KENWOOD KA-990V
¥ 79,800 (released in 1985)
Commentary
Pre-main amplifier equipped with VIG / DLD circuit.
In the VIG-DLD circuit, a VIG circuit that does not transmit the noise component of the power supply to the power amplifier stage is installed between the amplifier and the power supply. Clean energy is supplied to bring out the performance of the DLD circuit.
The VIG circuit is designed to have a low impedance from the amplifier side and a high impedance from the power supply side. Therefore, only the DC energy from the power supply is allowed to pass through, making it difficult for noise to pass through, thereby eliminating the ripple of the power supply, signal components, and current modulation distortion components.
In addition, by obtaining the same effect as a huge battery, the power supply capacity is greatly improved by a large power supply without ripple.
Other features include improving the bare characteristics of the power amplifier stage before applying NFB, realizing a wide bandwidth and low distortion rate, and solving problems caused by power supply such as dynamic crosstalk.
The power supply section uses a large transformer with more laminated cores, higher heat radiation effect, and lower winding impedance. Four 10,000 μ F block Chemi-Con are used.
In addition, the equalizer has a dedicated winding and all parts except for the power amplifier stage of the power amplifier are used as a stabilizing power source. In the circuit side, the high-performance output transistors are configured in a discrete configuration to expand the high-frequency characteristics and current supply capability range.
By separating the printed circuit board block by block and adopting rational construction in accordance with the signal flow, unnecessary wiring of wire is avoided and interference between each part is greatly reduced.
We have also introduced vibration analysis into the housing design and adopted a structure that is less likely to cause resonance even with vibrations caused by sound pressure from speakers or direct vibrations from the floor.
Keeping the design concept of the Σ drive installed in the L-02A, etc. as it is, it adopts the Σ drive typeB in pursuit of usability.
In a normal amplifier, impedance of pattern and wiring material, phase compensation coil, relay, and speaker selection switch are in addition to the NFB loop, which causes performance degradation at the output terminal of the amplifier. However, in the Σ drive typeB, by extending the NF loop to the speaker terminal, parts which cause distortion and sound quality degradation are put in the NF loop, and performance at the speaker terminal of the amplifier is improved.
In addition, all GND lines are concentrated at one point on the speaker terminal of the amplifier to suppress the increase of mutual interference caused by GND line patterns and wires.
The KA-990V is equipped with 8 input terminals with newly added CD and Tape-C positions.
In addition, it is equipped with a CD direct switch. When in the CD direct position, the input selector, mode and subsonic contact switches and the balance volume jump, simplifying the signal path and enabling higher quality CD playback.
All dubbing of A → B / C, B → A / C, and C → A / B is possible for the Route 3 tape terminals.
You can also record from the same source to two decks simultaneously.
The EQ amplifier section is equipped with a 40 ms super Hi / GmFET differential input and an IC-based EQ amplifier.
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Model Rating
| Type | VIG / DLD Integrated Amplifier | ||||
| Rated Output (Both Channel Operation) |
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| Total harmonic distortion rate (20 Hz to 20 kHz) |
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| Intermodulation distortion factor (60 hz : 7 khz = 4 : 1) | Tuenr, AUX, Tape → SP terminals : 0.004% (8 Ω at rated power) | ||||
| Frequency characteristic | Tuner, AUX, Tape → SP connector : 1 Hz to 180 kHz + 0 to 3 dB | ||||
| Damping factor (50 Hz) | 1000 | ||||
| Input Sensitivity / Impedance | Phono MM : 2.5mV/47k Ω Phono MC : 0.2mV/100 Ω Tuner, AUX, Tape : 150mV/47k Ω |
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| Signal-to-noise ratio (IHF-A) | Phono MM → SP terminal : 88 dB Phono MC → SP terminal : 70 dB (250 μ V) Tuner, AUX, Tape → SP terminal : 108 db |
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| Tone control | Bass, 200 Hz : 100 Hz ± 10 dB Treble, 3 kHz : 10 kHz ± 10 dB |
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| Loudness control (Volume-30dB) | +9dB(100Hz) | ||||
| Subsonic filter (-3dB) | 18 Hz, 6dB/oct. | ||||
| Rise time | Tuenr, AUX, Tape → SP terminals : 1.7 μ s | ||||
| Slew rate | Tuner, AUX, Tape → SP terminal : ± 100 V / μ s | ||||
| Output bandwidth (0.04% distortion factor) | Tuner, AUX, Tape → SP connector : 5 Hz to 70 kHz | ||||
| Phono maximum allowable input (1 kHz, THD 0.003%) |
Phono MM:200mV Phono MC:15mV |
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| Phono RIAA deviation (20 Hz to 20 kHz) | ± 0.3 dB | ||||
| Output Level / Impedance | Tape Rec : 150mV/330 Ω | ||||
| Pwer | 100 VAC, 50Hz/60Hz | ||||
| Rated power consumption (Electrical Appliance and Material Control Law) | 265W | ||||
| Power outlet | Power switch interlock : 2 systems, 100W Power switch not linked : 1 system, 400W |
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| External dimensions | Width 440x Height 158x Depth 420 mm | ||||
| Weight | 13.9kg |