Stories From the Road

By Allen Rowand

February 20, 2008

03: Cincinnati, or The Case of the Hanging Bass

The architecture was fighting us. There was a dome in the ceiling, to reflect the sound from the stage and pit into the house. Unfortunately, it was also reinforcing the bass in the system so we had to do some rather "radical" eq'ing. We got the system to sound good with our test tracks, then waited for the actors to hit the stage.

Once we got into the rehearsal, it became obvious that the vocals in the balcony were muddy. Since I was using my normal 7 microphone test rig, I started comparing the sound upstairs to the orchestra level (which sounded fine). During a break I sent test tones through the system and watched them decay in my spectragraph. It was apparent that the problem wasn't that the bass upstairs was too loud- the frequency response upstairs was very close to downstairs. There was a lobe at 180 Hz that was decaying much more slowly upstairs, by about 2/3 of a second.

After seeing this, I put in a very narrow filter in the speakers pointed into the balcony, and the problem immediately cleared up. Then we got to deal with all the "artistic" issues!

Until next time,
Allen