Thermionic Culture Snow Petrel Extra Gain 2-Channel Mic Amp

The Thermionic Culture Snow Petrel is a 2-channel high-gain valve mic preamp with no solid-state components in the audio path, originally designed around ribbon microphone use with the Coles 4038 but proven across a wide range of microphone types including large-diaphragm condensers. Gain is switchable from 40 to 75dB, making it well-suited to low-output ribbon and dynamic microphones that require more headroom from the preamp stage. Extra-low noise valves and special Sowter input and output transformers—custom-designed for this unit—deliver clarity from the quietest sources, while a higher-than-usual input impedance preserves microphone character and can be fine-tuned with Hi/Lo and Pad switches. When pushed into overdrive via the fine and coarse attenuators, the Snow Petrel produces a musical and progressive saturation characteristic of all-valve circuitry. Handmade and tested in Harlow, England.

Key Features

• Extra-low noise all-valve circuit — no solid-state components in the audio path; purpose-built for ribbon microphones and applicable to any microphone type
• Special Sowter transformers — custom input and output transformers designed for the Snow Petrel; contribute to the unit’s low noise floor and sonic clarity
• High input impedance — higher than standard mic preamps to preserve microphone character and clarity; adjustable with Hi/Lo and Pad switches to match individual microphones
• 40–75dB switched gain — wide gain range for low-output ribbon and dynamic microphones; switched for precise, repeatable settings
• HPF (high pass filter) — reduces proximity effect for close-miked sources
• Air control — adds high-frequency clarity; a characteristic of all-valve circuitry with none of the harshness found in solid-state designs
• Musical progressive saturation — when overdriven using the fine and coarse attenuators, the Snow Petrel produces smooth, musical harmonic saturation
• Handmade and tested in Harlow, England

Specifications

• Channels: 2
• Gain Range: 40–75dB (switched)
• Circuit Type: All-valve; no solid state in audio path
• Transformers: Sowter (custom; input and output)
• Input Impedance: Higher than standard; Hi/Lo and Pad switches
• HPF: Yes (proximity effect reduction)
• Air Control: Yes (high-frequency clarity)
• Construction: Handmade and tested in Harlow, England