Stories From the Road

By Allen Rowand

August 14, 2008

08: East Lansing, or You can always go back…

This year, the tour spent a lot of time returning to cities we'd previously played. With digital recall on most sound equipment it would be tempting to walk in and simply load the settings from the last time were in a venue. In this case we definitely didn't want to, for a few reasons:
1) We'd weren't thrilled with the way the venue sounded the first time we were here and
2) There had been architectural changes since our last visit

The venue: same bouncy pillars and reflective architecture.

Side view

Here you can see the change that was made- the black drape hanging along the wall in the upper right hand corner of the photo. To start looking at what the room was doing, I put 4 mics downstairs and 2 in the balcony. I ran pink noise through the system and let SpectraFoo average for a bit, then took an instantaneous snapshot of all the mics. I then averaged all the snapshots, and averaged just the orchestra and balcony.

All (red) vs. orchestra (blue)

While there's more deviation in the orchestra-only signal, the response is very representative of the overall average.

All (red) vs. balcony (teal)

Here you can see more pronounced deviation between the overall average and the balcony, most likely from reflections. There's also a pronounced falloff in the high end, from the distance between the speakers and the microphones.

During the orchestra and vocal rehearsals, I measure from different points. I was concerned with the difference in response between the first row and the last, but it's difficult to judge frequency differences when the displays are out of sync due to being 90' apart. To correct for this, I used the transfer function:

Delaying the microphones

I set the microphone in the front row orchestra to be the source, and the microphone in the last row of the balcony as the response. 'Foo immediately locked in at 90.75 feet and delayed the orch mic to the balcony. Now I could watch the two traces in time.

Spectragraph showing the delayed trace

All of these techniques let us get the system tuned much better than the last time we played here. Of course, the draping eliminating a lot of the reflections didn't hurt either!

Until next time,
Allen