Parallel Effects and DAWs

Most sequencing software doesn’t allow for adding parallel effects — but fortunately, there’s an easy workaround.

By Craig Anderton

In almost all cases, Digital Audio Workstation software assumes you want to put any track effects in series, one right after another. But what if you want to use parallel effects, where a track splits into various effects, which then mix back together to create a potentially more complex and detailed sound?

One option is to use a plug-in like BIAS' Vbox, or TC Electronic's late, great Spark FX Machine. These are essentially "plug-in hosts for plug-ins" that create a matrix of slots where you can insert effects in both series and parallel. Yet while these are convenient, you don't actually need any special kind of plug-in to do parallel effects.

SEND IN THE CLONES

The trick is to copy (clone) the track to which you want to apply the parallel effects, resulting in several parallel audio tracks. You then apply effects to these tracks as needed. For example, suppose you want to add a parallel effect to a piano track, where a noise gate lets through only the peaks; furthermore, this goes to a reverb that's panned far left. Meanwhile, a second noise gate sends a different set of peaks through a short delay, to a different reverb that's panned far right. You could do this with aux sends, but there's an alternative.

For this example, we need three parallel tracks:

• Straight piano only
  
  
• Straight piano + noise gate + reverb1 (panned left)
  
  
• Straight piano + noise gate + delay + reverb2 (panned right)
  
  

Copy the straight piano track two times for a total of three piano tracks. The first track is the "straight," unprocessed track. In the second track, insert the noise gate and reverb, then pan the track left. For the third track, insert the noise gate, delay, and second reverb, then pan that track right. (Of course, you could also just slide the third track behind a bit in time to create the delay, but sometimes it's a lot more convenient to just dial in a delay, particularly if you need to sync to tempo).

Three tracks are creating the parallel effects setup involving a piano, reverbs, gating, and delay. This example shows Cubase SX, but the same concept applies to virtually any sequencer/hard disk recorder.

Because tracks in today's DAWs are aligned with sample accuracy (and assuming the effects paths have delay compensation), you won't hear any flamming, comb filtering, or other undesirable effects when you combine the tracks.

"VIRTUAL MICS" WITH PARALLEL EQ

Here's a real-world example of using parallel effects to create a wider stereo image. In some ways pianos are fun to record, because they generate sound over a wide area. Stick a couple mics in the right places, and you'll end up with some great stereo imaging.

But other instruments, such as classical guitar, accordian, percussion, etc. don't have a wide stereo image if you hear them from more than a few feet away — although up close, it can be a different story. If you're facing a guitarist, your right ear picks up on some of the finger squeaks and string noise from the guitarist's fretting hand. Meanwhile, your left ear picks up some of the body's "bass boom." Although not as directional as the high-frequency finger noise, it still shifts the lower spectra somewhat to the left. Meanwhile, the main guitar sound fills the room, providing the acoustic equivalent of a "center channel."

This all became very clear to me when recording a guitar/keyboard duo, where the keyboard had a nice spread but the guitar kept getting shoved to the center of the image. What to do? I tried using two mics on the guitar, but the phasing issues were unacceptable. Then I thought about what made the sound "wider" as you got closer, and a solution suggested itself. I've also used the following technique to stretch a piano and organ's image beyond what I could obtain simply by using two mics; in fact, this basic principle works for most sound sources where the bass doesn't need to be in the middle of the stereo image.

The first step in simulating the effect of being close to the guitar was to clone the original guitar track to two more tracks. The first clone provided the "squeak" component by including a highpass filter that cut off the low end starting around 3 kHz, with 11 dB of total cut. This was panned right. The second clone for the "boom" channel used a lowpass filter with a sharp cutoff from 350 Hz on up. An additional shelf added a mild 3 dB of bass boost, kicking in at 125 Hz. This came in a little closer to center than the squeak channel.

I also needed to remove some low end from the "straight" channel to make some sonic space for the boom channel. Adding these two tracks to the main track pulled out some of the "finger squeaks" and "boom" components that were in the original sound, and positioned them in a more realistic stereo location. This also stretched the stereo image somewhat. And because these signals were extracted from one mic, there were none of the phasing problems associated with multiple mics.

These three EQ curves, when panned as described and mixed for the proper balance, create a much larger image that belies the fact a recording was done with a single mic.

As to mixing these three elements, the drastic amounts of high and lowpass filtering on the cloned channels brought their overall levels way down, even without touching the channel fader. If you isolate these tracks, it seems as if their impact would be non-existent due to the low level and restricted frequency range. But if you mix them in with the main channel, the entire sound comes to life…which is definitely a Good Thing.