EMPIRICAL LABS EL-Rx DocDerr and EL-DS DerrEsser Signal Processors with Horizontal EL500 Rack

EMPIRICAL LABS EL-Rx DocDerr and EL-DS DerrEsser Signal Processors with Horizontal EL500 Rack

EMPIRICAL LABS EL-Rx DocDerr and EL-DS DerrEsser Signal Processors with Horizontal EL500 Rack

EMPIRICAL LABS EL-Rx DocDerr and EL-DS DerrEsser Signal Processors with Horizontal EL500 Rack

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Expected availability: 7-14 business days

Product Highlights

  • DocDerr - 6 Sections of Processing
  • Pre-Amp and EQ
  • Compression with Mix Knob
  • Tape Emulation Circuit
  • DerrEsser - 4 Mode HF Processor
  • De-Esser, HF Compressor, HP, LP Modes
  • EL-500 - 2 Channel API 500 Series Rack
  • Includes XLR and 1/4" I/O on Rear Panel
  • 1/4" Instrument Input on Front Panel
  • Stereo Link and Phantom Power Switches
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This item is noncancelable and nonreturnable.

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  • 1Description

The EL-Rx DocDerr and EL-DS DerrEsser Signal Processors with Horizontal EL500 Rack from Empirical Labs combines a multi-purpose tone enhancement module and a multi-function dynamic filtering device; pre-installed in the EL500 rack.

The DocDerr offers six different sections of digitally controlled analog processing. A low-noise preamp capable of working with line level or instrument level signals is followed by four sections of EQ combining a two-position, high-pass filter with three parametric bands, each with its own set of carefully tuned frequency presets. By adjusting an internal jumper, the DocDerr offers a high quality instrument preamp with 16 dB of gain for acoustic guitar, bass, synths, and exotic plucked instruments. The dynamics section offers compression and a musical tape emulation circuit that softens and tames high frequencies and transient spikes. The Mix knob allows the user to blend the uncompressed signal with the compressed and saturated signal. The DocDerr is well suited for tracking, fine-tuning tracks during mixing, and studio-quality tone control.

The DerrEsser is an effective, level insensitive de-esser device that adjusts the high frequency gain on overly trebly or spiky vocals or other sources in an extremely musical manner. However, unlike other de-essers, the device allows for multiple use of its circuitry. In the DS mode (HF Limit OFF), the threshold can be set to tame harsh sibilance that results from an overly bright singer or from EQ'ing to make a vocal sound aggressive and clear. The DS threshold is not level dependent, and compares the amount of high frequency content to the low frequency content, so adjusting the overall level does not affect the threshold. It features VCA technology for glitch, distortion, and noise-free operation. The corner frequency is user adjustable with a high performance active crossover. The HF Limit mode essentially acts as a high frequency compressor. If there is enough high-frequency content to exceed the threshold, then gain reduction occurs. It is level sensitive, but responds much more to high frequencies and functions more of a general high-frequency smoothing device.

The Highpass mode uses a LISTEN function, where the user can employ the filter circuitry inside the DerrEsser to process their audio. With the LISTEN button in, and the HP/LP switch out, the user will be hearing the high frequencies controlled by the dynamic/compression circuits. The corner frequency is adjustable by the frequency knob. The Lowpass mode also uses the LISTEN function, but with the HP/LP button in, the user is now listening to the low frequencies, those not affected by the VCA and dynamic/compression circuits. This is a 12 dB per octave filter whose corner frequency can again be adjusted by the frequency knob.

The EL500 rack features a quiet power supply and offers both XLR and 1/4" rear panel inputs and outputs. In addition, a 1/4" instrument preamp/direct box input is on the front panel, which will automatically switch the left 500 module's input to this front 1/4" jack once something is plugged into it. Switches to link compressors and engage a 48V phantom supply are also provided. The DocDerr DerrEsser ships with a guitar adapter cable and a standard IEC power cord.

