Serpent Audio SB4001-SEPIA

The Serpent Audio SB4001 for the Karno Sepia is a stereo VCA bus compressor that delivers precision dynamic control through quad VCAs, wide threshold and ratio ranges, extensive sidechain filtering and classic stepped release modes combined with modern enhancements such as Grind harmonic drive and wet/dry blend.

Overview

Serpent Audio engineers this SB4001 variant specifically for integration within the Karno Sepia platform, allowing professional users to access the character and control of a high-end analogue bus compressor directly inside a modular, recallable workflow. The quad VCA topology increases accuracy and stability across the stereo field, while the threshold control from minus twenty to plus twenty decibels and ratio range from 1.5:1 to 10:1 provide detailed gain management. The compressor maintains an exceptionally flat frequency response of plus or minus 0.11 dB from 20 Hz to 20 kHz, ensuring transparency and reliability under all programme conditions.

Compression Architecture

This Sepia-compatible SB4001 carries the behaviour of the classic bus compressor lineage while adding contemporary control depth. Six ratios allow either subtle mix cohesion or assertive limiting, supported by ten selectable attack times that shape how the circuit interacts with transients. The stepped release settings recreate the time constants that define vintage mix bus compression, while alternate auto release introduces modern adaptive behaviour that responds fluidly to complex material. The variable release control provides continuous shaping beyond the stepped modes, expanding the range of envelope sculpting available inside the Sepia environment.

Sidechain Control and Filtering

The module includes a comprehensive sidechain feature set optimised for the Karno Sepia signal architecture. An external key input allows advanced ducking and rhythmic effects, while selectable high pass filters at 60, 90 and 120 Hz prevent low frequency energy from driving excessive gain reduction. Boost mode sharpens detector sensitivity, and slope mode shifts the compressor’s interpretive curve for greater firmness or gentler response depending on mix needs. These tools allow engineers to create highly controlled gain structures within a fully modular Sepia workflow.

Colouration and Blending

Grind mode adds a proprietary valve-style harmonic structure that introduces musical saturation and vintage tonal weight. The wet/dry blend stage enables internal parallel compression for tight punch and cohesion without sacrificing dynamic openness. Inside the Karno Sepia module system, this combination of transparent VCA operation and controllable harmonic colour creates a wide palette of sonic options for mix and mastering engineers.

Integration and Power

The Sepia version features true bypass switching to preserve signal purity when disengaged. Operating from ±16 V DC power rails, the unit maintains substantial headroom suitable for complex modern productions. Its stereo configuration ensures confident imaging and precise gain matching, and the external sidechain I/O offers flexible routing within analogue, hybrid or digital studio environments built around the Sepia modular platform.

Why Choose the Serpent Audio SB4001 for Karno Sepia

• It integrates classic analogue bus compression directly into a modular, recallable Sepia workflow

• It shapes mixes quickly using intuitive yet technically detailed controls

• It combines VCA transparency with optional harmonic weight for creative tonal enhancement

• It adapts to any genre or processing style through extensive time constants and ratio ranges

• It supports advanced routing, parallel compression and sidechain techniques with ease

• Stereo VCA bus compressor designed for the Karno Sepia module
• Quad VCA gain reduction for precision and stability
• Threshold control from -20 dB to +20 dB
• Ratio range from 1.5:1 to 10:1
• Frequency response ±0.11 dB from 20 Hz to 20 kHz
• Ten selectable attack times and six ratio options
• Classic stepped release settings and alternate auto release
• Variable release control for detailed envelope shaping
• Grind harmonic mode for valve-inspired saturation
• Wet/dry blend stage for internal parallel compression
• High pass sidechain filters at 60, 90 and 120 Hz
• Boost and slope modes for tailored sidechain behaviour
• External key input on 1/4 inch jack
• True bypass switching
• Operates on ±16 V DC rails

This item, like everything we supply, comes with the complete support of our expert team. Our excellent technicians have been specifying, building and supporting studios for over twenty years. If you have any problems with installation, setup or everyday use, they’re never more than a click away, and always happy to help.

You can contact them here.