DIATONE DA-U550

Commentary

A pre-main amplifier developed according to the orthodox way, avoiding coloring in all aspects of performance, function and design.

A single-stage, pure complimentary service OCL circuit is used in the circuit structure to minimize changes in sound quality by simplifying the signal path as much as possible.
All parts have extra space, especially the power transistor has been upgraded to Pc40W, and the radiator is one size larger than the conventional one.

Low-impedance speaker drives are also designed to ensure that the speakers are driven in the best possible condition.

It is equipped with separate terminals for preamp output and power amplifier input, and can be used separately with one slide switch.

A high-voltage low-noise silicon transistor is used for the equalizer circuit.

Two MIC input terminals and REC terminals are installed.

BAX-type deformation is used for tone control. Variable type is 11-position click-stop type.
It is also equipped with a loudness control and a high-cut filter.

There was a wood case as an option sold separately.

Model Rating

Type	Pre-main amplifier
Power Amplifier Unit
Output	Both channel operation : Single channel operation : Music : EIAJ: 26W + 26W (4 Ω) 20W + 20W (8 Ω) 32W/32W (4 Ω) 24W/24W (8 Ω) 62W (4 Ω) 50W (8 Ω) 60W (4 Ω)
Harmonic distortion factor	0.8% (at rated output) 0.06% at 1W output
Cross modulation distortion factor	0.18% at 1W output
Power bandwidth	10 Hz to 50 kHz
Frequency characteristic	10 Hz to 50 kHz -0.5 dB
Residual noise	0.3mV
Input Sensitivity / Impedance	1V/50k Ω
Preamplifier Section
Input Sensitivity / Impedance	Phono : 2.5mV/50k Ω Mic : 2mV/50k Ω Aux, Tuner, Playback : 150mV/50k Ω
Output level	Rec out:150mV Pre out:1V
Frequency characteristic	Phono : RIAA ± 0.5 dB Aux : 20 Hz to 30 kHz ± 0.5 dB
Tone control	Bass : ± 10 dB (100 Hz) Treble : ± 10 dB (10 kHz)
High-cut filter	-6dB/oct(8kHz)
Equalizer allowable input	130mV(1kHz)
Equalizer input conversion noise	-118dB
<General>
Power consumption	50W
External dimensions	Width 380x Height 133x Depth 301 mm
Weight	7.7kg
Separately Sold : Wood Case CA-550 (¥ 6,500) for 550 Series
External dimensions	Width 445x Height 165x Depth 297 mm