'sharp').


Junski


#35
Marah Mag
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RE: Hi/Low Pass filter VST? 2008/12/15 01:53:29 (permalink)
Nice demonstrations, Mike!

ORIGINAL: mike_mccue





Something I read on here some months ago inspired me to try the approach that your Sonitus illustration shows. I believe I used it on bass and an electric rhythm gtr bus. I quite liked the results. Just chopping off below the fundamentals that I wanted. In the mix, everything became more transparent. Perhaps "thinner," which can be both good and bad, depending on, well, lots of things. But it worked.

I believe this accounts for the overall lower level of the mix... I had to boost it (I used Boost 11) to get it to where it was comparable to other mixes at that stage of production. What was interesting was, it seemed easier to get it to sound "loud" without sacrificing the transparency and overly squashing it. As though the compressor wasn't responding to energy that it could detect but that wasn't actually contributing anything musically/aesthetically to the mix.

What's nice about the Sonitus for this kind of thing is that they're built in to the channel, though you only have direct access to the first 4 bands through the channel interface; you have to open the instance to get to the other bands if you need them. Can't say for sure if I took it to all 6 bands (I'm in self-imposed exile from DAWdom atm.) But the concept worked.

I can't say if there were any specific artifacts up in the harmonics... the "domino effect" you mentioned. But I figure that if I like what it sounds like, then any artifacts that are there are just part of the sound. Some of my favorite sounds were probably originally artifacts, if not outright "mistakes," so who knows. (Prior to this thread, I thought Butterworth was a maple syrup! So grains of salt are perhaps advised. )
post edited by Marah Mag - 2008/12/15 01:56:47
#36
Tom F
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RE: Hi/Low Pass filter VST? 2008/12/15 07:44:43 (permalink)
hi all again - inspired from this thread i did some testing and i just came to the conclusion that (IMO) such steep lowcutfilters are pretty neglectible...
all the classic stuff about cleaning up mixes in the right ranges and so on is well known to me (and should be to anyone who claims to make music) - but i thought that eventually here we had something new that could make a little more difference to what i already knew...
but in the end i see no practical use in using a lowcut stronger that maximum of 36db/ioctave (as for instance in sonnox eq)
actually very often even 18 db is enough and after hearing the results from what i tested i could neither see nor hear any "real" difference when cutting the lowband with that 300db/octave stuff...
sorry if i am to lazy to go into detail and if i have no such nice graphs, but i just can says that using that "rubber" thing suggested above has shown nothing so exciting that i would use it again - especially because of my scepticism about the q / resonating effects (actualy the rubber did a pretty good job there) and the already mentioned deterioeartion of 1st 2nd and 3rd harmonic structure of the filtered material ...i still got some sort of esoteric approach to "sound" per se - its good to assign different places to sounds in a mix but its surely not good to sort of technically stack together sort of bandpassed signal or should i say sticking together a lot of "frequency-castrated" audiotracks - i am sure the results will sound unnatural and not pleasant..
so my conclusion is: use what is needed with reason and in traditional way - no need for that extremem settings, espacially since there ares some million great sounding tunes out there that never have seen a butterworth filter...

cheers

ps: if i have missed sometihng please correct me - and again thanks for the interesting subject

edit: just for fun i tested 25* 36db lowcut of sonnox eq in serie and i have to say that (at least) that eq does not noticabely "corrupt" the higher frequencies - at least i would have expected more difference when applying about 900db per octave

what people here do with the sonnitus is legitimate because of the way the curves and q of the sonnitus are designed ...but i really would not stack a sonnox or a sonalksis eq - hey btw. almost all eqs have pretty nice lowcuts (waves rennaisance, linmb lowband. voxengoetc.etc..)

post edited by info@tomflair.com - 2008/12/15 07:59:06

...trying to be polite... quick temper...trying to be...
#37
The Maillard Reaction
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RE: Hi/Low Pass filter VST? 2008/12/15 09:59:27 (permalink)
Hi Tom,

I disagree mildly with your idea that low cutting aggressively may cause some sort of unnatural result.

