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Cary Audio CAD-805RS tube amplifier will bring new life to your favorite music

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Dale Davies |
CAD-805RS
Audio   The front panel is a handsome thick machined aluminum

The Cary Audio CAD-805 Reference Series (CAD-805RS) is the latest edition in the 805 series of single-ended mono block amplifiers that has been in continuous production since 1993.

CAD-805RSThe single-ended audio input signal from the outside world is passed to the control input grid of the first 6SN7 tube. This first 6SN7 stage is operating in a parallel dual triode conventional resistance-coupled Class A amplifier. This first gain stage is directly coupled to the next 6SN7 dual triode gain stage. This second stage is operating in a series anode constant-current Class A amplifier. This amplified audio signal is passed through a coupling capacitor to the grid of the 300B driver stage.

CAD-805RSThe 300B triode tube operates in a Class A single-ended mode utilizing fixed negative grid voltage on the 300B driver stage. This negative grid voltage is user-adjusted by the screwdriver pot at the rear of the CAD-805RS. The 300B is directly coupled to the grid of either a 211 or 845, 100-watt plate dissipation, triode output tube. The method of coupling at this stage is called an interstage transformer. This is an air-gap design with a flat frequency response from 30Hz to 23 KHz.

CAD-805RSThe audio signal from the 300B interstage transformer will drive the 211/845 output tube to 27 watts Class A output. With additional volume levels, the amplifier goes into a positive grid mode with a power output of 50 watts Class A2. In the case of the 211-output tube, the Class A2 power is on the order of 70 watts at clipping. The high-power output from the 211/845 tube is coupled to the loudspeaker via an air-gapped 150 watt continuous duty output transformer. This transforms the high impedance (8000 ohm primary winding) of the output tube to 4,8, or 16 ohms to drive the loudspeaker.

CAD-805RSThe front panel is a handsome thick machined aluminum that is available in either silver or black anodized finish. The CAD-805RS is equipped with a built-in meter on the front of the chassis. The adjustment pot is located at the rear of the chassis along with a bias jack for an external meter. To the left, the main power switch, to the right the ‘standby/operate’ switch which powers up the 211 or 845 output tubes. To the left is a rotary switch with a green jewel-like knob that chooses the appropriate bias for your choice of 211 or 845 output tubes.

July 1, 2019


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