An Introduction To The Ad-1000; Introduction And Features - Apogee AD-1000 Operating Manual

AD-1000 Operating Manual
Introduction
The AD-1000 is a multi-purpose stereo analog to digital converter combining a high quality dual-stage, triple
servo, analog 'front end' with 20 bit resolution. This combination provides unmatched sonic performance of 20
bit resolution, optimized for 20- and 16-bit applications such as digital tape recorders, disk-based audio work-
stations, and CD premastering. The AD-1000 includes Apogee's UV22 ® Encoding system, as used by mastering
facilities worldwide to capture 20 bit detail in 16-bit formats such as CD and DAT.
Analog Input Circuitry
The AD-1000 features a proprietary balanced discrete front end with a combined noise and distortion mea-
surement in the 0.001% range. The unit features XLR input connectors that will accept input levels from micro-
phones and line levels up to +28 dBu. The common mode rejection is typically 100 dB – surpassing even the
finest transformers – and provides very stable performance over a broad temperature range. Also incorporat-
ed, in front of the active circuitry, is a passive RF filter with hand-selected resistors and capacitors – matched to
better than one part per thousand – to roll off any outside interference, without the typical intermodulation dis-
tortion byproducts of active circuitry.
Input Selector and Gain Controls
The input selector is an 11-position switch providing maximum input flexibility. When the switch is in the center
MUTE position, the digital output still delivers a 'digital black' condition (all 0's) used for sync in many master-
ing and video applications. Rotating the selector clockwise, the next five positions select microphone input gain
in 10 dB increments. Used in conjunction with the LEFT and RIGHT input level controls, up to 54 dB of gain is
available (40 dB from the input selector and an additional 14 dB if the LEFT or RIGHT controls are fully clock-
wise). This combination allows the setting of the coarse gain with the input selector and fine calibration using
the LEFT and RIGHT controls. (Note: The LEFT and RIGHT controls can be bypassed and the gain can be rout-
ed to the multi-turn CAL pots if desired. See page 31 for details of this procedure.)
Line Level Inputs +4 dBu and –10 dBV
Two CAL positions are available by rotating the INPUT SELECTOR counter-clockwise from twelve o'clock. These
positions correspond to +4 (Pro) and –10 (Consumer) line level inputs. When either of these positions are select-
ed, the multi-turn CAL trim pots are enabled. (Note: The CAL pots can be bypassed and the gain can be rout-
ed to LEFT and RIGHT controls if desired. See page 31 for details regarding this procedure.)
Phantom Power
48 volt phantom power is supplied to both microphone inputs when this selector is in the ON position and the
input selector is in any MIC or the 12 o'clock mute position. The phantom voltage ramps up and down slowly
for quiet activation and uses highly accurate resistors for optimum performance.
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