ATI DA1008-1 User Manual

DA1008 AND DA2016

DISTRIBUTION AMPLIFIERS

OPERATING AND MAINTENANCE MANUAL

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DESCRIPTION

The DA1008/2016 output stage is capable of driving 600 ohm loads directly to +26dBm with total freedom from crossover distortion, high inherent linearity, 100dB open loop gain and 50MHz gain bandwidth product make this an ideal device for highest quality audio distribution. The absence of Transient Intermodulation Distortion may be detected by the smooth effortless high frequency output capability, the absence of the harsh, raspy sound typical of IC amplifiers driven to full output at high frequencies and the freedom from increasing harmonic distortion vs. frequency. A minimum of 40dB of loop gain is available for 100: 1 distortion reduction even at 20kHz.

INPUT

Input audio feeds a unity gain balanced differential input buffer stage (A1), which presents 30,000-ohm bridging impedance to the source. The input network is protected by clipping diodes (Dl-D4) from over voltage inputs and bypass capacitors (C3 and C4) for RF protection. A balance Potentiometer (R7) allows setting a precise null for common mode hum inputs. The second half of Al monitors the differential voltage appearing across the input terminals of the input buffer IC to detect clipping. The input clip LED on the front panel will light if audio inputs in excess of +26dBm peak.

OUTPUTS

Audio from the input buffer feeds eight output level adjusts potentiometers. Output stage gain is set for approximately 24dB so that for normal unity gain operation the audio taper pots are at 12 o'clock and provide a smooth, highresolution adjustment. More or less gain can be provided by changing only the value of Rx1 (R21-R81), see Modifications.

+26dBm output level Distribution Amplifiers (-1 and -2 models) omit the current boost stage components shown on the schematics (Q10, Q11, Q12, Q13, R13 and R18 in output 1). R13 and R18 are replaced with jumpers.

Transformer Outputs, +26dBm: DA1008-1, DA2016-1

The outputs of A2, A4, A6 and A8 are AC coupled to the output transformer primaries. The coupling capacitor prevents small DC offsets at the IC output from biasing the transformer and causing low frequency distortion. Transformer winding resistance and IC current limiting protect the outputs in the event of an accidental output short.

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