Kenwood KA-8100

A DC amplifier that provides amplification down to zero frequency without any phase shift, independent power supplies for low transient crosstalk distortion and outstanding signal to noise ratio of 85 dB for 2.5 mV input should make the KA-8100 the best performing integrated amplifier available today at any standard.

The DC power amplifier, first to be incorporated in an integrated amplifier by Kenwood engineers, has now been accepted as the ultimate in amplification of the audio signal. This amplifier provides gain to zero frequency without any phase shift. Independent power supplies are incorporated to eliminate Dynamic Crosstalk distortion, a phenomenon first exposed by Kenwood engineers. In addition there is a further separate power supply to the preamplifier stage which maintains the high level of sound quality. Output power is rated at a minimum of 75 watts per channel RMS driven into 8 ohms through 20 Hz to 20,000 Hz. Total harmonic distortion over the whole range is held to a very low 0.03%. Another indication of Kenwood's superior audio techno;ogy is the extremely high signal to noise ratio of 85 dB (91 dB 5mV, 97 dB 10mV) - a reminder that the KA-8100 is designed with the ultimate criterion of reproducing sound with the least possible noise or distortion.Other key design elements include an attenuator type Volume control, a Gain control and a specially contoured loudness control, all carefully designed to provide you with high tonal quality and flexibility.

Independent Dual Power Supplies Plus Separate Preamplifier Power Supply Eliminate Dynamic Crosstalk.

Complete channel separation is vital to sound quality, because any undesirable transfer of signal between channels may create reproduction with muddy sound, especially at low frequencies. This is a common problem with conventional single power supplies. Kenwood's discovery od Dynamic Crosstalk distortion has led to the development of separate independent power supplies (DPS), which successfully overcomes this problem by providing precise stereo imaging right down to the lowest frequencies. Each power supply employs a large power transformer, with two 10,000μF electrolytic capacitors in each filter circuit, assuring ample and stable power supply. In yet another separate power supply to the preamplifier stage, there is a full-scale transistorized voltage regulator which prevents any interaction between front and rear stages. With the elimination of Dynamic Crosstalk distortion, transient response is excellent. Each musical instrument is correctly localized and at its natural level and response is crisp and throughout the audible range.

High 85 dB S/N Ratio Is Achieved By Direct-Coupled FET Phono Equalizer.

*% dB (IHF-A Curve) signal-to-noise ratio is an exceptionally high value unrivalled in this class of amplifier. To achieve it, an elaborate 3-stage ICL differential amplifier uses an FET in the first stage, with current mirror load. The second stage is a Darlington circuit with current mirror load. The final stage is a pure complementary single-ended push-pull circuit using specially selected, paired PNP-NPN transistors. All this circuitry means that the preamplifier stage is similar in quality to the power amplifier stage. The extremely wide dynamic range and high stability achieved in phono amplifier is due to the large common mode rejection ratio (CMRR) - the ability of the amplifier to separate noise from signal. While full output can be attained with an input of only 2,5 millivolts, the use of the front panel Gain control at its +10 dB position further increases input sensitivity of the phono input to accommodate moving coil cartridges having an output of 0,8 millivolts

Sophisticated Tone Control Have Defeat Switch For Flat Frequency Response.

To match the acoustic characteristics of your listening room, speakers or cartridge, etc. you will probably want to "tailor" the sound individually. For this purpose, the KA-8100 is provived with highly stable, low-noise Baxandall type bass and treble tone controls. Adjustment is in 1,5 dB steps, with a maximum range of ±7,5 dB. Turnover frequencies operate at 150 Hz and 400 Hz for bass, and 3 kHz and 6 kHz for treble. Although the tone controls can be highly useful there may be times when they are not needed, and some purist actually prefer not to use them at all. In these cases, the KA-8100 tone controls are provided with a defeat switch position which allows the signal to bypass them, thus eliminating potential distortion which could lead to poor sound quality.

The Simpler The Circuitry The Better The Sound.

It's axiomatic at Kenwood that the more we reduce or eliminate long distortion-causing wiring, the greater the gain in overall tonal quality. We also believe that individual improvements in performance, however remarkable, are not so meaningful unless they relate to the total sound quality. This is why we have concentrated on simplifying circuitry in oreder to reduce potential distortion. Apart from the input capacitorless circuitry used in both the crucial equalizer and tone control sections, the whole internal layout has been redesigned. The new chassis design effectively separates large and small current circuits, so that there is no interaction betwen them. In fact, th elarge current block is isolated by heat sinks on either side and by a special shielding plate. The small current circuits are outside this enclosure. This construction significantly contributes to the high S/N ratio of the KA-8100. In addition, the input selector is mechanically extended to the rear panel, and the phono inputs are directly connected to their equalizers on the preamplifier circuit board - two important examples among our many wiring eliminations. In this way, thetonal quality of the KA-8100 can be realized to full advantage.

