Crown CM-30 Application Manual page 7

Mini Boundary Mics: Very small mics with a half-
supercardioid pattern. Three switchable models are
available:
MB-1: Plugs into a brass cup in the table.
MB-2: Plugs into a jack in the table.
MB-4E: Lowest cost. Cable fits through a small hole
in table.
These models require a Crown MB-100 or MB-200
interface. The MB-100 interface has connections for
an on/off switch near each user. The MB-200 inter-
face also allows remote sensing of switch closure, so
it can be used with a video switcher.
Automatic switching of mics
In this system, use an automatic mic mixer with sev-
eral mics. Choose one of these mic models:
PCC-130: Small mic with a half-cardioid pattern.
PCC-170: Larger mic with a half-supercardioid pat-
tern for extra clarity.
Mini Boundary mics: Very small mics with a half-
supercardioid pattern. Five models are available:
MB-1: Plugs into a brass cup in the table.
MB-2: Plugs into a jack in the table.
MB-3: Tubular; mounts in ceiling, wall or table.
MB-4: For temporary use. Has a thin cable with an
XLR connector.
MB-4E: Lowest cost. Cable fits through small hole
in table.
Models MB-1, MB-2 and MB-4E require a Crown
MB-100 or MB-200 interface. The MB-200 inter-
face allows remote sensing of switch closure, so it
can be used with a video switcher. Each interface can
take up to four mics.
Mic placement
Once you have chosen a suitable mic model, place a
group of them as shown in Figure 6.
Figure 6. Teleconference mic placement.
1. Place one mic at arm's length from each person, or
place one between every two people.
2. At a lectern, mount a Crown LM series lectern mic
of your choice. If the leader of the meeting moves
around while talking, he or she needs a lavalier mic.
Clip the mic onto the shirt, about 8 inches below the
chin.
3. If your mixer has phantom power, connect the
mics to the mixer mic inputs (Figure 7). Models
MB-1, MB-2, MB-4E connect first to the MB-100 or
MB-200 interface, then to your mixer.
Figure 7. Teleconference system block diagram.
4. If your mixer does not have phantom power, con-
nect the mics to a Crown PH-4B phantom power
supply. Connect the power-supply outputs to your
mixer mic inputs. Models MB-1, MB-2, and MB-4E
connect first to the MB-100 or MB-200 interfaces,
then to the PH-4B, then to your mixer.
5. Connect the mixer output to the line input in the
teleconference codec.
By following these suggestions, you can look for-
ward to clear sound in your teleconference and dis-
tance learning systems.