Audio Database

The pictorial image of Integra P-303

ONKYO Integra P-303
80,000yen(around the 1977 time)

Description
@
The preamplifier which investigated the high fidelity transmit with the necessary minimum stream composition.

In order to hold the high fidelity as a transmit system, practically, it is considered only as the change of man month, MC, Tuner, and one Tape each, a tone is begun as a necessary minimum functionality, and other coordination / change circuitries are omitted entirely. Furthermore, the thin structure suitable for simplifying the fluence of a signal is adopted.
Moreover, when multi-functionalization and a sound field correction are surely required, it is possible to extend a functionality by using optional system-unit Integra U-30 and audio equalizer Integra E-30.

In P-303, the design is carried out paying attention to the dynamic modulation (transitional cross modulation distortion) generated by the interference between the right-and-left channels between each functional block of a circuitry, and within the same block.
A power-source part and class generate the dynamic modulation generated like a music signal when the sharp transitional signal of a riser is inputted by the cross interferencee between the circuitries where the impedance of a heredity line results. In order to prevent this, in P-303, low-impedance-izing of a power feeding & power distribution line including a power-source part and a hyper-stability supplying of supply voltage are aimed at, and the multi-spray busline made from a copper plate with a high purity is adopted sharply. The copper plate of 0.008 ohm/cm is used for a bus-grounding line at the copper plate of resistance-value 0.0027 ohm/cm, and the bus hot line for }B powerings,The occurrence of the dynamic modulation is directly suppressed with the power-feeding scheme which links the branch of each circuitry block with the supplying trunk of a direct low impedance directly, respectively.
Furthermore, in order to hold this line to a low impedance over a wide band, the double stabilizer circuitry which let the constant-voltage regulated power supply pass doubly is adopted as a power-source part. Moreover, the capacitor for audio signals which was designed for the purpose of the object for audios and which was excellent in a distorted property or the temperature characteristic with a low loss and low leakage is adopted especially as the capacitor used for the interior.

D. With the L.C. (dual line construction) scheme, the right-and-left channel was separated completely and the interference between channels is eliminated. Moreover, to the output side of the Takanobu number level, by arranging each block in 1 in all linear line for the path of a signal, an interference of each inter-block is eliminated and purification of the circuit operation is attained from the input side of low signal level.
Furthermore, the aluminum material which is non-magnetic material was extensively adopted as the shielding case, and the double shielding is especially given to MC amplifier part.

The modification of a linearity is measured by adopting the Class-A full up-and-down symmetrical type push pull scheme which has improved the hfe property combining PNP and NPN on all the stages of MC amplifier, equalizer amplifier, flat amplifier, and buffer amplifier.

In a first rank differential and the differential-amplifier part of the equalizer amplifier of a three-step 8 stone stream compositionBy low-impedance-ization of a signal system, equivalent noise resistance is reduced and the SN ratio is raised at the same time it uses high resisting pressure and a super-low-noise PCT scheme silicon epitaxial type transistor (2SC1681, 2SA841).
Moreover, in the RIAA constant circuitry, it excelled in the frequency characteristic or a transient and the outstanding property has been acquired by using G class (less than }2% of capacity deflection) of the polypropylene film capacitor of the small unguided aluminum foil structure of tandelta.

The 4-unit precision attenuator type volume which can be interlocked and controlled before and behind flat amplifier is used for volume control, and it has improved the SN ratio when narrowing down a volume.

In order to prevent the it1 noise generated at the time of ON/OFF of a power switch, the transient killer circuit using the taken a break type reed relay developed newly is adopted. The influence by the contact resistance of the relay at the time of a using is usually suppressed by including in a shunt type rather than putting into a signal circuit directly like before.

The low input-impedance type of 6 stone stream compositions which use a super-low-noise transistor by a triple push pull is adopted as MC amplifier part.

In order to remove the capacitor in NF loop completely, the wide band circuitry of DC amplifier stream composition is adopted as the flat amplifier part of interstage.
By adopting the dual transistor incorporating the chip of two low-noise transistors, it excels in a thermal equilibrium property and stable DC amplifier with the sufficient direct-current amplification factor ratio 1}0.02 and balance is formed in a first rank differential-amplification circuitry.

For the coupling capacitor, the film capacitor of the unguided extended foil structure was used, and the failure of the tone quality is prevented to it.

Internal

Rating of a mode
Form Stereo preamplifier
Input sensitivity/impedance Phono MC (50ohm drive): 100 microvolt/10 ohm
Phono man month: 2.5mV / 30kohm, 50kohm, 100kohm
Tuner, Tape play:150mV /, 50kohm
Accessory-Rcv: 1.5V/82kohm
An Output power/impedance Tape rec(Phono): 150mV / 12kohm
Accessory-Send: 1.5V/100 ohm
Output: 1.5V (a maximum of 15V) / 600ohm
Phono maximum permissible input (THD 0.05%)
MC: 13mV(1kHz)
63mV(10kHz)
MM: 330mV(1kHz)
1600mV(10kHz)
Frequency characteristic Phono man month(RIAA deflection): 20Hz-20kHz}0.2dB
Tuner and Tape:3.5Hz-200kHz+0 -1.5 dB
THD (at the time of 3V output)
20Hz - 20kHz
Phono MC: 0.03% or less
Phono man month: 0.006% or less
Cross modulation distortion (at the time of an Output power) 0.01% or less (SMPTE 70Hz:7kHz=4:1)
SN ratio (IHF-A network) Phono MC: 70dB (50ohms of inputs)
Phono man month: 83dB (input shunt)
Tuner, Tape: 100dB (input shunt)
Input/output polarity Phono MC: Negative phase
Phono man month: Inphase
Tuner, Tape, Acc-Rcv: Inphase
The semiconductor used Transistor: 52 pieces
Diode: 29 pieces
AC output switched: Three lines
unswitched: One line
Total:1100VA
Power source AC100V, 50Hz/60Hz
Power consumption 20W (Electrical Appliance and Material Control Law specification)
Dimensions Width 450x height 83x depth of 370mm
Weight 7.5kg