Audio Database

Image of DA-55U
Commentary

The first amplifier announced by Diatone.

A quasi complimentary service SEPPP OTL parallel push-pull circuit is used.

The preamplifier section uses a 3-stage direct-coupled amplifier with a large amount of negative feedback to minimize degradation of various characteristics.
The equalizer amplifier section is also an NF type with a 3-stage direct-coupled amplifier, and the quality is controlled within 0.5 db of the deviation from the RIAA curve.

The tone control section employs a step-type tone control using a rotary switch. It has a characteristic and straightforward change curve depending on the method of switching elements.

An electronic switch type protection circuit using a silicon thyristor is adopted to protect the power transistor.

It is equipped with a muting circuit that cuts off the speakers for 3 to 7 seconds after power is turned on to prevent damage to the speakers due to clipping noise when power is turned on.

A 4-channel volume is used for volume adjustment, and the S/N ratio for small output is improved by adjusting both the input and output sides of the preamplifier section.

A highly reliable epoxy-based printed circuit board is used.

The preamplifier section and main amplifier section can be used independently.

In the DA-55U, terminals are provided on the horizontal surface and part of the upper lid of the cabinet is made into a slide mechanism to improve operability.

Uses the same Eurasian cheek oak finish as the diatone speaker.

Model Rating
Type Stereo pre-main amplifier
Output / Distortion Continuous output : 100W + 100W (4 Ω) / 0.3% or less
Music Power : 130W + 130W (4 Ω) / 0.5% or Less
Output impedance 4 ~ 16 Ω
Input Sensitivity / Impedance Phono1, 2 : 3mV/30k Ω
Tape, Tuner : 100mV/250k Ω
Aux : 100mV/250k Ω (Semi-fixed)
Output level Rec out:100mV
Tape moni:100mV
Tone control Low frequency : ± 6 dB (100 Hz in 2 dB steps)
High frequency : ± 6 dB (10 kHz, 2 dB step)
Filter Low Frequency : 50 Hz -12dB/oct-cut
High Frequency : 9 kHz -12dB/oct-cut
Frequency characteristic Preamplifier section : 20 Hz to 50000 Hz ± 1 dB
Main Amplifier : 15 Hz ~ 70000 Hz ± 1 dB
S/N Aux : 75 dB or more
Damping factor 30 ~ 40 (8 Ω)
Transistor used Silicon transistor x44
Diode x17
Two thyristors
Pwer AC100V
Power consumption 260VA
External dimensions Width 460x Height 170x Depth 420 mm
Weight 17kg