Studio One’s macro controls can be used to create a convincing 2D panning effect.
Circular panning is a method of simulating two-dimensional spatial placement of sources in two-channel audio, especially sources that are not entirely stationary for the duration of a piece. Conventional amplitude panning does a fine job of left-right positioning, but front-back positioning is much tougher to do in two-channel stereo. (It turns out to even be a little tricky to do convincingly on surround systems, but Studio One is not surround-capable anyway.) I’ve effectively used circular panning in projects with sources that were supposed to fly through the 2D soundfield, but also on projects where some sources popped up now and then, each time in a different location.
Screen 1: The order of plug-ins is important.
The challenge with circular panning, as always in mixing techniques, is in finding a solution that is useful across several kinds of playback scenarios. Binaural techniques can be fun when heard on earbuds, but are less effective over speakers. The techniques I discuss here are intended for speaker use, but sound good over earbuds and ‘phones, as well.
With two channels played through speakers, placement directly behind the listener is very difficult, so the circular panning technique here will be restricted to a soundfield lying entirely in front of the listener. We are going to accomplish this by exploiting a few of the most basic aural cues with plug-in parameters controlled from the X-Y pad macro controls in Studio One to make a useful circle panner.
Not As Easy As It Sounds
Since amplitude panning works fine for left-to-right positioning, you might think we’re already halfway home before we’ve even started. Not so fast. Notice that the wording above describes the X-Y controllers as working with plug-in parameters of which channel panning is not one. The channel pan control will not be found in the list of available parameters when you configure a macro control.
So, as a starting point, we’ll need to find a plug-in with an onboard pan control and insert that on our channel. Of Studio One’s built-in effects, either PreSonus’s Dual Pan or the Binaural Pan can be used. I kind of liked how the Binaural Pan sounded on what I was doing and went with that.
We will simulate front-to-back panning, the real challenge, with two good distance cues: decreasing level and decreasing direct-to-reverberant ratio. Both of those parameters are available on most decent reverbs. I used the Open AIR convolution reverb included in Studio One Pro in my example; substitute another reverb of your choice, if you wish.
Screen 2: Click the Channel Editor button to access macro controls.
When you instantiate your plug-ins, be sure that the panner comes before the reverb in the effects chain (that is, in a higher insert slot). This ensures that the source gets left-right panned through the reverb’s space, instead of the reverb return being panned left and right, as would happen if the panner was downstream of the reverb in the signal path. In screen 1, you can see that I put a compressor as the first thing in line, which I did because I found some of the level variations in the source messed with the positioning I was trying to impose. This may not be needed in all circumstances.
What kind of reverb is appropriate depends on the source material and the desired effect. I typically find larger spaces to give more dramatic, but less convincing, results. That is, circular panning in halls and cathedrals is fun, but not terribly effective for positioning. On the other hand, medium to large room reverbs work very well for me in suggesting source positions.
Pad Moon Rising
With a panner and reverb on our source channel, both left-right and front-back mechanisms are in place. Now let’s get them under the control of an X-Y pad. Click the Channel Editor button for the channel on which you have instantiated the panner and reverb and the Channel Editor should open directly to the macro controls window, ready to operate. If you see a row of knobs but no X-Y pads, click the triangle at the bottom of the window to drop down the drawer with the X-Y pads, as in screen 3.
Screen 3: The Macro Controls window provides sophisticated, multi-parameter control over plug-ins. The X-Y pad at the lower left is configured for circular panning. The circled triangle button reveals the X-Y pads if they are not visible when the window is opened.
We need to configure the pad before we can use it, so click on the wrench icon in the upper-left corner of the macro controls window and the knobs will give way to three columns: macro controls on the left, plug-in parameters on the right, and mapping of controls to parameters in the middle, as shown in screen 4.
In the right column, locate the pan parameter of whatever plug-in is performing your left-right panning. Drag that parameter to the left column and drop it on the Pad1-X macro control. The middle column immediately displays the mapping of the X axis to the pan parameter. This will probably be all you need to do for left-right control. Check it by clicking the wrench icon again to put the macro controls in their performance mode, starting some audio playing, and dragging left and right in the X-Y pad. The sound should follow your dragging.
