Audio Database


DIATONE DA-F550 35,000yen(1973 release)
38,000yen(around the 1975 time)

It is the FM/AM tuner which attained high sensitivity and quantity selection degree-ization by kneading circuit composition.

The monolithic IC and the peak separation 1MHz discrete transformer which were excellent in the phase linear ceramics filter or the limiter effect are used for a FM IF stage. Thereby, many characteristics, such as the degree of effective selection and the distortion characteristic, are improved.

The FM-MPX noise filter is carried and noise can be removed at the time of FM stereo reception.

The double balance differential circuit which used iC is adopted as FM multi-circuit. This has improved the distorted characteristic compared with the circuit of the conventional diode use.

The mould type thing excellent in the environmental capability of temperature and humidity is adopted as a FM-MPX transformer. The separation easily influenced by - temperature and humidity especially by this is improved.

The small muting circuit of a pop noise is adopted. In this circuit, it is not concerned with ON/OFF of muting operation, but since the bias conditions of a transistor become always fixed, the pop noise is stopped small.
The muting level is 20dB.

The career leak filter is carried. In this circuit, the filter by LC is aligned with 19kHz and 38kHz, and career leak is suppressed.

The tuning circuit has employed as IF stage of AM circuit triple Cheung IFT who became three steps, and sound quality and the degree of selection are raised.

In the back panel, the FM DET OUT terminal is carried so that FM detection output can be pulled out, and correspondence to FM4ch broadcast is aimed at on it.

They are DA-U550 and a design of the pair. Moreover, DA-U550 and a common wood case were sold as the option option.


Rating of a mode
Form FM/AM tuner
<FM tuner part>
Antenna A 300-ohm balance, 75-ohm disequilibrium
Practical speed 1.8 microvolts (IHF)
The degree of effective selection 60dB(IHF)
Capture ratio 1.5dB(IHF)
Image disturbance ratio 60dB
IF disturbance ratio 70dB
1 / 2 IF disturbance ratio 60dB
S/N 70dB
AM oppression ratio 50dB
THD (100% abnormal conditions) mono:0.2%
Separation 40dB(1kHz)
Muting ON/OFF is possible.
MPX noise filter ON/OFF is possible.
<AM tuner part>
Antenna Ferrite bar antenna
Practical speed (S/N 30dB, bar antenna) 55dB
The degree of selection 35dB (±10kHz)
Image disturbance ratio 40dB
S/N 50dB
Output Fixed:150mV
Variable: 0-700mV
Power consumption 15W
Dimensions Width 380x height 133x depth of 301mm
Weight 6.8kg
Option Wood case CA-550 (5,500yen)