Audio Database

The

SANSUI AU-D55F
49,800yen(1981 release)

Description
 
The Integrated Amplifier which adopted the super FF (feed forward) system.

A super FF system is an original system adopted in the AU-F Extra serieses, and is the technology born by combining the feed-forward theory which Dr. H-S and Black invented, and NFB.
NFB mainly acts on the distorted modification in an audio frequency band, and also is carrying out the role which takes out the opposite phase distortion for feed forward. In the audio frequency band, NFB became an entity, feed forward became an entity out of the audio frequency band then, by this, and distortion is canceled. All distortion that this generates in the power stage theoretically is reduced.
This system consists of symmetrical 2 pole output summing networks which made full use of the error collection amplifier and the newest computer technology for amplifying a distorted denial signal.

The super FF system is adopted as the power amplifier part, and it has whole page differential-amplification DC amplifier composition.
The cascode bootstrap interconnection is adopted as the 3rd step for low-noise FET at the first rank.

The dual bridge scheme which strengthens a power source by raising the utilization factor of energy is developed and adopted at the power-source part. to the conventional scheme which was rectifying for a positive and negatives [ of two each ] diode, by the dual bridge scheme, the diode of four each is adopted and the rectification effect is improved 30%.
Moreover, since there is no power transformer middle point grounding and the grounding point is insulated from the chassis through diode, the stray current more than needed does not flow into a chassis, and it does not have an ill effect on a signal grounding point.
Furthermore, a Tip-of-the-Day grounding scheme is adopted as all the groundings, and high-quality sound-ization is attained more by making the circuit for light emitting diode, and a protector circuit into an independent source.

The quality of the disk was thought as important in the equalizer-amplifier part, and the High-precision equalizer is adopted.
This extended the frequency characteristic to 100kHz, and high SN and low distortion are attained.
Moreover, the MC/man month compatible equalizer corresponding to MC and man month is adopted by switching gain.
Furthermore, it is stopping with the Subsonic Filter which the record curved and built in a surge super-low-pass in か student じる, and distortion.

While attaining shortest-ization of a signal path, the equalizer part and the power part are separated completely. Furthermore, flux-free thought was advanced and the predrive stage and the power stage are isolated with the large-sized heat sink.

It has composition which included the tone control circuit in NF circuitry of the power part.

All the inputs have adopted the direct-access input selector which can be chosen by one-touch.

An aluminum Naked began to delete in a main volume, and elegance is adopted.

The loudness and the high filter are carried.

Bus NM
Heat

Rating of a mode
Form Super FF&DC amplifier
<Power amplifier part>
Effective output (10Hz - 20kHz, THD 0.004%) 50W+50W (8ohm)
THD (at the time of 20Hz - 20kHz, and an effective output) 0.004% or less (8ohm)
Cross modulation distortion (60Hz:7kHz=4:1, SMPTE) 0.006% or less (8ohm)
Dumping factor (new IHF, 1kHz) 40 (8ohm)
Frequency characteristic (1W) DC-300kHz+0 -3dB
TIM distortion (the Sawtooth method) Below a limit of measurement
Slew rate ±150v/microsec (8ohm)
Rise time 0.9microsec
<Preamplifier part>
Input sensitivity/impedance (1kHz) Phono1, 2 man-month:2.5mV /, 47kohm
Phono1, 2 MC: 250 microvolts/100 ohms
Tuner, Aux, Tape Play1, 2:200mV / 47kohm
Phono maximum permissible input (1kHz) Phono MM:170mV(THD 0.01%)
Phono MC:12mV(THD 0.1%)
an Output voltage/impedance (1kHz) Tape rec (Pin): 200mV (47kohm)/600ohm
THD (at the time of 1kHz and 6V output) Phono man month: 0.0025% or less
RIAA deflection (man month, Rec out) 20Hz-100kHz+0.2 -0.5 dB
SN ratio (A network, a short circuit) Phono man month: 84dB or more
Phono MC: 65dB or more
Tuner, Aux, Tape play1, 2:105dB or more
Channel separation (1kHz) Phono: 72dB or more
Tuner, Aux, Tape play1, 2:90dB or more
Tone control Bass: ±10dB (50Hz)
Treble: ±10dB (10kHz)
A high filter 10Hz (-3dB, 6 dB/oct)
Loudness 100Hz (+8dB), 10kHz (+5dB)
Audio muting -20dB
<Synthesis>
Power dissipation 130W
Dimensions Width 430x height 112x depth of 334mm
Weight 7.3kg