You are here

Sound Foundation Kill Switches

Wilf Smarties tinkers with some kill switches.
Published August 1995

UK designers have done it again. Not content with building cars to be driven on the wrong side of the road, we (or rather, London‑based DJ equipment manufacturers Sound Foundation) have now come up with the Kill Switches, a 19‑inch rack unit that doesn't... well actually, it does fit into 19 inches, but the trouble is, the height bears no relation to the standard spacing of 45mm, being a chunky 60mm, the same as the unit is deep. You'd need 2U of rack space to accommodate the Kill Switches, although they do stand up on a flat surface on their own rather nicely, by virtue of the fact that all the audio connectors are mounted on the 60mm x 60mm sides of the chassis. There was obviously no room here for the egress of the integral mains cable, which consequently emerges (in a totally wardrobe kind of way) from the top! DJ culture is well used to this 'prototype' approach to electronic construction, where basic functionality comes well before any thought of glamour.

The Kill Switches are designed primarily for DJs who want to add selective frequency band muting to their consoles, affording added creativity in a performance/mix. For example, with the Kill Switches, the hi‑hat pattern of one record could be mixed in with the bass and percussion from another. You could use a stereo graphic EQ to achieve a similar result, but the effect would not be as extreme or instantaneous. The frequency bands — below 200Hz, (Bass), 200Hz‑3.5kHz (Mids), and above 3.5kHz (Tops) — are muted by the three fat and sturdy LED‑equipped 2‑pole toggle switches on each side of this two‑channel unit. Around the side are left and right pairs of phono jacks for the turntable/CD player inputs, and for the output.

Internally, the unit is built around a couple of 3‑way electronic frequency‑dividing networks, such as would more normally be found driving a multiway PA system. Feeding a stereo signal into either Phono or CD input pair resulted in a mono output, suggesting that the left and right inputs are summed prior to entering the electronic crossover. Most club systems operate in glorious mono, where this limitation will not be noticed. However, if you wanted to audition a stereo signal through the Kill Switches, or maybe just use it as a turntable preamp, you'd have to use both channels of the unit.

The technology behind the Kill Switches has been licensed from Intimidation, another UK company, who make the acclaimed Don DJ mixer (watch out for the Don 2 very soon, folks). Though a spokesperson was seriously intent on not disclosing anything about the filter circuits — what can be so secret about such a well‑documented area of electronics? — I was at least told that the switches were specially commissioned, because simple 2‑pole equivalents were no longer available.

Having been in a fair few DJ boxes, I can report that the Kill Switches would not look out of place, and would be easy to use in a dark and confined space in the heat of the mix. Electronically, they work fine, and are priced well within the reach of any budding bedroom DJ. Wilf Smarties