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proDuct DeScription / connectionS
Description
The SDB-2.1, SDB-4.1 and the SDB-6.1 are high-power, dual-source, autoformer-
based speaker selectors with individual volume controls for 2, 4 or 6 areas/rooms.
Dual-source operation means either one of two different amplifiers/receivers
can be chosen to power selected speakers independently. For example, you can
choose to listen to jazz music in a couple of rooms and classical music in all the
others. Each room has its own input selector, volume control and on/off switch,
located on the front of the unit. The SDB speaker selectors work with all speakers
rated from 4 to 8 ohms, and amplifiers rated for 4 to 8 ohm loads.
Setting the Impedance
The impedance of the autoformers in SDB speaker selectors is set at the factory
to be proper for most applications. The SDB-2.1 comes set at 2X; the SDB-4.1
at 4X; and the SDB-6.1 at 8X. However, if certain applications require changing
the impedance setting, simply remove the cover of the unit and re-position the
jumpers on the autoformers to the necessary impedance-matching setting.
Russound SDB Speaker Selectors autoformers can be set to impedance-matching
settings of 2X, 4X or 8X.
1.
Determine the amplifier's minimum impedance. Consult the individual
product specifications or the back panel of the amplifier near the speaker
terminals. AC impedance is measured in ohms.
2.
Identify the correct impedance-matching chart below according to your
amplifier's minimum impedance: either for a 4 ohm amplifier or an 8 ohm
amplifier. If your amplifier is 6 ohm stable, use the 8 ohm chart.
3.
Determine the impedance for each pair of speakers (see its manual).
4.
Determine the total number of 4 ohm pairs of speakers (rows on charts).
5.
Determine the total number of 8 ohm pairs of speakers (columns on
charts).
6.
Use the appropriate row and column to determine jumper settings.
0
1
0
-
1X
1
1X
2X
2
2X
4X
3
4X
4X
4
4X
8X
5
8X
8X
6
8X
8X
7
8X
8X
8
8X
2
Impedance Matching For 8-ohm Amplifiers
0
1
2
0
-
1X
2X
1
2X
4X
4X
2
4X
8X
8X
3
8X
8X
8X
4
8X
Impedance Matching For 4-ohm Amplifiers
2
3
4
5
6
1X
2X
2X
4X
4X
2X
4X
4X
4X
4X
4X
4X
4X
8X
8X
4X
8X
8X
8X
8X
8X
8X
8X
8X
8X
8X
8X
8X
8X
8X
8X
8X
8X
8X
Russound SDB Series Installation Manual
Connections
All SDB models have 4-pole screw down removable terminals for speaker and
amplifier connections. These accept wire up to 12 gauge.
Remove the terminal by firmly pulling it out of its 4-pole connector. Strip about
3/8" of insulation from the ends of all wires to be connected. If necessary, twist the
exposed conductor to insure that no loose strands exist. Insert the wire ends into
the screw down connector, being careful to observe proper channel and polarity.
Tighten the screws on the connectors. Connect the amplifier(s) and each speaker
pair to the appropriate connector.
Speaker connections can support multiple speaker pairs wired in parallel or series,
provided their combined impedance is a minimum of 4 ohms.
Setting System Volume
It is important to properly adjust an impedance-matching system to avoid
distortion or DC clipping (DC voltage will be produced from an amplifier that is
overworked or that has an improper load). These can cause an amplifier/receiver
to go into protection, and can cause autoformers on volume controls to heat
up, damaging system components. To set up the system, the amplifier/receiver
volume should be at its lowest setting, and the selector volume control should be
at the highest setting. Slowly adjust the amplifier/receiver volume to a level that is
acceptable for the amplifier to produce without clipping.
Operation
To operate the SDB speaker selector, simply power the amplifiers and select a source
for each amplifier. At the speaker selector, turn on the selected pair of speakers and
select AMP A or AMP B. Set the volume by rotating the control clockwise to increase
volume or counter-clockwise to decrease volume. The SDB speaker selectors allows
operation of any combination of speakers selected to either amplifier A or B.
8-ohm Pairs
3
4
5
6
4X
4X
8X
8X
8X
8X
8X
8X
8X
8X
8-ohm Pairs
7
8
9
10
4X
4X
8X
8X
8X
8X
8X
8X
8X
8X
8X
8X
8X
8X
8X
8X
8X
8X
7
8
8X
8X
8X
11
12
13
14
15
8X
8X
8X
8X
8X
8X
8X
8X
8X
8X
8X
16
8X
Rev. 5
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