Review: dbx 580: 500 Series Microphone Preamp

I’ve always been a fan of the dbx sound. Whether it be patching a kick or bass guitar through a vintage 160VU compressor, tweaking a 160A in a live rig, or running a vocal through a 902 de-esser in an old 900 series rack. There have been few more reliable or sonically useful brands throughout the last 30 years in both live and studio environments. Owning a 900 series rack of compressors and EQs myself, I was doubly curious to check out the new and very affordable 500 series modules recently released by dbx. In the next issue of AT we’ll be looking at the new compressor, de-esser, EQ modules — which build on the heritage of the older designs as well as an innovative subharmonic synthesiser. For this issue, we’ll be focussing on dbx’s new foray into the world of preamplification — the 580 microphone preamp.

LAID OUT RIGHT

I’ve got to say right off the bat that I love the look and feel of the 580 preamp. I don’t know if it’s dbx’s long experience with designing compact circuits for the 900 series cards but I’ve seldom seen a better laid-out set of controls on a 500 series unit (and I’ve used and reviewed a lot of ’em). There’s plenty going on in terms of controls with continuously variable gain, high and low ‘detail’ boost and low cut filter knobs as well as no less than six switches for phantom power, 20dB pad, polarity invert, low cut enable, detail enable and mic/instrument selection. Add to that a lovely backlit VU meter for output gain, a variety of coloured LEDs that indicate which of the controls are engaged, plus a peak meter and a jack input for Hi-Z instruments, and you’ve got a very well populated front panel that nevertheless is clear and easy to ‘read’. In use the dbx 580 feels very pro with all controls being smooth to the touch and the switches robust in operation. The busy front panel is surprisingly quick to acclimatise to. The only control that is slightly difficult to get at is the phantom power switch and this is fine by me as its location makes it very difficult to accidentally engage — a smart and subtle bit of design nous by dbx.

DEVIL IN THE DETAIL

Perhaps the most notable feature of the 580 preamp is the inclusion of high and low ‘detail’ controls which are basically EQs under another name. The high detail control introduces a shelving filter with a corner frequency of 10kHz, useful for adding top end clarity and focus on things like vocals and acoustic instruments. Low detail is a more complex circuit that simultaneously introduces a bell filter boost centred around 125Hz and another bell filter cut around 400Hz. The combination of these two EQs plus the low cut filter (a 12dB/oct Bessel filter that is continuously variable from 30-300Hz) means there is a tremendous amount of tonal sculpting available prior to hitting tape or DAW.

The preamp circuit itself is a fast solid-state design offering up to 60dB of clean gain, probably not enough for old school passive ribbons and dynamics on quieter sources, but more than adequate for most other applications. There’s no ‘warmth’ or ‘drive’ controls to be seen so if you’re looking for saturation effects best to look elsewhere. I know I’m not alone in often liking to use gear that has an inherent colour and/or drive to it for imbuing sources with character, but having said that, there are many situations where what is required is a clean, transparent signal path with quick transient response that allows things like drums and percussion to pass through unscathed. Such preamp circuits retain their clarity and punch under duress, and this is where I see the dbx 580 doing its best work.