1-Channel Zero Distortion Preamplifier™


Where to Buy

The ZDT Zero Distortion Preamplifier™ series  is based on discrete circuitry designed by David Blackmer, establishing a new standard of sonic excellence in electronics. This exacting new standard provides frequency response from 1Hz to 200kHz +0.5dB, a rise time of 0.27 microseconds and distortion of less than 1 part per million (0.0001%), eliminating all possibility of sonic degradation. These preamps are so fast, so clean and so transparent that you don’t even know they are there. It is like plugging your microphone into a “piece of wire with gain”. You will hear clarity and detail with the ZDT preamps that is not available in any other preamp at any price.

  • Zero Distortion – less than one part per million
  • High output level +30dBu
  • Very Low Output Impedance will drive long lines without interference or signal loss
  • True 48 volt phantom, polarity reverse & clip indicator
  • Separate XLR & 1/4” Phone (t-r-s) outputs, each with its own gain/level controls
  • 1/4” Phone connector output will drive balanced or unbalanced inputs
  • Lowest Noise of any preamp on the market
  • Full Differential (balanced) from XLR in to XLR out – no internal conversion to single-ended
  • All Discrete Components; Class A Amplification (No ICs in the signal path)
  • Greater Transparency with minimum signal path and minimum features

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

Power Requirement: 120V AC (100V and 200-240V versions available)

Input: 1 XLR Female balanced transformerless

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

Outputs: 1 XLR Male balanced transformerless (stepped)
1 ¼” TRS XLR Fem. balanced transformerless (variable)

Dimensions: Half rack space 1.75” x 8.75” x 10.375”

Weight: 4 lb. (1.8kg)

“…absolutely uncompromising preamplification that lets your sources come through with only your mics and other processors to flavor them…”
“…sound is completely uncolored and noise is just about as low as it gets…”
Wyatt Hill, a seasoned recording engineer, has done direct A/B comparisons between the Earthworks® ZDT preamp and other premium preamps: Manley® Tube Mic Dual, Grace Design M801, Avalon Design AD 2022 & VT-737sp. Universal Audio 2-610, TRUE Systems Precision 8, Focusrite® ISA 828 & Red 1.

Wyatt explains his A/B comparison experience: “I bought my first Earthworks Zero Distortion Technology preamp over ten years ago from the suggestion of my Sweetwater Sales Engineer, Jeffrey Green. This preamp was amazing! The sound was ridiculous! It was so clean and pure. From that moment anytime I thought about buying another preamp I had to compare it with the Earthworks preamp. When comparing the Earthworks ZDT preamp to the Precision 8, Focusrite® and others mentioned above, there really was No comparison. The other preamps were clean but they lacked in the big beefy sound that I got from my Earthworks ZDT preamp. I thought these preamps were clean until I compared them to the Earthworks ZDT. I could hear detail and punch and airiness in the Earthworks ZDT that I could not hear in the other preamps. The Grace preamp comes the closest to the Earthworks preamp in sound but still falls short of the Earthworks stunning clarity, sheen and sparkle! The Manley® Tube preamp is a different animal. Compared to the Earthworks ZDT, the Manley® was clean and had that nice tube sound, but lacked the depth and airiness that the Earthworks has. After comparing the Avalon 2022 & VT-737sp, Universal 2-610, Focusrite® ISA 828, Red 1 and Precision 8 to the Earthworks ZDT, it was very obvious that these other preamps could not live up to the performance of the ZDT preamp! They all sounded so thin and dull compared the Earthworks ZDT. Hearing is believing! In conclusion, I would have to say my favorite preamp is the Earthworks ZDT hands down with the Manley® following in 2nd place and Grace in 3rd place. However, if I were forced to choose between the Earthworks ZDT and the Manley® Tube preamp, I would choose the Earthwork ZDT, as it is all around a great preamp that sounds superb!”

“If you have some great microphones (any mic), the Earthworks ZDT preamp will make a significant difference. You will be hearing (really hearing) your mic’s for the first time. The Earthworks ZDT preamp is so pure and clean that you can hear detail and characteristics from your microphone that other preamps just cannot deliver. It’s like comparing Belden cable to Mogami® cable. There’s no comparison. All my microphones sound great through the Earthworks ZDT preamp with a detail I have never heard before.”

“If anyone else were to do the comparisons that I have done with the Earthworks ZDT preamp, I feel very confident that most if not all would come to the same conclusion I have come to. The proof is in the hearing! Specs may be important but bottom line, hearing is believing and that’s what is important when you are recording tracks in the studio.”

“When clients come to my studio they are blown away by the pristine clarity and cleanliness of the Earthworks ZDT preamp. My clients expect the best and that’s exactly what they get with the Earthworks ZDT. You just can’t beat it!”

“When a new preamp comes out I always compare it with Earthworks ZDT. Although, many people buy preamps for color or to color the sound, I feel that that is what microphones are for. To me quality comes first! Having a great quality preamp comes first then a great microphone to add certain characteristics and color to your sound.”

“If I had my way and could afford it, I would have all Earthworks ZDT preamps in my studio with a couple of Manley’s for the tube sound. In my opinion these are the best preamps on the market. The Earthworks ZDT preamps are awesome! You ask, ‘Where’s the beef?’ It’s in the Earthworks ZDT! Bottom line the Earthworks ZDT preamp delivers the cleanliness, airiness, punch, detail, sheen, sparkle and clarity any engineer would love to have. I know that is a lot adjectives to describe this preamp but it is true. See or should I say hear it for yourself and you decide. The Earthworks ZDT preamps are hands down, the best preamps on the market!”

Other ZDT Preamp Models

521 One Channel 500 Series ZDT Preamp Go
1022 Two Channel ZDT Preamp Go
1024 Four channel ZDT Preamp Go