Make A Surround SASS Array

Soundmixer Gary Pillon came up with a clever way to mount two Crown SASS-P MKII stereo mics and two MB-4 mics to create a high-quality surround miking array. Two SASS mics are arranged back-to-back. They can be mounted on a common bracket, which you mount on a mic stand or camcorder. Or they can be mounted on two separate mic stands spaced about 1 meter apart.

Gary used the surround SASS array to build a complete virtual person system. The mic outputs feed a chest-worn digital audio recorder.

Gary is shown below with a surround SASS array mounted on a camcorder.

Here it is mounted on a Fig Rig:

 
Photos and Panasonic HD camera courtesy of Joel Knoop.

We also call the Surround SASS Array the "BBP" Array, which stands for "Billingsley, Bartlett, Pillon". Mike Billingsley and Bruce Bartlett developed the SASS mic, while Gary Pillon and Bruce Bartlett developed the Surround SASS array.

You can omit the rear MB-4 microphone if you want the system to be 5.1 surround. Each MB-4 mic mounts on the downward-slanting face of the SASS as shown. This puts the MB-4 mic capsules and the PZM capsules on a circle when the SASS mics are 2.5 inches apart. This circle matches the Holosonic Reference Theater circle.

According to our listening tests, the surround imaging of the array is very sharp except at the left and right sides. When the mics are mounted a few inches apart on a bracket, low frequencies are localized toward the listener while high frequencies are localized in the loudspeakers. When the mics are spaced about 1 meter apart, most of the frequencies are localized in the loudspeakers. You might get the same effect with two close-spaced SASS mics by delaying the rear channels about 3 msec.

The figures below show how to construct a mounting bracket from a 0.187-inch (3/16-in.) thick sheet of aluminum. This bracket is not commercially available. It holds two SASS mics back-to-back separated by a few inches.

 

Assembly:
Build one of the mounting brackets shown above. If you don't have a # 8-32 tap, you could just drill out those holes and use # 8-32 nuts.

Next, follow the procedure below for each microphone. You will need an Allen wrench that fits the bolts that hold the SASS back panel, and another wrench that fits the bolts that hold the SASS swivel mount.

1. Remove the back panel of the SASS and pull out the chassis. Be careful not to rip the wires.
2. In the bottom of the SASS is a 1" x 2" plate with crimped-on nuts. Gaffer-tape this plate in place so that it will not become loose when you remove the mic's swivel mount in Step 4.
3. Replace the chassis and back panel.
4. Remove the Allen bolts from the swivel mount.

Now you will attach the bracket to both SASS mics. You will need three # 8-32 bolts and nuts (not supplied).

1. With the SASS mics upside down, place the bracket so that the holes in the bracket align with the holes in each SASS mic.
2. To hold the bracket in place, re-install the screws that held the swivel mounts. Be careful not to strip the threads.
3. Using the three # 8-32 bolts and nuts that you supplied, screw one swivel mount to the center of the bracket.

The MB-4 has a higher output than the SASS, so set its record-level meter to match the SASS record-level meter when a person speaks in front of the mic. To reduce wind noise, put a piece of foam under the windscreen near the MB-4 to create an airspace.

We think you'll enjoy the wonderful spaciousness and precise imaging you'll hear with the BPP Array.