Model A27M User Guide
©2004, Shure Incorporated
27B1424 (Rev. 3)
Printed in U.S.A.
STEREO MICROPHONE ADAPTER
The Shure model A27M is a stereo microphone adapter
designed to hold two microphones in selectable positions for
stereo broadcasting, recording or sound reinforcement. It
allows two microphones to share one stand without losing
independent positioning flexibility. The A27M permits coin-
cident or closely spaced mounting with a wide range of di-
rectional angles, and vertical microphone separations of 1
1/4 inches (31.8 mm), 2 5/8 inches (66.7 mm) or 4 inches
(102 mm).
The A27M consists of two vertically stacked sections that
rotate on their centers. Each contains a 5/8"-27 threaded
stud and locking ring to accept a variety of microphones.
The bottom section contains a 5/8"-27 adapter for mounting
on a microphone stand. A cable clamp for holding micro-
phone cables is included.
Installation
To install the A27M, follow these steps:
1. Determine the vertical separation between microphones
you desire. Minimum separation (coincident spacing) is
generally desirable, but it may be necessary to provide
greater spacing to accommodate the size or style of the
microphones. By repositioning the sections of the
A27M, the threaded studs may be 1 1/4 inches (31.8
mm), 2 5/8 inches (66.7 mm) or 4 inches (102 mm)
apart.
2. To reposition the sections, unscrew the knurled knob at
the top of the A27M and slide the two black sections off
the vertical rod. Reposition the sections with the studs
positioned for the vertical spacing desired. Replace the
knurled knob.
3. Attach the microphones or swivel adapters (such as the
Shure A57D or A57E) to the 5/8"-27 studs.
4. Attach the A27M to a microphone stand with a 5/8"-27
mounting thread.
5. Insert the microphones in the swivel adapters, loosen
the knurled knob on the top of the A27M, and position
the microphones for the desired response angles. The
top of the knurled knob contains reference marks every
45o; these may be used to position the microphones at
the desired angle (see Figure 1).
FIGURE 1
6. Tighten the knurled knob, attach the microphone cables,
and use the supplied cable clamp to fasten the micro-
phone cables to the A27M.
7. Raise the microphone stand to the desired height. Fig-
ure 2 shows a pair of Shure SM81 microphones
mounted in an “ORTF” configuration on the A27M.
FIGURE 2
