Empirical Labs DocDerr 500 Series Multi-Purpose Tone Module

(No reviews yet) Write a Review
Usually ships within 24 hours
2.00 LBS
Calculated at Checkout
  • Empirical Labs DocDerr 500 Series Multi-Purpose Tone Module
  • Empirical Labs DocDerr 500 Series Multi-Purpose Tone Module
  • Empirical Labs DocDerr 500 Series Multi-Purpose Tone Module
  • Empirical Labs DocDerr 500 Series Multi-Purpose Tone Module


One of the newer members of the Empirical Labs family is the DocDerr, a 500 series multi-purpose tone enhancement module that houses six different sections of digitally controlled analog processing.  With over two years of meticulous development and testing behind it, the DocDerr provides an unprecedented combination of power and musicality in a compact, easy to use format. Empirical Labs' first compressor in the API 500 format.

An extremely 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.  An internal jumper can turn the DocDerr into an unparralled instrument preamp with 16dB of gain, ideal for acoustic guitar, bass, synths, exotic plucked instruments, etc.

The versatile EQ is followed by a unique dynamics section which offers renowned Empirical Labs compression at an unprecedented price, and an extremely musical tape emulation circuit that softens and tames high frequencies and transient spikes.  We believe it’s the best single knob “knee” compression available in this format.

One of the pivotal features of the DocDerr is the “Mix” knob which allows the user to blend the uncompressed EQ’s signal with the compressed and saturated signal.  This parallel compression technique, used by top recording and mixing engineers for many years unlocks a whole world of sonic possibilities.

Like all ELI 500 series modules, the EL-Rx is available with either horizontal or vertically oriented front panel configurations, and is “Linkable” for using our famous compression on stereo sources.

The DocDerr is ideal for tracking, for fine-tuning tracks during mixing, or as a killer solution for the gigging "acoustic" musician in search of studio quality tone control.


  • Super low noise line input, or instrument preamp, with famous Empirical Labs compression. Six digitally controlled analog sections of processing
  • Incredibly dense processing module available for the API 500 series format
  • Four sections of Equalization – One High Pass and 3 parametric bands.
  • Empirical Labs first compressor for 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. A must try on vocals and bass!
  • Complex compressor envelope generator. Fast, yet musically saturates at high gain reduction. Program dependant 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 6dB gain
  • Traditional and digitally controlled analog combined in new topology
  • A “BAD!” Hard Clip Indicator lights – A “Bad” Clip LED that lets user know he is within 1dB of hard clipping. It monitors most every section for internal clipping
  • Highest quality Components. All metal film and Roederstein resistors in the audio path - top quality components, most being high temperature military specparts
  • User modifiable elements, including the Compressor. Lots of future options!
  • Three year unlimited warranty. Built and calibrated in USA
View AllClose


Processing - Six digitally controlled sections of analog processing
Frequency response - 3 Hz to 180 kHz on eq section (-3dB points)
Dynamic range - 120 dB from maximum output (.5%THD soft   clipping) to minimum output.   Noise floor with Mix on 0 is typically   – 91dBu
Distortion range - between .0006% and 10% at 1KHz, depending   on mode and settings
Maximum Input before hard clipping - +22dBm,  “ Line In” mode.   Maximum Output (Mix at 0) - +28.5dBm
Compressor Dynamics Time Constants - Attack time is around 1mS.  Release .2 sec, fixed internally. Stereo Linkable for stereo tracks.  With the EL500 powered rack, the push of a button enables linking
Input Impedance - 120k Ohm, Instrument In Mode, output impedance is less than 75 ohms.  20K input impedance in balanced Line in mode
Guitar adaptor cable included
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

View AllClose

0 Reviews

View AllClose