Earthworks 1021 Single Channel Owner's Manual - page 2
Description
Earthworks Zero Distortion Technology™ (ZDT) precision microphone
preamplifier is a discrete-component Class A bipolar input circuitry device. The
primary signal path from the balanced XLR input to a balanced and symmetrical
XLR output is completely differential (the signal is never converted to single-
ended). The are no transformers or electrolytic capacitors in the signal path. All
connectors and switches are gold-plated.
The ZDT preamplifiers have extremely flat wideband frequency response
from 1Hz to 200kHz, slew rate of 22V/µs, and the lowest self-noise available
from any preamplifier on the market. The nonlinear distortion is kept well
below one part per million even at the highest signal levels (below clipping).
Each channel has separate phantom power switch, polarity reversal, and mute
switch that turns off the output while keeping the microphone powered and the
gain unchanged. A separate ¼” output has additional vernier gain reduction of
up to 20dB after the stepped gain.
The ZDT preamplifiers are available in single (Model 1021), two- (Model
1022), or four-channel (Model 1024) versions. The multi-channel preamplifiers
have separate signal boards divided by electromagnetic shields to minimize
crosstalk.
Specifications
Frequency Response:
2Hz to 100kHz ±0.1dB, 1Hz to 200kHz ±0.5dB
Settling Time:
1.4µs
Distortion:
XLR out: less then 1ppm (0.0001%); ¼” out: 0.001%
Input Noise SD E
noise
: 1.6nV/Hz
½
@ 20dB gain; 0.6nV/Hz
½
@ 60dB gain
EIN:
-132dBV @ 20dB gain; -143dBV @ 60dB gain
Slew Rate:
22V/µs
Output DC Offset:
±1mV typical, servo balanced
Power Requirements: 120V AC (100V and 220-240V versions available)
Input:
1 XLR Fem. balanced transformerless
Input Impedance:
10kohm phantom ON, 100kohm phantom OFF
Outputs:
1 XLR Male balanced transformerless (stepped)
1 ¼” TRS Fem. balanced transformerless (variable)*
Output Impedance:
5 ohm nominal
Max. Output Level:
+33dBu (37V peak-to-peak)
Dimensions H x W x D: 1 rack space 1.75” x 19” x 10.375” (1021 is ½ rack)
Weight:
1024, 1022: 6lb (ship.: 10lb); 2.7kg (ship.: 4.5kg);
1021: 4lb (ship.: 7lb); 1.8kg (ship.: 3kg)
*note: on some units the ¼” TRS outputs may be incorrectly labeled as “unbalanced”
Block Diagram of the Signal Path
Front Panel (one channel)
48V phantom switch
(yellow LED)
clip indicator
(red LED)
power indicator
(green LED)
variable gain
0 to -20dB from the
step (¼” output)
stepped gain switch
5 to 60dB to XLR
output
standby
switch mutes
the output
polarity
reversal
switch
Rear Panel (one channel + power)
variable gain out
(balanced)
mic input
AC voltage and
serial number
stepped gain out
(balanced,
symmetrical)
IEC power connector
fuse compartment
Important: the XLR stepped output is fully differential, that is, it has
equal and opposite signal present on pins 2 and 3. NO extra gain stage is
used, and the preamp relies upon the signals on pins 2 and 3 to be equal
and opposite for distortion correction.
Never short pin 2 or pin 3 of the
male XLR output connector to ground (pin 1)!