The Coil Audio CA-70 MK2 Preamp is based on a two-stage circuit invented by Western Electric in 1913. It was licensed and built by various audio manufacturers from the 1930s through the 1950s. RCA, Gates, Western Electric, and Langevin were just a few that utilized this elegant and simple single-ended design.
Each Coil Audio CA-70 Preamp uses their own custom interchangeable transformers and NOS capacitors, resistors, and octal tubes. With the addition of a flexible pad network, the Negative Feedback tone shaping, and inter-stage volume control, it's like Mid Century with a Modern twist. You must have the Coil Audio PS6 Rack to power the Coil Audio CA-70 Preamp.
Coil Audio CA-70 MK2 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, High, 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 HIGH 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 stage 6J7 and 2nd stage 6C5 tubes. It sets the final level and offers further control of the two-stage gain structure.
Coil Audio CA-70 MK2 Preamp Features
- 16 ga. Stainless Steel Module with Integrated XLR I/O
- Coil Audio CT-110HN high nickel input and CT-41 output transformers installed.
- 12-Step Switched Negative feedback tone control with LOW/HIGH filters.
- Two-stage 6J7/6C5 vacuum tube single ended parafeed circuit.
- 42db-54db of available gain.
- 150 Ohm and 2k Mic input, 20k Line input, 600 Ohm output.
- 4 Position PAD for both Mic and Line Input.
- True 180-degree Phase Switch
- Up to 6 PS6 MK2 Series Modules mount into 7U PS6 Rack Tray.
- Hand built and tested in the USA.
Coil Audio CA-70 MK2 Preamp Includes
- Coil Audio CA-70 MK2 Preamp
- Manufacturer Warranty
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