ONKYO Integra A-820GTR

Commentary

A pre-main amplifier equipped with a super servo integral system and a delta turbo power supply.

In addition to theoretically supporting the cause of the power of large power sources, we have adopted a new circuit called "Delta Turbo Power Source," which reduces the factor that hinders the reproduction of energy sensation to about 1/10 of the conventional one.
The power supply circuit of an amplifier generally consists of a transformer, a rectifier and a Chemicon for smoothing. In operation, the DC current charged in the Chemicon acts like a battery to supply power to the speakers.
However, when the Chemi-Con actually operates, the impedance of the Chemi-Con varies depending on the frequency of the audio signal, so it sometimes does not work as a battery according to theory. In other words, when the frequency of the audio signal is high, the impedance becomes sufficiently low, so there is no problem. However, when the frequency of the audio signal is low, the effect of the transformer connected in parallel with the Chemi-Con appears.
In other words, the distortion generated in the AC power supply on the transformer side directly affects the power circuit, and this hinders the reproduction of the low-frequency energy sense.
When the capacitance of the Chemi-Con is small, the charge current fluctuates in synchronization with the audio signal, especially for low-frequency audio output when it is charged with the current, and intermodulation distortion occurs. Furthermore, for low-frequency audio signals, this distortion source is connected to the Chemi-Con and Para, so the effect will appear in the power amplifier circuit.
The Delta Servo Power Supply was developed as a result of clarifying the mechanism of strain generation in the power supply as described above. The cross modulation strain generated in the power supply can be reduced to approximately 1/10 (-20dB) while the Chemi-Con and Transformer remain the same size as before.
In other words, the effect equivalent to 10 times the size of the power supply circuit is obtained.

Super Servo Integral System is adopted in the amplifier section.
Due to external factors such as the sound pressure of other channels in the sound field, the electromotive force induced in the speaker flows into the output stage of the amplifier with a time lag equal to the propagation time of the sound wave. This causes intermodulation distortion due to non-linear characteristics of the output stage.
By completely eliminating this time-difference intermodulation distortion, we have removed the veil of the playback sound field that had been squeezed between the left and right speakers.
In addition, servo feedback is applied from both the + and - terminals on the output side of the amplifier to its input side to cut out harmful noise components, especially at very low frequencies, and to suppress noise components, which are the basis of distortion generated in the impedance accumulated by a very small amount of various resistances in the ground line.

It uses a straight high-gain equalizer for MC and a 2-amp configuration with only the power section. Both of them have improved naked characteristics and a low feedback system of less than 1/10 of the conventional system, which ensures improved hearing quality and stable operation.
As for the tone circuit, in place of the method of always keeping extra gain in preparation for tone boost, a direct tone composed only of passive elements which have little effect on tone quality is adopted, so that you can enjoy better tone quality without tone defeat.

It is equipped with a softness switch that can change the resolution and control the character of sound according to the quality of the input program source.
For example, it makes sound easier to hear when combined with low-grade sources such as AM broadcasting, or extremely unique cartridges or speakers.

In order to prevent the amplifier circuit board itself from being shaken by the air vibration caused by the reproduced sound, generating microphonic noise and making the reproduced sound muddy, super stabilizer is used as a special structural reinforcement material.

It uses Onkyo's original linear switching system, and has low distortion rate comparable to class A and high efficiency of class B.

Non-magnetic material is used to suppress generation of harmful high-order harmonics.

Built-in protection circuit.

Pure gold plated input / output terminals are used.

Uses a special noise-improving resistor.

Model Rating

Type	Pre-main amplifier
Rated Output (20 Hz ~ 20 kHz)	120W + 120W (AUX → SP Out, 8 Ω, both channel drive)
Total harmonic distortion rate (20 Hz to 20 kHz)	0.008% / 0.006% (AUX → SP Out, at rated output / at 1/2 output) 0.003% (Phono MM → Rec Out, 3 V) 0.01% (Phono MC → Rec Out, 3 V)
Intermodulation distortion factor (AUX → SP Out)	0.008%
Powerbandwidth	5 Hz to 100 kHz (IHF -3dB, THD 0.2%)
Damping factor	100 (1 kHz, 8 Ω)
Frequency characteristic	Phono → Rec out/RIAA Deviation : 20 Hz to 20 kHz ± 0.2 dB AUX to SP Out : 2 Hz ~ 100 kHz + 0 -3dB
Input Sensitivity / Impedance	Phono MM : 2.5mV/47k Ω, 100k Ω Phono High MC : 2.5mV/100 Ω Phono MC : 150 μ V/100 Ω, 330 Ω Tuner, AUX, Tape Play : 150mV/47k Ω
Phono maximum allowable input (1kHz/10kHz, 0.05%)	Phono MM:300mV/1400mV Phono High MC:300mV/1400mV Phono MC:19mV/90mV
Output Voltage / Impedance	Tape Rec : 150mV/2.2k Ω Pre Out : 1.5V/600 Ω
S/N ratio (IHF short)	Phono MM:88dB Phono MC:70dB Tuner, AUX, Tape Play : 100 dB
Tone Control (Vol-16dB)	Bass : ± 8 dB (70 Hz) Treble : ± 8 dB (20 kHz)
Loudness	+ 4 dB, + 6 dB (100 Hz)
Subsonic filter	15 Hz 20 Hz, 6dB/oct.
Muting	-20dB
Pwer	100 VAC, 50Hz/60Hz
Power consumption	200W (Electrical Appliance and Material Control Law Standard)
AC outlet	Unswitched-1 (200W) Switched : 2 (200W total)
External dimensions	Width 471x Height 175x Depth 431 mm
Weight	23kg