Alice 504T – Mic Pre with limiter & transformers

Alice 504T – Mic Pre with Limiter & Transformers combines transformer-coupled microphone amplification with a classic analogue limiter in a 500 Series module. Designed and manufactured in the UK, it provides up to 77 dB microphone gain and a maximum output level of +22 dBu. Microphone and line input selection allows the module to accommodate different recording and signal-processing requirements.

Transformer-Coupled Microphone Amplification

The microphone input combines a transformer with dedicated Alice circuitry, designed to capture microphone detail while adding the tonal character associated with the company’s analogue designs. Gain is distributed across four low-noise amplifier stages to maintain overload margins. The published microphone frequency response extends from 20 Hz to 20 kHz, with a +0/−1 dB tolerance.

Classic Ted Fletcher Limiter

Alice 504T incorporates a limiter based on Ted Fletcher’s 1979 design for the Alice 828 portable mixer. Its soft-knee characteristic and approximate 12:1 ratio provide dynamic control within the recording chain. The limiter can be switched in or out, allowing the preamplifier to operate without limiting when required. This combines microphone amplification and selectable peak control within the same module.

Input Selection and Filtering

Switchable phantom power accommodates microphones that require external powering, while microphone/line selection provides input flexibility. The high-pass filter has a 6 dB-per-octave slope and is 3 dB down at 75 Hz, helping reduce unwanted low-frequency content. As a 500 Series module, the 504T is intended for installation in a compatible powered host chassis; confirm chassis compatibility and available power capacity before ordering.

Basic Specifications

• Model: Alice 504T.
• Format: 500 Series microphone preamplifier.
• Microphone input: transformer-coupled.
• Amplifier topology: four low-noise gain stages.
• Microphone frequency response: 20 Hz–20 kHz, +0/−1 dB.
• Maximum microphone gain: 77 dB.
• Maximum input level: approximately −10 dBu, as published.
• Maximum output level: +22 dBu.
• Limiter: soft knee, approximately 12:1.
• High-pass filter: −3 dB at 75 Hz, 6 dB/octave.
• Switching: phantom power, microphone/line and limiter in/out.
• Manufacture: United Kingdom.