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1U, 2 module rack for API 500 series compatable modules. Features ultra quiet power supply, instrument line input, flush-mount front panel.

The DerrEsser is a multi function dynamic filtering device, in an API 500 series module format. In its basic “DS” mode, the DerrEsser is an effective, level insensitive de-esser, which is a device that will adjust the high frequency gain on overly trebly or spiky vocal, or other source. By using a crossover technique, and dividing the audio up into a high frequency range and a low frequency range, the DerrEsser can use its Voltage Controlled Amp to turn down comparatively high or harsh high frequencies in an extremely musical manner. However, unlike other de-essers, the device is not limited to just de-essing, and allows for multi use of its circuitry

Besides Bypass, there are essentially four modes of the DerrEsser:

DS Mode – (Bypass Button IN, all other buttons OUT). As a de-esser in the DS mode (HF Limit OFF), one can set the threshold to tame harsh S’s (sibilants) that result from an overly bright singer or from EQ’ing to make a vocal sound aggressive and clear. In this mode, the dyamic action is “level insensitive”, as the detector circuitry compares the High Frequency content to the low frequency content, Overall signal level doesn’t matter at all. When there is enough HF compared to LF, the threshold is exceeded and the DerrEsser starts to turn down the frequencies above the crossover point set by the Frequency control on the front panel. Again, great care was taken to ensure this DS section meets the Empirical Labs reputation for originality and ease of use. We use the latest technology VCA, specially selected for glitch free, distortion free, and noise free performance. The time constants were carefully selected and the corner frequency is user adjustable with a high performance active crossover.

HF LIMIT – (Bypass Button IN, HF LIM IN, all other buttons OUT). In this mode, the DerrEsser looks at the general level of the High Frequencies only. Think of it 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. This mode can also act as a de-esser but is more of a general high frequency smoothing device.The HF limiter is probably the first carefully tailored soft knee HF limiter in existence. We believe both the DS and HF LIM modes offer the highest performance of any similar device

HIGHPASS – (Bypass Button IN, Listen IN, HP/LP OUT, HF LIM doesn’t matter). By using the “LISTEN” Function, the user can employ the superb 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 that are being controlled with the dynamic/compression circuits. The corner frequency is adjustable by the Frequency knob. Once the LISTEN switch is engaged, all bargraph LED’s should light as indication.

LOWPASS – (Bypass Button IN, Listen IN, HP/LP IN, HF LIM doesn’t matter). With the LISTEN button IN, and 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.

1U, 2 module rack for API 500 series compatable modules. Features ultra quiet power supply, instrument line input, flush-mount front panel.



The concept of British Mode came from an unusual setting on the classic UREI 1176LN limiter. The unit was designed to have only four ratios, each ratio being engaged by selecting one of four buttons. However, as early as 1980 (or before), renegade recording engineers, always on the lookout for something a little more “over-the-top”, found that you could make all four buttons stay in if you pressed them just right. What resulted was a very aggressive sound that had some elements of the unit’s 20:1 ratio, but with an unusual knee and new envelope shape. Somewhere along the line, someone called it “British Mode”, and the name stuck.

The EL8-X has the advantage of being able to selectively apply this aggressive characteristic - not just to the new “British” ratio (1:1) - to any of the ratios, simply by engaging the dedicated “British Mode switch.


The original Distressor stereo link function used a summing and phase detection method, which allowed slight stereo image shifting. Although frequently desirable for its phase correction, and its “thickening” on open room mics and other stereo sources, this approach can sometimes be a problem on stereo program material where the producer/engineers want to maintain absolute left/right balance at all times. With the new “Stereo Image Link” option, the EL8-X now has three link options - the original “phase” link, the new Image Link and the combination of the two, phase and image linking - something never before offered on any compressors or limiters.

  • Frequency response - 2 Hz to 160 kHz in clean audio mode (+0, -3 dB).
  • Response is shaped in distortion modes (Dist 2, Dist 3).
  • Dynamic range - 110 dB from max. output to min. output in 1:1 mode.
  • Greater than 100 dB signal to noise in distort 3 mode.
  • DC coupled output - High quality input caps.
  • Input impedance - 20K Ohms, Output impedance is < 75 ohms
  • Time constants - Attack range 50uS - 50mS.
  • Release range .05 sec to 3.5 seconds, normal modes and up to 20 seconds in 10:1 opto mode.
  • Three user-selectable saturation modes (Normal, Dist 1, Dist 2).
  • Digitally Controlled Analog - Gives the user several different compressors within one unit.
  • Several ratios use different circuitry.