Professional Logarithmic Attenuator Type Volume Control And Gain Control

Because the human ear is non-linear, and usually poor in low-frequency perception, the KA-8100's full-scale attenuator type volume control provides logarithmic attenuation for naturally balanced sound even at low volume levels. In addition, the gain control (selectable at -10 dB, 0, +10 dB) allows more precise volume adjustment when used in combination with the Volume control. The Gain control can also be used as a muting switch.

High. Low and Subsonic Filters

The High filter cuts off at 8 kHz to eliminate recird scratch or othyer high frequency noises. The Low filter cuts off at 40 Hz. Both filters roll off at the rate of 12 dB/oct. In addition, there is a Subsonic filter which slopes at 6 dB/oct, cutting off at 18 Hz. This allows all subsonic influences such as those generated by record warp or turntable rumble to be eliminated without disturbing the lowest audible frequencies. like the tone circuits, the filter circuits can be switched out of the signal path when not needed.

New Loudnes Control Is An Aid To Tonal Quality

The versatile loudnes control provides a variety of compensation functions using a total of six contours, controlled by two knobs. As well as compensating for poor human audio perception at low frequencies, it provides extra boost at low frequencies when needed. It also provides compensation for poor low frequency response in some speaker systems. The circuit permits a three-level boost in the volume level at -30 dB volume level at either 100 Hz or 50 Hz. Boost is made in increments of 3 dB. Few other manufactures provide such a comprehensive aid to tonal quality.

Flexible Tape Circuit With Tape-Through Facility

With inputs permitting two tape decks to be connected, the KA-8100 features a variety of editing functions such as source or tape monitoring on A or B, inter-deck dubbing, and there's a unique tape-through circuit that permits dubbing while simultaneously listening to a different source.

The Kenwood Professional Touch

The KA-8100 has a professional look and feel , with every knob and control thoughtfully designed for maximum ease of use. Inside, too, the circuitry is innovative and often well in advance of prevailing standards. As a pace-setting specialist audio manufacturer, Kenwood believes that audio components have one overriding purpose - to provide you with reproduced sound quality that mirrors the original signal. Whatever kind of music you enjoy, the' KA-8100 will faithfully reproduce it, with the minimum of distortion, over the whole dynamic range. After all, this is what hi-fi is all about.

Specifications:

Power Amplifier Section

Both Channels Driven: 2 x 75 watts, 8 ohms at 1 kHz; 2 x 90 watts, 4 ohms at 1 kHz

Dynamic Power Distortion: 330 watts 4 ohms

Total harmonic Distortion: 0.03% at rated power into 8 ohms; 0.01% at 1 watt into 8 ohms

Intermodulation Distortion (60 Hz : 7 kHz = 4 ; 1):

0.03% at rated power into 8 ohms; 0.01% at 1 watt into 8 ohms

Power Bandwidth: 5 Hz to 50,000 Hz

Frequency Response: DC to 100,000 Hz +0 dB, -1,5 dB

Signal to Noise Ratio: 115 dB (short circuited)

Damping Factor: 50 at 8 ohms

Input Sensitivity/Impedance: 1.0 V/50 kohms

Speaker impedance: from 4 to 16 ohms

Preamplifier Section

Input Sensitivity/Impedamce:

Phono 1, phono 2: 2,5 mV/50 kohms,

Tuner, Tape A, B, Aux: 150 mV/50 kohms

Signal to Noise Ratio (IHF .A):

Phono 1, phono 2: 85 dB for 2,5 mV , 91 dB for 5,0 mV , 97 dB for 10 mV input

Tuner, AUX, Tape A, B: 110 dB for 150 mV input

Maximum input Level for Phono 1: 250 mV (RMS), THD 0,02% at 1 kHz

Output Level/Impedance:

Tape REC (PIN): 150 mV/220 ohms

Tape REC (DIN): 30 mV/80 kohms

Pre OUT: 1 V/470 ohms

Frequency Response:

Phono: RIAA standard curve +0,2 dB, -0,2 dB

AUX, Tape: 7 Hz to 50,000 hZ +0 dB, -1 dB

Bass Tone control:

Turnover at 150 Hz : ±7.5 dB at 50 Hz

Turnover at 400 Hz : ±7.5 dB at 100 Hz

Treble Tone control:

Turnover at 3 kHz : ±7.5 dB at 10,000 Hz

Turnover at 6 kHz : ±7.5 dB at 20,000 Hz

Loudness Control (at -30 dB Volume Level):

1 at 50 Hz 1) +3 dB, 2) +6 dB, 3) +9 dB

2 at 100 Hz 1) +3 dB, 2) +6 dB, 3) +9 dB

GAIN Control: +10 dB, 0 dB, -10 dB

Subsonic Filter: 18 Hz, 6dB/oct

Low Filter: 40 Hz, 12 dB/oct

High Filter: 8 kHz, 12 dB/oct

General

Power Requirements: 50/60 Hz 120 - 240 V

Power Consumption: 600 watts

A.C.Outlet: Switched 2, Unswitched 1

Dimensions (W x H x D): 430 x 149 x 384 mm (15-15/16" x 5-7/8" x 15-1/8")

Weight: 14,5 kg (32,0 lbs) Net