AEA Stereo Bars & Arrays Stereo Protractor

AEA Stereo Bars & Arrays Stereo Protractor — a compact 6-inch (approx. 15 cm) stereo mounting bar with engraved angle markings at 0°, 90°, 110°, and 180°, enabling precise two-microphone placement for XY, ORTF, and close coincident stereo techniques on a single stand, supplied with three locking rings.

Setting a 90° angle between two microphone axes is intuitive — it is visually obvious. Setting 110° for ORTF is a different matter: the difference between 100° and 110° is invisible without a reference point, and an angular error translates directly into asymmetry in the stereo image between left and right channels. The Stereo Protractor solves this mechanically: engraved angle marks on the microphone mounting heads allow the exact included angle between mic axes to be set without a protractor, string line, or trial and error. TapeOp Magazine put it accurately in their review — 90° you can guess, 110° you cannot.

Compact Format for Tight Miking Situations

The 6-inch format is a deliberate design choice. The Stereo Protractor does not replace the SMP-17 or SMP-1M bars in applications requiring wide physical microphone spacing — it handles coincident and near-coincident techniques where both microphones need to be as close together as possible. Used above a point source — a solo instrument, a guitar amplifier, a drum kit in close position — where a full-metre bar would be logistically excessive. Two 5/8" threads accept clips or adapters from any microphone manufacturer, and the central stand mount point installs on a standard mic stand without additional couplers.

Techniques Covered by the Angle Markings

Four engraved reference points — 0°, 90°, 110°, 180° — cover the key coincident and near-coincident stereo techniques. 90° is XY and Blumlein (with figure-eight microphones). 110° is ORTF — a cardioid pair spaced 17 cm apart with each mic angled 55° off the central axis. 0° and 180° are reference positions for calibration and symmetry verification. The three locking rings included in the kit secure both microphone positions and the stand mount without thread play.

KEY FEATURES

• 6" (approx. 15 cm) length — compact format for coincident and near-coincident techniques in tight miking situations.
• Engraved angle markings: 0°, 90°, 110°, 180° — precise XY, Blumlein, and ORTF setup without measuring tools.
• Two 5/8" microphone threads — accepts clips and adapters from all manufacturers.
• Three locking rings — stable threaded connections without play.
• Single-stand mounting — central mount point for standard microphone stand, no additional couplers needed.

TECHNICAL SPECIFICATIONS

• Type: Compact stereo protractor bar
• Length: 6" (approx. 15 cm)
• Angle markings (engraved): 0°, 90°, 110°, 180°
• Microphone threads: 2 × 5/8" (standard)
• Kit contents: bar + 3 × locking ring
• Supported stereo techniques: XY (90°), Blumlein (90°, with figure-eight mics), ORTF (110°)
• Country of manufacture: USA (Pasadena, CA)