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Introduction
Your JSS4-VC2 Speaker Selector-Volume Control is designed to operate with up to 4 pairs of
loudspeakers of 4, 8, and 16 Ohms impedance in any combination. It can be used with one or
two stereo amplifiers, or with 4 Channels of a surround-sound type sound system. Each of the
4 output Control channels can be individually switched to the amplifier connected to A INPUT,
or one connected to the B INPUT. Thus it is convenient to listen to different program material
in different rooms, swap front and rear channels in a surround-sound system, etc.
Impedance loading protection for the power amplifier (s) is built-in, and fully automatic. Four
100 Watt AUTOMATCH attenuators are employed, pre-set so that the worst-case operating
condition (four pairs of-4 Ohm speakers operating simultaneously at maximum volume) will
appear as a 4 Ohm load on the amplifier. Higher impedance speakers and/or lower volume
settings of the controls will reflect a higher impedance to the amplifier, so that safe operation
is assured.
Since impedance matching protection is achieved by use of AUTOMATCH transformers, there
is no heat generated in the matching process- this assures safe operation in a closed
environment. There are no extra buttons to operate that must be remembered to maintain
safe operation. An additional advantage is that there is no power loss in the JSS4-VC2. There is
a level drop of -6 dB to the speakers at maximum volume settings of the JSS4-VC2 controls (at
the factory setting), but this is not a power loss. When all 4 controls are set at maximum volume,
the full power of the source amplifier is available, divided equally among each of the 4 speaker
pairs.
Both the A and B amplifier inputs are identical, and completely independent of each other.
Speakers selected for operation with the A amplifier input will have the same impedance
protection as those that may be operating with the B amplifier. The number of pairs of speakers
in operation on either channel will have no effect on any operating on the other.
Other JSS4-VC2 features include power handling capability of up to 100 Watts RMS continuous
at 8 Ohms in any switching mode. The LEFT and RIGHT channels are completely separate
to assure safe operation with alt types of amplifiers, including those with bridging outputs.
The volume attenuators are tapped auto-transformer type with attenuation of 3 dB/step except
for the last 2, which are 4 and 6 dB. These controls do not heat up in operation, nor do they
deteriorate over long time use.
Connecting
Connections to amplifiers and speakers are illustrated in the back of these instructions.
Remember that the LEFT and RIGHT circuits are separate, so connections must be made correctly
or the system will not operate properly.
Heavy duty push-to-open connections are provided on the rear panel to insure positive, long
lasting, connections. To make connections, strip about 3/8" of insulation from the wire end.
Push the connector tab toward the rear panel to open the hole. Insert the stripped wire end
into the opening , and release the tab. Make sure no loose ends stick out to cause problems.
Check that the bare wire, not the insulation, is connected to the hole.
If only one amplifier is to be used, connect it to the AMPLIFIER A terminals as shown. Make
sure the + and -, and L and R channel connections are correct to avoid unsatisfactory operation
or dead channels.
The same precautions should be used when connecting the speakers, crossed channels, polarity,
or grounds will result in improper operation.