Here's the situation that got me thinking about lo-cuts recently. I'm currently working with a Traditional Irish ballad ensemble. I have an acoustic guitar, mandolin, flute, hammer dulcimer and 3 vocals.

I forgot to add lo-cuts on my template and so found myself adding 12 instances of lo-cut to each .cwp file. We had 14 song/projects in this two day session. That's 168 instances.
As I was adding instances of Sonitus FX EQ to each track I was thinking to myself... "there has to be a specialized lo-cut that's super lite weight and actually CUTS the lows rather than just turn them down."

I got to dwell on this while adding each and every instance, all while realizing that the Sonitus FX EQ hi-pass slope wasn't steep enough for my confidence that the bass uglies would disapear.

Now here's the most important point to consider...

Recording on a nice analog system would have provided a built in automatic low cut. OK, I've never tracked on 2" tape and maybe that does go that low but I've also never recorded to tape and had sub 30 Hz artifacts swimming around for the rest of the production process. this is a circumstance that I'm now realizing is common in digital workflow.
For example, when I record to a Beta camera (yes we still send Beta tape to New York and L.A. with frequency) I never use lo-cut on my mic or mixer... I let the actual tape recording mechanism act as, for all practical purposes, a lo-cut filter. It going to do it anyway... so any cut I make in front of the tape deck is redundant (of course there are other compelling reasons to use lo-cut at the mic or mixer)

So, anyways, here I am with 12 tracks of acoustic musicians recorded with SONAR... none are playing anything near the bass range, but because the sound is made up of 12 tracks (which ISN"T natural) the bass builds up. I'm attracted to the idea of eliminating all the sub frequencies that don't really exist in that music. I WANT to filter out any proximity effects, the resonance of the house we recorded in, the jet plane 10 miles away, etc etc.

If it's true that there are no side effects than I'm definitely going to pursue using these steep cut-offs.

I've heard of stacked filters before... I know I'm just illustrating and old concept... I'm glad it's sparked some conversation.

I would like to learn more about the technicalities.


Hi Junski, Yes I saw a 4-6% CPU increase as well with the SynthEdit EQ I made. I know that would translate favorably to my new DAW but still it would not compare well to other EQ choices. :-(

"by the graphs, stacking five filters in GlissEQ gives result of a 20th order filter = 120dB/octave, though the roll-off is for 4th order filter ... not very 'sharp'"

It took me while to understand what you were saying... now I think I do. One thing, are you comparing the slope just using the graph? Or some practical knowledge about filter theory? Is it a 20th order filter? Or just similar to one?

Are you saying that the stock Sonitus filter is a 4th order?

best regards,
mike



#38
Junski
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RE: Hi/Low Pass filter VST? 2008/12/15 12:14:22 (permalink)
ORIGINAL: mike_mccue

....

It took me while to understand what you were saying... now I think I do. One thing, are you comparing the slope just using the graph? Or some practical knowledge about filter theory? Is it a 20th order filter? Or just similar to one?

Are you saying that the stock Sonitus filter is a 4th order?

best regards,
mike




I don't know Sonitus other but by the animation you linked, ... it's looks like being 2nd order filter implementation? ... stacking six of these results 72dB/octave... w/ much 'slower' roll-off what you would get w/ 12th order filter).

What comes into GlissEQ, quote from VoxengoGliss EQ User's Guide:

Q: Am I right in assuming that the High/Lowpass filter has a static slope of 24db?

A: Yes, you are right - they are 24dB/oct filters at their default (2.54) bandwidth setting.


As 4th order filter produces a roll-off of 24dB/octave ... (you can see this also in picture below) ... stacking five of these results 120dB/octave as I mentioned already (can be seen in picture as well ... just check where the -120dB is achieved ... @ 40Hz which is 80Hz/2 ...) but the roll-off speed again ....





'bout IIR filter structures:
- http://cnx.org/content/m11919/latest/
- http://www.bores.com/courses/intro/iir/5_struct.htm
- http://www.bores.com/courses/intro/iir/5_para.htm


Junski
post edited by Junski - 2008/12/15 12:37:46


#39
The Maillard Reaction
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RE: Hi/Low Pass filter VST? 2008/12/15 12:47:19 (permalink)
Thanks Junski,

I grew up thinking in terms of Q and using my ears while working with hardware EQ... dB slopes and Hz values are less familiar to me when working with EQ's so it took me a while to follow your train of thought.

