Coil Audio CA-70S MK2 Single-Channel Microphone/Line Amplifier

The Coil Audio CA-70S MK2 single channel preamplifier is a 2U standalone version of Coil's CA-70 PS6 preamp module. Power is housed on board, and a streamlined control layout. It boasts the exact same American style circuit, tubes, transformers, and high-end components as its PS6 sibling but with an elegant, user-friendly design. Simply put, the CA-70S is the easiest way to get those classic heavy Octal tube tones into your studio.

WESTERN ELECTRIC TWO-STAGE CIRCUIT

The CA-70S preamplifier pays homage to the classic American two-stage circuit invented by Western Electric in 1913 and manufactured by multiple companies from the 1930s through the 1950s – most notably RCA, Gates, and Langevin. This old octal tube circuit has a huge thick tone and is what many consider to be the quintessential “old tube preamp” sound. The CA-70S MK2 uses Coil Audio transformers, high quality capacitors, resistors, and NOS octal tubes. For the microphone input stage the CA-70S uses the CT-110HN Super-Mu transformer based on a rare 1950s high fidelity coil. Detail oriented, it adds an excellent top and bottom extension with a smooth, breathy saturation. On the line out it uses the CT-41 transformer based on a popular 1960s Peerless design. Frequency response is ruler flat from 20 Hz to 30 kHz, dipping just below 1 dB at 60 kHz. Its smooth saturation imparts a rich, wooly, high fidelity sound to anything passing through it.

CONTROLS

The (INPUT) pad section contains a phase reverse switch, and a 4-position pad network: 0 dB -6 dB, -12 dB, and -19 dB. 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. Clockwise increases negative feedback, producing a darker tone with a smooth, dampened harmonic structure. 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 is placed between the 1st stage 6J7 and 2nd stage 6C5 tubes and sets the final level output level.

COIL AUDIO CA-70S MK2 FEATURES:

• Standalone version of Coil's CA-70 PS6 preamp module in a 2U steel enclosure with integrated power supply
• CT-110HN high nickel input and CT-41 output transformers installed
• Negative feedback tone adjustment with LOW filter
• Two-stage 6J7/6C5 vacuum tube single ended circuit
• 42 to 54 dB of available gain
• Flexible input pad section for Mic or Line level operation
• 150 Ohm Mic input, 20k Line input, 600 Ohm output
• NOS tubes, signal caps and resistors, PEC 2W carbon pots
• Slow Ramping/Linear regulated power supply to prolong tube life
• Hand-built and tested in the USA