Audio Database

Image of F-120D
Commentary

An FM/AM stereo tuner equipped with a digital direct decoder TypeII that digitally demodulates the FM signal itself at once and does not generate distortion or noise in principle.

The digital direct decoder uses a pulse converter to convert the signal output from the IF section into a digital signal of 1.26 MHz. The digital direct decoder then sends a multiplier for stereo demodulation at once and multiplies it by a 38 kHz subcarrier (sine wave). This is a simple method.
Since FM signals are detected and demodulated as digital signals from the pulse converter to stereo demodulation, there is no need for an anti Birdie filter, which has been the cause of signal loss and distortion, and excellent characteristics are obtained by making maximum use of the characteristics of digital signals that do not generate distortion or noise.
This D. D. recorder was selected as a monitor by the Swedish National Broadcasting Station due to its excellent characteristics.
The F-120D is equipped with a digital direct decoder TypeII, which is a further consideration of the waveform of the digital signal itself.
A C-MOS IC is used in the pulse converter that converts FM signals into digital signals, improving the accuracy of the digital waveform itself, and realizing a further constant distortion rate and high SN ratio.

The front end uses a linear front end to improve RF intermodulation characteristics. High reception performance is achieved by a high-performance twin varicap and a unique balance hold capacitor system.
In addition to high stability achieved by the installation of a balanced mixer, various types of interference rejection capability are also greatly enhanced.
In addition, in order to maintain a linear relationship between the frequencies of the antenna tuning stage and the antenna tuning stage and the local oscillator and to suppress the occurrence of distortion.

In the IF section, the first stage amplifier uses a Darlington differential IC with a wide dynamic range, high gain, low noise, and high gain and high signal-to-noise ratio.
In addition, we have adopted a highly reliable crystal oscillator circuit for the oscillator circuit of the frequency conversion section (1.26 MHz), which is an important section for sending signals to the D. D. Decoder TypeII. In addition to improving stability and SN ratio, we have also reduced drift due to environmental changes such as temperature and humidity.
In addition to these features, two stage switching of the IF band is also installed so that high quality can always be obtained according to the difference of reception conditions.

In order to make the best use of the high sound quality of D. D. Decoder TypeII, the overall including parts is polished.
After the pulse converter, there is no LC filter until the output part, and distortion and sound quality degradation caused by the LC filter are completely eliminated.
In addition, we have further improved the semiconductor capacitor for the tuner used in the F-120. By coating the exterior with an epoxy coating, vibration is suppressed and distortion factor is further reduced.
In addition, the power supply section has been thoroughly reviewed by installing a large power transformer similar to that of an amplifier, using a oxygen-free copper wire for power supply wiring, and using a power cord with polarity indication.
In the low-pass filter section of the final stage, an active filter is used in place of a passive filter using a coil to obtain higher sound quality.

The PLL circuit of the quartz synthesizer employs a unique pulse swallow method, and the reference frequency is set at 25 kHz. By leaving the reference frequency outside the audible band, the cause of noise caused by the reference frequency remaining in the signal line is eliminated.

The digital control signal is transmitted using a full static control method.
Since only one data can be put on one signal line, deterioration of the SN ratio is suppressed.

A high sensitivity of 150 μ V/m has been achieved by adopting a large loop antenna for AM and using an FET buffer for the tuning coil.

By adopting a wide range ceramic filter, etc., a substantial AM part is realized.

Equipped with a Random / E Preset that allows you to select 8 FM/AM stations each, 8 FM + AM random stations and 8 FM + AM random stations with the switch on the rear panel.

Equipped with a 3-step signal indicator that can check the reception status appropriately.

The side wood in the picture is sold separately.

In addition to the black model, there was also a silver model.

Model Rating
Type D. D. Decoder TypeII FM/AM Tuner
FM Tuner Section
S/N ratio 50 dB sensitivity Mono : 1.77 V, new IHF 16.2 dBf
Stereo : 21.0 μ V, new IHF 37.7 dBf
Practical sensitivity (Narrow, 75 Ω) Mono : 0.95 μ V, new IHF 10.8 dBf
SN ratio (at 85 dBf input) mono:98dB
stereo:90dB
Harmonic distortion factor (Wide) Mono : 0.008% (100 Hz), 0.006% (1 kHz), 0.01% (10 kHz)
Stereo : 0.01% (100 Hz), 0.009% (1 kHz), 0.05% (10 kHz)
Capture ratio Wide:0.8dB
Narrow:2.5dB
Effective selectivity Wide:30dB(400kHz)
Narrow:60dB(300kHz)
Stereo separation Wide : 70 dB (1 kHz), 54 dB (20 Hz to 10 kHz)
Narrow : 40 dB (1 kHz), 40 dB (20 Hz to 10 kHz)
Frequency characteristic 20 Hz to 15 kHz + 0.2 -0.8 dB
Image interference ratio 70dB
IF interference ratio 100dB
Spurious interference ratio 80dB
AM suppression ratio 70dB
Subcarrier suppression ratio 65dB
Muting action level 5 μ V (25.2 dBf)
Antenna input impedance 75 Ω Unbalanced Type
<AM Tuner Section>
Practical sensitivity 150 μ V/m (built-in antenna)
Selectivity 25 dB (± 9 kHz)
Signal-to-noise ratio 55dB
<General>
Output Level / Impedance FM (100% modulation) : 650mV/900 Ω
AM (30% modulation) : 150mV/900 Ω
Power supply voltage 100 VAC, 50Hz/60Hz
Power consumption (Electrical Appliance and Material Control Law) 14W
External dimensions Width 420x Height 61x Depth 312 mm
Weight 4.5kg
Sold Separately Sidewood JA-F120 (¥ 2,500)