Go for Baroque

Seldom do I get the opportunity to do a show in one of western Canada's finest acoustic facilities. So when Chris Morrison of the Foothills Brass invited me to help with the sound for their Go for Baroque concert at the Rozsa Center, I jumped at it. This concert featured Christine Azad playing accompanying harpsichord to their five piece brass ensemble. They wanted to increase the level of the harpsichord, to be heard amongst the brass, but still sound natural. Ms. Azad was VERY particular about this last point. I assured her I would do my best.

To achieve this goal three targets were identified: 1, Harpsichords play at about 30 dBA below a 5 piece brass ensemble so I needed lots of gain before feedback. 2, The sound has to appear to come from the harpsichord. The best way to do this is to have it actually come from there. 3. To keep the sound natural all coloration must be kept to a minimum.

To meet these targets I used my Acoustic Guitar Amp on stage, next to the harpsichord. This device is a quasi-dipole radiator so it has a partial null front and back. I combined this with another custom loudspeaker (normally used as a matching sub, which can be configured full-range) to fill the null at the front. I then positioned these on stage so the rear null would fall where the microphones are placed and as close to the harpsichord as practicable.

My choice of microphones surprised the in-house engineer. I used a Sennheiser e609 and a Sennheiser 541. Both of these microphones have a ruler flat frequency response AND a narrow pickup pattern in the harpsichord's range. They also have a detailed, open sound, similar to that of some high-end large diaphragm condenser microphones. These were mounted directly on the harpsichord itself, in the apexes of the outside curvature, facing the strings. There is a natural sweet spot in each of these places (corner loading).

In addition to the on-stage setup I used my new pair of dipole loudspeakers for a split-stack house main. The signal from the microphones was attenuated in the low frequencies, to correct for the broadening of their pickup pattern, and also to minimize induced footfall since there were accompanying dance performances. It was also delayed 12.9 ms to the stage setup and a further 10.1 ms before going to the mains. I was a little surprised that these numbers were so high but during the sound check various combinations were tried and listened to from various places in the house. This combination worked the best. Every building is unique.

The result? I was able to achieve 22 dB gain with the stage setup alone. (6dB before feedback.) My "house main" was used only to provide a few more dB while the brass was doing it's best (98 dBA, 4th row center). During the sound check some of the musicians thought the balance was a little off, the harpsichord being just a tad loud, which it was. Christine was relieved at the purity of tone but unfamiliar with the time delay. She soon got used to it though. Another of the musicians listening from house center asked if the sound system was actually on. I assured him it was.

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