Coil Audio CA-286 — PS6 Modular Tube Microphone Preamplifier

The Coil Audio CA-286 is a modular microphone and line preamplifier paying tribute to the classic European two-stage amplifier designs of the 1950s and ’60s—the circuit topology that defined the sound of broadcast and studio recording for a generation. Built around a two-stage EF86/6267 pentode vacuum tube circuit with Coil Audio’s own CT-110HN and CT-41 transformers, the CA-286 delivers the rich, detailed midrange and high-fidelity character associated with the finest vintage EF86-based preamps. The module mounts into the Coil Audio PS6 Rack Tray and Power Supply, accepting up to six CA Series amplifiers in a single chassis. Hand-built and tested in the USA.

Key Features

• Two-stage EF86/6267 pentode vacuum tube circuit with 42dB–60dB of available gain
• CT-110HN Super-Mu high-nickel input transformer—based on a rare 1950s high-fidelity coil; adds top and bottom extension with smooth, breathy saturation
• CT-41 line output transformer—based on a classic 1960s Peerless design; ruler-flat 20Hz–30kHz response with rich, wooly saturation
• Interchangeable input and output transformers for tonal flexibility
• 6-position input pad network with phase reverse: four mic pads (–6dB, –12dB, –19dB at 150/250Ω) plus two line-level positions (L1, L2) for DAW, tape, or line source integration
• NF (negative feedback) control: counter-clockwise brightens and raises harmonics; clockwise darkens and smooths harmonic structure
• HIGH switch for gentle upper-frequency filtering; LOW switch for front-to-back low-end placement in the soundstage
• OUTPUT knob positioned between the first and second EF86 stages for final level control
• NOS tubes, signal caps and resistors, PEC 2W carbon pots throughout
• Mounts into the Coil Audio PS6 Rack Tray (up to six CA Series modules per rack)
• Hand-built and tested in the USA

Specifications

• Circuit: Two-stage EF86/6267 pentode vacuum tube
• Tubes: EF86/6267 (NOS)
• Gain Range: 42dB–60dB
• Input Transformer: CT-110HN Super-Mu high-nickel (interchangeable)
• Output Transformer: CT-41 (interchangeable)
• Mic Input Impedance: 150Ω
• Line Input Impedance: 20kΩ bridging
• Output Impedance: 600Ω
• I/O: Transformer balanced
• Power: Coil Audio PS6 Rack Tray and Power Supply (sold separately)
• Construction: Hand-built and tested in the USA