That all makes sense now.

best regards,
mike


#40
kwgm
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RE: Hi/Low Pass filter VST? 2008/12/15 13:38:36 (permalink)

ORIGINAL: mike_mccue

Hi Junski,

Are you saying you just wrote up a quick DSP plugin that had a 4th thru 64th order Butterworth filter design?

I'm curious; what's the difference between doing the 5 nodes in series as I did and doing them as a packaged multi order filter?

I fooled with the VST analyzer a bit I guess that's what you are using for you analysis and screen shots?

What VST that's publicly available that has something like the 64th order Butterworth filter you made? I see less info about the type of filter and more often see a (to me) vauge Hz rating. Perhap's there's one that also has a nice FFT analysis built in?

It seems like a specific Lo-Cut like this VST could be real useful.

Finally, I thought even Butterworth filters made a resonant peak when they got too steep... am I wrong about that?

thanks a bunch!
mike


edit to add: Ah SynthEdit. I have a license and really enjoy that program... but I sort of faded away from it when it got hung up with multicore processors... has it been updated yet?

edit to add:

Hi Junski, where did you find the Butterworth and Chebyshev HP Filter modules for Synth Edit?


You guys are right -- an EQ's low-shelf does nothing to control sub-bass rumble. You must aggressively filter around 40hz to clear it out, and you will bring out your "musical" bass by doing so.

You're worried about side effects, so let me put on my EE hat and share what I know about filters, as well as share a little of my experience working in the low end.

Mathematically, the difference between cascading 2nd order filters and using n-th order Butterworth/Chebyschev - type filters is difficult to summarize in words, but is easily seen in the frequency response graph for each filter types. These differences are slight, and of course they're non-linear, and they give each filter its characteristic sound. There are other side effects that come from pushing the resonance characteristics of a filter, but you're not talking about that aspect here so I'll ignore them for now -- just dont forget about these differences when you increase Q.

Here's what's important -- the one side effect that just might effect your sound is the phase-distortion (shift) introduced by each filter stage.

All filters cause a phase distortion in the affected signal which change the sound ever so slightly. That's why linear-phase EQ (L-P EQ) is such a valuable mastering tool -- they don't produce a phase shift in the signal, and no phase shift means there's no change in the timbre of the original sound using LP filters. (They use an algorithm that is very cpu intensive, which is why you can't track and mix using a good L-P EQ, and imho, if you can play along while using a pluging claiming to be an L-P EQ without being bothered by severe (> 500ms) R-T tracking latency, then that plugin is probably not using L-P algorithms, but a hybrid of traditional digital filter techniques and something else, which is inducing more phase distortion than you may desire.)

When you 'stack' the filters in the Sonitus EQ, the phase changes of each filter stage are summed into the output signal, which can produce frequency domain artifacts causing some harsh-sounding odd-harmonic components to become evident in the higher frequencies of the output signal. This is usually an undesired phenomenon, though some claim to enjoy this harshness in they're preferred music type.

What can you do about it?

You can use your common sense and not apply cascaded filters to your entire mix -- only use this roll-off technique on those components that cause rumble.

However, some sounds just don't work well with cascade filters, period. These are generally sounds that have both low and high frequency components, like big percussion instruments, percussive basslines, certain Moog sounds, harsh low-register piano tones, and a host of others. In this case, use a higher order filter, or consider bouncing and freezing these tracks using an L-P EQ.

Good discussion going on here -- thanks for allowing me to participate.

--kwgm
#41
UnderTow
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RE: Hi/Low Pass filter VST? 2008/12/15 16:20:07 (permalink)

ORIGINAL: mike_mccue

This is what I'm speaking/thinking about... I don't know enough about filters but it seems like there should be some easy way to ERADICATE any data below a certain frequency with a one click plugin while feeling confident you were not building a resonant peak near the cutoff.


