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A-9C General Purpose 20-Watt Amplifier

A-9C General Purpose 20-Watt Amplifier


  • Full 20 watt output--push-pull 6L6 tubes
  • Separate bass and treble tone controls
  • True hi-fi performance ±1 db 20 to 20,000 cycles
  • Four switch-selected compensated inputs
  • Miniature tubes for low hum and noise level

The Heathkit model A-9C Amplifier offers you the least expensive route to real high fidelity performance. It employs push-pull 6L6 tubes to provide full 20 watt output. The preamplifier, main amplifier, and power supply are all on one chassis. Thus one compact unit fills the need for a good high fidelity amplifier with only a minimum cash investment. Designed primarily for home installations, the model A-9C is also capable of fulfilling public address requirements.

It has excellent gain characteristics and full 20-watt power output. The preamplifier section features four separate inputs, each properly compensated and selected by panel-mounted selector switch. It has separate bass and treble tone controls, each offering 15 db boost and cut. It employs twin-triode miniature tubes in preamplifier, tone control, and phase splitter stages for low hum and noise levels.

A-9C Schematic Diagram

A-9C Schematic Diagram

The output transformer is tapped at 4, 8, 16, and 500 ohms to match most any speaker system. The power transformer is shielded and is one of the heavy-duty "potted" type. A detachable front plate is employed on the model A-9C so that the plate can be removed and installed on the outside of the cabinet where the shafts protrude through, for custom installations.

Ease of kit assembly has been assured by supplying a detailed step-by-step instruction manual with the kit. A specialized knowledge of electronics or wiring techniques is not required. This amplifier is a true high fidelity unit, covering 20 to 20,000 CPS within ± 1 db. Total harmonic distortion is less than 1% at 3 db below rated output, and the quality of audio output available is excellent. A fine unit with which to start your own hi-fi system.

Specifications—Power Output: 20 watts. Frequency Response: ± 1 db-20 to 20,000 cps at 1 watt. Total Harmonic Distortion: 1% (at 3 db below rated output). Tone Controls: Bass (at 30 cps)—15 db boost, 15 db cut; Treble (at 15 kc)—15 db boost, 20 db cut. Tube complement: 12AX7 magnetic phono preamplifier and input amplifier, 12AU7 voltage amplifier and phase splitter, 12AU7 voltage amplifier and tone control amplifier, 2-6L6G push-pull pentode power amplifiers, 5V4G Rectifier. Dimensions: 14" x 8 7/8" x 7 3/8" high. Power Requirements: 110-125 volts AC at 50/60 cycles. Shipping Weight: 23 lbs.

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