DocDerr Module
  • Super low-noise line input, or instrument preamp, with famous Empirical Labs compression. Six digitally controlled analog sections of processing
  • Four sections of Equalization: One High Pass and 3 parametric bands
  • Empirical Labs first compressor in the API 500 format. It is an aggressive compressor that follows the EQ, tailored to acoustic instruments, and plucked attacks, but good on just about anything. Great for vocals and bass
  • Complex compressor envelope generator. Fast, yet musically saturates at high gain reduction. Program dependent release
  • Saturation circuitry that scrunches the highs and allows hotter levels like tape. Uses filtering combined with germanium clip circuitry to soften loud high frequencies
  • Mix control to allow user to blend an un-compressed EQ’d signal back in with the compressed saturated signal. When on 0, only the EQ’d signal is put out
  • Adapter is provided for free, allowing a guitar, bass, etc to be plugged straight into the rear of your API powered rack
  • DC coupled input and outputs
  • Selectable single-ended or differential output. Differential out adds 6 dB gain
  • Traditional and digitally controlled analog combined in new topology
  • A “BAD!” Hard Clip Indicator LED that lets user know it's within 1 dB of hard clipping. It monitors most every section for internal clipping
  • High Quality Components: All metal film and Roederstein resistors in the audio path - top quality components, most being high temperature military spec parts
  • NOTE: With all the processing, the DocDerr draws slightly more current than the API 500 spec, but has worked perfectly in all racks tested. Six have been tested in the API Lunchbox and other racks, without overloading the power supply
  • User modifiable elements, including the Compressor
  • Built and calibrated in USA
  • High performance analog De-esser
  • HF Lim Mode, as well as standard De-Ess – High Frequency limiting with a tailored soft knee. The Dynamic Section can be used for De-essing or smooth high frequency softening
  • A “BAD!” Hard Clip Indicator LED lets user know it's within 1 dB of hard clipping. It monitors several sections within the DerrEsser for possible clipping
  • Unity Gain in and out – 6 dB of gain available
  • Foolproof operation - it's almost impossible to clip or get a bad sound
  • Industry standard API 500 Series Rack compatible
  • True bypass
  • High reliability parts and military grade switches and relays
  • Hand built and calibrated in USA
EL500 Rack
  • Unique Flush Mount system for durability & looks
  • Super quiet ±16V supplies
  • More than 280mA available on both supplies
  • 48V Phantom supply with 35mA of current
  • Link Switch to stereo-link two compressors
  • Built in DI “Inst In” (Instrument In) for high impedance inputs built into front panel
  • "Inst In" THD is less than .0006%
  • A performing musician can use the "Inst In" combined with his favorite modules, using the high quality preamp on this front panel jack
  • Auto-Sense on “Inst In” jack
  • XLR & 1/4" Inputs and Outputs. A total of 9 input and output connectors
  • Front panel Link-Switch for stereo linking dynamic devices such as compressors/limiters/gates
  • Power Consumption: 14W maximum; 9W typical with modules installed
In the Box
EMPIRICAL LABS EL-Rx DocDerr and EL-DS DerrEsser Signal Processors with Horizontal EL500 Rack
  • Guitar Adapter Cable
  • IEC Power Cord
  • Limited 3-Year Warranty
  • Table of Contents
    • 1Description


    Multi-Purpose Tone Module
    Frequency Response 3 Hz to 180 kHz on EQ section (-3 dB points)
    Dynamic Range -120 dB from maximum output (0.5% THD soft clipping) to minimum output, noise floor typically -91 dBu
    Distortion Range 0.0006 and 10% at 1 kHz
    Outputs DC coupled
    Input Impedance 120 kOhms in instrument mode
    20 kOhms in balanced line-in mode
    Output Impedance 75 ohms
    Maximum Input Before Clipping +22 dBm, line-in mode
    Maximum Output +28 dBm
    Attack Time Approx. 1 mS
    Release Time 0.2 seconds, program dependent, fixed internally
    Power Consumption Typical: 2 W
    Maximum: 4 W
    Power Supplies 16 V
    Frequency Response 3 Hz to 120 kHz (-3 dB points)
    Dynamic Range -115 dB from maximum output (0.5% THD soft clipping) to minimum output, noise floor typically -93 dBu
    Distortion Range 0.0035 and .01% depending on setting
    Inputs and Outputs DC coupled
    Input Impedance 20 kOhms
    Output Impedance < 51 ohms
    Attack Time < 1 mS
    Release Time 0.04 seconds, fixed internally
    Power Consumption Typical: 4 W
    Maximum: 8 W
    Current 35 mA
    THD 0.0006%
    Inputs/Outputs 9 x XLR and 1/4" plugs
    Phantom Power 48 V
    Power Supplies ±16 V, 280 mA
    Power Consumption Typical: 9 W
    Maximum: 14 W
    Dimensions (W x D x H) 19.0 x 10.0 x 1.8" / 48.3 x 25.4 x 4.4 cm
    Weight Not specified by manufacturer


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