Audio Database

The pictorial image of Integra A-755mkII/70

ONKYO Integra A-755mkII/70
69,800yen(1974 release)

Description
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The Integrated Amplifier of the mkII series which renewed the design while improving Integra A-755.

Including NF circuitry for controlling a tone property, the conventional tone amplifier changed inside low-pass a riser and a falling property with various members, and had had an ill effect on the tone quality. The simulation by a computer was put into practice among this fraction, and many problems are solved.
In tone amplifier, in order to insert the variable beta circuit for giving a tone property in NF circuitry, it has four time constants on super-low-pass one. If this time constant is not chosen carefully, it does not become the flat amplifier which was excellent in feedback stability. In order to improve this, the circuitry advantageous to securing feedback stability to low-pass enough is selected and adopted, and it has become the stable large circuitry of the phase margin.

Low-pass and the cut-off of a high region will arise in an open loop in any circuitries.
While balancing a high region and low-pass well and keeping a high region cut-off high in a simple circuitry, it is a circuitry called the two-step stream composition of a 1 step of differential grounded emitter so that dynamic ranges enough also with a simple stream composition may be secured.

The PNP type with few structure top 1-/f noises was chosen as the transistor, and impedance level is set as the best point of the noise property of a transistor.

While adopting as a tone circuitry the differential circuit which cannot be easily influenced by a voltage fluctuation, the cross modulation by the voltage fluctuation of a power amplifier part is prevented by supplying through a }2 power-source type low-voltage circuitry called 1.7% of voltage regulation.

A whole page is covered and the technology developed in the conventional Integra serieses, such as power amplifier of the pure contest whole page hardwired-connection structure where the transient response property has been improved, and an OP-amp type equalizer circuitry, is also supplied.

The wood case was an option.

Rear
Internal
Internal

Rating of a mode
Form Integrated Amplifier
<Power amplifier part>
Output power (1kHz) 8ohm: 35W+35W
4ohm: 40W+40W
Dynamic power (IHF 8ohm) 130W
THD (T. H.D., 1kHz) 0.1% or less (at the time of an Output power)
0.03% or less (at the time of 10W output)
0.03% or less (at the time of 0.5W output)
Cross modulation distortion (S. M.P.T.E, 70Hz:7kHz=4:1) 0.05% or less (at the time of an Output power)
Power Band Width (IHF-3dB, THD 0.3%) 10Hz - 100kHz
SN ratio (an IHF A network, an input shunt) 110dB or more
Dumping factor (DC-20kHz) 8ohm: 60
4ohm: 30
Load impedance 4ohm-16ohm
Gain 24.5dB
Output-terminal Speaker:A, B, an A+B switching
Headset jack
<Preamplifier part>
Input sensitivity/impedance Phono1, 2:1.2 mV, 2.4mV, 4.8mV / 50kohm
Tuner, AUX1, 2, Play:100mV /, 50kohm
THD (1V, 1kHz) 0.03% or less
Cross modulation distortion (S. M.P.T.E, 70Hz:7kHz=4:1) 0.05% or less (1V)
RIAA deflection (Phono1, 2) 20Hz-20kHz}0.5dB
Phono maximum permissible input
(1kHz/10 kHz, THD 0.1% (R. M.S.))
: with an Input sensitivity of 4.8mV 500mV/2000mV
: with an Input sensitivity of 2.4mV 250mV/1100mV
: with an Input sensitivity of 1.2mV 125mV/550mV
S/N (an IHF A network, an input shunt) Phono1, 2:75dB or more
Tuner, AUX1, 2, Play: 90dB or more
An Output voltage/impedance
Pre Out (at the time of a 100kohm load intensity) Output power: 1V/2.7kohm
Maximum output: 4V/2.7kohm
Rec Out(Phono) Output power: 100mV / 12kohm
Tone control (2dB step type) Treble: }10dB (10kHz and F-Shift 2kHz o'clock)
Bass: }10dB (100Hz, F-Shift, 400Hz o'clock)
Turnover frequency Treble: 2kHz, 8kHz, Defeat
Bass: 400Hz, 125Hz, Defeat
Loudness (volume 30dB o'clock) +5dB/70Hz
Light filter High-Filter: 5kHz, 20kHz, 6dB / oct
Low-Filter: 10Hz, 30Hz, 6 dB/oct.
Muting -20dB
<Synthesis>
The semiconductor used Transistor: 37 pieces
Diode: 25 pieces
Power source AC100V, 50Hz/60Hz
AC output Switched: Two lines, 200VA
Unswitched: One line, 200VA
Power consumption Electrical Appliance and Material Control Law specification: 91W
Maximum electric power consumption: 210W
Dimensions Width 440x height 150x depth of 386mm
Weight 11.5kg
Option Wood case CW-5 (3,000yen)