ATI Audio DA1008-1 User Manual

Page 3

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Active Balanced Outputs, +26dBrn
DA1008-2, DA2016-2

An additional equal and out of phase output is provided by unity gain inverters
A3, A5, A7 and A9 driven from the outputs of A2, 4, 6 and A8. Since the output
summation across the load results in 6dB of additional level, the first stage gain
is reduced proportionately to maintain the level set potentiometer near 12 o'clock
for unity gain operation. Both outputs are capacitor coupled to the load and
protected by 150-ohm current limiting resistors in each line. Since both Hi and Lo
outputs are driven, neither output terminal should be grounded. Unbalanced
loads may be driven from either the Hi or the Lo output with reference to ground.

MONITORING

An attenuated output sample from each channel is routed through a 9 pin
connector P2 to the Power Supply and Monitor board. The output is sampled at
the transformer primary by Rl 10 and Rl 11 (Channel 1) or on the output side of
the protection resistors in differential output units by Rl 12 and Rl 11.

POWER SUPPLY AND MONITOR BOARD

MONITOR AND METERING

Monitor inputs from the amplifier boards are applied to analog multi-plexers A8
(output group A) and A9 (group B) through connectors P5 and P6 respectively.
The multi-plexer outputs are summed and applied to a two-channel headphone
amplifier (A4) designed to individually drive the tip and ring of stereo
headphones. A front panel level control adjusts headphone output. The phone
output is designed to drive 600 ohm or higher headphones but will drive low
impedance phones at reduced level without damage.

The multi-plexer output also drives the meter circuits through calibration pot R8.
Additional sections of A4 form an active full wave rectifier with switchable gain.
The front panel meter calibration switch allows 0 VU meter readings with nominal
output levels of +4, +8 or +18 dBm sine wave. The three colors, 12 segment,
three quad comparators A5, A6, and A7 drive peak reading LED meter display.

Pressing the front panel SCAN marking which actuates a zero motion switch
mounted behind the panel on the display board makes selection of the desired
output for monitoring and metering. This switch gates on oscillator A10 that
drives the binary counter all to select one of 16 inputs applied to A8 and A9. Al 2
and AB drive the numeric readout.

This manual is related to the following products:

DA1008-2 DA2016-1 DA2016-2