Denon TU-335 (circa 1976–1977)
The Denon TU-335 is a Japanese-market FM stereo tuner from the mid-1970s. It was priced at ¥54,800 (around 1976-1977, depending on the source). An optional wood cabinet, the ACA-5, cost another ¥5,000. Little historical documentation survives beyond the specifications. There are no formal reviews, no production-run details and no owner forums to speak of. The period spec sheets give a remarkably complete technical picture, though.
The TU-335 was positioned as a serious analog tuner, and it shares technology with Denon's TU-500 and TU-355. The front end is a boardless package with a high-precision frequency-linear 5-row varicon and a low-noise dual-gate MOS-FET in a triple-tune circuit. The local oscillator is a clap-type design that resists voltage and temperature drift. Denon claimed the stability was good enough that no AFC circuit was needed. The IF stage runs four 2-element ceramic filters into a ratio detection circuit. The MPX section uses a PLL IC followed by an independent LC 3-stage low-pass filter to kill pilot and subcarrier leakage.
The specs back up the engineering. Practical sensitivity is 1.7 µV (IHF) and effective selectivity is 85 dB. Signal-to-noise is 80 dB mono and 75 dB stereo, and mono THD is 0.1% at 1 kHz. Separation is rated at 50 dB at 1 kHz, holding 40 dB from 50 Hz to 10 kHz. The tuner covers the Japanese FM band of 76-90 MHz. Anyone outside Japan should know the dial scale reflects that range, not the wider 87.5-108 MHz used elsewhere. One owner in Thailand reported receiving 87.5-108 MHz stations well despite this, but that's an anecdote, not a spec.
The front panel is clean for the era. It has toggle switches rather than slides, a signal level scale and a tuning meter. On the back is a multipath detection terminal for optimizing antenna placement. There's also a built-in 440 Hz test tone oscillator, handy for calibrating tape deck levels or checking channel balance. Outputs are both fixed (1 Vrms at 100% modulation) and variable (0-1.5 Vrms). Output impedance is low, so two devices can be driven simultaneously without degradation. Power consumption is 17W, and the unit weighs 6.5 kg.
One Japanese owner mentions using the TU-335 paired with a PMA-235 amplifier and requesting replacement of ICs and transistors showing migration. That's the only maintenance data point on record. The tuner appears on the used market, with one listing at $572 in late 2025, but there's no consistent pricing trend to report.
Known Specifications
- Type: FM stereo tuner, 76–90 MHz (Japanese market)
- Practical sensitivity: 1.7 µV (IHF); 3.5 µV (S/N 50 dB, mono)
- Effective selectivity: 85 dB (IHF, two-signal method)
- S/N: 80 dB mono, 75 dB stereo
- THD: 0.1% mono, 0.15% stereo (1 kHz)
- Separation: 50 dB (1 kHz); 40 dB (50 Hz–10 kHz)
- Output: fixed 1 Vrms; variable 0–1.5 Vrms
- Dimensions: 396 × 147 × 281 mm; 6.5 kg
- Price: ¥54,800 (circa 1976–77); ACA-5 wood cabinet ¥5,000
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