ONKYO Integra A-4500
¥ 58,000 (around 1975)
Commentary
A pre-main amplifier of the Integra GT series designed with an emphasis on musical performance.
The equalizer amplifier section is based on the circuit used in the Integra MKII Series. In addition, a constant current drive circuit is used for all stages of the operation amplifier IC to ensure high stability. In addition, a ± 2 power supply and differential amplifier circuit are used, and a constant voltage circuit that is less affected by power supply fluctuations is used to prevent degradation of sound quality due to voltage fluctuations.
In addition, we focus on the bare characteristics before applying NF, and aim for further improvement by applying stable NF after realizing sufficiently low strain rate with bare characteristics.
The RIAA compensation circuit is precisely calculated to achieve 0 deviation in design, and by carefully selecting elements, variations due to component errors are minimized.
The tone amplifier section uses the same operational amplifier IC as the equalizer amplifier section. The tone amplifier section also has stable dynamic characteristics. Moreover, the circuit technology developed in the Integra MKII series has been introduced to give an emphasis on musical performance.
Equipped with a tone defeat circuit.
Pure complimentary service all-stage direct connection OCL circuit is adopted for the power amplifier section. In addition, transistors with excellent characteristics are carefully selected for the drive stage and power stage. In addition, mirror capacitance is examined and the pair characteristics of PNP and NPN are made uniform to improve bare characteristics.
The power supply section uses a transformer with good regulation and a large-capacity capacitor developed especially for acoustic equipment.
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Model Rating
| Type | Pre-main amplifier |
| Power Amplifier Unit | |
| Rated output | 50W + 50W (8 ω, 1 kHz) |
| Total harmonic distortion rate (1 kHz) | 0.1% or Less (at Rated Output) 0.03% or less (at 10W output) |
| Intermodulation distortion factor (SMPTE70Hz : 7 khz = 4 : 1) | 0.05% or Less (at Rated Output) |
| Power Band With (IHF -3dB, THD 0.2%) | 10 Hz to 90 kHz |
| Signal-to-noise ratio (IHF, A network input shunt) | 110 dB or more |
| Damping factor (DC ~ 20 kHz) | 60 (8 Ω) |
| Load impedance | 4 Ω ~ 16 Ω |
| Output terminal | Speaker : A, B, A + B Headphone jack |
| Preamplifier Section | |
| Input Sensitivity / Impedance | Phono1, 2 : 2.5mV/50k Ω Mic : 5mV/50k Ω Tuner, Play1, 2 (Aux) : 100mV/50k Ω |
| Total harmonic distortion factor (at 1 v output) | Not more than 0.03% |
| Intermodulation Distortion Factor (SMPTE, 70 hz : 7 khz = 4 : 1) | 0.05% or Less (at 1 V Output) |
| RIAA deviation (30 Hz to 15 kHz) | ± 0.5 dB or less |
| Phono Maximum Allowable Input (1kHz/10kHz) | 200mV(970mV)RMS 560mV(2.71V)P-P |
| S/N (IHF A network, input shunt) | Phono1, 2 : 70 dB or more Tuner, Play1, 2 (Aux) : 90 dB or higher |
| Output Voltage / Impedance | Din : 30mV/50k Ω (at 100k Ω load, rated output) Rec out : 100mV/10k Ω (open-end rated output) |
| Tone control | Treble : ± 10 dB at 10 kHz, F-shift at 2 kHz Bass : ± 10 dB at 100 Hz, F-shift 400 Hz |
| Filter | High Filter : 5 kHz, 6dB/oct. Low Filter : 30 Hz, 6dB/oct. |
| Muting | -20dB |
| <General> | |
| Semiconductor used | Transistor : 25 IC : 4 Diode : 17 pcs |
| AC Output | Switched:150VA Unswitched:150VA |
| Pwer | 100 VAC, 50Hz/60Hz |
| Power consumption | 105W (4 Ω load, Electrical Appliance and Material Control Law) 300W (4 Ω load, maximum power consumption) |
| External dimensions | Width 410x Height 143x Depth 297 mm |
| Weight | 9kg |
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