Audio Database


73,000yen(around the 1978 time)

The Integrated Amplifier which aimed at the characteristic improvement by direct-current-izing high level input or subsequent ones.

In order to improve a low-pass phase distortion and transient distortion, dual FET which the Diatone developed is adopted and direct-current-ized to the power block. Moreover, as ICL-OCL composition, the pre-block excluded the condenser from the signal course after high level input, and has improved the standup and transient of sound.
Moreover, improvement in S/N is aimed at by improving how to use a first rank transistor.

MC head amplifier part is using the transistor different from former based on the idea of regazing at the transistor itself. Furthermore, the circuit composition which decreases a noise also about a circuit is adopted. The characteristic is improved compared with the case where this uses a pressure-up transformer.
Moreover, a MM/MC car type cartridge can connect Phono2 only for MM cartridge Phono1.

The power level indicator by 15 LED located in a line with V character type is carried. Moreover, the power level indicator ON/OFF switch is carried in DA-U 680S.

It has been independent about the power source of a pre-block and a power block, and a high fever and the magnetic influence which are generated from a power block become difficult to attain to a pre-block, and are raising the stability of an element and a circuit.

A tape deck is connectable two lines. Moreover, a tape duplicate mechanism can perform easily the copy to the tape 1 -> tape 2/the tape 2 -> tape 1.

Bass/Treble can switch two steps of turnover frequency of tone control.
Moreover, the tone-defeat switch is carried.

- Carry a muting switch of 20dB, and the Subsonic Filter.

There were two kinds, DA-U680 to which equipped the carrying handle for rack-mounted one and the ON/OFF switch of the power level indicator was abbreviated, and DA-U 680S which carries an indicator ON/OFF switch.


Rating of a mode
Form Integrated Amplifier
<Power amplifier part>
Output 80W+80W (8 ohms, 20Hz - 20kHz)
85W+85W (8 ohms, 1kHz)
THD 0.01% (at the time of 8 ohms and an Output power)
0.005% (at 8 ohms, the time of 1W output 20Hz - 20kHz)
Output bandwidth (IHF 0.1% distortion, 8ohms) 10Hz - 70kHz
Input sensitivity/impedance 1V/50kohm
S/N (A network, input end short-circuit) 120dB
Dumping factor 60 (8 ohms, 20Hz - 20kHz)
<Preamplifier part>
Input sensitivity/impedance Phono1, 2 MM:2.3mV /, and 50kohm, 100pF
Phono2 MC: 0.1mV/ten ohms
Tuner, Aux, Tape1, 2:150mV/50kohm
An Output voltage/impedance Pre out: 1V/600 ohm
Rec out: 150mV/50kohm
THD (Pre out, 1V)
VR -20 dB, 20Hz - 20kHz
Phono1, 2 MM: 0.005%
Phono2 MC:0.01%
Tuner, Aux, Tape1, 2:0.004%
S/N (A network) Phono1 MM: 84dB (input end short-circuit)
Phono2 MC: 77dB (47ohms of input end termination)
Tuner, Aux, Tape1, 2:108dB (input end short-circuit)
Tone control Bass: ±10dB (100Hz, 50Hz)
Treble: ±10dB (10kHz, 20kHz)
Muting -20dB
Subsonic Filter 18Hz, 6 dB/oct
Power source AC100V, 50Hz/60Hz
Dimensions DA-U680: Width 480x height 154x depth of 385mm
DA-U 680S: Width 424x height 154x depth of 374mm
Weight DA-U680:14kg