Earthworks
Earthworks 521 ZDT 500-Series Mic Preamp
Best transparent amplification for professional studio recording.
Experience pristine audio with this high-quality microphone preamp designed for the 500-series format. It utilizes advanced Zero Distortion Technology for unparalleled sonic clarity and transparency, delivering sound with virtually no distortion. Offering up to 60dB of transparent gain in precise 5dB steps, it features an ultra-wide frequency response from 1Hz to 200kHz. The solid-state, transformerless, Class A design ensures superior common-mode rejection, an excellent overload margin, and an incredibly low noise floor, making it ideal for all microphone types.
$999.00
Owner Satisfaction
4.7
/ 5
Category Rank
48
/ 566
#48 in Microphone Preamps
Price vs Category Average
-38%
Below average
Form Factor
500
/ Series Module
Who it's for
- Audio engineers prioritizing pristine, true-to-source sound reproduction.
- Professionals recording quiet instruments or requiring high gain without noise.
- Recording artists and engineers needing precise capture of complex audio.
Who should skip it
- Producers seeking a distinct sonic signature or vintage warmth from their preamps.
- Budget-conscious home studio owners or hobbyists looking for affordable options.
- New users without existing 500-series infrastructure or seeking standalone units.
Performance breakdown
Sonic Transparency
Zero Distortion Technology delivers an incredibly clean and uncolored signal path.
Frequency Range
The ultra-wide bandwidth captures subtle nuances far beyond human hearing limits.
Noise Floor
Virtually silent operation ensures your recordings remain free of unwanted hiss.
Gain Precision
Stepped controls allow for repeatable, accurate gain staging during critical sessions.
Versatility
Handles any microphone type with ease, though it lacks onboard processing tools.
Build Quality
Robust 500-series construction feels reliable and ready for professional studio environments.
Key Specs
Form Factor
500 Series Module
Circuit Type
Solid State, Transformerless
Preamp Circuitry Type
Class A
Phantom Power
48V
Gain
Switchable from 5 to 60 dB in 5 dB steps
Frequency Response
1Hz to 200kHz +/-0.5dB
Total Harmonic Distortion
< 0.0001%
Output Level
+30 dBu
Know before you buy
Earthworks' Zero Distortion Technology is designed to eliminate the subtle harmonic colorations often introduced by preamp circuitry. This results in an exceptionally clean, transparent signal that captures your microphone's output exactly as it sounds, without adding any unwanted character or grit.
Yes, the 521 ZDT is an excellent choice for ribbon microphones. Its ultra-low noise floor and high-quality gain allow you to capture the delicate nuances of ribbon mics without introducing hiss, even when you need to push the gain for quieter sources.
The 5dB steps provide precise, repeatable gain settings, which is ideal if you need to match levels between takes or stereo pairs. While it lacks a continuous gain knob, the stepped design ensures that your settings remain consistent and easy to recall for future sessions.
No, the 521 ZDT is strictly a microphone preamp and does not feature a dedicated instrument (DI) input. You will need a separate DI box if you intend to record high-impedance instruments like electric guitars or basses.
While the human ear cannot hear frequencies at those extremes, this wide bandwidth ensures that the preamp maintains perfect phase linearity and transient response within the audible spectrum. This results in a more 'open' and detailed sound, particularly in the high-frequency transients of percussion and acoustic instruments.
The 521 ZDT is compatible with any standard 500-series rack that provides the necessary power requirements. As long as your chassis is properly powered and meets the standard 500-series voltage specifications, this module will function perfectly.
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Ask Hayley anything about this product before you decide.
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$999