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Reason / Record: Stereo Vision

Reason Notes & Technques By Robin Bigwood
Published May 2010

We show you how familiar devices can be manipulated to create stereo effects in Reason and Record.

Auto-pan is a cinch to set up — just use a Subtractor synth LFO to modulate your mixer's pan knob.Auto-pan is a cinch to set up — just use a Subtractor synth LFO to modulate your mixer's pan knob.

Reason and Record offer a wide and varied range of audio effects, but neither is particularly well endowed with stereo processors. We're going to look at how some standard devices can be re-purposed to make up for the deficit.


Splitting a mono channel in two and then delaying one 'half' of it is a simple but extremely effective pseudo‑stereo technique.Splitting a mono channel in two and then delaying one 'half' of it is a simple but extremely effective pseudo‑stereo technique.

Electric pianos, clean electric guitars and synths can all sound great with a touch of auto-pan, but there's no dedicated effect device for this. However, it's really easy to set up, using a synth and a single rear-panel CV connection.

To achieve it, all you need to do is modulate the mixer pan control for your instrument or track. Start by creating a synth (a Subtractor is a fine choice), and as it's only going to be used as a modulation source, hold down the Shift and Alt keys as you do, to prevent a sequencer track being created for it and to stop automatic patching to the mixer. Viewing the rack's rear, drag a cable from the Subtractor's LFO1 modulation output to the Pan CV In socket of the mixer channel (or, in Record, the Mix or Audio Track device) for the instrument you want to auto-pan. In the screen above, I've got it hooked up to the NNXT's mixer channel.

Now, viewing the front of the rack, you can set the rate of auto-pan with the Subtractor's LFO1 Rate knob. The Amount knob doesn't do anything here, so if you need a deeper or shallower effect, flip the rack again and adjust the CV knob beneath the Pan CV In socket on your mixer channel. Of Subtractor's LFO1 waveforms, triangle is the most useful for a conventional auto-pan, but switch to square for that old-school Fender Rhodes treatment.

Stereo Width

Reason / Record: Stereo Vision

Being able to control the stereo width of sources is a useful technique. Applied to a mix, exaggerated width can add a feeling of spaciousness and grandeur. Maybe more useful still is the ability to restrict width. This can help individual stereo tracks like pianos, acoustic guitars and drum overheads (or submixes) sit better in a mix, and not dominate other narrower or mono tracks with unnatural width.

Now, there is a device for this: the MClass Stereo Imager. Propellerhead don't give technical details of how it works, but it's almost certainly a Mid/Side processor, and it allows the perceived width of a stereo signal to be widened and narrowed. With a built‑in crossover, which allows independent stereo adjustment for low- and high-frequency bands, it's intended more as a mastering tool, but you can use it on individual devices. To use it on an NNXT string pad, for example, just right‑click on the NNXT and choose it from the Create submenu. As long as your individual track doesn't include much low-frequency content, you can then turn the crossover right down (to 100Hz) and use the right‑hand Hi‑band width knob. Otherwise, set the crossover to a higher value, and try the possibilities the dual‑band design offers, such as widening the treble but narrowing the bass, for a 'spacious yet focused' feel.


The theory and practice of splitting and routing a mono source into Malström's twin filters.The theory and practice of splitting and routing a mono source into Malström's twin filters.

What the MClass Stereo Imager can't do is widen a mono signal, but that's often a desirable thing to do, for pads in Subtractor (which only has a mono output), old mono‑output synth or Mellotron samples, or (in Record) acoustic guitars and backing vocals recorded in mono. What we're talking about is creating 'pseudo' stereo, and there are techniques that can achieve this, without slapping on a reverb. All involve splitting the mono source signal in some way, and the tool for that job is the Spider Audio Merger and Splitter device. Let's look at one possible way forward, creating a pseudo‑stereo Subtractor pad.

The gist of the setup is this. We're going to split the Subtractor's mono output into two. One of the signals will go to the left input of a mixer channel (or, in Record, a Mix device), and the other will feed the right input, after picking up a short delay from a DDL1 delay. See the screen above for how that looks in practice. By decorrelating the signals in this way we can achieve a nice sense of width. Here's a step-by-step guide:

Reason / Record: Stereo Vision

1. Create a Spider Audio splitter and DDL1 with the Shift key held down, to prevent automatic routing from occurring.

2. Patch the Subtractor's audio output into the Spider's 'A (L)' socket. Now the four sockets to the right split off four copies.

3. Hook up one of them to a left mixer (or Mix device) input. Then hook up another to the left input socket of the DDL1.

4. Take the DDL1's left output and drag a cable to the right input of the mixer channel you chose in step three.

Using the DDL1's front-panel controls, switch the time unit to MS (milliseconds) and dial in a value of about 50ms as a starting point (feel free to experiment with smaller or larger values). Make sure Feedback is at zero, and keep Pan in the middle and the mix control to 100 percent wet. Your Subtractor pad should now have a nice, spacious spread across the stereo image.

Comb Filtering

The Malström's filters set up to process separate feeds of the same mono source.The Malström's filters set up to process separate feeds of the same mono source.

Creating a stereo effect by splitting a mono feed and delaying one channel works great for pads and other sounds with slow attacks, but is less well suited to transient-rich sources like guitars, pianos and percussion. For these, you can end up with an undesirable ping‑pong or slap‑back effect. So here's another, slightly more sophisticated method of creating stereo from mono that doesn't suffer from those problems, and can give remarkably convincing results. It still splits the mono signal in two, but each 'half' is processed by complementary comb filters, courtesy of a Malström synth. In the diagram at the foot of the page, you can see how it looks on paper, and in the adjacent screen how it looks patched into an audio track in Record.

The real key to this technique is how you set up Malström's filters. As the screenshot below shows, both filters have to be enabled, by clicking the yellow tick-boxes above their names. The Shaper module and the link from Filter B to the Shaper should be disabled. Then a good way forward is to set both Filter A and B to 'Comb +', and turn Res (resonance) right down on both.

After this, it's all about experimentation, tweaking the large Freq knobs and the smaller Spread knob at bottom right. The comb filters are effectively taking a series of slices out of your input's frequency spectrum, and by using slightly different Freq settings for each filter you ensure the left and right channels sound different, with some divergence in their phase relationship too. Some Freq values can dial in slight tone changes, but you can achieve natural‑sounding results with both set to values somewhere around 30 or 40. The Spread knob becomes a stereo width control. Leave it fully clockwise for the full effect, or limit width by turning it down. Comb-filter aficionados will know that more extreme effects are possible by combining filters with opposing polarities — so one set to 'Comb +' and the other set to 'Comb ‑'. The problem is that the 'Comb ‑' mode applies a bass cut, but if that's not a problem for the track or device you're processing, feel free to try it out.    

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