Audio rate filter modulation?

[unkow]

So... I don't have an analog synth, and it doesn't look like I'm getting one any time soon. But I'm curious about the whole "audio rate filter modulation" that digital synths supposedly cannot replicate.

I did some searching on the 'net, but the only examples I could find were either from digital synths, or behind a paywall. Can you point me to some good examples of this famous audio rate filter modulation? Are there some well-known tracks that feature this sound?

[Ah_Dziz]

Digital oscillators can modulate one another at audio rate. They can also do it in ways that are extremely similar to how analog synths do it. It's just FM synthesis. Or some other parameter being modulated similarly with a full bandwidth OSC.

Go to the Falstad realtime spice applet if you wanna build some simple analog style modulation.

[BertKoor]

He asked about modulating the filter, not oscillator.

[chk071]

So... I don't have an analog synth, and it doesn't look like I'm getting one any time soon. But I'm curious about the whole "audio rate filter modulation" that digital synths supposedly cannot replicate.

I did some searching on the 'net, but the only examples I could find were either from digital synths, or behind a paywall.

You can demo payware synths.

I'd get Monark for that, as it allows to modulate the filter with the third oscillator (which allows for very fast modulations in the audio range): https://www.native-instruments.com/en/p ... hs/monark/

What you will notice is that, unlike (digital) synths which don't allow for modulation in audio rate, audio rate modulation won't "fall apart" at higher rates. It won't produce unwanted artifacts, which resemble noise at some point. It will sound smoother. If that's what you would like to know.

[wonshu]

Have a look at u-he Bazille and ACE too.

[Dirtgrain]

I'm thinking Vurt would have some good examples.

[t3toooo]

I'm thinking Vurt would have some good examples.

Isn't that the guy who do it all hardware in a software forum?

[Unaspected]

He asked about modulating the filter, not oscillator.

It's still FM though.

I'd recommending comparing with The Drop at full oversampling. That's still where it's at for me.

[zerocrossing]

Plugin synths with very good audio rate filter modulation include…

Repro (via poly-mod)
Legend
Reaktor Blocks (make sure you run it at 2x your sample rate)
Softube Modular
Dune 3
Massive X
MSoundFactory (must have oversampling turned up)

I’m sure there’s more, but those are my favorites.

[unkow]

Thanks for all the recommendations! Would you say that all these VST's are successful at emulating the (theoretically un-emulate-able according to some internet experts) audio rate filter modulation of a HW analog synth?

Also, is there some "canonical" tune that features a HW synth performing audio rate filter modulation? Like "Tom Sawyer" is the canonical filter sweep tune.

[Dirtgrain]

No examples so far--maybe it's not a part of any music that made it to the masses. I'll keep thinking about it, but nothing comes to mind so far.

[HOTF]

Plugin synths with very good audio rate filter modulation include…

Repro (via poly-mod)
Legend
Reaktor Blocks (make sure you run it at 2x your sample rate)
Softube Modular
Dune 3
Massive X
MSoundFactory (must have oversampling turned up)

I’m sure there’s more, but those are my favorites.

you can also fm the filter in DIVA iirc

[Andreya_Autumn]

What DAW do you use?

I ask because Surge XT is actually pretty dang good at this, but only if oversampled to absurdity. The reason is that the LFO's in reaper run at sample rate/32 which for ordinary project sample rates becomes very limiting. Even a sine wave modulator will give bad results already on mid-range notes.

Reaper nowadays natively allows individual plugins to be oversampled, making it viable to run an individual Surge instance at 384k or even 768k (!), and at those rates you can make bass sounds with square wave filter FM, or if you use sine wave modulation you can get keys as well.

If you aren't on reaper, but have metaplugin or some other way of oversampling the plugin, that'll work too. Or if your computer can run your whole project at those crazy rates.

I've never messed with hardware filter FM, so I can't speak to the similarities. But I love the sounds I'm getting in their own right. The basses especially sound banging.

Upsides are, well Surge is free. It also has a very wide range of filter models to play with, many are non-linear and the distortions sound great for this purpose.
Obvious downside is the CPU hit. No surprises there. Also, not all of those filters were built with this kinda absurd oversampling in mind, most work fine but a couple don't and will output nasty pops. Stay away from the "smooth" version of the regular 12dB/24dB filters, and you should be good. Maybe use a limiter too just to be sure. Surge has one among the built-in fx.

[Andreya_Autumn]

Oh, and if you do wanna try it the method is:

1:Select one of the voice LFO's.

2:Then click the keytrack modulator.

3:Assign it to the LFO rate.

4:Set modulation depth to the exact same value as the LFO rate setting itself (default 1 hz).

5:Now set the LFO rate to the frequency of equal-tempered middle C, or a division thereof. If you want very smooth tracking, with no phasing in the modulation, you need at least five decimal places of precision. 261.62558 works great for me, it still phases but very slowly. 130.81279 is one octave down, and works even better tbh.
You can't go an octave up because 512 hz is the highest value input it'll accept.

(Very helpfully, the proportion of LFO rate and its keytracking depth stays the same when you change the LFO rate. So if you've done steps 2-4 right you don't need to worry about that.)

Now you assign the voice LFO to a filter and melt some things.

[Andreya_Autumn]

Oh, and you wanted examples. Check this out:

That Sai'ke filter FM plugin sounds great too. There's a new version since that video with some more capabilities. Though obviously since it comes after the synth, so it can only work monophonically. But for basses and leads that's fine.