PreSonus Blog

Open Air: Much More Than Just Reverb

After doing some fairly “normal” tips for the last few Fridays, let’s go a little crazy—and explore some interesting sound design and rhythmic possibilities.

Open Air is a wonderful convolution processor, but it’s helpful to remember it can load any audio file, not just room and reverb impulses. I’ve said many times it’s more fun to ask “what if?” than “how do I?”, because “what if” is all about experimentation. So I asked “What if I’m using a drum loop, and also load that same loop into Open Air as an impulse?” You might not use the resulting sound all the time, but give this technique a try—you’ll hear an entirely new type of percussive effect.

  1. Make sure the loop itself matches the song’s tempo, and it isn’t just stretched to fit. If it was stretched to fit, select the loop and type Ctrl+B to make the length change permanent.
  2. Copy the loop (e.g., to an empty track). Open Air doesn’t seem to like high-level drum loop impulses, so drag down the top envelope handle to reduce the level by at least -6 dB. Again, select the loop and type Ctrl+B to make this change permanent.
  3. Drag the copied loop into the Open Air waveform window, and now you have a cool drum impulse.
  4. The odds are it will sound pretty dreadful; if needed, start by reducing the Open Air Gain control to prevent distortion.
  5. The EQ settings are really important (Fig. 1). I’ve had the best results by cutting back on the low frequency shelf, and boosting the high frequency one. To adjust EQ, temporarily set the Mix to 100% so you can hear the results of any changes easily; after the EQ is tweaked, adjust the Mix amount to taste.


Figure 1: Typical Open Air settings when modulating a drum loop by itself.

Remember that the drum loop is still acting like a reverb, so it will build up a bit over time until the level stabilizes, and the processed sound will have a tail as long as the loop.

Next, there are several ways to add variations. First, you don’t have to convolve a loop with itself—check out the audio example.

The first four measures are a drum loop convolved with itself. The second four measures convolve the original drum loop with a tom loop, while the final four measures convolve the original drum loop with a percussion loop.

Altering the Open Air Length can create interesting effects, especially when using a rhythmically related length—like half or 1/3 the length. With sparse loops, longer lengths can work too, like 1.33, 1.5, or 1.66 the length (get out your calculator, and work with the number that’s shown under the Length control). Additional EQ and processing can add even more interest.

And remember to experiment with other types of impulse as well—pads, voices, guitar chords, whatever! You never know what you’ll discover.