Tags: posts polarity-music Audio-Effects Bitwig Mixing Preset Tutorial Bitwig-5.2.3

Linear Phase Frequency Splitters in Bitwig

Tutorial | Sep 13, 2024

In this video, I demonstrate how to split audio signals into multiple frequency ranges without introducing significant phase issues, particularly in Bitwig Studio. While traditional analog-modeled EQs and tools like Ozone 8 introduce phase offsets or latency, I showcase methods such as using the spectral FX frequency split in Bitwig and custom convolution presets to achieve clean splits. I provide these custom presets for free in the description so viewers can experiment and give feedback.

You can watch the Video on Youtube

Summary

Maybe you don't watch the video, here are some important takeaways:

Hey folks, welcome back to another video! Today, I'm going to show you how to split audio signals into multiple frequency ranges without significantly altering the phase—a challenge we often face in audio production. This method is particularly useful in Bitwig, though it's applicable elsewhere too.

Starting with the issue at hand, I demonstrated using an analog-modeled EQ in zero latency mode. When I adjust the bands, you can see that not only the frequency content changes, but the phase also gets altered, causing phase offset. This is quite normal for zero latency EQs and typically isn't problematic except in certain scenarios—like when using a low cut, which can cause a 180-degree phase flip at the cutoff frequency. This phase flip can lead to issues such as the kick drum's frequencies canceling out when they overlap with a bass sound that's been low cut at the same frequency. While some producers might not see this as a major problem and could resolve it using sidechaining or simply by listening, others demand precision and zero dB losses.

Next, I showed how this phase issue could be managed using Ozone 8 by iZotope. In its analog mode, it behaves like a standard EQ with inherent phase distortion. However, switching to its digital mode introduces latency (about 64 milliseconds) but preserves the phase perfectly. Ozone 8 exemplifies the trade-off between latency and untouched phase.

We then explored EQ+ in Bitwig. It introduces minimal latency (0.4 milliseconds) and shows some slight phase offset in higher frequencies, but nothing particularly severe.

Moving on to Bitwig's FX-3 frequency split, I showed how this device also introduces some phase inversion at crossover points, a common issue in multi-band processors, including popular ones like OTT. Awareness of this phase behavior is crucial, especially if you're stacking several of these devices in your effect chain.

We also discussed Bitwig's spectral effect called Frequency Split, which splits the signal into multiple sine bins using FFT. This device maintains a clean phase response but introduces some latency (around 42 milliseconds). You can adjust the crossover frequencies and the bleeding between bands to make the transitions more natural sounding.

Finally, I introduced my custom convolution-based frequency splitting preset. By using impulse responses from linear phase EQs, I created a multi-band splitter that maintains a clean phase without significant latency issues. These presets, including a five-band splitter, were experiments I conducted recently. This convolution method can be used to craft clean phase multi-band splits, even an adjustable low cut, though with some concessions like parameter jumps and fixed crossover frequencies.

In conclusion, whether or not a bit of latency or phase shift impacts your production largely depends on your specific needs and the precision you're aiming for. I provided several preset downloads for you to experiment with—ranging from OTT style splitters to adjustable low cuts—inviting you to try them out and share feedback.

Thanks for watching this video! If you enjoyed it, leave a like and comment below. See you in the next one. Bye!

Transcription

This is what im talking about in this video. The text is transcribed by AI, so it might not be perfect. If you find any mistakes, please let me know.
You can also click on the timestamps to jump to the right part of the video, which should be helpful.

