Constant Voltage (70/100 V) Mode - Tannoy VLS SERIES Operation Manual

superior to a lower power amplifier running at 100%. An amplifier with insufficient drive capability will not
allow the full performance or the loudspeaker to be realised. (See technical specifications section for
recommended amplifier power.)
When using amplifiers from different manufacturers in a single installation, make certain that all amplifiers have
closely matched gains. (Variation should be less than +/- 0.5 dB.) This precaution is important to the overall
system balance when only a single active crossover is being used with multiple cabinets. When possible, it is
recommended that the same amplifiers be used throughout.
Series/parallel connections - When running low-impedance loudspeakers in parallel, care must be
taken not to allow the impedance to drop too low, as damage may be sustained by the amplifier. Most low
impedance amplifiers will be able to handle loads of 2 ohms to 8 ohms. This means for example that when
using an amplifier with 2 ohm load rating, up to three VLS 30 or six VLS 7/15 may be connected in parallel
per output, although care should be taken as impedance varies with frequency and at some frequencies the
impedance will drop to below 2 ohms.
5.3 Constant voltage (70 /100 V) Mode
In constant voltage distributed systems, normally a number of loudspeakers are connected in parallel to a single
amplifier output. Connect the positive (+) conductor from the amplifier or prior loudspeaker in the system to a
positive (+) barrier strip terminal and the negative (-) conductor to a negative (-) terminal. The other parallel
barrier strip is available for connecting additional loudspeakers.
A multi-position rotary switch on the rear input panel selects either the low-impedance operating mode or the
high-impedance modes (70 V or 100 V) with available transformer taps. When using VLS Series loudspeakers in
distributed line systems, the transformer can be tapped with available power levels shown in the table below:
70 V 100 V
5 W 9.5 W
9.5 W 19 W
19 W 37.5 W
37.5 W 75 W
75 W 150 W
150 W -
5. Wiring and connections
VLS Series Operation Manual rev 1.0.0
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