Samson ZM125, Owner'S Manual

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6
Using Passive Speakers
If you are using passive (un-powered) speakers, you
need to first decide where you will place your ZM
series mixer/amplifier. If the speakers in a particular
sound zone are less than 100 feet away, connect the
wires from the amplifier to your passive speakers
directly.
NOTE: This type of wiring is known as "home-run wiring"
since you are making a direct connection from the
amplifiers in the equipment rack to the speakers located
in the sound zone room.
Be sure to check the impedance of the speakers you
are using. The ZM Series amplifiers can run at 4 ohms,
so connect one 4 ohm or two 8 ohm speakers on the
ZM Series 4-Ohm output. If the speakers in a particular
sound zone are further than 100 feet, you should
consider placing the amplifier in the same room as the
sound zone or use a constant voltage speaker system.
Using A Constant Voltage Speaker System
If your installation requires multiple speakers and
long cable runs you should consider running a 70 volt,
constant voltage system. Constant voltage systems
became the installation standard in the mid-1900’s
offering a cost effective solution for installations using
multiple speakers and long cable runs. The idea was
borrowed from the cross-country power grid where
voltage is stepped up and therefore the current is
reduced allowing huge amounts of power to run over
long distances on relatively small, lower cost cable.
Ultimately the voltage is stepped down and delivered
to the customer over a short, heavy gauge cable.
Designing an Installation Plan
Now, take some time to consider where you need to
have sound in your particular installation. After you have
decided where you need to create sound zones, you can
consider your speaker selection, but first decide where
you are going to locate your equipment rack.
Locating Your Equipment Rack
Since the ZM Series amplifiers and ZM series are
standard 19-inch rack mount devices, you should
consider using an equipment rack, such as one of the
Samson SRK series. To select a good location for your
equipment rack, you should consider several points
including the proximity to each of the sound zones,
if the users need to access the gear to change CD’s or
to adjust a volume level and if you have a convenient
location to the electrical service, to name a few. You will
need to consider the length of wire runs and routing
necessary to make the connections from the equipment
rack to the various sound zones. Depending on the
speakers you choose, and the length of cable runs you
need to make, you may choose to run speaker level or
line level to the sound zones. If you are using passive
(non-powered) speakers, you will need to connect the
output channels of the ZM series to an input channel of
the ZM Series amplifier and run speaker wire. However,
you need to be careful to pay attention to the wire
gauge and total length of the wire run. If you are using
powered (active) speakers you can run long distances
using the balanced outputs directly from the ZM series.
Since the ZM series's output connections are terminated
using Euroblock connectors, the wiring can easily be run
in advance of the equipment installation.
Another type of installation is one that uses speakers
and amplifiers (like the ZM Series) with 70-volt
transformers, which are commonly referred to as
Constant Voltage systems. The benefit of a constant
voltage system is you can run long lengths of wire and
have many speakers connected to a single amplifier.
You can also balance the level of each speaker by using
one of the available transformer settings. The ZM series
mixer/amplifiers are ideal for this thanks to their built-in
25/70/100 volt output transformers.
Selecting Speakers for Each Zone
To select the speakers, you need to consider a few
important issues like where you are going to place
your power amplifiers, using powered or un-powered
speakers, or if you need to run a 70-volt distributed
sound system. The following sections provide a brief
overview on how to connect active and passive
speakers or a constant voltage system in a typical
installation.