65 – Thor Crossfading Techniques

Since everyone seemed to enjoy the Thor tricks I posted last week, I thought I would continue with the Thor synth and show you a few more ways to work on your synth and sound design chops in Thor. This time, we’re going to discuss the art of crossfading inside Thor. And hopefully you’ll learn some new tricks along the way.

Since everyone seemed to enjoy the Thor tricks I posted last week, I thought I would continue with the Thor synth and show you a few more ways to work on your synth and sound design chops in Thor. This time, we’re going to discuss the art of crossfading inside Thor. And hopefully you’ll learn some new tricks along the way.

The idea of crossfading can be found in any DAW and you might even have a crossfader on your MIDI Controller as well; that’s just how important it can be. And when you think of crossfading, you usually think of a DJ crossing over from song to song. All of this is valid. However, there are many other ways to cross-fade, and as all good sound designers understand, crossfading can provide an unlimited supply of variety and movement to your sound.

In this series, I’m going to show you a few things you can do inside Thor to gain access to a variety of cross-fading techniques. So let’s get started.

The project files can be found here: thor-x-fade-examples. They include a set of Thors and Combinators to show the various examples I’m putting forth here. Check them out to see how the techniques below are applied.

Introduction: What’s a Crossfader?

First of all let’s define what a crossfade is. Put simply, a crossfade is a control that moves from sound “A” to sound “B,” such that when the crossover is at the middle, an equal part of both “A” and “B” can be heard. As the control starts at the leftmost position, all of “A” will be heard, while none of “B” will be heard. At the rightmost position, all of “B” will be heard and none of “A” will be heard. That’s it in a nutshell.

From an engineering or electrical perspective (which is faithfully recreated in Reason), there are two types of crossfades that can be created: “Linear” crossfade and “Equal Power” crossfade. Without going into too much discussion about these, it’s important to know that the majority of the time you will want an “Equal Power” crossfader control, as opposed to a “Linear” crossfader control. And it’s also important to know that setting up an Equal Power Crossfader in Reason takes a little more work. Linear crossfaders tend to dip in volume as the control nears the middle between sound “A” and sound “B,” which is usually not what you want. For a more in-depth explanation, you should read Kurt (Peff) Kurasaki’s great article on the subject: One Hand in the Mix: Building Crossfaders using the Combinator.

Starting off Slow: Crossfading Oscillators

When you think of designing a sound, you will always start by selecting an oscillator. Since Thor has 6 to choose from, this means we can either crossfade between two similar oscillators set differently, or crossfade between two entirely different oscillators altogether. And the great part is that Thor comes with a pre-built crossfader to do just that: The Mixer “Balance” knob.

Here’s a short video to showcase how to crossfade between oscillators:

Taking things a bit further: Crossfading Filters

The next thing we should take a look at is a way in which to crossfade filters inside Thor. When you start crossfading filters, you would select an Oscillator, and then send them into two different filters. The problem here is that if you use the number assignments to send the Oscillators into the Mixer (buttons 1, 2, and 3) and then on into the two filters (set up in Filter slot 1 and 2), you’ll soon realize that You will always have a mix of both filters in your final output. In a basic one Oscillator sent to two different filters scenario, you’ll end up duplicating the oscillator and will always hear this duplicated sound through the two filters in the final output.

The solution is to break the normal chain of events and bypass the mixer altogether. Turn off all the Oscillator assignments going into the mixer (de-select all button 1, 2, and 3 assignments between the Oscillator and Filters 1 and 2). Instead, have the Oscillator sent to both filters directly, and then use a Rotary to act as the scaling knob for these two assignments. This has the effect of controlling the direction of the oscillator going into filter 1 and filter 2 (controlling the amount of sound passed through into both filters). Doing it this way provides a usable crossfade for both filters, and puts it neatly on a Rotary; all within Thor.