[00:00:11] Hey folks, welcome back to another video and today I want to show you how to split
[00:00:16] audio signals into multiple frequency ranges without changing the phase too much in a very,
[00:00:24] or at least for Bitwig in a very unusual way. So first I show you the problem or what the problem
[00:00:29] is. So we have here a normal modeled or analog modeled EQ zero latency and we have here an EQ
[00:00:36] analyzer. So when we change here some bands, you can see we change the frequency content,
[00:00:42] but we also alter here the phase. So we introduce a bit of phase offset, right? And this is completely
[00:00:50] normal and it's also completely fine. Every EQ does that or every zero latency EQ does that.
[00:00:57] And I also have no problems with this. But sometimes you want to introduce here something like in
[00:01:04] low cut. And with the low cut we bring in here also a completely phase inversion at the center
[00:01:15] frequency of this EQ cut. And this can sometimes lead to problems when you want to mix sounds in
[00:01:22] this frequency range. So let's say you have a kick drum, you have 80 Hertz and you have this
[00:01:30] bass sound here that is low cut at this frequency and you lay out the kick drum with the bass sound
[00:01:37] and here we have this 180 degrees flip. Sometimes you can then cancel the kick drum or certain
[00:01:45] frequencies of the kick drum out with this phase inverted sound here. So you can lead to problems.
[00:01:52] In my opinion, it's not a big problem because first you hear it when something is wrong down there.
[00:01:58] And secondly, you can prevent this problem by sidechaining. So you sidechain the bass
[00:02:09] with the kick drum. So you duck the bass completely away and you don't have overlapping sounds there.
[00:02:14] Maybe sometimes you want to connect the bass with the kick drum.
[00:02:21] But you can fiddle it around and you can hear when it sounds right or when it sounds off in my
[00:02:26] opinion. So it's not a big problem usually. But there are very precise producers out there
[00:02:32] that really want to nail this sound down here to never waste any 0.00 dB, you know, loudness.
[00:02:42] So it's very important for them. So I want to show you here how to circumvent this maybe in an
[00:02:50] unusual way. So this is how normal EQs behave or normal analog modulated EQs behave.
[00:02:56] And we switch now here to a BST plug-in called Ozone 8. And this one does kind of the same thing.
[00:03:07] We cut and we change here at the center frequency the phase offset. And it gets even worse or more
[00:03:16] prominent when you change the steepness of the filter. We introduce more and more of these
[00:03:24] phase inversions here with the 24 dB per octave filter. We have again this 180 degrees flip.
[00:03:30] So then you have an option inside of Ozone. We sadly don't have this in Bitwig EQs. But here
[00:03:38] in Ozone you can do it. We can switch to a digital mode. And now we introduce latency because the
[00:03:46] EQ needs a bit of time to analyze what's going on. So the digital EQ into this latency we have to
[00:03:54] compensate here for this in the EQ analyzer. And now you can see we have kind of a very untouched,
[00:04:01] very linear phase response here, right? And we can make the curvature steeper and it doesn't do
[00:04:10] anything at the center frequency. We bring in here a bit of phase distortion down here, but there's
[00:04:15] no audio content here. We cut everything away, right? But at the center frequency here nothing
[00:04:21] happens. So this is how it works inside here of the Ozone EQ. Again, we have now a frequency cut.
[00:04:31] We don't touch the phase, but this time we pay with the latency. So we introduce a lot of latency
[00:04:39] here. Can we see this actually here? Let me see. Ozone introduced latency of 64 milliseconds,
[00:04:47] right? Compared to analog here. You can see there's no delay or no latency introduced. So it's only
[00:04:54] the digital mode that does this. But sometimes you want to have the phase clean, rock solid,
[00:05:02] so you need to pay for that in a certain way. And that's also true for a lot of audio processes.
[00:05:09] You never do just one thing. You always trade one thing for the other. It's never just one thing
[00:05:16] that you change and then the rest is untouched. So when you make something loud, right, you trade it
[00:05:23] off or you trade it with transparency, for instance, right? So and the other way around. So
[00:05:32] you're always, it's always a trade off. That's what I want to say. Okay, so let's disable here.
[00:05:36] Ozone go back to this and let's see here how EQ plus looks like.
