Why didn’t I think of that? – A thought, that went through my head on a late afternoon, while visiting a workshop with LAWO (a German broadcasting console manufacturer) and Sennheiser/Neumann last November. Just graduating from my second college course (live sound engineering), I went there to pick up some tricks from veterans, or whatever you want to call those with experience and willing to share it. The day had been interesting thus far, though it was only towards the end, while talking about a classic festival and how the Tonmeister engineering it approached the task. Yes, I know nothing special so far, but bear with me for another moment. What caught my eye (or ear) was the way, he used the desk’s bus structure (an Innovason Eclipse for those interested) to pan the signals, using different delays on the buses.
Flashback – Psychoacoustics lecture: How do we know, where a sound is coming from?
Well basically, our brain uses three things to determine the origin of a sound:
- Volume: A signal, that’s louder at our right ear, than our left is perceived as originating from the right. Nothing spectacular, every pan-pot works that way.
- Time difference: A signal, from the right reaches our right ear a little bit earlier than our left one. So there is a small time difference or delay.
- Frequency: Signals originating from the back have a slightly different frequency response to those from the front, due to the form of our ears.
All right, but what’s the point of it? Mixing a show in stereo (what we tend to do living in the 21st century) creates the issue, that ultimately not everyone is going to hear everything, because hard panned signals will only go to one side of the PA. However, sending the signal to both, left and right, and delaying it will enable the people around the on-axis to have a nice stereo image, while the ones off to the sides still hear everything, too.
Sounds great, right? Well everything in live has its ups and downs. First of all, this techniques only works for lower frequencies. Delaying a signal ultimately means manipulating the phase. And if the phase relation between left and right reaches 180° or 1/2 of the wavelength, then it will be perceived as two seperate signals, rather than one.
Secondly, and already mentioned, delaying the signal on one side means to alter the phase relation. This works quite fine while working with only two sources (L/R) but is bound to create some problems when delay lines and InFills are introduced.
Last but not least, there is a practical problem – most digital mixing consoles don’t support the structure necessary to create the bus matrix needed or limit the amount of buses (looking at you Venue).
A great trick, that I keep up my sleeve, and definitely will see some use, when I get the setup to try it in a proper show environment. Also, something, that the manufacturers out there might consider – wouldn’t it be great if we could choose, how we want our pan-pot to work – based on volume, delay or a combination?