Heiserman Audio H251

The Heiserman H251 is a premium large-diaphragm valve microphone designed for professional studio recording, offering versatile polar patterns and meticulous vintage-inspired engineering.

Overview

Engineered with precision for demanding studio environments, the Heiserman H251 features the Generation 4 Hk12 capsule, constructed with brass and an acrylic-chambered backplate. The capsule utilises 6-micron gold-sputtered DuPont Mylar® to achieve superior transient response and sonic clarity. Two master machinists in North Carolina handcraft every component, ensuring exceptional consistency and mechanical precision.

Internal Design

The microphone incorporates a faithful recreation of the original 251 circuit, including an acrylic circuit board, full acrylic head assembly and the original rotational pattern switch for selecting cardioid, omnidirectional or figure-8 polar patterns. The head assembly houses the authentic Ck12 saddle with felt and foam damping for mechanical stability.

Electronic Components

The circuit employs high-spec Vishay and Takman Rex resistors, alongside NOS polystyrene and PIO capacitors, delivering consistent tonal performance. The output stage features a true-to-original wet Tantalum capacitor, enhancing harmonic detail and warmth.

Transformer and Tube

The T14/1 transformer, reverse-engineered from a pristine 1961 vintage unit, delivers balanced output with enhanced low-end response and smooth high frequencies. The microphone runs a 6072 TAD Premium Highgrade vacuum tube, providing low noise performance and classic valve character.

Construction and Finish

The Heiserman H251 features a robust metal body with an automotive-grade Siemens Grey painted finish for durability and aesthetic authenticity. The system ships with a custom bulletproof power supply with global voltage switching, a 7.5-metre Sommer tube microphone cable with a custom 251-style connector, and a rugged flight case for secure transport.

Performance

The microphone offers a sensitivity of 17mV/Pa ±1dB, a frequency response spanning 20 Hz to 20 kHz, and a maximum SPL handling of 130 dB. The self-noise measures just 10dBA, ensuring pristine recordings, while selectable impedance options of 200 ohms or 50 ohms provide flexibility for different recording chains.

• Large-diaphragm valve microphone with cardioid, omni and figure-8 patterns
• Generation 4 Hk12 brass and acrylic-chambered capsule with 6µm gold Mylar®
• T14/1 transformer based on a pristine 1961 vintage design
• 6072 TAD Premium Highgrade vacuum tube for low-noise performance
• Acrylic circuit board and head assembly with rotational pattern switch
• Premium components including Vishay resistors and wet Tantalum capacitor
• Automotive-grade Siemens Grey finish with bulletproof PSU and rugged flight case

This item, like everything we supply, comes with the complete support of our expert team. Our excellent technicians have been specifying, building and supporting studios for over twenty years. If you have any problems with installation, setup or everyday use, they’re never more than a click away, and always happy to help.

You can contact them here.