[00:05:42] Suggest. So EQ plus introduced a small little latency here, 0.4 milliseconds for some reason.
[00:05:57] And it also comes already with some kind of phase offset here in the upper frequencies.
[00:06:02] But in my opinion, it's not a big deal. And also phase issues in the upper frequencies are not a
[00:06:09] problem at all. I think you even want to have some phase offsets in the upper frequencies because
[00:06:14] it kind of glues the sound together. I would say. But that's how it is. This is how EQ plus looks
[00:06:21] like. So when we bring in here a boost or a cut, it does more or less the same thing as EQ plus.
[00:06:28] And it's also kind of zero latency. I mean, 0.4 milliseconds is basically nothing. Okay, so this
[00:06:36] is EQ plus. Then we have here our main topic for the day. Let's suggest here this. And now we have
[00:06:48] an 3 FX 3 frequency split. So we have a low frequency here. We have a mid frequency.
[00:06:55] And we have a high or top frequency. So we could use this here to put some processes into these
[00:07:03] boxes, phasor or compression or whatever. And I like to use this FX 3 all the time.
[00:07:14] But you need to be aware of it that you bring in here some phase
[00:07:18] inversions at these crossover frequencies. So when we change it across over, we also change these
[00:07:25] positions. So you need to be aware of that. And when you, of course, use multiple of these here
[00:07:32] in row, right, you bring in more and more of these phase inversions. So that's something you need to
[00:07:39] know if you want to keep the signal clean or if you don't want to touch the phase or, you know,
[00:07:45] you have some issues with that at certain points in your production. So that's how the FX 3 behaves.
[00:07:54] And that's also not really a big problem because we also have here OTT, which is a VST. A lot of
[00:08:05] people use that. We can see we have the same thing here. We have phase inversions at these
[00:08:12] crossover frequencies. And you can also see where these crossover frequencies are. It's typical
[00:08:18] OTT splitting here at 88 Hertz and also 2.5 K here. Okay, you can't change these crossover
[00:08:27] frequencies, I think in this plug in here. But that's how it is. Okay, so OTT also does this
[00:08:35] and a lot of other multi band processors do this. You have to be aware of that.
[00:08:40] Okay, so then we have here a spectral effect.
[00:08:45] That's called frequency split in Bitwig studio. And we also have here a bit of latency now.
[00:08:54] We can see 42 milliseconds. It's even less than the ozone EQ.
[00:09:03] But we need a bit of time to do an FTT process internally to split the signal into multiple
[00:09:10] sine bins, right? And then alter the signal and then combine it then at the end of the device again.
[00:09:19] So this is how it looks like here with the frequency split. So you can see we have multiple bands
[00:09:26] now here. So we can use this also as a band splitter. And then we can change the loudness
[00:09:31] of these bands and these frequency cuts here are pretty steep. It's not something that sounds great
[00:09:40] when you do it. It sounds very spectral because in nature this probably never happens to your ears
[00:09:46] that at a certain point all the frequencies go completely away, right? So we have here in this
[00:09:53] frequency split device this kind of crossfade amount. So we can bleed these cuts into each other
[00:10:02] by small amounts. And you can see here we have then this make it sound more natural. So this is
[00:10:12] how I want to put it. And you can see here the face is never changed. The face is rock solid.
[00:10:19] So this is a way of splitting the signal to multiple frequency bands without touching the
[00:10:25] face too much. That's the frequency split. But again we pay for this here with some kind of latency.
[00:10:33] I think this is also your default preset if I'm not wrong. So you need to have four splits because
[00:10:41] we have four boxes and we put them here in each of these boxes different frequency range. I think
[00:10:50] this is here. This one it's not really ordered. The red one is the middle one. You can change
[00:10:57] here this by nudging this around. But it's a great device actually for also splitting
[00:11:05] the signal. I use it sometimes not all the time but sometimes. Okay so then we have a device
[00:11:11] that's actually a preset I want to share with you. And it also introduces a bit of latency
[00:11:17] that's not compensated here because it's not a device. And it looks like this. So we have here
[00:11:23] crossover frequencies 88 and then 2.5. So it's an OTT splitter or a type of OTT splitter. So we
