Samson POWER AMPLIFERS SZ1120 - Manual (Page 10)

6
Using Active Speakers
In a larger installation, you may use a combination of
passive speakers connected to your SZ Series amplifier
along with some active, or self powered speakers in a
different zone. When using active speakers, you can
connect the S zone’s outputs using the balanced line
level signals. In this case, you will run line level signal
from the S zone’s Zone Output over the long wire
run to the input of the powered speaker located in
the sound zone. For more information on wiring for
balanced signals, see the Input Wiring Guide on page
12 of this manual.
Using Passive Speakers
If you are using passive (un-powered) speakers, you
need to first decide where you will place your power
amplifier. If the speakers in a particular sound zone are
less than 100 feet away, you can locate your SZ series
power amplifier in the same rack as the S zone and
connect the speaker wires from the amplifier to your
sound zone.
NOTE: This type of wiring is known as "home-run wiring"
since you are making direct connections from the
amplifiers in the equipment rack to the speakers located
in the sound zone room.
In this case, you would connect the S zone’s Zone
Output to the SZ Series Input and then run the speaker
wires to the passive speakers. Be sure to check the
impedance of the speakers you are using. SZ Series
amplifiers can run at 4 ohms, so connect one 4 ohm or
two 8 ohm speakers on each SZ output channel. 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.
IMPORTANT NOTE: Only licensed and insured
professional sound contractors should install Constant
Voltage Systems. Samson assumes no liability for any
installation.
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 SZ series amplifers and S zone 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 S zone to an input channel
of the SZ 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
S zone. Since the SZ Series' and S zone's inputs and
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 SZ 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 SZ series
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.