Antelope Audio Antelope Audio A4-1B Opto Valve Compressor 2025 - Black / Blue

Тhe A4-1B Tube-Optical Compressor combines the warmth of classic tube compression with the precision and flexibility of modern technology. Faithfully recreating the iconic Scandinavian sound, the A4-1B boasts a fully analog circuit for the audio signal, built with the highest quality components to ensure precise and transparent compression. It also comes with а stand-alone app and DAW plugin for remote control, automation and filtering for targeted compression, provide a seamless experience for audio professionals seeking both authenticity and innovation.

• All-analog design preserving the true sound of classic opto-valve compression
• Custom transformers & hi-end tubes for tight low-end and high-fidelity audio
• Remote control via a stand-alone app, or DAW plugin (VST3, AU and AAX), with automation and preset recall
• Proprietary motorized potentiometers ensuring instant remote response
• User-configurable high-pass, band-pass and de-essing filters

As Authentic as It Gets.

Crafted with premium analog components, the A4-1B is not just a compressor—it’s a testament to the timeless quality of true analog engineering. A painstakingly accurate signal path, premium tubes, and custom UK-made transformers combine for unparalleled musicality and low-end richness, matching precisely the compression behavior of the original. Even when pushed to the limit, the A4-1B remains transparent, breathing new life into vocal tracks, bass, keys, or percussion. 

Classic Sound, Modern Engineering.

The A4-1B combines analog warmth with modern engineering for unparalleled performance. Its efficient power supply ensures stability and reliability with automatic voltage adaptation, while DC heating for the tubes minimizes noise and enhances tonal warmth. Digital control technology streamlines compression adjustments, offering faster and more precise operation. And thanks to the automated opto-cell calibration system, compression characteristics are perfectly matched in a stereo pair, staying exactly the same even after decades of use.

Bringing Analog into the Digital Age.

The A4-1B also comes with a stand-alone app, as well as a DAW plugin (available in VST3, AU and AAX formats), offering full integration into your digital setup. Proprietary motorized potentiometers allow settings to be applied instantly to the hardware, while the preset system ensures easy recall for consistency across sessions and quick A/B testing. Attack, Release, Gain, Threshold, and Ratio can be automated directly from the DAW, just like with any native plugin. The extended filter section includes low pass, high pass, and band pass filters for sidechain applications, and the de-es mode with a narrow band pass filter helps clean up vocals and instruments with precision.

The stand-alone remote control app is automatically installed upon activation of the device. The DAW plugin can be downloaded from the Plugins tab of the Antelope Launcher.

Features

Authentic sound and compression

• 100% purely analog circuit for the audio signal
• High-quality components ensuring superior sonic performance
• Custom-designed UK transformers and high-quality tubes
• Pre-sorted opto-cell for optimal compression precision
• All tube-based push-pull amplifier
• Continuously variable ratio, attack and release time
• Fixed, manual and hybrid timing modes
  

Modern performance and stability

• Ensured compression precision over time
• Modern power supply for tube longevity and reduced humming
• Consistent stereo-link performance via calibration system
• VU-meter for monitoring input, compression and output
• Multiple reference levels for metering
  

A4 – Antelope Audio Analog Automation

• Remote control via a stand-alone app, or DAW plugin (available in VST3, AAX and AU formats)
• Settings instantly applied on hardware via proprietary motorized potentiometers
• Comprehensive file preset system, with option for quick A/B testing
• Automation for attack, release, gain, threshold and ratio via DAW plugin
• Extended filtering section with low pass, high pass and band pass filtering for side chain signal
• De-essing mode utilizing narrow band pass filter

In-the-Box Content

• A4-1B analog compressor
• Power cable
• USB-C to USB-C cable
• Get Started leaflet
  

Technical Specifications

Compressor:

Ratio: 2:1 to 10:1

Threshold: off to -40 dBu

Attack: 0.5 ms to 300 ms

Release: 50 ms to 10 s

Gain: off to +30 dB

Maximum output level: +24 dBu

Maximum input level: +24 dBu

Noise level: < -80 dBu 

Input impedance: 10 kOhms differential

Output impedance: <60 Ohm

Frequency response: 20 Hz to 20 kHz ±1 dB

Power: 95 V/245 V, 50-60 Hz:

Dimensions – device (approx.)

Height: 88 mm (3.47 in)

Width: 483 mm (18.98 in)

Depth: 252 mm (9.92 in)

Weight: 4.4 kg (9.70 lbs)

Dimensions – box (approx.)

Height: 140 mm (5.51 in)

Width: 640 mm (25.20 in)

Depth: 350 mm (13.78 in)

Weight: 6.5 kg (14.33 lbs)

Operating temperature

0-50°C, 32-122°F