The Modulation Bus Routing Section (MBRS) looks like this:

Osc1 : 100 > Filt1 In : -100 > Rotary 1

Osc1 : 100 > Filt2 In : 100 > Rotary 1

The front panel of Thor would look like this:

Crossfading Filters in Thor setup: The front panel
Crossfading Filters in Thor setup: The front panel

And here’s a video to outline how you set it all up:

Using Crossfading to Access the Oscillator’s Envelope Amount Knob

This next approach will show one way to solve a problem that has annoyed me since the inception of Thor. If you do a lot of sound design using Thor, you’ll come up against an issue with the Filter Envelope knobs. Put simply, you can’t modulate them or automate them inside Thor. It’s one of the few parameters, along with the sync Oscillator buttons and bandwidth sliders, which you can’t control using the MBRS. Of course, you can put Thor inside a Combinator and use the Combinator programming to map this parameter to a Combinator Rotary. But that’s a bit of a waste of a device.

So here’s one solution to do everything within Thor. The idea is to duplicate the exact same filter in filter slots 1 and 2. Both filters have the exact same parameters, except filter 1 Envelope knob is set to zero (0) and the filter 2 Envelope knob is set to 127. From here, we can use the same crossfading filter trick we used before and set up the Rotary to cross between these two filters. In essence, the crossfade works as an envelope amount increase knob. Voila!

But this trick is not without it’s downsides. Though you can send any number of oscillators through both filters. In essence you are losing 1 filter slot (don’t forget you still have filter slot 3 if you want to add a filter into the mix). So this trick is really only useful if you have a setup where only 1 or 2 filters are needed. If you need a third filter or more, you’ll have to send the audio output to additional Thor(s) and use this additional Thor(s) filters.

Here’s what the Thor front panel looks like when we want to access the Envelope knob:

Crossfading Filters to access the Envelope Amount Knob in Thor
Crossfading Filters to access the Envelope Amount Knob in Thor

And here’s a video to outline how you set it all up:

One thing you might not have thought about: Crossfading LFOs

This next trick is probably one of the more interesting ways to crossfade elements in Thor. And it’s probably not thought about too much by new recruits to the Reason world. However, it’s a useful setup and can provide some more advanced modulation options. One LFO on it’s own can deliver some nice modulations, but how about mixing two LFOs together? This setup can open you up to a world of new modulations in your sound design. And it’s really not hard to accomplish at all. In this instance, you’ll want to create a second device (Subtractor, Malstrom, or another Thor) in order to access two free-running LFOs.

The essence of this design is to take a secondary LFO source, and send that into the CV1 input on the back of Thor. Once you do that, you gain access to this LFO and can combine it with Thor’s LFO2. Set up both LFOs with different waveforms, and add them to a Rotary, and you have yourself an LFO crossfade in Thor. This can then be used to modulate any parameter in Thor you can think of (Amp Envelope parameters, Oscillator FM Frequency, Filter Frequency, etc.).

The MBRS would look like the following:

LFO2 : 100 > Filt1 Freq : -100 > Rotary 1

CV In1 : 100 > Filt1 Freq : 100 > Rotary 1

And here’s a short video to show you the setup:

So that’s it in a nutshell. Crossfading various parts of Thor can be a lot of fun, and provide a very useful avenue to explore modulations, sound possibilities, and all kinds of crazy routings. What other crossfading ideas do you have? Perhaps crossfading between two Oscillators’ FM Frequency might be an interesting idea. And how about setting up another Rotary to crossfade two LFO’s which affect this FM Frequency. You can do it all inside Thor. No need to step outside too far to get it accomplished.

Good luck in all your music making. I hope this helps to inspire you next time you are designing that killer sound in Thor.

12 – Crossfading Mals & Filters

Since Ed’s Thor Shaper article, I’ve been thinking about how to use this information in real-world examples. One idea is to crossfade the Grain Samples in the Malstrom and another idea is to crossfade all 4 Thor filters to affect one sound source. Lots of fun!

