ONKYO Integra P-388
¥ 200,000 (around 1992)
Stereo preamplifier equipped with super balance circuit.
It uses a double differential amplifier circuit that combines a flat amplifier circuit with Onkyo's original double differential amplifier circuit and double super servo. It is compatible with any balanced or unbalanced input and realizes direct and stable operation.
In addition, in order to take advantage of the characteristics of the cartridge, an optimized equalizer circuit exclusively for MM/MC is adopted.
By using dedicated input terminals and eliminating switching circuits, simple amplification with the minimum number of contacts is achieved.
Direct Signal Flow Construction is used to simplify signal paths inside the chassis and to connect them at the shortest distance.
The switching circuits for balanced and unbalanced inputs are made independent of each other, and the signal is sent to the microprocessor by the operation of the input selector for total control.
In addition, the switching circuit for unbalanced input is placed near the input terminal, and the switching circuit for balanced input is placed just before the master volume to shorten the wiring.
The master volume is placed on the flat amplifier input in the center of the chassis and is operated from the front panel via an extension shaft to minimize the distance of the low-level wiring.
The power supply section employs a super-shunt power supply that combines a super-linear power supply and a shunt regulator, which are not affected by load fluctuations. The power supply circuit that supplies the MC equalizer amplifier, MM equalizer amplifier, flat amplifier (L), and flat amplifier (R) is mounted completely independently.
This reduces AC infrastructure noise and reduces the influence on other circuits.
The power transformer uses a LASER transformer with a modified core that reduces the magnetic resistance by increasing the width of the outer part. In addition, the core is carefully shielded with a silicon copper plate shield material to reduce the leakage flux to 1 / 30 compared to the conventional EI core transformer.
In addition, 3 laser transformers for the flat amplifier, equalizer amplifier and control circuit are used completely independently to reduce the influence on the amplifier section that handles the signal and to eliminate interference between each stage.
The layout is such that the digital control part housed in the front panel, the power supply part which supplies power to each stage, and the signal path are connected by the shortest distance.
Furthermore, by adopting a 3 box structure in which each amplifier section is completely shielded, digital noise and power supply noise do not adversely affect each stage of the amplifier section.
Both the volume and input selector employ a mechanical system driven by a motor. It can be controlled at hand using a remote control while suppressing the generation of non-linear distortion like semiconductor switches.
Compared to conventional volumes, the master volume uses a custom-made 4-series volume made of carbon resistance with an ultra-low distortion rate of -40dB. It also uses film capacitors and other parts made by Raderstein of Germany, which was decided to use after repeated trial listening.
The resistor uses parts such as a high-precision large carbon resistor (3/4W type), a 70-micron copper foil substrate, a balanced die-cast XLR type 3P connector, a gold-plated machined pin jack, an ultra-low impedance Chemicon for power supply, and an extra-thick cap-tire AC cord.
|Preamp with super balance circuit
|Input Sensitivity / Impedance
|Phono MC : 160 μ V/100 Ω
Phono MM : 2.5mV/47k Ω
Balanced CD, Line : 150mV/30k Ω
CD, Tuner, Line, Tape Play : 150mV/15k Ω
|Rated output voltage / impedance
|Output Balanced : 1V/200 ohm, up to 10 v
Output Unbalanced : 0.5V/100 ohm, up to 5 v
Tape Rec : 150mV/560 Ω
|Phono maximum allowable input
(THD 0.05%, 1 kHz)
|MCRIAA deviation Tape Rec : 20 Hz to 20 kHz ± 0.2 dB
MM RIAA deviation Tape Rec : 20 Hz to 20 kHz ± 0.2 dB
CD → Output Balanced / Unbalanced : 0.8 hz to 170 khz + 0 to 3 db
|Total harmonic distortion factor (THD, 20 Hz to 20 kHz
Output 3 v, Volume -30dB)
|Phono MC : not more than 0.005%
Phono MM : not more than 0.0008%
Balanced CD, CD : 0.0005% or less
|Cross modulation distortion factor
|0.003% (SMPTE 70 Hz : 7 kHz = 4 : 1 at rated output)
|Signal-to-Noise Ratio (Output = Balanced
A · weighted, input short)
|Phono MC : 81 dB (0.5 mV input)
Phono MM : 92 dB (5 mV input)
Balanced CD, CD : 105 dB (150 mV input)
|Power supply voltage
|100 VAC, 50Hz/60Hz
|Power consumption (Electrical Appliance and Material Control Law)
|Width 475x Height 30x Depth 418 mm