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DBX 1066

Compressor/Limiter/Gate By Paul White
Published December 1996

Does the dbx 1066 represent one in the eye for its competition? Is it a device for Norman‑lizing signal levels, or does it Harold a new era in signal processing? Paul White tries to keep off the puns long enough to find out.

American company dbx are probably best known for their tape noise‑reduction system, and in the studio, their Over Easy compressor. After counting the knobs on their 1066, you could be forgiven for thinking that this is their Over Complicated model. First impressions can be deceptive, though, and closer inspection reveals that each channel of this two‑channel device actually comprises three largely independent sections: an expander/gate, a compressor, and a peak limiter. Gated compressors are nothing new, but the only model I've worked with before that gives you gating, compression and separate peak limiting is the Drawmer 241.

Layout & Controls

Connection to this 1U processor is via either balanced XLRs or balanced TRS jacks, and two further unbalanced jacks per channel provide a means to insert an equaliser or other device into the side‑chain input. The operating level may be switched between +4dBu and ‑10dBV.

The layout of the control panel is slightly confusing, in that there are no clear dividing lines between the three sections of each channel, so it isn't immediately obvious which controls relate to the compressor and which ones to the expander/gate. As it happens, the expander uses just two of the controls: Threshold and Ratio. To bypass the expander, the Threshold control must be turned to its 'off' position; a pair of LEDs, one red and one green, show whether the signal is being expanded or not.

The compressor section may be switched to operate in Over Easy mode — dbx's interpretation of soft‑knee — or conventional hard‑ratio mode, and like all the buttons on the 1066, its related button lights up when active. As with the expander, red and green LEDs show whether the input is above or below threshold, and a further amber status LED shows when compression is taking place in the Over Easy section of the compression range — a nice touch. A conventional 12‑section LED gain‑reduction meter is also fitted, and there's also an 8‑section level meter which can be switched to track the input or output level.

It's well known that low‑frequency sounds tend to dictate a compressor's behaviour, and sometimes this leads to a dulling of the sound, so dbx have added a Contour switch, which filters some bass end out of the side‑chain. In effect, Contour makes the compressor less sensitive to bass sounds, thus preserving high‑frequency detail. A Side Chain Monitor switch enables you to hear the side‑chain signal after processing by whatever is connected into the external loop, and a Side Chain Enable switch makes it possible to bypass any external side‑chain processing without having to repatch. The side‑chain monitor facility is particularly useful if you have a parametric EQ connected for de‑essing, as it allows you to hear exactly which frequencies are being picked out.

The compressor controls are standard: Threshold, Ratio, Attack and Release. Even though there's a separate limiter, it's still possible to crank the compressor ratio up to infinity. For applications where the nature of the programme material is constantly changing, an Auto attack and release setting is available. Once the signal has been compressed, you can make use of the familiar make‑up gain control, here labelled Output.


The limiter section comprises a single knob and a threshold LED, but the simplicity of the controls belies what's going on inside the box. In fact, limiting is achieved in two stages, the first being 'Instantaneous Transient Clamp' — complete with obligatory trademark. This applies a soft logarithmic clamp function to ensure that the signal doesn't exceed the limit set by the 'PeakStopPlus' (trademarked, obviously) level control by more than a couple of dBs.

Stage two employs 'Intelligent Predictive Limiting', and it doesn't take too much intelligence to predict that this term also carries the familiar trademark logo. Its job is to monitor the input, then let the gain‑reduction stage know, just in the nick of time, when a biggie is coming, so that it can attempt to pull the signal down below the level where the Instantaneous Transient Clamp clobbers it. Because the PeakStopPlus limiter is a failsafe device designed to work with absolute levels, it comes right at the end of the signal path, after the make‑up gain control. In real life, such limiters are there as protective measures, but just occasionally, hard limiting can also be a useful creative effect.

A Stereo Couple button links the two channels for true stereo operation, and each channel has its own Bypass button, controlling a relay‑switched hard bypass. Once you know what the controls do, the layout looks a lot less complicated than when you first open the box.

In Use

The 1066 is quite straightforward to use. In stereo link mode, the left‑hand set of controls takes over, and any illuminated switches on the right‑hand channel go out. As you might expect, there's a significant subjective difference between Over Easy and hard‑knee operation — and as you flip between the two, you notice that gain reduction starts at lower threshold settings with Over Easy selected. On a test piano track, a hard‑knee setting which produced minimal gain reduction on peaks increased to around 6dB of gain reduction when Over Easy was chosen.

Unless the degree of compression is kept fairly low, neither hard‑knee nor Over Easy is particularly transparent, with hard‑knee, as expected, producing the most positive compression. I get the impression that this unit was designed for people who like to use compression to create vocal or instrumental effects, rather than for invisible mending. The Contour control's action is subtle, but it does help prevent HF detail from suffering and doesn't seem to change the amount of gain reduction being applied too significantly.

The expander works smoothly and predictably, while the limiter is fast and positive; you can hear it working (unless the amount of limiting is kept to a minimum), but the side‑effects are far less intrusive than those of clipping, especially if you're feeding a digital recorder, which won't tolerate any excess input signal. The signal path is, predictably, superbly clean and quiet, with plenty of headroom.

Operationally, I found the 1066's controls difficult to identify, because of the small legending and its position beneath the control knobs. The lack of well‑differentiated areas on the front panel tended to exacerbate this problem, and the fact that all the buttons are grey when not lit up doesn't help much, either. In a studio, this unit would need to be mounted at a carefully‑considered height in a rack to overcome these problems, while in a live situation (in poor lighting conditions), there's potential for getting hopelessly lost.


I found the 1066 to be a combination of really good features and minor irritations, the poor control visibility probably being the biggest worry. I liked the illuminating buttons, the separate threshold indicators, and the unambiguous way in which control shifts to the left channel in stereo link mode. I was slightly disappointed, however, that I couldn't achieve more transparent compression when needed. With the Auto function engaged, using a 4:1 ratio with 6dB or so of displayed gain reduction resulted in quite audible compression, even in Over Easy mode. When you want to use a compressor as an effect, the 1066 sounds exactly right and works beautifully on vocals, drums, basses and so on, but for the times when you need to be more subtle, finding the right settings can be tricky.

The compressor market is more crowded now than it has ever been, with a choice of valves, FETs, VCAs, opto‑isolators and who knows what else — and every type has a unique effect on the sounds it processes. In the case of the 1066, the new dbx V2 (trademarked, naturally) VCA delivers pristine audio quality, yet this is anything but a sterile‑sounding compressor. For many engineers, the dbx approach to compression is the definitive gain reduction treatment, and the 1066 provides plenty of character and scope for creativity without sacrificing the dbx sound. I'd feel less comfortable about using the 1066 for more subtle compression jobs, but if you're a fan of the dbx sound and want to combine it with a good expander/gate and a peak limiter, this has to be the box to go for.


  • Classic dbx compressor sound.
  • Separate gate and limiter.
  • Useful range of control options.


  • Panel legending and layout not as clear as it could be.
  • Sometimes difficult to set up transparent compression.


A flexible and powerful gain‑control processor combining compression, limiting and gating. Better as a creative tool than for routine level control.