Add a channel of "wire with gain" to your 500 Series Rack

Where to Buy

  • Clean, uncolored 500 series preamp
  • Solid-state, transformerless
  • Switchable 48V phantom power
  • Polarity invert switch
  • Peak amplitude clip detection
  • Transparent gain switchable from 5dB to 60dB in 5dB steps
  • Ultra-low noise floor
  • Ultra-wide bandwidth
  • Suitable for most ribbon, dynamic or condenser microphones
  • Requires a 500 series rack

Based on the Earthworks ZDT Zero Distortion Preamplifiers™ technology designed by David Blackmer, the 521 brings the exacting standards of the Earthworks Zero Distortion Technology preamplifiers to the convenient 500 series format.

The solid state 521 features switchable phantom power, polarity invert, and peak amplitude clip detection, just as in the original 1021 single channel ZDT Preamp. The transformerless output stage of 521 ZDT easily drive long cable runs without loss of quality, making it ideal for long cable runs. Transparent gain is switchable from 5dB to 60dB in 5dB steps.

The Earthworks microphone preamplifier topology provides outstanding common mode rejection, excellent overload margin and an incredibly low noise floor, combined with the ultra wide bandwidth of the ZDT Preamps and distortion of less than 1 part per million. This exceptional level of performance is maintained over an extensive range of impedances applied to the input making the 521 suitable for practically any microphone – ribbon, dynamic or condenser.

Preamp Type: Solid State

Number of Channels: 1

Frequency Response: 2Hz to 100kHz ±0.1dB, 1Hz to 200kHz ±0.5dB

Impulse Response: 1.4µs

Distortion: XLR out: less than 1ppm (0.0001%); 1/4” out: 0.001%

Input Noise: 1.6nVHz½ at 20dB gain; 0.6nV/Hz½ at 60dB gain

EIN: -132dBV at 20dB gain; -143dBV at 60dB gain

Slew Rate: 22V/µs

Output DC Offset: ±1 mV typical, servo balanced

Input / Output Connector: 500 Series EDAC Edge connector

XLR Input Impedance: 10KΩ phantom on, 100KΩ phantom off

Front Panel Balanced Out: ¼” TRS XLR Fem. balanced transformerless (variable)

Dimensions: 1 500 series rack space 1.5” x 5.25” x 6”

Weight: 0.8 lb. (0.36kg)

SOS_sh_90px“The Earthworks 521 ZDT is a stunning microphone preamplifier. Its ability to deliver a noiseless, distortion-free, completely flat response across such a wide frequency range is something that I have never encountered before.”
audiomedia_logo“Recordings through it have weight and body and take EQ and compression well – the low noise floor being especially useful in the latter processing scenario.”
“…the ZDT preamps provide an extremely natural and 3-dimensional representation of the source, without any high-frequency smearing or crunchiness…”
“From drums to voice and instruments in between, this is a preamp that does as advertised and adds nothing to the sound. Where the 521 really excels is in how gosh darn quiet it is!”
resolution-logo“The pair of the ZDT pre and the QTC40 is, as you’d expect, a good one giving an overall sound that does really put you right in front of any instrument.”

Other ZDT Preamp Models

1021 One Channel ZDT Preamp Go
1022 Two Channel ZDT Preamp Go
1024 Four channel ZDT Preamp Go