Audio Database

Image of Integra A-817XD
Commentary

Pre-main amplifier with supercharger power supply and optical drive amplifier.

Unlike conventional power supplies, we have developed a supercharger circuit that can continuously charge the Chemi-Con is mounted on both the + side and - side.
The supercharger does not have ripple fluctuations of 100Hz/120Hz. Moreover, since the charging current is controlled while monitoring the power supply voltage, there is almost no fluctuation in the power supply voltage. The stability is comparable to that of a large-capacity power supply with a transparent capacitance of approximately 300 times.

A photovoltaic element is mounted in the differential amplifier section at the first stage of the power amplifier section, and a newly developed optical drive amplifier that amplifies by light energy is adopted.
This dramatically stabilizes the reference voltage, which previously fluctuated unstably due to the influence of the speaker drive current or ripple, and enables highly stable amplification.

The bottom chassis is made of 2 mm thick steel plate, twice as thick as conventional ones, and the chassis thickness other than the bottom is increased by 20%, making the whole chassis more rigid.
In addition, a double-structure insulator made of copper plate and cork material is used in the leg part to suppress vibration propagation from the floor surface. The cork material used in this insulator changes the area between the power supply side with transformer load and the circuit side with less load in consideration of load distribution.

The power supply section and circuit section are separated by a 2-box chassis structure, and the circuit section is further separated into a voltage amplification stage for handling very small signals and a power stage for handling large outputs. Therefore, a U-shaped heat sink is, and electromagnetic coupling is cut off by a closed loop with this heat sink as a wall.
In this heat sink, heat radiation fins are arranged independently on the right and left sides, and the length of the fins is unequal between 14 mm and 18 mm to disperse resonance.

In the power supply section, two 10-mm-thick stabilizers are mounted on the core of the heavy power transformer in a sandwich structure from both sides to control the power transformer, which is the source of vibration inside the amplifier.
In addition, a special rubber insulator is used in the lower part of the transformer to reduce vibration propagation to the chassis.
The power supply Chemi-Con employs a twin-roll Chemi-Con with two pairs of positive and negative foils wound around it, and the internal resistance (ESR) is reduced to approximately one third of the impedance of conventional Chemi-Con.
The rectifier diode is a high-speed diode whose response time (reverse recovery time) is less than 1/10 of that of conventional products.

A gold-plated pin jack is used for the CD input, and a large vise type is used for the speaker terminal.
Also, very thick AC cord with polarity display, H-shaped copper bus plate for power supply part, 8 square copper bus plate for power amplifier part, high-fTPc200W 2-point stop type power transistor is adopted.

Equipped with a source direct switch that sends all sources directly to the power amplifier via a dedicated volume.
When this switch is set to the TONE position, it can be adjusted by direct tone. When it is set to the Processor & Tone position, it can be used to control the connected external Gray.

Equipped with video input / output terminal.

Model Rating
Type Supercharger mounted optical drive amplifier
Power Amplifier Unit
Rated Output (20 Hz ~ 20 kHz) 105W + 105W (CD → SP-OUT, 8 Ω, Both channel drive)
120W + 120W (CD → SP-OUT, 6 Ω, Both channel drive)
Dynamic Power 190W + 190W (6 Ω)
235W + 235W (4 Ω)
295W + 295W (2 Ω)
Total harmonic distortion rate (20 Hz to 20 kHz) 0.004% (CD → SP-OUT, at rated output, 8 Ω)
Intermodulation distortion factor (20 Hz to 20 kHz) 0.004% (CD → SP-OUT at Rated Output)
Powerbandwidth 5 Hz ~ 100 kHz (IHF-3dB THD 0.2% 8 Ω)
Damping factor 100 (1 kHz 8 Ω)
Frequency Response (CD → SP Out) 2 Hz ~ 100 kHz + 0 -3dB
Input Sensitivity / Impedance Phono MM : 2.5mV/47k Ω
Phono MC : 160 μ V/220 Ω
CD, Tuner, Tape-PB, DAT-PB, Line : 150mV/47k Ω
Processor-In : 150mV/47k Ω
Video, VCR-PB : 150mV/47k Ω
Rated output voltage / impedance Tape-Rec, DAT-Rec, VCR-Rec : 150mV/560 Ω
Processor-Out : 150mV/560 Ω
Video input / output VCR-PB, DAT-Rec, Video, BS, Video Moni out : 1Vp-p/75 Ω
Equalizer Amplifier Section
Frequency response (RIAA deviation, Phono → Rec) 20 Hz to 20 kHz ± 0.2 dB
Phono maximum allowable input
(1kHz/10kHz, 0.005%)
MM:210mV/1000mV
MC:13mV/65mV
Total harmonic distortion factor
(20 Hz to 20 kHz, Rec3V output)
MM:0.003%
MC:0.015%
Overall Characteristics
SN ratio (IHF-A filter input short) Phono MM : 94 dB (5 mV input)
Phono MC : 75 dB (0.5 mV input)
CD, Tuner, Tape-PB, DAT-PB, Line : 107 db
Tone Control Maximum Change
(Volume -16dB)
Treble : 20 kHz, ± 8 dB
Bass : 20 Hz, ± 10 dB
Contrabass : 20 Hz, + 10 dB
Muting -20dB
Power supply voltage 100 VAC, 50Hz/60Hz
Power consumption 210W
AC outlet Switched : 2 systems, total 100W
Unswitched : 1 line, 100W
External dimensions Width 435x Height 169x Depth 392 mm
Weight 16kg