|ONKYO Integra P-303
|80,000yen(around the 1977 time)
The preamplifier which investigated the high
fidelity transmit with the necessary minimum stream composition.
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.
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.
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
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
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.
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.
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
||Phono MC (50ohm drive): 100 microvolt/10 ohm
Phono man month: 2.5mV / 30kohm, 50kohm, 100kohm
play:150mV /, 50kohm
|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%)
||Phono man month(RIAA deflection):
Tuner and Tape:3.5Hz-200kHz+0 -1.5 dB
|THD (at the time of 3V output)
|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)
man month: 83dB (input shunt)
Tuner, Tape: 100dB (input shunt)
||Phono MC: Negative phase
Tuner, Tape, Acc-Rcv: Inphase
|The semiconductor used
||Transistor: 52 pieces
Diode: 29 pieces
||switched: Three lines
||20W (Electrical Appliance and Material
Control Law specification)
||Width 450x height 83x depth of 370mm