Screen 4: In this mapping editor, parameters are assigned to macro controls and the response curves and values are set. Assignment is accomplished with drag-and-drop, and multiple parameters can be changed by a single macro control, with each parameter having its own scaling and values.
Our main front-back positioning cue is going to be the dry/wet mix on the reverb, so we go back to the macro controls configuration window, locate the Dry/Wet Mix parameter in the Mix subfolder of Open AIR in the right column, drag it to the right column, and drop it on the Pad1-Y parameter. Click the wrench icon, play some audio, and drag up and down.
You may find, as I did, that the crossfade from dry to wet isn’t quite even when moving from ‘front’ to ‘back’. The curve shape makes all the difference in how a parameter changes the sound, so click on the curve graphic in the Trans (which stands for ‘transition’ in PreSonus-speak, but would be more accurately termed ‘transfer function’) part of the Dry/Wet Mix row in the middle column and the curve editor will appear. In the example, I dragged the handle in the middle of the curve down just a little to give a slight exponential bend, which sounded smoother to me.
At this point, dragging around the X-Y pad already should be giving you a pretty good circular movement, but we can improve it. One thing that didn’t work for me was that the signal got more reverberant at the ‘back’, but was just as loud there as at the ‘front’. To fix that, drag the Gain parameter in the same Mix folder to the left column and drop it on Pad1-Y, as you did with the Dry/Wet Mix. Now the Y axis will control both parameters simultaneously. (Studio One suffers from many inconsistencies in terminology. For the sake of clarity: the Dry/Wet Mix parameter controls the Mix knob on Open AIR’s front panel, while the Reverb Mix parameter controls the ER/LR knob on the front panel.)
We want increasing Y-axis values to result in decreasing gain, so click on the curve graphic to open the Gain curve and click the Invert button; the curve’s polarity flips. Though the sound should be a bit quieter at the ‘back’ (top) than at the ‘front’ (bottom), we don’t ever want the signal to disappear, so the gain should never go all the way down to its minimum value. In fact, we only need a fairly small level difference between front and back to make the illusion a bit more convincing, so we will scale the curve. Drag the handle on the left to the desired gain for dry signals, and the handle on the right to the gain for signals that are all wet (so to speak). In my case, a difference of about 7dB between the two handles worked well, as in screen 5.
Screen 5: The scaling applied to output gain is modest, starting about 2.4dB below unity and decreasing to about 9.6dB below unity. Note that there is a very slight curve added, as well. Our ears generally do not hear linear changes as sounding natural, and sometimes only a little bit of curve is needed to smooth things out.
Early One Morning
Give this a listen and it should be sounding pretty convincing. I liked it, but decided to throw in one more trick I’d used before for front/back placement. Strong early reflections can suggest proximity to the source and feel more immediate and ‘front’ to me. Find the Reverb Mix parameter in the Mix subfolder of the Open AIR line and drag that to the Pad1-Y control to add it to the other two parameters.
I use loud early reflections with no reverb tail for the front, and reverb tail with no early reflections for the back. The Reverb Mix parameter goes from all early reflections up to all reverb, so I just left the default linear curve. However, early reflections work best when they are mixed subtly enough to be felt, but not clearly heard, so some work scaling the curve might be needed. The complete X-Y pad configuration is shown in Screen 4.
But wait. Isn’t there one more major cue for distance we haven’t used? Yes, we left out pre-delay, which is because changing pre-delay on the fly creates ugly muting artifacts. So we’ll skip out on that one cue today, though we could add it by placing a sweepable delay in between the panner and the reverb. Circular panning will never approach actual surround sound in drama and effectiveness, but once all of the appropriate parameters have been mapped and are tuned, dragging around on the X-Y pad nevertheless gives a reasonably convincing and interesting 2D positioning effect.
