The Gates Level Devil is a versatile and highly reliable audio amplifier designed for professional broadcasting and audio applications. It features four stages of audio amplification alongside a robust control section, providing precise control over signal levels and maintaining audio fidelity even in challenging conditions.
The power supply includes both unregulated and regulated voltage sections, ensuring stable operation for critical stages. Two OB2 tubes regulate the current fluctuations, while a silicone diode bridge rectifier powers the first stage filaments. The Gates Level Devil is equipped with input pads that provide up to 30 dB of attenuation, making it flexible enough to handle a wide range of input levels from -35 VU to +27 VU.
Its differential amplifier configuration enhances noise rejection, offering high in-phase signal cancellation, particularly useful in environments where interference may affect audio quality. Additionally, the push-pull configuration within its amplification stages ensures balance and stability across all stages.
The device also includes a sophisticated peak limiting control section with a full-wave rectifier and a gated circuit to prevent signal overdrive. The expander circuit, driven by negative bias control, allows for a controlled increase in gain of up to 10 dB, while minimising distortion. These features ensure that the Gates Level Devil maintains clean and precise amplification, even when used in demanding broadcasting scenarios.
Field tests have proven the Gates Level Devil’s ability to feed TV transmitters without the need for additional peak limiters, making it an ideal choice for FM and television broadcasting. The system includes an expander circuit that can be disabled when needed, providing flexibility in various operational contexts.
With its comprehensive limiting and expansion capabilities, the Gates Level Devil offers professional-grade performance, making it a reliable solution for managing complex audio signals with minimal distortion. Its rugged construction and stable design have made it a trusted tool in the world of professional audio engineering.
The Gates Level Devil’s abilities as a compressor-limiter are particularly advanced, making it highly effective for managing dynamic range in professional audio applications.
Compressor Functionality: The Gates Level Devil can smoothly reduce the amplitude of louder signals while keeping quieter sounds intact. This is achieved through its input pads and control mechanisms, which allow it to adjust incoming signal levels with precision. The device handles signal compression by ensuring that input levels ranging from -35 VU to +27 VU are kept within a desired range, protecting the audio from distortion or over-amplification. Its push-pull signal processing also helps in maintaining consistent audio output, balancing the signals from various stages to ensure uniformity.
Limiter Abilities: As a limiter, the Gates Level Devil is designed to prevent signal peaks from exceeding a set threshold. This is managed by its peak limiting control section, which consists of a phase inverter and a full-wave rectifier. The rectifier works with a gating voltage, ensuring no negative voltage is passed until the signal exceeds the threshold – set at approximately 27.6 V RMS. The limiter kicks in when the signal goes beyond this point, passing negative voltage to the load and reducing the gain of the V1 and V2 stages to stop the signal from rising further. This gating function helps prevent over-amplification, effectively capping the signal to avoid distortion or damage to connected equipment.
Attack and Release Control: The Gates Level Devil’s attack time is fast – around 10 milliseconds – ensuring that it reacts quickly to prevent transient peaks from distorting the signal. The release time can be adjusted between 1.5 to 2 seconds, which helps in gradually restoring the signal’s dynamics after limiting, avoiding abrupt changes in output.
Peak Limiting Section: The peak limiting circuit uses a combination of tubes and resistors to monitor and control signal voltage, preventing clipping and distortion in high-output scenarios. It grounds excess voltage and adjusts the bias on key components to prevent peaks from overloading the system. The limiting circuit is capable of handling signals that exceed normal operating levels without introducing noticeable audio artefacts.
Expansion and Compression Control: Additionally, the expander section of the Gates Level Devil works to enhance quiet signals without introducing noise. The expander reduces gain when the signal drops below a certain threshold, minimising background noise and other low-level unwanted sounds. When signals exceed a certain level, the expander amplifies the audio smoothly, allowing up to 10 dB of gain. This functionality allows it to handle both compression and expansion tasks efficiently, providing comprehensive control over dynamic range.
The Gates Level Devil’s compression and limiting abilities ensure that audio signals are managed effectively, with peak limiting to protect equipment and compression to maintain balanced dynamics. These features make it an excellent choice for broadcasters and audio engineers who need to manage high-fidelity audio under varying signal conditions.
