Marantz 4100

Quadraphonic integrated amplifier with selectable 2-channel and 4-channel operation, independent tone and balance controls, and vari-matrix simulation for stereo-to-quad sound

Overview

The Marantz 4100 is a quadraphonic integrated amplifier. It plays conventional two-channel stereo and four-channel material. A built-in decoder section (marked P500 on the schematic) handles most quad matrix formats. It also reproduces discrete 4-channel programs, plus standard stereo and monaural sources. The Dimension control simulates 4-channel sound from 2-channel sources using Marantz's exclusive vari-matrix circuit. One user describes the effect as “kind of like being right in the middle of a stage, different sound everywhere.”

Specifications

Power output (two channel mode)	60 watts RMS per channel into 8 ohms
Power output (four channel mode)	25 watts RMS per channel
Power output mode	Selectable via rear panel "AMPLIFIER MODE" switch for 4x 25 watt or 2x 60 watt operation
Shipping weight	38 Pounds

Design

The Marantz 4100 features dual potentiometers and sliders on the front panel for independent front and rear bass, treble, and balance controls. It has a "Local/Remote" switch that bypasses front panel volume and balance when set to 'remote', intended for use with an optional wired remote. The amplifier includes a built-in decoder section (P500) for matrix formats and supports plug-in decoder modules like the SQA-1 and SQA-2/SQA-2B for CBS's SQ encoded albums. In two-channel mode, only one pair of 8-ohm (minimum) speakers should be used. The rear panel includes pre-outs, main-ins, multiple tape monitor loops, and auxiliary inputs for full system integration.

Market

A typical used unit was listed for $799.95 in 2018. An estate sale example was recorded at $380 the same year. Heavily used units often show browning on the four white plastic bulb housings. Plug-in SQ decoders (SQA-1, SQA-2) are frequently sold separately on eBay and can add value, though some users find them overpriced and underperforming. Scratchy audio usually means the pots and sliders need cleaning with contact cleaner. Never switch between 4x25W and 2x60W modes while powered, or you can damage the amplifiers. Setting the "Local/Remote" switch to "Remote" without a connected remote gives no output.