Since Ed’s Thor Shaper article, I’ve been thinking about how to use this information in real-world examples. One thought came from a post I saw on the Props forum. Basically, the issue was that you can’t assign the Malstrom Grains to a Combinator Rotary to effectively switch between the 80+ Grain Samples. It’s pretty easy to assign and switch between Modulator waveforms using a Rotary, but not the actual samples in the Malstrom. So this got me thinking of how you could go about switching between these Samples. And truth be told, there’s probably some really obscure way to do it which uses Thor and some heavy CV connections. But here is something that might just inspire you and be the next best thing.

You can download the project zip file here: crossfading-malstroms-and-filters. This file contains 2 rns files with the Combinator setups explained below. One is a 16-Malstrom crossfader, and the other is a 4-way Thor filter crossfader. I would recommend you download them and open them up as you read. It will make things a little easier that way.

Crossfading 16 Malstrom Grain Samples

In this setup, I’m using 16 Malstrom devices and each device is sent to a Mixer Channel in two 14:2 Mixers. The CV from the various Thors are sent to the Mixer Levels, where the level trim knobs are pushed all the way right, and the Mixer channel Levels are set to zero. If you haven’t already seen Ed’s interesting and enlightening tutorial on the subject, you should read it here: Ed’s Thor Shaper Tutorial. It goes through using the Sine Wave Shaper in Thor to create a 4-way Crossfader. In this way, you can cross-fade between 4 different Malstroms. Each Malstrom’s Oscillator A is set to a different Sample.

Since you have 4 Rotaries, each Rotary is set to 4 Malstrom devices. Giving you a total of 16 different Oscillators. Also, since one or more oscillators will be playing at any one given time, I’ve set up each button on the Combinator to mute the specific series of Oscillators. Button/Rotary 1 affects the first group of 4 (Malstroms 1-4), Button/Rotary 2 affects the second group of 4 (Malstroms 5-8), and so on. Only 10 Malstroms should be applied to a single Mixer because you can only map 10 parameters from any one device to the Combinator, and you need all 10 channel mutes mapped to the various Combinator buttons.

To take this a step further, you could create 6 Combinators, which together would contain the full 82 Oscillator Samples used by the Malstrom. Then you could crossfade between any oscillator you like. The sweet spots for each of the rotaries are as follows:

0 = Oscillator 1 Full Level

42 = Oscillator 2 Full Level

85 = Oscillator 3 Full Level

127 = Oscillator 4 Full Level

Any integer between those values will provide a crossfade between the two Oscillators on either side of the value. This can be seen as a downside or an upside. If you want a pure switch between Oscillator 2 and 4 for example, you can automate the Rotary to go straight from 40 to 85 in your sequencer using a Rotary automation lane. In this sense, you can use the Rotary as a 4-way button switcher between each Oscillator.

On the downside, you couldn’t effectively crossfade between Oscillator 2 and Oscillator 6 (on Rotary 2) the way the current Combinator is set up. But if you Reorganize the way the buttons mute, you could effectively do this. I’m open to anyone who has any other suggestions on how this could be achieved. Another downside is that since a different Malstrom is used for each Oscillator, you’ll have to tweak the settings on each Malstrom to get exactly the sound you want. If you want to keep everything consistent between all Malstroms, you’ll have to do it through automation (the easiest way I think). Simply automate one parameter on the first Malstrom in the sequencer, and copy that automation clip into every other Malstrom’s automation lane. It’s a bit of a pain, but it will keep all Malstroms in line, if that’s what you want.

On the upside, since there are 16 different Malstroms, you can fine tune the sound of each of them separately. If you have all the mutes off, you can effectively crossfade between 4-8 Malstrom sounds/devices at once just by shifting the Rotaries around. This adds some very interesting Sound Layering potential.

As it stands, the first 16 Oscillators from the Malstrom are applied to the 4 Rotaries on the Combinator. As I said, you could build up a stack of 6 Combinators to include all the Malstrom Oscillators. In this way you can build up various sounds and switch between the various Oscillators. Does this help anyone out?

Crossfading all 4 Thor Filters, and then some. . .

