Antelope Audio A4-1B Analog Automated Opto Valve Compressor - Ultimate

The A4-1B Ultimate is the flagship version of Antelope Audio's revolutionary opto-tube compressor, delivering the full analog experience fused with the complete power of digital automation, recall, and control. Designed for modern producers who demand the tactile quality of premium analog gear and the precision of plugin-based workflows, this version unlocks the A4-1B's entire potential.

Built around a meticulously engineered all-tube circuit with custom transformers and hand-picked premium tubes, the Ultimate version reproduces the silky compression and harmonic depth of classic vintage units " but enhances them with next-level functionality. With proprietary motorized potentiometers, plugin-based control, and DAW automation, every setting is instantly recallable and adjustable in real-time, both physically and virtually.

Included only in the Ultimate version are powerful extras such as sidechain filtering with de-essing, dynamic preset management, Opto-cell auto calibration, and high-precision VU metering control. Its plugin (VST3/AU/AAX) offers full automation of every parameter - Attack, Release, Gain, Threshold, Ratio - all of which physically move on the hardware via motorized controls, giving you unmatched feedback and responsiveness.

• Signature Analog Compression Sound: Delivers the smooth, musical tone of classic opto-tube compressors with 100% analog signal path.

• Motorized Hardware with DAW Control: Includes full integration with DAW plugin (VST3, AU, AAX) for remote control and real-time automation.

• Unlimited Preset Recall & A/B Comparison: Save, load, and switch between presets instantly - perfect for fast workflows and consistent results.

• Plugin Included - Full License: Comes with the A4-1B plugin for total software/hardware integration and modern workflow enhancements.

• Responsive Automation: Automate threshold, attack, release, ratio, and gain from your DAW - reflected instantly on the hardware.

• Advanced Sidechain Features: Built-in plugin filtering with high-pass, low-pass, band-pass, and dedicated de-essing mode.

• Auto Calibration System: Maintains long-term accuracy and stereo matching with built-in opto-cell testing and alignment tools.

• Selectable Timing Modes: Use fixed, manual, or hybrid attack and release timing for tailored dynamic shaping.

• Multiple Metering Reference Levels: Choose between -10 dBu, 0 dBu, +4 dBu, and +20 dBu reference points for precise VU monitoring.

• Modern Power Supply: Efficient, quiet PSU with automatic voltage adaptation and DC tube heating for reduced noise.

• Custom Analog Hardware: Built with UK-made transformers, premium tubes, and proprietary motorized potentiometers for lasting performance.

GENERAL SPECIFIATIONS:

• 100 percent analog audio circuitry

• All tube-based push-pull amplifier design

• Pre-sorted opto-cell for ultra-precise compression

• Hand-selected premium vacuum tubes

• Custom UK-made input and output transformers

• High-grade components for maximum sonic fidelity

• Frequency response: 20 Hz to 20 kHz +/- 1 dB

• Input impedance: 10 kOhm differential

• Output impedance: less than 60 Ohm

• Maximum input level: +24 dBu

• Maximum output level: +24 dBu

• Noise level: less than -80 dBu

COMPRESSOR PARAMETERS:

• Ratio: continuously variable from 2 to 10

• Threshold: adjustable from off to -40 dBu

• Attack: 0.5 ms to 300 ms

• Release: 50 ms to 10 s

• Gain: adjustable from off to +30 dB

• Modes: fixed, manual, hybrid compression

METERING & CALIBRATION:

• VU meter monitoring: input, output, gain reduction

• Selectable reference levels: -10 dBu, 0 dBu, +4 dBu, +20 dBu

• Built-in opto-cell calibration and test system

• Optimized for consistent stereo link operation

ADVANCED DIGITAL INTEGRATION:

• Fully motorized potentiometers for physical and remote automation

• DAW plugin control via VST3, AU, AAX formats

• Real-time bidirectional sync between plugin and hardware

• Full automation of attack, release, gain, threshold, and ratio

• Preset recall system with fast A/B comparison support

• Unlimited preset saving and recall within DAW sessions

• Extended sidechain filtering: high-pass, low-pass, band-pass

• Dedicated de-essing via narrow band-pass side-chain filter

POWER & ENVIRONMENT:

• Input voltage: 95 V to 245 V, 50/60 Hz

• Modern PSU with automatic voltage adaptation and DC tube heating

• Operating temperature: 0 to 50 degrees C

PHYSICAL DIMENSIONS:

• Unit dimensions (H x W x D): 88 x 483 x 252 mm

• Unit weight: 4.4 kg

• Box dimensions (H x W x D): 140 x 640 x 350 mm

• Shipping weight: 6.5 kg

INCLUDED IN ULTIMATE VERSION:

• A4-1B analog compressor

• Power cable

• USB-C to USB-C cable

• Get Started leaflet

• A4-1B Plugin Perpetual License leaflet (Ultimate edition)