Audio Database

Image of DA-U680S
Commentary

This is a pre-main amplifier whose characteristics are improved by DC conversion after the high-level input.

In order to improve phase distortion and transient distortion in the low range, dual FET developed by Diatone is adopted in the power block for DC. In addition, the pre-block has ICL-OCL configuration to eliminate capacitors from the signal path after high-level input and improve the rise and transient characteristics of sound.
We have also improved the S/N ratio by reviewing the usage of the first stage transistor.

The MC head amplifier uses a different type of transistor based on the idea of looking at the transistor itself. In addition, a circuit configuration that reduces noise is adopted for the circuit, which improves characteristics compared with the case of using a step-up transformer.
Phono1 can be used exclusively for MM cartridges, and Phono2 can be used for both MM and MC types of cartridges.

The DA-U680S is equipped with a power level indicator ON/OFF switch with 15 LEDs arranged in a V-shape.

Since the power supply for the pre-block and power block is independent, it is difficult for the high temperature and magnetic influence generated from the power block to reach the pre-block, and stability of elements and circuits is improved.

Two tape decks can be connected and the tape duplication mechanism facilitates copying from Tape 1 to Tape 2 or Tape 2 to Tape 1.

The turnover frequency of the tone control can be switched between two levels for both Bass and Treble.
It also has a tone defeat switch.

Equipped with a -20dB muting switch and subsonic filter.

There were two types : the DA-U680 equipped with a rack-mount carrying handle and omitting the power level indicator ON/OFF switch, and the DA-U680S equipped with an indicator ON/OFF switch.

Model Rating
Type Pre-main amplifier
Power Amplifier Unit
Output 80W + 80W (8 Ω, 20 Hz to 20 kHz)
85W + 85W (8 ohm, 1 khz)
Harmonic distortion factor 0.01% (8 Ω at Rated Output)
0.005% (8 Ω, at 1W output, 20 Hz to 20 kHz)
Output Bandwidth (IHF 0.1% distortion, 8 ω) 10 Hz to 70 kHz
Input Sensitivity / Impedance 1V/50k Ω
S/N (A network, input terminal short) 120dB
Damping factor 60 (8 Ω, 20 Hz to 20 kHz)
Preamplifier Section
Input Sensitivity / Impedance Phono1, 2 mm : 2.3mV/50k Ω, 100 pF
Phono2 MC : 0.1mV/10 Ω
Tuner, Aux, Tape1, 2 : 150mV/50k Ω
Output Level / Impedance Pre out : 1V/600 Ω
Rec out : 150mV/50k Ω
Harmonic distortion factor (Pre out, 1 v
VR -20dB, 20 Hz to 20 kHz)
Phono1, 2 mm : 0.005%
Phono2 MC:0.01%
Tuner, Aux, Tape1, 2 : 0.004%
S/N (A Network) Phono1 MM : 84 dB (input terminal short)
Phono2 mc : 77 dB (47 Ω termination at input terminal)
Tuner, Aux, Tape1, 2 : 108 dB (input terminal short)
Tone control Bass : ± 10 dB (100 Hz, 50 Hz)
Treble : ± 10 dB (10 kHz, 20 kHz)
Muting -20dB
Subsonic filter 18 Hz, 6dB/oct.
<General>
Pwer 100 VAC, 50Hz/60Hz
External dimensions DA-U680 : 480 mm wide x 154 mm high x 385 mm deep
DA-U680S : Width 424x Height 154x Depth 374 mm
Weight DA-U680:14kg
DA-U680S:14kg