Next, let’s take a look at how we can crossfade all of Thor’s filters to affect one synth sound. In this case, it’s fairly simple to set up. First, create a Combinator, and set up Ed’s 3 Sine Shaper Thor’s to handle the CV like the previous example (along with a 14:2 Mixer). Then create a Thor and load up a synth sound. Start off with something simple so that you can really hear the different filters affecting the sound. Then create a Spider Audio CV Merger / Splitter, and send the synth’s Left and Right Audio Outputs to the splitter’s inputs. Create 4 Thors underneath the splitter and send each of the 4 splits to these respective Thor’s Audio Inputs 1 and 2. Finally, send the 4 Thor’s Left and Right Audio Outputs to the first four 14:2 Mixer channels.

The setup with The Sine Shaper CV and Audio outputs from Thor into the Mixer
The setup with The Sine Shaper CV and Audio outputs from Thor into the Mixer
The Thor Synth Audio being split and sent through the 4 Thor Filters
The Thor Synth Audio being split and sent through the 4 Thor Filters

On the front of the Rack, add a Low Pass Ladder Filter in the first Thor’s Filter 3 Slot. The settings for this filter are shown in the image below. In addition, add the following into the Modulation Bus Routing System (MBRS):

Audio In1: 100 > Filt3 L.In

Audio In2: 100 > Filt3 R.In

The Low Pass Ladder Thor Filter settings on the front Panel
The Low Pass Ladder Thor Filter settings on the front Panel

Enter the same settings in the other 3 Thors, but with different filters, so you have the State Variable filter in Thor 2, Comb filter in Thor 3, and Formant filter in Thor 4. While you’re at it, play around with the Global ADSR envelope so that it sounds to your liking for the 4 different filters. It’s ok if these settings are different for each filter. This will just make your sound more interesting. One thing I kept the same across all 4 Thor Filters is the FX section (Delay and Chorus). This way, when the filters are transitioned, the FX remain similar across the board.

Now let’s turn to our Combinator section and do some serious routings in the Mod Matrix. Here’s the settings you will need for each of the Thor Filters (they are the same for all 4, but must be applied to all 4):

Rotary 1 is reserved for the Filter Crossfade, so I’m not going to go over it here. You can see it in the Project File rns.

Rotary 2 > Filter 3 Freq: 0 / 127

Rotary 3 > Filter 3 Res: 0 / 127

Rotary 4 > Filter 3 Global Env Amount: 0 / 127

Button 1 > Delay On: 0 / 1

Button 2 > Delay Sync: 0 / 1

Button 3 > Chorus On: 0 / 1

Button 4 > Filter 3 Global Env Invert: 0 / 1

Mod.W > Filter 3 Drive: 50 / 127

The Combinator Mod Bus Routing settings for each of the Filters
The Combinator Mod Bus Routing settings for each of the Filters

Now, what’s happening is that the Mod Wheel controls the drive amount on each of the Filters, While Rotary 1 cross-fades all the filters. This is the main Rotary, and it has the same sweet spots as the previous Malstrom patch. Rotary 2 and 3 control the Frequency and Resonance of the filters, and Rotary 4 adjusts the Envelope of the filter. Button 4 inverts this envelope. The remaining buttons are left for the Delay, Delay Sync and Chorus. Since all the parameters are the same for all the filters, they all shift together. This can be a positive or a negative. You can’t individually set the filters, but at least they sound pretty good when transitioned. Depending on your ADSR settings for the Global Filter, the Envelope Rotary and Envelope Inversion Button may be different for each filter. But as I said before, this can add some nice variety to the sound.

Use this Combinator as a template for your own sounds. All you have to do is add your own patch into the Thor “Synth” or change the Thor “Synth” to any other Synth or Sampler device if you like. Then you’re in filter crossfading heaven.

A huge thanks to Ed for being the inspiration for these patches. Please let me know what you think and if you can think of any other applications that this crossfading technique can have, by all means share it with us. Until next time, have fun with these.