Unfortunately your frequency analyser doesn't tell you the whole story. It doesn't show you the phase shifts and the group delays. Whatever type filter you use, there is always a trade-off. Butterworth have the aforementioned phase shifts and group delays. Linear Phase filters have pre/post ringing. FFT filters have imprecisions in the time domain (or the frequency domain) and possibly other artefacts. Etc.

Instead of trying to eradicate everything below a certain frequency, in my experience, it makes more sense to try and tame any unwanted frequency to an acceptable level while keeping the rest of the signal's integrity as well as possible. Staking five filters doesn't usually achieve that.

I'm usually happy with the Sonitus EQ's hipass filter with a Q of 0.7 for most material. For more critical stuff and working on lower frequencies like bass and kick drum I tend to use PSP Neon HR. For extreme stuff I might use the Sony Oxford EQ set to 36 dB/Oct. But that is very very rare.

UnderTow
#42
The Maillard Reaction
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RE: Hi/Low Pass filter VST? 2008/12/16 19:39:29 (permalink)
Thanks to both.

If it's known that you are causing lots of phase problems with the stack then I will just not pursue it.

I guess it's time to grab a book and refresh my memory about filter designs :-)

One question though, is it the stack or the number of active nodes? In other words do you have the same problem if using all the nodes in a more familiar manner?

I think part of my interest was spurred by the fact that I had/have just hooked up my Subwoofer for the first time in a couple years (its a JBL LSR6312SP) and then went straight into recording with a Traditional string quartet... while forgetting to place lo-cuts in my template... and so I was just thinking about it all more so than usual.

best regards,
mike


#43
Junski
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RE: Hi/Low Pass filter VST? 2008/12/17 14:58:22 (permalink)
ORIGINAL: UnderTow

...

Unfortunately your frequency analyser doesn't tell you the whole story. It doesn't show you the phase shifts and the group delays. Whatever type filter you use, there is always a trade-off. Butterworth have the aforementioned phase shifts and group delays. Linear Phase filters have pre/post ringing. FFT filters have imprecisions in the time domain (or the frequency domain) and possibly other artefacts. Etc.

Instead of trying to eradicate everything below a certain frequency, in my experience, it makes more sense to try and tame any unwanted frequency to an acceptable level while keeping the rest of the signal's integrity as well as possible. Staking five filters doesn't usually achieve that.

...

UnderTow



Here are some results I got from measures done for GlissEQ and for my test HP_Filter_VST using C-W. Budde's VST Plugin Analyzer (measured: Magnitude, Harmonic Distortion, Phase A/B, Group Delay, Time and Power). Settings are based on HP settings used in examples of Mike's animations.

Sorry 'bout the size of pictures in tables ... by right_mouse_clicking the image and then selecting "Show picture" you can see pictures in original size.


Junski

post edited by Junski - 2008/12/17 15:00:41


#44
xohol
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RE: Hi/Low Pass filter VST? 2008/12/17 15:04:28 (permalink)
i usually go to my Waves SSL channel for low pass and high pass filters:

#45
UnderTow
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RE: Hi/Low Pass filter VST? 2008/12/17 16:10:30 (permalink)

ORIGINAL: Junski


Here are some results I got from measures done for GlissEQ and for my test HP_Filter_VST using C-W. Budde's VST Plugin Analyzer (measured: Magnitude, Harmonic Distortion, Phase A/B, Group Delay, Time and Power). Settings are based on HP settings used in examples of Mike's animations.


As you can see, GlissEQ already affects the signal when no filter is engaged. My guess is that that is due to the oversampling. (High Quality mode). You can also see that as you add nodes, the phase shift plots get more and more jagged.

Mike, in the end it is really about listening. The graphs might tell you that an EQ causes a phase shift but it won't tell you how it sounds... My point was really that looking at frequency analysers might lead you to the wrong approach. Remove enough sub/bass so that you don't hear it any more and it doesn't affect the mix. But don't try and remove everything simply because it shows up on a frequency plot. That's all.

UnderTow
#46
The Maillard Reaction
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RE: Hi/Low Pass filter VST? 2008/12/17 16:39:02 (permalink)
That's really cool Junski! I'll have to get to broad band to really sort through it.

Thanks for sharing!

best,
mike


#47
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