KENWOOD KA-990D
¥ 79,800 (around 1986)
Commentary
Pre-main amplifier using New VIG / DLD circuit.
The New VIG / DLD circuit is equipped with a cascode bootstrap circuit between the amplifier and the power supply, which is used in the conventional power circuit, to cut the noise component of the power supply. This circuit supplies clean energy to the power amplifier and demonstrates the performance of the DLD circuit that realizes high-quality high power.
The DLD circuit combines two high-power and low-power amplifiers with a dedicated power supply to drive each of them. This circuit realizes an energy-rich sound that cannot be heard in the conventional 130W class.
In addition, by stabilizing the power supply line and enabling constant voltage operation, various characteristics of the power amplifier before applying NFB are improved, and wide bandwidth and low distortion factor are realized.
A Σ drive is used to suppress distortion when mounting speakers.
In a normal amplifier, impedance of the pattern and wiring material, phase compensation coil, relay, contact of the speaker selector switch, etc. in addition to the NF loop cause performance degradation at the output terminal of the amplifier. However, in the Σ drive, by extending the NF loop to the speaker terminal, parts which cause distortion and sound quality degradation are put in the NF loop, and the performance up to 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, so that mutual interference caused by GND line patterns and wires and digital noise generated by peripheral devices are suppressed.
The equalizer amplifier section is equipped with a 40 ms Hi-Gm FET differential input and a high-SN, low-distortion circuit using an IC. This circuit reduces interference from the power supply reproduces natural sound with a wide dynamic range and low noise.
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 capacitors are used.
In addition, the equalizer has a dedicated winding, and all parts of the power amplifier are stabilized power sources except for the power amplifier stage. This makes up a strong power supply.
On the circuit side, the high-performance output transistor is made into a discrete configuration to expand high-frequency characteristics and current supply capability range.
It uses a simple construction that reduces excess wire drawing and improves crosstalk.
In addition, the case has a multi-frame structure with a frame attached to each block, and the vibration is dispersed by the fact that each piece is small and the resonance point differs due to the size and shape of each piece.
A CD direct switch is installed in order to transmit the high-quality sound of CD as it is.
Dual Rec Selector with source selector function is installed.
This allows you to record a CD while listening to the tuner, or to record the same source simultaneously on Tapes 1, 2, and 3 because the source signal is output during tape dubbing.
Equipped with a winking power indicator with a protection operation display function.
It is equipped with tone control and loudness control.
Model Rating
| Type | NEW 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) | CDs, Tuenr, AUX, Tape → SP terminals : 0.004% (8 Ω at rated output) | ||||
| Frequency characteristic | CD, Tuner, AUX, Tape → SP connector : DC ~ 200 khz + 0 -3dB (1 hz ~ 180 khz) | ||||
| Damping factor (50 Hz) | 1000 | ||||
| Input Sensitivity / Impedance | Phono MM : 2.5mV/47k Ω Phono MC : 0.2mV/100 Ω CC, Tuner, AUX, Tape → SP terminal : 150mV/47k Ω |
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| Signal-to-noise ratio (IHF-A EIAJ / Input Short CP-301) |
Phono MM → SP Terminal : 78dB/87dB Phono MC → SP Terminal : 74dB/70dB (250 μ V) CD, Tuner, AUX, Tape → SP terminal : 80dB/108dB |
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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 | + 9 dB (100 Hz, Volume-30dB, 30 Hz) | ||||
| Subsonic filter (-3dB) | 18 Hz, 6dB/oct. | ||||
| Output bandwidth (0.04% distortion factor) | CD, 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 | 300W (Electrical Appliance and Material Control Law) | ||||
| 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 | 13.5kg |