Sonar: Hidden Sources Of Distortion

Track down hidden sources of distortion, make your audio playback more reliable, and manage your window Layouts.

One of Sonar's strongest points is that it can handle Groove Clips (Acidised files that can be time/pitch-stretched). However, I recently noticed a strange problem where, even though Groove Clips were normalised to something less than 0dBFS, the track meters sometimes indicated overload. As I couldn't figure out a solution myself, I asked the Cakewalk brain trust if perhaps the meters showed clipping at a value slightly less than zero, but Cakewalk confirmed that the meter clip point is 0dBFS. Hmmm...

Eliminating Groove Clip Distortion

After putting in a lot of editing hours on my next loop library, I finally figured out what was going on. If a file plays back without distortion, is converted into a Groove Clip, and plays back at its 'native' tempo, it will not distort. However, speeding up or slowing down the song may cause slight volume increases that push the overall level past the point of overload. This is because the DSP that does the time-stretching relies a lot on crossfading, so if phase-coherent audio sections overlap, the signal peaks can add up and clip. This effect is not predictable. For example, a 120bpm Groove Clip might distort at 80bpm and 140bpm, but not 160bpm. So, when creating Acidised files, my final step is now normalising them to -3dBFS.

Unfortunately, Sonar does not allow normalising to anything other than 0dBFS. You might think that normalising within Sonar then selecting 3dB Quieter from the Process menu's Audio submenu would accomplish the same result as normalising to -3dBFS. For some reason, though, that's not the case. So, I use Syntrillium's Cool Edit Pro v2 to call up the file and normalise it from there. Tick the Decibels Format box, tick Normalise To and enter '-3dB', leave DC Bias Adjust unticked, then click OK. So far, I have yet to create a Groove Clip that will distort, regardless of tempo, when normalised to -3dBFS although, of course, anything is possible...

There is one fine point: if you click on a Groove Clip within Sonar and select Cool Edit Pro from Sonar's Tools menu, Sonar will not let you go there, because it assumes that wave editors can't handle Groove Clips. However, Cool Edit Pro v2 can process Groove Clips and retain the Acidising markers. Therefore, I just open up Cool Edit Pro v2, and call up the loop file from there.

Managing Window Layouts

The Layout function lets you add, name, or delete particular layouts of windows and pane sizes. I first found out how useful this could be while working on a project that involved extensive use of both MIDI and digital audio, which required switching back and forth a lot between the Piano-roll view and the main Track view. So, I set up Layouts for the two views, which simplified switching between them. Any time you want to save a particular Layout, choose add from the View menu's Layouts submenu. This brings up a window where you can name the Layout. After naming it, click OK, which adds the new Layout to the list.

You probably don't want to go too nuts with Layouts, as scrolling through a long list of Layouts to find the one you want is kind of annoying, but I found I didn't need too many. In addition to the Layouts mentioned above for the Piano-roll and Track views, I created three more:

• Console view on top. I don't use the Console view very much, except to take advantage of the 'long-throw' faders for those few instances where I'm writing automation on-screen instead of using the Radikal Technologies SAC2.2 control surface. I arranged the Layout so the console's right edge extends slightly beyond the right-most side of the Track view. That way, if the Track view is on top, it's easy to click on the console's edge to bring it back to the front again.
• Sample editing. This changes the Time Ruler Format to Samples, and makes the Clips pane section very wide compared to the Tracks pane (when sample editing you usually don't need to access the aux send controls, ins and outs, and so forth).
• Track info. This is the usual Track view, but with the Tracks pane extended way to the right, with just a bit of audio showing. Calling up this Layout provides the equivalent of a Console view without having to use the console, as you can see auxes, pans, the complete track names, which effects are loaded in the FX Bins, and so on. In particular, this makes it easy to sort out the panning.

The Window Layouts function has a couple other notable options. If you tick Close Old Windows Before Loading New Ones, open windows that are not a part of the new Layout are closed before the new Layout is loaded. I find this helps keep clutter to a minimum. I also tick When Opening A File, Load Its Layout. In addition to being able to save Global Layouts, when you save a Song with a particular window Layout this Layout will be called up when you open the Song. If this box isn't ticked, then Sonar opens to the usual default Track view.

Finally, to make the Layout window as convenient as possible, I use the Key Bindings function (accessible from the Options menu) to assign the window to function key F2. Make sure Computer is selected as the Type Of Keys, scroll down the Key List until you see F2, then click on it. Next, scroll down the Function list until you see View Layouts. Click on it, then click on Bind. Now hitting F2 will call up the Layouts window, and once it is open you can use your computer keyboard's arrow keys to select the desired Layout, hitting Return to load. No mousing required!

Creating Crossfade Loops For Pads

Suppose you have a great sustained synth pad, like a drone or held note (or even a guitar power chord), and you want to turn it into a loop. Unless the loop start and end points share the same level and timbre, the process of looping will impart a rhythmic quality due to the change in sound when the loop repeats. Of course, this diminishes the pad effect.

Fortunately, as long as there's some audio in the original sample prior to the loop start point, there is a solution to this problem which we can borrow from the sampling world, called crossfade looping. Note that, for best results, the part you want to loop should not be normalised; there should be at least a few decibels of headroom, because what we're about to do may increase the signal level by a couple of decibels in a few places.

To begin, turn the section you want to loop into its own Clip by adding a split at the start and end (place the Now time over the start and press the 'S' key, then do the same for the end). Next, delete any audio to the right of this newly-created Clip. Copy the Clip to the right so that its beginning butts up against the end of the original. Now slip-edit the beginning of the copied Clip toward the left, which creates a crossfade with the end of the original Clip. As a result, upon reaching the end of the loop, the original Clip will include some of the audio leading up to it — the secret of creating a perfect splice.

Now all you need to do is split once more at the end, so that the crossfaded section is on top of the original loop. Draw a marquee around the combination of these two Clips to select them, then choose Bounce To Clip(s) from the Edit menu. The crossfaded section will mix in with the original Clip. If you loop this Clip, the transition from end to beginning should be seamless. All that's left is to turn it into a Groove Clip — the quickest way to do this is to select the Clip, then type Ctrl+L. You may want to go into the Loop Construction view to tweak the slice points so that pitch-stretching is available over the widest possible range, but Sonar's default loop points will probably do the job.

This Layout is extremely useful when you want an overview of all of a tune's parameters. For each track you can see the name and number, track type, volume, pan, effects, first aux send parameters, status (mute, solo, record), and metering.