DS-500 Opto
De-esser

Opto De-esser for the 500 Series Format

Back in 2001, while designing the Quartet Tube Record- winning Quartet Tube Recording Channel, I decided that it needed a de-esser as one of the four elements. Though I'd never bothered to look into how they operate – much less built one myself – I blindly went off and started tinkering. Attempts at de-essing via the sidechain of a compressor to pull down the amplitude of the "s" worked ok, but did not sound natural to my ears or leave enough of the "s" to make it recognizable.

So, I decided to try using the fast opto cell from the OCL-2 as part of a triggerable LC notch filter, which covers a specific range of fundamental frequency where the "s" is most annoying. By varying the depth and the band- width of the notch, I discovered that there is a sweet spot where the "s" is recognizable, but not splashy. Because the sweet spot is often singer-dependent, I added a depth control to allow the user to determine how much of the "s" to leave in. Owners of the Quartet often praised the de-esser, and found it effective in many other applications, including removing finger squeaks in acoustic guitar tracks, and "wisp" sounds on electric bass.

Ten years (and many requests) later, I've been convinced to put out the de-esser in a stand-alone 500 series card. It is identical to the one in the Quartet, but implemented around a unity-gain class A solid-state line stage.

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Specifications

Format: API®  500 series standard, fully compatible
Input Impedance: 20KΩ, balanced
Output Impedance: less than 50Ω
Gain: unity (0 dB)
Max. Output Level: +27dBu, balanced
Threshold: off to +30dB of detector gain
Detector: 11 center frequencies at 3.4, 4.5, 5.7, 6.6, 7.5, 8.0, 8.8, 9.4, 10.0, 10.5, and 11.5 kHz
Depth: continuously variable from -2 to -10 dB
Frequency Response: +/- 1 dB from 10Hz to 20kHz
Noise Level: better than 90 dB below +4dBu, 0-80kHz
Total Harmonic Distortion: less than 0.01%, 20-20kHz

 

Fast Features

Identical to the De-esser in the award-winning Quartet Recording Channel · Opto-Inductive notch filter using our proprietary fast opto cell · Highly selective inductive detector · Class A solid-state signal path · Handcrafted in the USA

 

Notes:
0dBu = 0.775 Vrms
All noise measurements are unweighted, 20 - 20,000 Hz bandwidth
All Specifications are subject to change without notice