Luxman T-310 (1973–1975, with some sources citing 1974–1975 or 1976)
An export-only tuner that put Dolby B noise reduction on FM.
Overview
The T-310 was sold only outside Japan, likely because there was limited domestic interest in Dolby-encoded broadcasts. It was aimed at European and North American audiophiles who wanted more than tuning accuracy. It has a 4-gang FM front end, dual-gate MOS-FETs in the RF stage, and a phase-locked-loop (PLL) multiplex decoder that minimized distortion even under weak signal conditions. The tuner got the same engineering rigor as the amplifier or preamp.
The Dolby B circuit was not an afterthought. It was fully integrated, with calibration (CAL) detectors and meter adjustments so the user could align the decoder. It could reduce noise by up to 10 dB on compatible broadcasts. The same circuit could be looped through a tape deck and used as a cassette noise-reduction unit, which counted for something when tape hiss was the enemy. Mono signal-to-noise ratio is 80 dB, and stereo separation is 40 dB at 1 kHz. HiFi-Stereo (April 1977, p.125) noted that distortion measurements for comparable Luxman tuners were "the lowest we have ever read for any tuner at any price," though the review didn’t name the T-310 specifically. The engineering lineage suggests it would have performed no worse.
Key Features
4-Gang FM Tuning with Dual-Gate MOS-FET Front End
The T-310 uses a 4-gang variable capacitor for FM front-end tuning, which ensures precise tracking across the 87.5-108 MHz band. Paired with dual-gate MOS-FETs in the RF stage, it delivers an IHF sensitivity of 1.8 µV (10.8 dBf) and a muting threshold of 3.0 µV (17 dBf). That makes it good at pulling in weak signals without amplifying noise. This combination was a hallmark of high-end tuner design in the mid-70s. Luxman gave it low distortion, high selectivity and stable operation.
Five-Pole Phase Linear and Linear Delay Filters
Between three ICs and the IF amplifier sit the five-pole Phase Linear and Linear Delay filters, which shape the intermediate frequency response. They are behind the T-310’s 70 dB alternate channel selectivity and 90 dB IF rejection, so it can isolate stations in a crowded band. By minimizing crosstalk and phase anomalies, they also contribute to the 40 dB stereo separation at 1 kHz. That performance rivals or exceeds many tuners twice its age.
Hermetically Sealed Coils in MPX Decoder
Temperature drift can wreck stereo decoding accuracy, especially in the multiplex (MPX) stage where timing is everything. To deal with that, the T-310 uses hermetically sealed coils in the MPX section for consistent performance across operating temperatures. FETs control the audio gates, giving fast, low-distortion switching. That matters most when decoding Dolby B-encoded broadcasts, where timing errors could compromise noise reduction.
Three-Stage AM IF with Switchable Filters
The AM section is no afterthought. It uses a 3-gang design with three IF stages and 18 dB/octave switchable filters, backed by voltage regulators for clean power. Adjacent-channel rejection is strong, with an 85 dB IF rejection spec and 80 dB image rejection.
Phase-Locked-Loop Multiplex Decoder
Instead of a traditional Foster-Seeley discriminator, the T-310 uses a phase-locked-loop (PLL) multiplex decoder. This gives better stereo separation and lower distortion, especially under weak signal conditions. It is one of the reasons the tuner holds a THD of just 0.15% in mono and 0.3% in stereo, despite the added complexity of the Dolby B circuit. The PLL design also improves capture ratio, rated at 1.0 dB, meaning the stronger signal quickly dominates during multipath interference.
Dolby B Noise Reduction with Calibration
The defining feature is a full Dolby B noise reduction system for FM broadcasts. The T-310 includes calibration detectors and meter adjustments, so the user can fine-tune the decoder. It was built in with the same care as the rest of the circuitry and can reduce noise by up to 10 dB on compatible broadcasts. Few stations ever adopted Dolby FM.
Tape Loop, 4CH Output, and Dual Multipath Outputs
The T-310 also does routing. It has a tape loop for recording, a 4CH output (likely intended for quadraphonic systems, though not decoded internally), and two multipath outputs. Those jacks let the user monitor multipath distortion in real time, which helps with antenna placement. FM frequency response is rated at 20 Hz to 15 kHz (+0.2 / -1.8 dB), with a subcarrier product ratio of 60 dB for clean stereo demodulation.
Historical Context
The T-310 was the last in a lineage that included the WL500, WL550, and T-550, models released between 1970 and 1973. It was positioned as a complement to Luxman’s L-308 or L-309 preamps, for system builders who wanted more from their tuner than basic reception. It never appeared in Japanese catalogs, likely due to limited domestic demand for Dolby FM. The T-300, its closest sibling, was functionally identical except for the absence of the Dolby FM circuit and related switches. That makes the T-310 the only model in the series with the feature. It was originally priced at 1,798 Deutsche Mark, and was aimed at audiophiles in Europe and North America.
Collectibility & Value
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