Wolff Audio RefPre - 500 Series Reference Microphone Preamp

The Wolff Audio RefPre is a transformerless 500 Series reference microphone preamp designed for absolute transparency, ultra-low noise and rock-solid repeatability. With up to 70 dB of gain on tap, dedicated ribbon mic protection, a wide 10 Hz to 80 kHz frequency response and a continuously variable output fader, it is built for engineers who want to hear exactly what their microphones and instruments are doing, nothing more and nothing less.

From critical sampling and emulation work to pristine vocal chains and detailed drum recording, the RefPre delivers a clean, accurate signal that stands up to the most demanding studio environments. Stepped gain, fine trim control and a clear signal LED make it easy to set precise levels, while front and rear connectivity plus a dedicated Hi-Z input ensure it drops seamlessly into modern hybrid workflows.

Ultra-Transparent, Transformerless Design

At the heart of the RefPre is a transformerless circuit and meticulously optimised signal path, engineered to keep distortion and artefacts to an absolute minimum. With distortion as low as 0.0005 percent at 60 dB of gain and an equivalent input noise of -125 dBu, it preserves the true character of your microphones and instruments. This makes it an ideal partner for high-resolution condensers, measurement mics and sampling systems where every nuance matters.

Precision Gain Staging and Output Control

The stepped rotary gain control offers settings from -10 dB to 60 dB in 10 dB increments, giving you repeatable, recallable gain positions for consistent sessions and easy A/B comparisons. A ±6 dB trim control lets you fine-tune levels between steps, while the continuously adjustable output fader allows smooth control from full attenuation to maximum output. Together, these tools give you precise command of gain staging into converters, compressors and other downstream gear.

Dedicated Ribbon Mic Mode and Phantom Safety

Ribbon microphones get special treatment with a dedicated mode that adds an extra 10 dB of gain, taking the total available gain up to 70 dB. In this mode, the RefPre automatically adjusts impedance to suit passive ribbons and engages a phantom power lockout to prevent accidental 48V application. This combination of extra clean gain, automatic matching and built-in protection makes the RefPre a confident choice for delicate ribbon mics on quieter sources.

Wide Frequency Response and High Headroom

With a frequency response of ±0.5 dB from 10 Hz to 80 kHz, the RefPre captures extended low end and airy high frequencies with equal authority. A maximum output level of +28 dBu provides generous headroom, allowing it to handle hot signals from modern condensers and close-miked drums without folding. When you need to tidy up the bottom end, the switchable 80 Hz high-pass filter with a 12 dB per octave slope helps remove rumble and handling noise before it ever hits your converters.

Flexible Connectivity and Clear Metering

The RefPre offers both front and rear microphone input access, making it easy to integrate into patchbay-based studios or plug straight in at the rack. A dedicated high-impedance instrument input with its own preamp is accessed via the mic/instrument switch, providing a clean, direct path for guitars, basses and other instruments. A signal LED glows green when audio is present and flashes red at +18 dBu, giving you an instant visual cue as you approach clipping.

• Ultra-Transparent, Transformerless Signal Path - The RefPre’s transformerless design and minimal circuitry deliver an exceptionally clean, uncoloured sound. With ultra-low noise and vanishingly low distortion, it faithfully reproduces the character of your microphones and instruments, making it ideal for critical recording, sampling and emulation work.
• Stepped Gain with Trim and Output Fader - Gain is set in precise 10 dB steps from -10 dB to 60 dB, with a ±6 dB trim control for fine adjustment and a continuously variable output fader for final level setting. This combination gives you accurate, repeatable gain staging and smooth control into converters and outboard processors.
• Ribbon Mic Mode with Phantom Lockout - Engaging ribbon mode adds 10 dB of extra gain, automatically optimises impedance and locks out phantom power. This protects sensitive ribbon microphones while providing the additional clean gain they often require, giving you confidence when working with premium ribbon designs.
• Wide Bandwidth, High Headroom and HPF - A wide 10 Hz to 80 kHz frequency response, +28 dBu headroom and a switchable 80 Hz high-pass filter equip the RefPre for demanding modern sessions. You can capture full-spectrum detail without unwanted low-frequency rumble, even when working with high-output mics on loud sources.

General

• Format: 500 Series reference microphone preamp
• Design: Transformerless, ultra-transparent signal path

Gain and Level Control

• Main Gain Range: -10 dB to 60 dB (stepped in 10 dB increments)
• Ribbon Mic Mode: Additional 10 dB gain (up to 70 dB total)
• Trim Control: ±6 dB fine adjustment
• Output Control: Continuously adjustable output fader (full attenuation to maximum)

Inputs and Outputs

• Microphone Inputs: Front and rear panel access
• Instrument Input: High-impedance front-panel input with dedicated preamp
• Source Selection: Front-panel mic/instrument switch

Microphone and Instrument Functions

• Ribbon Mic Mode: Auto impedance adjustment and phantom power lockout
• Polarity: Switchable polarity reverse
• Phantom Power: 48V with safety lockout in ribbon mode
• High-Pass Filter: Switchable 80 Hz, 12 dB per octave

Performance

• Frequency Response: 10 Hz to 80 kHz, ±0.5 dB
• Equivalent Input Noise: -125 dBu
• Distortion: 0.0005 percent at 60 dB gain
• Maximum Output Level: +28 dBu

Metering and Indicators

• Signal LED: Glows green on signal detection
• Clip Indication: LED flashes red at +18 dBu