Klark Teknik DN-9340 Helix
A two-rackspace digital equalizer that swapped the faders for a touchstrip. Working engineers had to trust it.
Overview
The DN-9340 Helix is not a graphic EQ in the usual sense. It's a two-rackspace digital processor. Each of its two channels gets a 31-band graphic, a 12-band parametric, four configurable filters, and a delay line, all usable at once. Klark Teknik's own product description, as printed in Mix (January 2003, p.31), calls it a "five mode dual 31-band graphic EQ, a dynamic EQ and a dual 12-band parametric." The Helix name was new for the line, but the company's association with equalization was not, and the DN-9340 leans hard on that heritage.
The interface is the obvious question. There are no sliders. Klark Teknik replaced the familiar bank of 31 faders with a front-panel touchstrip. Press a finger on the strip to grab a frequency, then tap or hold above the red line to boost it, below to cut. A fluorescent display shows the band being accessed and the positions of the 31 virtual faders, and it can be toggled to show the resultant EQ curve at the output of the selected channel. An alphanumeric readout gives the frequency in Hz, the amount of boost or cut in dB, and the filter number. Mix (April 2003, p.102) reviewed the unit under the headline "Bringing Digital EQ to a Whole New Level." The reviewer's verdict on the touchstrip is worth reading in full, because it's the most divisive thing about the design.
The touchstrip does allow one trick analog graphics can't do. Press two fingers at the ends of a range of frequencies and the bands group. Then a single finger controls the whole group. Anyone who has tried to draw a broad shelf by hand across a dozen adjacent sliders will see the appeal. Rotary encoders below the display handle the parametric side.
The graphic EQ's bandwidth behavior is configurable, and one of the responses deliberately mimics the Klark Teknik DN27 analog EQ. Small boosts and cuts stay broad and gentle, while large ones narrow the bandwidth so corrective moves don't drag neighboring bands with them. The emulation shows up across the Helix system. Mix (January 2003, p.31) singles out the DN27 and DN360 bandwidth responses as a selling point of the line. The DN9344 slave unit performs the same audio functions as the DN-9340 minus the controls and display.
The feature that gives the Helix its name in the marketing is Threshold Dependent Equalization, or T-DEQ. Two bands per channel can be set to engage only when signal level crosses a threshold, with adjustable attack and release. The textbook use is a PA that turns harsh when pushed. Program a T-DEQ to cut around 3.5 kHz once the level climbs, and the correction arrives only when the problem does. Bypass is layered to match: the whole unit at the home page, individual functions at the function pages, even single graphic faders. A delay line stays available alongside the EQ, and the rear panel allows up to 64 channels of Helix processing to be chained over standard cabling.
Integration is what sold the system to Midas houses. Via RS-232, the Helix links to Midas Heritage and Legend consoles, so soloing a bus on the desk brings that channel up on the master DN-9340. No hunting for the right Helix page mid-show. Mix (November 2002, p.44) described the Auto-Solo function as calling the relevant channel or bus to the control surface for instant access. The DN9344 single-rack slave extends the channel count, and it needs at least one DN-9340 or a PC as master.
Real-world use followed the touring and installation market the unit was built for. A November 2003 issue of Pro Audio Review (p.?) documents a Telex-supplied system at Rossi's Blue Star Steakhouse in which DN9340 Helix processors sat alongside a Midas Venice 320 console. The 2004 Merlefest main stage rig listed a DN9340 among its outboard. These are rooms where the EQ has to work fast and survive a tour.
Collectors and studio owners should treat the DN-9340 as a working tool rather than a shelf piece. It's a two-rackspace digital unit from the early 2000s, and its value is in the touchstrip, the T-DEQ, and the Midas console link. None of that translates to a home stereo rack. Buyers should confirm the fluorescent display and touchstrip work, since both are the interface and neither is easily substituted. The DN9344 slave is the more common sight in rigs, and a DN-9340 without a companion loses much of its point.
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