Rare early-1970s Pioneer QC-800A 4-Channel (Quadraphonic) Preamplifier. This high-quality control amplifier was designed as the matching preamp for Pioneer’s QM-800A power amplifier and supports both discrete 4-channel and matrix (including SQ) operation, while also functioning fully as a conventional 2-channel stereo preamp. It features independent front/rear tone controls, individual channel level controls, multiple tape monitors, and comprehensive input switching.

Serial Number: SL1400695 (shown on the rear chassis label)

Key Features:

• Full 4-channel preamplifier with discrete and matrix modes (Regular Matrix + SQ)

• Independent Bass & Treble controls for Front and Rear

• Individual Level controls for all four channels (CH1–CH4)

• Master Volume

• Mode selector: 2CH Front/Rear, 4CH Matrix, 4CH Discrete, Check

• Input Selector: Phono 1, Phono 2, Tuner, Aux 1, Aux 2

• Tape Monitor 1 & 2

• Low & High Filters

• Muting (-20 dB)

• Front & Rear headphone jacks

• Multiple RCA inputs/outputs for 4-channel operation

• Voltage selector (110/120/130/220/240 V)

• Original wood cabinet with brushed silver faceplate

• Made in Japan by Pioneer Electronic Corp.

• Power consumption: 5 W

Condition

This unit presents in excellent cosmetic condition for its age. The walnut-style wood cabinet shows rich, clean grain with only light, normal handling marks. The silver faceplate, knobs, switches, and lettering are clean and intact. The rear panel shows expected light age-related marks and dust but remains complete with original labeling, voltage selector, fuse holder, AC outlets, and power cord.

Please examine all photos carefully for the best assessment of cosmetic condition.

This unit is being sold as-is / untested. We have not powered it on or verified any functions. It is offered for parts, restoration, or as a collector display piece. No guarantees of working condition are made or implied.

Sold as-is with no returns.

A solid and desirable example of Pioneer’s early-1970s quadraphonic preamp design. Clean cosmetic examples continue to attract interest from both quad collectors and those seeking a high-quality vintage control preamp.

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