Kenwood KR-6340 (1973–1975)
A 40W/ch stereo receiver that doubled as a quadraphonic pioneer—complete with built-in SQ and RM decoding, ready for a four-channel experiment that never quite stuck
Overview
The Kenwood KR-6340 isn’t just another silver-faced receiver from the early '70s—it’s a time capsule of an audio format war. Marketed as a "Two-Four" receiver, it straddled the line between conventional stereo and the short-lived quadraphonic boom, offering 40 watts per channel in stereo mode and stepping down to 15 watts per channel when driving four speakers. Built between 1973 and 1975, this receiver was designed for owners who wanted to future-proof their systems, whether or not that future ever arrived. Its dual identity—solid-state workhorse and experimental decoder—makes it a curious artifact for collectors who appreciate gear built at the edge of a trend.
Kenwood didn’t just bolt on decoding; they integrated it. The KR-6340 came with built-in SQ (Stereo Quadraphonic) and RM (Regular Matrix) decoder circuits, eliminating the need for an external processor. , and it speaks to Kenwood’s ambition during a period when spatial audio felt like the next frontier. But while the hardware was ready, the ecosystem wasn’t—quadraphonic records remained niche, and many owners likely never flipped the switch to four-channel mode. Today, that capability adds charm rather than utility, a reminder of how often audio innovation outpaces adoption.
Specifications
| Manufacturer | Kenwood Corporation |
| Product Type | Stereo & Quad Receiver |
| Year of Production | 1973–1975 |
| Power Output | 40W per channel (stereo, 8Ω) [conflicting: 35W/ch], 15W per channel (quadraphonic, 8Ω) |
| Frequency Response | 20 – 15,000 Hz (±1.2 dB, FM) [conflicting: 20Hz to 20kHz] |
| Total Harmonic Distortion | 0.08% [conflicting: 0.8%] |
| Tuning Range | FM, MW |
| Decoder Circuits | SQ, RM |
Key Features
40W/ch Stereo Power with Quadraphonic Downgrade
At its core, the KR-6340 delivers 40 watts per channel into 8 ohms in stereo—a respectable figure for medium-sized rooms in the early '70s. But the real story is the drop to 15 watts per channel when operating in quadraphonic mode. That steep reduction reflects the limitations of shared power supplies and thermal management in early multi-channel designs. It’s a trade-off: spatial immersion at the cost of headroom.
Built-in SQ and RM Decoder Circuits
Unlike most receivers of its class, the KR-6340 doesn’t require an external decoder to play quadraphonic records. The inclusion of both SQ (CBS’s matrix system) and RM (a competing format) decoding meant it could handle multiple encoding standards—a rare flexibility.
Collectibility & Value
The Kenwood KR-6340 trades today between $250 and $325, depending on condition and functionality. Units with working relays and clean audio channels command the higher end, while those with intermittent right-channel dropouts or relay issues sit at the lower margin. The "fly spec paint" on the top panel is a textured coating prone to chipping and discoloration over time. More serious are reports of transistor failures and power relay issues, with some units clicking audibly before cutting out audio entirely. Given the complexity of the quadraphonic circuitry, full restoration often requires a complete recap and relay servicing. As one Reddit user noted, “Unless you decide to recap the whole unit, price will likely not go over $350.”
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Related Models
- Kenwood KA 990EX (1980-1981)
- Kenwood KA 400 (1970-1972)
- Kenwood KR 7020 (1977-1979)
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- Kenwood kx-630 (1980-1982)
- Akai AM-2850 (1975)
- Akai AP-206 (1975)
- Nakamichi BX-1 (1985)
- Acoustic Research research-ar-17 (1978)
- Acoustic Research AR-19 (1994)