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Introduction
The VTC Pro Audio NS21P is a premium quality integrated subwoofer and power amplifier. Created as an easy-to-setup
addition to any P.A., the VTC NS21P will extend the bass of a typical sound system with the least amount of complication.
The VTC NS21P has been designed to operate with a line level signal.
Configuration
The VTC NS21P may be used in several different configurations. The basic system is a single VTC NS21P used for each full
range enclosure or multiple VTC NS21Ps along with individual full range enclosures
Level Control
A setting of 0 dB on the VTC NS21P Level control is the correct starting point when setting up a sound system.
From there, adjustments can be made for the best sound. The 0 dB mark refers to the setting that will give full power
when the line input is used and the input signal is at a level of +4 dBV.
Processing
The VTC NS21P provides Highpass and Lowpass filtering. The highpass filtering provides protection against
frequency content that could damage the subwoofer driver. This filtering is optimized for the driver/enclosure
combination. No additional subsonic/highpass filtering is required. The low pass filtering provided is adequate
for the subwoofer side of the subwoofer to woofer crossover. The user may choose to provide additional lowpass
filtering depending on the application. The electronic highpass and lowpass filtering each have 24dB/Oct. 12 dB is
placed before the excursion limiting and an additional 12 dB is placed after the limiting for both filter functions.
LINK Jacks
The Link jacks are set up to make it easy to hook up your VTC NS21P to any audio system with a minimum of hassles.
The Link jacks are connected in parallel and can be used to daisy-chain other VTC NS21Ps or full-range enclosures.
The VTC NS21P does not alter the signal to the daisy chained enclosures and will not draw any power
from the host amplifier/processor driving them. Also, note that an external crossover is not necessary when
using the VTC NS21P.
The Link jacks allow many VTC NS21Ps to be connected in a string (parallel). There is no practical limit to the
number of VTC NS21Ps that may be connected together.
Protection
The VTC NS21P has circuitry to prevent clipping, over current and over excursion. At high levels the limiter will limit the gain
of the VTC NS21P and hence if the user attempts to set the subwoofer level control at a high level, the resulting setting will
be incorrect. The level control should be set while operating at low levels (under 10 watts). The input circuit will clip and the
dynamics of the bass will be lost if the level control is set too high, the red Clip indicator signifies when this occurs. This can
happen without audible distortion since the filters will filter out the distortion.
At high power levels, when the limiter is operating, increasing the subwoofer level control will not increase the output.
Do Not increase the setting while operating at high levels.
NOTE: The VTC NS21P built-in stand mounting adapter can be used to support some VTC Pro Audio enclosures.
Maximum pole extension for mounted enclosures is 48-inches for 85 lb. enclosures and 60-inches for enclosures that are
less then 55 lbs.
WARNING: Larger or heavier cabinets should not be used!
