Audio Database

TU-D707
Commentary

An FM/AM tuner with an emphasis on sound quality equipped with a digital quartz lock system developed with high precision crystal.

Equipped with SANSUI's original digital quartz lock system (PAT. PEND) which realizes high-precision reception.
The receiving frequency is detected by the frequency counter controlled by the crystal oscillator. If the frequency deviates, the D/A converter generates a voltage proportional to the error and provides a feedback voltage through a low-pass filter to stabilize the local oscillation frequency.
In addition, the center of the IF is equipped with an offset function that enables precise adjustment, and locking operation at the minimum distortion rate is possible.

The front end is composed of three low-noise dual-gate MOS FETs and a wide-gap precision five link varicon, improving sensitivity and interference rejection capability.
The IF section employs a 10-stage IF circuit utilizing a Darlington differential IC, and has sufficient margin in amplification and limiter characteristics.

The county delay characteristic is flattened by adopting an equivalent quantity variable county delay equalizer.
In addition, a Darlington differential IC is adopted to flatten the dynamic group delay characteristics, and high SN ratio and low distortion rate characteristics are realized.

A newly developed triple-base Darlington differential IC is used for the high power ratio detector.

In order to eliminate beats due to interference signals of nearby radio waves, a phase-linear adjustable channel filter equipped with a group delay equalizer is installed after the detector to improve the SN ratio in actual use.

To prevent the pilot signal that divides the FM stereo broadcast transmission into L and R from damaging the music signal, we have adopted a pilot canceler circuit in the MPX decoder that erases pilot carriers before entering the switching circuit.
In addition, the 19 kHz pilot signal that drives the VCO (voltage controlled oscillator) of the PLL is extracted with a band-pass filter with sharp characteristics, enabling stereo playback with a good sense of localization.

It uses a newly developed automatic noise filter to ensure clear sound.

AM band selection switch is adopted, and WIDE and NARROW are separately installed in the IF filter of AM section.
A 3-pole wide-band IFT is adopted for the IF band filter to ensure the band required for Hi-Fi reception.

A double-tuned circuit is adopted for the antenna tuning circuit of the AM section.
As a sharp filter with an expanded bandwidth, sound quality and interference rejection capability are improved.

Equipped with FM muting switch, FM IF wide/narrow2-stage switching, FM300 Ω / 75 Ω coaxial antenna terminal, AM IF wide/narrow band switching, output level adjustable terminal, fixed output terminal, multi-path observation terminal, calibration oscillator, etc.

Model Rating
Type FM/AM Tuner
<FM Part>
Practical sensitivity (IHF) mono:9.0dBf
stereo:15dBf
50 dB quieting sensitivity (IHF) mono:12.5dBf
stereo:34.0dBf
Signal-to-noise ratio Mono : 83 dB or higher
Stereo : 80 dB or more
Distortion Factor (IHF, 65 dBf, stereo) 100 Hz : 0.09% or less
1 kHz : 0.06% or less
6 kHz : 0.15% or less
Encapsulation Ratio (IHF) 0.9 dB or less (wide)
Selectivity (IHF) Narrow : 80 dB or more (400 kHz)
Wide : 50 dB or more (400 kHz)
Spurious response ratio (IHF) 110 dB or More (83 MHz)
Image Response Ratio (IHF) 110 dB or More (83 MHz)
IF Response Ratio (IHF, Balanced) 110 dB or More (83 MHz)
RF Intermodulation (IHF) 75dB(83MHz)
AM suppression ratio (IHF) 60 dB or more
Stereo Separation (1 kHz) 50 dB or more
<AM Department (narrow)>
Practical sensitivity (IHF, bar antenna) 50dB/m (300 μ V/m)
Selectivity (± 9 kHz) 33 dB or more
Signal-to-noise ratio 50 dB or more
Distortion factor (30% modulation, 80dB/m) Not more than 0.35%
Image Response Ratio (IHF) 70 dB or More (1000 kHz)
IF response ratio 70 dB or More (1000 kHz)
<General>
Variable output voltage / impedance 0 ~ 1V/2.5k Ω
Rated power consumption (Electrical Appliance and Material Control Law) 22W
External dimensions Width 430x Height 168x Depth 402 mm
With Rack-Mount Adapter : Width 482x Depth 419 mm
Weight 9.6kg
With Rack-mount Adapter : 10.1 kg
Sold Separately Rack-Mount Adapter BX-7 (1 pair, ¥ 3,000)