Earthworks 521 ZDT

Stephen Bennett checks whether Earthworks’ 500 series preamp lives up to its ‘like wire with gain’ claim.

Quad electronics, purveyors of high-quality hi-fi, once used the tag line ‘straight wire with gain’ for its equipment, the implication being that any amplification system should merely increase the level of the incoming signal without adding any coloration of its own. These days, at least when it comes to microphone preamplifiers, the opposite seems to be true, with oodles of products on the market stuffed with valves, transformers, and phenylalanine (I made the last one up) purporting to add sonic ‘colour’ to their offerings.

So, is there a need for a preamplifier that just, well, amplifies without adding its own sonic character? Earthworks seems to think so, because, on opening the dinky little aluminium case that the company’s new 521 ZDT 500 series preamplifier ships in, the first thing that strikes you are the words ‘like wire with gain’ printed on the slim manual. So, the gauntlet is down. Does the 521 ZDT live up to this claim, and if so, is this really what recordists want – or need – from a preamplifier?

Earthworks is probably best known for its range of high-quality microphones which have found wide popularity among engineers who are keen on capturing accurate representations of a musical performance, especially in the jazz and classical worlds. So it’s hardly surprising that the company’s first ‘lunchbox’ format preamplifier is designed to add as little of itself to the signal chain as humanly – and electronically – possible.

Based on David Blackmer’s Zero Distortion Preamplifier technology (of DBX noise reduction fame – he really doesn’t like noise!) the 521 ZDT is housed in the usual single slot API 500 series case with the power and input and main output connections being provided by the lunchbox chassis itself. The 500 series format really suits preamps as there are usually few controls and the minimal available space doesn’t get cluttered. The 521 ZDT’s black burnished front panel features 48V Phantom powering, a clip LED, a phase flip switch, a standby switch, and a stepped rotary gain control covering +5dB to +60dB in 5dB increments.

Read the rest in our March digital edition.

The reviewer

Stephen Bennett has been involved in music production for over 30 years. Based in Norwich he splits his time between writing books and articles on music technology, recording and touring, and lecturing at the University of East Anglia.