I recently learned a trick to create analog reverb/echo that doesn’t use a digital plugin.

As part of the Disquiet Junto group, I heard about sound design legend Walter Murch’s trick for adding ambience to a sound recorded in a studio.

I love old studio tricks and foley work etc so I had to give this a try.

Technical Details

Here’s a video of Murch describing the technique:

Originally I was going to try to use some of my cassette field recorders to do this entirely analog. But alas, my decks won’t record with their varispeed controls enabled. So I had to find a digital method.

The simplest seemed to use sample rate (the digital analog of tape speed).

  1. Set up my usual M/S array in my studio, and recorded at 44.1khz. [Pitch is normal on this recording]
  2. Switched my digital system to play back and record at 96khz. This raised the pitch of everything I recorded in step 1. This is necessary for the trick to work. [Pitch on playback is raised]
  3. Set up my M/S mic array in the middle of the room and played back the recording from step 1 which was sped up in step 2, recording at 96khz. The purpose of this step is to record the room echo. [Pitch of this recording is raised]
  4. Switched the digital system back to play at 44.1khz, bringing everything back down to the original pitch but, importantly, extending the response time of the room echo recorded in step 3. This makes the room sound much much larger. [Pitch of this playback is normal]
  5. The trick added a fair bit of noise to the sound, but wasn’t really grating, more a “hushhhhh” than a “hiss.” I can imagine circumstances where I’d even love that sound. I used a shelf EQ to back it off just a little though.

I really loved the result of this. It definitely adds a new and unique sound to the mix.