The Coil Audio CA-286 Preamp is a two-stage amplifier based on circuits used by Langevin, Collins, Gates, and Telefunken during the 1950s and 60s. Each amplifier uses our own custom interchangeable transformers, NOS capacitors and resistors, and a pair of NOS EF86 vacuum tubes.
With the addition of a flexible input pad network, the Negative Feedback tone shaping, and inter-stage volume control, the CA-286 is a timeless and flexible amplifier that compliments any microphone collection. You must have the Coil Audio PS6 Rack to power the Coil Audio CA-70 Preamp.
Coil Audio CA-286 Preamp Controls
- The (INPUT) pad section contains a phase reverse switch, and a 5 position attenuation network of Balanced H-pads. The first four positions are various 150/250 Ohm mic pads; -6 db, -12 db, and -19 db. The final (LN) position allows line-level signals to run through the amplifier providing tone-shaping capabilities while mixing. It works as both a second-stage booster for other preamps, and a summing/buss amp for program and mix material. Two amplifiers can also be chained together to create the multi-stage, high gain recording path of a vintage tube console.
- The NF, HI, and LOW controls all interact to create a unique tone-shaping circuit. The NF control varies the amount of Negative Feedback present in the circuit. Counter-clockwise brightens and moves the sound forward while raising harmonics and sensitivity. Turning it clockwise increases negative feedback, producing a darker tone with a smooth, dampened harmonic structure.
- The HI switch transitions from the natural openness of the tubes, to a gentle filtering of upper frequencies. The LOW switch reacts with the NF, boosting or cutting low frequency while moving the low end from front to back in the sound stage.
- The Output control knob is placed between the 1st and 2nd stage EF86 tubes. It sets the final level and offers further control of the two-stage gain structure.
Coil Audio CA-286 Preamp Transformer Options
Preamp Input Transformer
- CT-110: A nickel/iron microphone input transformer based on a punchy 1960s small signal coil. It's perfect for all-around use and excels at high transient material. Its design gives it a very forward and rich mid-range, with smooth saturation in the highs and lows.
- CT-110HN: A super-mu microphone input transformer based on a rare 1950s hi-fidelity coil. Detail oriented, it adds an excellent top and bottom extension, and smooth, breathy saturation.
Line Input Transformer
- CT-41: A line output (or input) transformer based on a popular 1960s Peerless design. Frequency response is ruler flat from 20Hz to 30kHz, dipping just below 1db at 60kHz. Its smooth saturation imparts a rich, wooly, and hi-fi sound to anything that runs through it.
- CT-11: A Universal 1:1 line isolation transformer. Based on another 1950s coil design, it imparts a rich, hi-fi sound to any signal. The impressive frequency response of +/- .5db from 20Hz - 60kHz make it an unbeatable performer for isolation or balancing unbalanced signals and devices.
Coil Audio CA-286 Preamp Features
- Two-stage EF86/6267 pentode vacuum tube-based circuit
- 42db-60db of available gain
- Flexible input pad section for mic or line level operation
- Transformer balanced. 150 Ohm or 10k input, 600 Ohm output
- Interchangeable/Optional input and output transformers
- NOS tubes, signal caps & resistors, PEC 2W carbon pots
- Up to Six CA Series Amplifiers mount into our PS6 Rack
- Hand Built and Tested in the USA
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