Yamaha CT-Z1 (c. 1978)

The Yamaha CT-Z1 is a Japan-market FM/AM tuner from around 1978, priced new at ¥24,800. It was the budget model in Yamaha's lineup - one Japanese enthusiast blog called it the "廉価版" to the somewhat higher-grade CT-1010, whose AM section it closely resembles. Beyond that, the historical record is thin. The Archive has found no professional reviews or official marketing materials for this model.

The AM section is the interesting part. A detailed teardown on the Radio Experimenter's Blog (ja9ttt.blogspot.com) calls it an innovative design that breaks from conventional transistor radio practice - "目から鱗のAMチューナ" (an eye-opening AM tuner). The CT-1010 used a separate local oscillator. The CT-Z1 saves one transistor by using a PNP-transistor self-oscillating converter. The RF amplifier is not omitted, and the AM section is built from discrete components in a non-typical layout: antenna tuned circuit → non-tuned collector-side RF amplifier → mixer → separate local oscillator → IFT + ceramic filter → one stage of non-tuned IF amplifier → voltage-doubling rectifier type diode detector. AGC is applied to the first three stages. The design avoids stacking multiple IFT stages, which the blogger suggests was to prevent degrading frequency characteristics. The -3dB points measure 120Hz at the low end and 2,420Hz at the high end, and the frequency response does not change with reception frequency. The same source notes the image ratio is not good ("イメージ比は芳しくありませんでした") and that sensitivity is intentionally not high. One commenter observed the AM section uses an "AM2連FM3連ギア付きのバリコン" (AM 2-gang, FM 3-gang geared variable capacitor), common in inexpensive tuners of the era. Another called the interior "スカスカ" (sparse).

The FM side is more conventional. The front end uses a junction-type FET and a 3-gang variable capacitor. The IF stage uses an IC-based differential amplifier. The MPX section uses NFB (negative feedback), PLL, and IC-based circuits, and the NFB is a Yamaha approach to reducing noise and distortion. The AM section omits the usual bar antenna and uses a combination feed system that forces an FM antenna to serve as the AM antenna. A two-way meter works as a tuning meter on FM and a signal meter on AM. The front panel is sparse, with few switches, the blogger notes. The tuner includes FM muting, an FM stereo indicator, a Rec calibrator, and five station markers.

Listening impressions from the Radio Experimenter's Blog are modestly positive: "実際に聴いてみた感じはなかなか心地よくトランジスタ・ラジオとはひと味違うものを感じます" - quite pleasant, a different flavor from a transistor radio. The AM frequency response, though, is "Hi-Fiソースとは言いにくい" (hard to call hi-fi). The same blogger found his unit's tuning had drifted and the FM-MPX VCO was out of alignment with age. A rough adjustment improved it considerably.

Known specifications: FM practical sensitivity of 1.9 µV/10.8 dBf (IHF, 300Ω), capture ratio of 1.0dB, effective selectivity of 60dB (IHF), S/N of 80dB mono / 73dB stereo, THD of 0.1% mono / 0.2% stereo, and stereo separation of 40dB at 1kHz. AM practical sensitivity is 18 µV with 25dB selectivity. Power consumption is rated at 4W. The unit measures 435 × 139 × 332 mm and weighs 4.7kg. Output is 0.775V fixed.

Collectibility data is anecdotal. One blogger found his unit at a Japanese recycle shop for a single 500-yen coin. A Korean marketplace listing asked 120,000 KRW for a unit described as clean with good FM reception. A Yahoo! Auctions Japan listing closed at ¥16,500 for a unit with some exterior scratches but confirmed working. The CT-Z1 was made in Japan.

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Yamaha CT-Z1 vintage audio equipment - eBay listing photo 1

YAMAHA CT-Z1 FM AM Stereo Tuner Vintage 1978 Model Tested Ja

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Yamaha CT-Z1 (c. 1978)

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