Audio Database

Image of Integra A-817GTR
Commentary

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

We have developed and adopted the Delta Turbo Power Supply in order to obtain an effect close to the ideal power supply in the same size as the conventional one.
This reduces the generation of special intermodulation distortion in the power supply section, which adversely affects sound quality, by -20dB compared to conventional power supplies.

Super Servo Integral System is adopted in the amplifier section.
The electromotive force induced in the speaker by external factors such as sound pressure emitted from the reverse channel speaker is directly fed back to the amplifier by the microphone effect of the speaker. This electromotive force with a time difference as much as the sound travels through the space causes time difference distortion due to the linearity of the output stage of the amplifier.
This problem is reduced by a special linearity correction circuit compared with the conventional one.
In addition, the servo mechanism applied to the + - pole of the output side of the amplifier reduces harmful ultra-low frequency components and noise components that cause distortion due to the total impedance of the power supply.

In order to make the most of the performance of the MC cartridge, the GTR Series is equipped with a high-gain straight equalizer amplifier, which is designed mainly for high-quality MC playback, rather than merely adding a head amplifier or booster transformer.
In addition, the purity of sound is improved by a complete two amplifier configuration in which the tone amplifier and buffer amplifier are omitted and input directly to the high-gain power amplifier.
In addition, the final stage of the equalizer amplifier is class A push-pull so that the signal can be sent to the next stage with low distortion to cope with heavy loads in the high frequency range.
In addition, we examined the bare characteristics of both the equalizer and power to improve the overall linearity and adopt a low feedback system that is also effective in terms of audibility.

It uses a direct tone method which is an original tone control.
Since the tone amplifier, which had many problems in sound quality, is omitted and the tone is changed by using the loudness circuit related to volume control, the circuit is composed only of passive elements which have no problems in sound quality.
This reduces variations in sound quality.

Linear switching method is adopted for operation of output transistor.
There is no difference from class B in that two transistors are used, but the linearity of the joint of the operation curve, which is a problem, is corrected by a unique bias circuit to obtain always linear operation characteristics as a whole.
As a result, the crossover distortion is equivalent to class A amplification and the efficiency is class B.
High fTThe use of power transistors keeps switching distortion within a negligible range.

In addition to the shielding material of the circuit, all necessary parts are made of non-magnetic materials such as copper, brass and aluminum, avoiding the use of magnetic materials such as iron.

MC2 and MM1 cartridge selectors are installed in order to obtain the best matching.
The phono input pin jack is plated with pure gold to reduce the influence of contact resistance, etc.
All models are fully equipped with 5 levels of mode switching (Norm, Rev, R + L, L, R).

Special noise-improving resistors with excellent frequency and distortion characteristics are used for important circuits.

Model Rating
Type Pre-main amplifier
Rated Output (20 Hz ~ 20 kHz) 80W + 80W (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)
0.015% (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 (1 kHz, 8 Ω) 100
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 : 2.9mV/47k Ω
Phono High MC : 2.9mV/100 Ω
Phono MC : 280 μ V/330 Ω
Tuner, AUX, Tape Play : 150mV/47k Ω
Phono maximum allowable input
(1kHz/10kHz, 0.05%)
Phono MM:250mV/1200mV
Phono High MC:250mV/1200mV
Phono MC:23mV/110mV
Output Voltage / Impedance Tape Rec : 150mV/2.2k Ω
S/N ratio (IHF short) Phono MM:87dB
Phono MC:72dB
Tuner, AUX, Tape Play : 100 dB
Tone Control (Vol-16dB) Bass : ± 8 dB (70 Hz)
Treble : ± 8 dB (20 kHz)
Loudness +6dB(100Hz)
Subsonic filter 15 Hz, 6dB/oct.
Muting -20dB
Pwer 100 VAC, 50Hz/60Hz
Power consumption 135W (Electrical Appliance and Material Control Law Standard)
AC outlet Unswitched-1 (200W)
Switched : 2 (200W total)
External dimensions Width 435x Height 142x Depth 392 mm
Weight 11kg