Kenwood - KA-990EX high class Solid state amplifier

An integrated amplifier designed to provide more pure sound quality with a thorough anti-vibration design.
2x 200W RMS!

We have newly developed and adopted a strut air suspension to suppress noise and distortion caused by external vibration.
This suspension is a unique independent suspension vibration absorption system. Vibration from the floor is first absorbed by the special elastic rubber at the grounding section. Furthermore, large amplitude vibration that could not be absorbed by the special elastic rubber is smoothly absorbed by the following coil spring and air damper.
In addition, these main parts are made of aluminum die-cast movable parts with high rigidity, and vibration from the floor is eliminated as much as possible.
In addition, the casing is made of a high-strength vibration-proof casing bonded with iron plates. By increasing the weight and adopting new structures such as logical flow construction, sound quality degradation is prevented.

In order to reduce the effect of sound quality degradation caused by home power supply, we have adopted an independently developed clean cyclone power supply.
By adding a special clean cyclone device to the transformer winding, this technology does not change digital noise in the high-frequency range into secondary voltage. This improves the bare characteristics of the power supply itself and improves the quality.
In addition, by fusing with the DLD circuit that eliminates the interference between the voltage amplification stage and the power stage that occurs through the power supply, and with the NEW VIG circuit that improves the SVR of the amplifier, the influence of the AC power supply and power supply circuit on the amplifier circuit is reduced.

The New VIG / OLD circuit is a circuit system originally developed by Kenwood, in which a VIG circuit, which does not transmit the noise component of the power supply to the power amplifier, is installed between the amplifier and the power supply, and the performance of the DLD circuit is utilized to improve sound quality.

This eliminates the ripple, signal components, and intermodulation distortion components from the power supply, and supplies clean energy to the power amplifier. At the same time, it achieves the same effect as a huge battery. The ripple free large power supply greatly increases the power supply capacity.

The internal structure employs a 5-box logical flow construction. The shield plate completely separates the small signal and large signal, digital signal and analog signal, and each signal processing part and power supply to suppress mutual interference.
In addition, by placing the transformer in the center, the merits of the strut air suspension can be maximized, and vibration damping effect is also improved.

The heat sink uses a chimney type heat sink with excellent heat radiation effect and vibration isolation.

Equipped with a Σ drive circuit that reduces distortion.
In the Σ drive, the NF loop is connected to the speaker terminal of the amplifier, and parts which cause distortion and sound quality degradation are put in the NF loop, and generation of distortion is suppressed.
In addition, all GND lines are concentrated at one point on the speaker terminal of the amplifier to suppress mutual interference caused by ground line patterns and wires, and to prevent digital noise generated by peripheral devices.

Dual Rec Selector with Source Selector function and CD Direct Switch are installed.


Manufacturer: Kenwood
Model: KA-990 EX
Years of manufacture: 1987 - 1989
Made in: Japan
Color: Black
Type: Integrated amplifier
Remote control: -
Power consumption: 270 W
Dimensions (W x H x D): 440 x 171 x 441 mm
Weight: approx. 15.5 kg
Original price approx.: DM 1,200

Connections

Number of inputs:

Phono MM: 2.5 mV / 47 kΩ, max. 200 mV (1 kHz, 0.03% THD)
Phono MC: 0.2 mV / 100 Ω, max. 15 mV (1 kHz, 0.03% THD)
High-level: 150 mV / 47 kΩ
Number of outputs:

Tape REC 1, 2: 150mV

1 pair of speakers
Headphones

Technical Specifications

Continuous Power Output: (at THD)
8 Ohms: 2 x 110W (20Hz - 20kHz, 0.004% THD)
6 Ohms: 2 x 140W
4 Ohms: 2 x 180W
2 Ohms: 2 x 210W
Dynamic Power Output:

8 Ohms: 2 x 125W
6 Ohms: 2 x 175W
4 Ohms: 2 x 235W
2 Ohms: 2 x 335W
Total Harmonic Distortion: 0.004% at rated power
Damping Factor: 1000
Frequency Response: 5 - 80,000 Hz
Rise Time: 5µs
Signal-to-Noise Ratio:
Phono MM: 87dB
Phono MC: 70dB
High level: 108dB
Tone control:
Bass: ±10 dB at 100 Hz
Treble: ±10 dB at 10 kHz
Loudness: 100Hz/10kHz +10/+5dB
High filter: -10dB/10kHz
Low filter (subsonic): -9 dB/100 Hz
Mute: Yes
Direct/Line Straight: Yes

Pictures are description
Signs of use here and there on the case

Carefully shipped