Radio Shack 32-2054 Owner's Manual page 7

You can connect another MP-40 amplifier to this
jack (shown on page 3) to double the size of your
PA system. This lets you use up to four
microphones and two turntables
(or two auxiliaries) sound sources.
Use a shielded cable with phono plugs at each end
to connect the amplifier. Connect the cable between
the two amplifiers' MIX BUS jacks. For the best
results, use the most appropriate cable length.
You can connect one or more 4-, 8- or 16-ohm
speakers to the amplifier, with or without
transformers. To ensure equal volume from each
speaker, all the connected speakers should have
the same impedance rating.
Proper phasing is important when you use more
than one speaker in the same room or area.
Out-of-phase speakers can lose up to one-half of
their potential volume, and can have a significantly
decreased bass effect
Most speaker terminals are color-coded or have a
mark that indicates the terminal's polarity. Usually,
terminals with positive polarity are red or have a
plus (+) symbol, and terminals with negative polarity
are black or have a minus (-) symbol. Phasing is
correct when you connect + to + and - to -.
Before you connect speakers to the amplifier, you
must determine the total speaker impedance.
To determine total speaker impedance, you must
first decide if you are connecting the speakers in
series, parallel, or a series/parallel combination.
±
.
±
Proper phasing occurs when
speakers are set to allow
sound to flow in the same
direction.
• A total speaker impedance
higher than 16 ohms or
lower than 4 ohms can
damage your amplifier.

• When determining the total
speaker impedance, first
determine whether you are
connecting the speakers in
series, parallel, or a series/
parallel combination.
±
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