KENWOOD K270

Commentary

A large integrated audio system that combines an amplifier, CD player, and tuner.

The final transistor of the amplifier section is equipped with TRAITR, a unique device of Kenwood.
This is the world's first single-chip temperature detection and compensation circuit. It is a final transistor with five terminals. Since the temperature detection element is placed on the same chip as the transistor, the temperature can be detected almost in real time. The distortion caused by a small signal due to the change of the operating point, which occurs when the conventional temperature detection transistor is attached to the radiator, is suppressed.

In order to make the most of the capabilities of the TRAITR, we have adopted a super linear drive circuit that reduces the switching distortion and crossover distortion generated in the final stage circuit by local feedback to the driver stage. This ensures stable operation of the main NFB circuit.
We have also adopted a linear TRAITR circuit based on TRAITR's concept. An operational amplifier is used for the first stage circuit of the amplifier. The dynamic linearity of the first stage circuit is improved by taking advantage of the feature that both functions and temperature operate in the same chip.

An a-class amplifier and a current detection feedback circuit are installed to improve close range and low volume playback.
In principle, the A-class amplifier does not cause crossover distortion or asymmetric distortion, so the linearity of the small signal level is improved.
In addition, the current detection feedback circuit (CNFB) is a circuit that reduces distortion by detecting the distortion component of the speaker from the current flowing in the speaker and feeding it back to the input side, while the NFB reduces distortion by returning the opposite component from the output of the amplifier to the input. This circuit reduces distortion in the low range by detecting the distortion component of the speaker from the current flowing in the speaker and feeding it back to the input side.

An elliptical ring core toroidal transformer is used for the power supply.
There is little leakage of magnetic flux, sound is smooth, and does not affect surrounding circuits. In addition, power conversion efficiency is improved by the elliptic structure in which the winding can be wound tightly.

The CD player is equipped with a 24-bit Fine D. R. I. V. E. that achieves 64 times higher precision than the conventional 24-bit 8-fs D. R. I. V. E. This allows even minute signals, which were previously discarded as digital noise, to be sent to the 24-bit D/A converter with data closer to the original sound, improving the sense of reality and solidity.
In addition, two independent transformers for digital and analog systems, and pure CD direct inside the chassis are used to improve sound quality.

The tuner section has a 4-row front end to improve reception characteristics.
The 40 station preset and timer preset and timer functions improve operability.

A shutter mechanism is adopted as a sound pressure shielding structure.

Equipped with an SP equalizer that can be turned ON/OFF depending on where the speaker is set.

CD-TEXT is supported.

Model Rating

Type	Large integrated audio system
Amplifier Unit
Rated output (20 Hz to 20 kHz, 0.02%)	Class AB : 40W + 40W (4 Ω) Class A : 10W + 10W (4 Ω)
Maximum Practical Power (EIAJ)	Class AB : 65W + 65W (4 Ω) Class A : 17W + 17W (4 Ω)
Signal-to-Noise Ratio (IFF-66)	Phono MM:77dB Line (AUX, MD) : 103 dB
Input Sensitivity / Impedance	Phono MM : 2.5mV/47k Ω Line (AUX, MD) : 200mV/47k Ω
Output Level / Impedance	MDRec : 200mV/1k Ω Subwoofer Pre Out : 2.0V/600 Ω
<CD Player Part>
Reading system	Noncontact optical readout (semiconductor laser)
D/A converter	1-bit (24-bit Fine D. R. I. V. E.)
Oversampling	32fs(1,411kHz)
Tuner Section
Receiving frequency band	FM : 76 MHz to 90 MHz AM : 531 kHz to 1,602 kHz
Practical sensitivity of FM	Mono : 1.8 μ V (75 Ω) 16.2 dBf
AM practical sensitivity	16 μ V (600 μ V/m)
<General>
Power supply voltage	100 VAC, 50Hz/60Hz
Rated power consumption	110W (Electrical Appliance and Material Control Law)
Maximum external dimensions	Width 296x Height 136x Depth 373 mm
Weight	7.7kg
Attachment	Remote control