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Antelope Audio A4-1B analog Opto-Tube compressor with digital control


A4-1B  ANALOG AUTOMATED OPTO VALVE COMPRESSOR

The Future of Analog Gear

A4-1B combines the legendary sound and design of analog Opto-Tube compressor with modern-day workflow enhancements. Experience its signature hardware audio processing or take it a step further by accessing an array of contemporary functionalities.

Highlights

  • 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, with automation and preset recall

  • Proprietary motorized potentiometers ensuring instant remote response

  • User-configurable high-pass, band-pass and de-essing filters

Features

Authentic Analog Sound

  • 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 attack and release time



Automated calibration systems

  • Ensured compression precision over time

  • Modern power supply for tube longevity and reduced humming

  • Consistent stereo-link performance via calibration system

  • Multiple reference levels for metering

  • VU-meter for monitoring input, compression and output



A4 – Antelope Audio Analog Automation (optional)

  • Remote control via VST3, AAX or AU plugin, or standalone control app

  • Settings instantly applied on hardware via proprietary motorized knobs

  • Comprehensive file preset system

  • 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-esser mode utilizing narrow band pass filter

ALL OUT ANALOG

A4-1B was designed to preserve vintage Opto-Tube units' highly praised smoothness and musicality. Even when pushed to the limit, the compressor remains transparent, breathing new life into vocal tracks, bass, keys, or percussion. A4-1B sounds and reacts just like the legendary hardware that inspired it allowing you to apply the legendary sound of Opto-Valve compression to your modern production.

Under the Hood

Revolutionized Analog Power

High-quality components ensure A4-1B's superior sound and performance consistency across the whole frequency spectrum. This all-analog powerhouse was made to last and faithfully follow the legacy it was built upon. Custom UK-manufactured transformers allow for a tight low-end and high-fidelity audio reproduction. The signature sound of the unit is achieved thanks to its premium tubes. Those provide A4-1B with extra analog warmth and precision. Electricity is the heart and soul of high-end analog gear so we packed A4-1B with an efficient PSU incorporating advanced automatic voltage adaptation for even greater stability and noise reduction.

A4-1B is the first in a series of automated outboard analog units developed by Antelope Audio. We want to introduce high-quality audio hardware to the current generation of audio producers and artists. Thanks to proprietary digital technologies these units will not only be given a new life but will be adapted to the current standards of the professionals and enthusiasts. This all-analog design allows the units to be used traditionally but the brand new digital features unlock their full potential potential.

Supreme Digital Control

The A4-1B digital control panel is available both as a standalone app and as a VST / AU / AAX plugin compatible with any modern-day DAW. The unit is easily integrated into fully digital, all-analog, or hybrid studio setups. The intuitive software makes preset management a breeze so you can apply your signature settings to various sessions and access them from any place in the studio.

Responsive Automation

The A4-1B motorized potentiometers will not only instantly react to any change you apply on the hardware unit physically or digitally, those can also be fully automated in the app or control panel. The value of any parameter of the unit, including the compressor Attack, Release, Gain, Threshold, and Ratio can change throughout your session – just as if you are using a native plugin.

Preset Recall and A/B

The software control panel allows for fast and easy preset recall but just like any other Antelope Audio plugin and unlike most analog gear, it allows you to do A/B preset comparisons quickly and easily.

Filtering and De-Essing

By modern-day standards filtering and side-chain are crucial features of compressors. The legacy unit that inspired A4-1B wasn’t built with these requirements in mind so we added them as unlockable extras to the digital-only feature set of the unit. The available High, Low, and Band-Pass Filters are useful for targeted compression. De-essing capabilities and Side-Chain compression are crucial for a unit, known as one of the go-to compressors for vocal processing, and are also accessible via the software panel of the unit. 

CALIBRATED TO PERFECTION

Among the many stand-out features of A4-1B are its calibration systems. These ensure consistent performance and long-term reliability of the tubes of the unit, a crucial feature when using dual units for enhanced stereo matching. A4-1B offers an Opto-Cell Test System, and self-calibration of the VU meters, and the meter reference level (- 10 dBu / 0 dBu / +4 dBu / +20 dBu). The motorized potentiometers can also be readjusted. All three calibration types are accessible in the unit’s control panel.

As Authentic as It Gets.

The A4-1B captures the essence of legendary compression. A painstakingly accurate signal path, premium tubes, and custom transformers combine for unparalleled authenticity and low-end richness. The precise opto-cell detection system guarantees precise compression characteristics, matching the authentic behavior of the original. 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.

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. These innovations not only improve the device's efficiency but also enhance the overall user experience, making the A4-1B a perfect blend of classic sound and modern precision for professional audio workflows.

Bringing Analog into the Digital Age.

The A4-1B also has access to the optional A4 software suite, allowing for remote control via VST3, AAX, or AU plugin, or standalone app, offering full integration into your DAW setup. Proprietary motorized knobs allow settings to be applied instantly to the hardware, while the preset system ensures easy recall for consistency across sessions and A/B testing. Attack, Release, Gain, Threshold, and Ratio can be automated directly in the DAW plugin, just like with any native tool. 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 A4 software suite is available as an optional addon, as part of a monthly or annual membership plan. The A4-1B comes with 1 year of Antelope Membership for free, including the full suite of Synergy Core Native plugins, as well as all new releases and updates.

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

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