[00:11:31] have the low end. You can change this here and the top. You can bring this down or maybe push
[00:11:38] the mids. And we can also put processing in here. So we can use it for compression or distortion or
[00:11:45] whatever. So the big question now is how does it work? Well it's actually pretty simple. I use
[00:11:50] just impulse responses here. You can see there are different impulse responses here from EQs.
[00:11:56] So I just sampled linear phase EQ for these frequency ranges. Put it here into the convolution
[00:12:06] device. Mix 100% wet gain is 100% and then you get the same effect. There's a bit of
[00:12:12] space here in the front and in the end there's the pre-ringing there's the compensation you need to do.
[00:12:17] And yeah you can use the convolution device basically to split signals with this.
[00:12:25] I also made different versions of this. So I have here also a five split for instance.
[00:12:32] Looks like this. We have here 0 to 200, 200 to 1000K,
[00:12:40] 1K, 5K, 5K to 10K and then 10K to 22K the rest of the frequency spectrum. So you can see you
[00:12:52] can use this to EQ stuff without touching the face. I only made two presets here. This one,
[00:13:00] the first one, the OTT splitter and this one. And I also tried to make here some kind of low cut.
[00:13:08] It looks like this. It's a very steep cut but you can change here the cut frequency by
[00:13:18] using this macro. But here the problem is this was actually inspired by some early in the early
[00:13:25] 2000s. Some people invented some EQs based on impulse responses and I did here the same. I just
[00:13:34] put a lot of different EQ settings with impulse responses in multiple lanes or layers and then I
[00:13:44] just switch here between the layers. So the trade-off with this method is that you have
[00:13:51] parameter jumps. So from here to here it's basically 10Hz always. So 20Hz, 30Hz cut, 40Hz cut, 50Hz cut,
[00:14:02] 60Hz cuts and so forth. So it's the trade-off is more or less that you have parameter jumps. But
[00:14:09] it kind of works. It was more or less like an experiment yesterday. I want to show you this.
[00:14:14] I put you also here the presets in the description below if you want to download this and want to
[00:14:19] give it a try. It actually works pretty well but like I said the trade-off is that you bring in a
[00:14:25] bit of latency. I think 20 or 30. How long are these? 33 milliseconds of latency. All these
[00:14:35] impulse responses have the same length. That's important that you have this center thing here
[00:14:41] at the same position. You can try to make some weird things here by offsetting this.
[00:14:47] Get something like this or bring in here this EQ. Let me bring this back here. Or maybe switch back
[00:14:59] here to this cut. Or there's an EQ cut here. Suggest. And then you change the EQ. You can kind
[00:15:15] of tilt the spectrum with this. It's interesting. You can change the pitch of the impulse response.
[00:15:24] So you get some weird effects and artifacts with this. You probably can also sound design.
[00:15:28] I haven't tried it yet. Multiple presets. Also multiple impulse responses. You can download
[00:15:36] here in the description for free. Like I said I have this low cut preset here.
[00:15:41] The cut frequencies. Then X-split. This is the five band splitter. That's the one band splitter.
[00:15:49] Two band splitter here. Looks like this. It's from 0 to 88 and 88 to 22.
[00:15:56] So you can use the stand to maybe process everything that's above 88 hertz. If you want to
[00:16:04] process a bass sound and you don't want to touch the sub, you can use this for this.
[00:16:11] Also trade off is you can't change the crossover frequency. If you want to have a different crossover
[00:16:18] frequency, you need to render different impulse responses. That's the big thing. But usually
[00:16:27] you want to have this kind of the same center or crossover frequencies in different splitters.
[00:16:32] Okay. So we have here this preset, this preset, this and then this one here. This was the first one I
[00:16:39] showed you. Three band splitter. Yeah. I put this in the description below. So you can try it out.
[00:16:45] You can experiment with it. Maybe give me some feedback. What do you think about it? If it's
[00:16:49] worth to use it? If it sounds bad, it sounds pretty clean. You can put everything through it.
[00:16:55] It sounds completely clean. You can also see it here in the EQ analyzer. It doesn't do anything.
[00:17:00] So yeah, that's it for this video. Thanks for watching. Leave a like. Leave a comment.
[00:17:08] And thanks for watching. See you in the next video. Bye.