Akai AT-K33 - User Manual

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Overview

The Akai AT-K33/L/J and AM-U33/J are a stereo integrated amplifier and an FM/AM stereo tuner, respectively, designed to work together as a high-fidelity audio system. This manual provides detailed information for both models, including specifications, dismantling procedures, controls, principal parts locations, voltage conversion, and adjustment procedures.

Akai AT-K33/L/J FM/AM Stereo Tuner

Function Description:

The AT-K33/L/J is an FM/AM stereo tuner designed to receive radio broadcasts across various frequency bands. It features digital frequency display, signal strength indicators, and stereo reception capabilities. The tuner is equipped with controls for power, FM mode selection, muting, and band selection, along with a tuning knob for precise station selection. Specific models (AT-K33L) also include LW band reception and an AM antenna selector.

Important Technical Specifications:

FM Tuner Section (AT-K33/L):

Tuning Frequency Range: 87.5 MHz to 108.0 MHz
Usable Sensitivity (300 ohms): 1.9 µV
Capture Ratio: 1.3 dB
Selectivity (IHF, 400 kHz): 65 dB
Image Rejection: 56 dB
IF Rejection: 90 dB
Spurious Rejection: 85 dB
AM Suppression: 60 dB
Sub Carrier Suppression: 85 dB
S/N Ratio (Mono/Stereo): 73 dB / 65 dB
T.H.D. (Mono/Stereo): 0.10% / 0.15%
Stereo Separation (1 kHz): 45 dB
Muting Level: 22 dB

AM Tuner Section (MW - AT-K33/L):

Tuning Frequency Range: 525 kHz to 1,605 kHz
Usable Sensitivity (Bar/Ext.): 100 µV/m / 10 µV
Selectivity (IHF): 30 dB
Image Rejection: 48 dB
IF Rejection: 33 dB
S/N Ratio: 50 dB
T.H.D.: 0.3%

LW (AT-K33L only):

Tuning Frequency Range: 135 kHz to 350 kHz
Usable Sensitivity (Bar/Ext.): 200 µV/m / 17 µV
Selectivity (IHF): 30 dB
Image Rejection: 45 dB
IF Rejection: 33 dB
S/N Ratio: 50 dB
T.H.D.: 0.3%

Output Section:

Output Level (FM 100% Mod./AM 30% Mod.): 775 mV / 250 mV
Output Impedance: 3.3 kohms
Power Consumption: 10W
Dimensions: 440(W) x 98(H) x 290(D) mm (17.3 x 3.9 x 11.4 inches)
Weight: 5.35 kg (11.8 lbs)

FM Tuner Section (AT-K33J):

Tuning Frequency Range: 76 MHz to 90 MHz
Usable Sensitivity (300 ohms): 1.9 µV
Capture Ratio: 1.3 dB
Selectivity: 65 dB
Image Rejection: 60 dB
IF Rejection: 85 dB
AM Suppression: 60 dB
S/N Ratio (Mono/Stereo): 73 dB / 65 dB
T.H.D. (Mono/Stereo): 0.08% / 0.12%
Stereo Separation (1 kHz): 48 dB
Frequency Response: 20 Hz to 15 kHz, ±1 dB
Muting Level: 22 dB

AM Tuner Section (AT-K33J):

Tuning Frequency Range: 525 kHz to 1,605 kHz
Usable Sensitivity: 100 µV/m
Selectivity: 30 dB
Image Rejection: 48 dB
S/N Ratio: 55 dB
T.H.D.: 0.3%

Output Section (AT-K33J):

Output Level (FM 100% Mod./AM 30% Mod./CAL. Tone): 775 mV / 250 mV / 388 mV
Power Requirement: AC 100V, 50/60 Hz
Power Consumption: 10W
Dimensions: 440(W) x 105(H) x 290(D) mm
Weight: 5.4 kg

Usage Features:

Digital LED Display: Provides clear indication of the tuned frequency.
Signal Strength Indicators: Visual representation of the received signal strength.
FM Muting Indicator: Shows when the muting function is active.
FM Stereo Indicator: Lights up when a stereo FM broadcast is received.
Tuning Knob: For manual station tuning.
AM/FM Selector: To switch between AM and FM bands (AT-K33L only).
MW/LW Selector: To select between MW and LW bands (AT-K33L only).
CAL Tone Switch: For calibration tone output (AT-K33J only).
Antenna Terminals: For connecting external FM/AM antennas.
AM Ferrite Bar Antenna: Built-in antenna for AM reception.
Output Jacks: RCA outputs for connecting to an amplifier.

Maintenance Features:

Dismantling of Unit: Detailed photographic instructions for disassembling the unit for service.
Voltage Conversion: Instructions for internally switching power requirements for different regions (U/T model only).
Tuner Adjustments: Comprehensive procedures for FM and AM section adjustments, including:
- FM Center Voltage and Distortion Factor adjustments.
- Signal LED Sensitivity and Digital LED Display Frequency adjustments.
- High/Low Range Scale and Sensitivity adjustments.
- Muting Level adjustment.
- PLL IC Free Running Frequency adjustment.
- Stereo Separation adjustment.
- AM IF Coil and Scale Indication adjustments.
Tuning Cord Threading: Instructions for re-threading the tuning cord.
P.C. Board Classification: Lists and identifies various printed circuit boards within the unit.

Akai AM-U33/J Stereo Integrated Amplifier

Function Description:

The AM-U33/J is a stereo integrated amplifier designed to amplify audio signals from various sources and drive loudspeakers. It features multiple input selectors (Phono, Tuner, Aux, Tape 1, Tape 2), tone controls (Bass, Treble), loudness compensation, and a power meter. The amplifier also includes a headphone jack and outputs for two sets of speakers.

Important Technical Specifications:

Power Amplifier Section (AM-U33):

Rated Power Output: 43 watts per channel, minimum RMS, at 8 ohms from 20 Hz to 20,000 Hz with no more than 0.05% total harmonic distortion.
Power Bandwidth (IHF -3 dB): 5 Hz to 70 kHz/8 ohms (Total harmonic distortion: 0.1%)
Signal to Noise Ratio (IHF-A) (Phono/Aux): 85 dB / 102 dB
Residual Noise (IHF-A): 180 µV/8 ohms
Channel Separation (IHF): Better than 60 dB at 1 kHz
Damping Factor: More than 60 (1 kHz, 8 ohms)
Output (Speaker/Headphone): 4 to 16 ohms

Preamplifier Section (AM-U33):

Input Sensitivity/Impedance (Phono/Aux, Tuner, Tape): 3 mV/47 kohms / 150 mV/100 kohms
Output Level/Impedance (Tape Rec/Pre Out): 150 mV / 1V/600 ohms
Frequency Response (Phono RIAA Deviation/Tuner, Aux, Tape): 20 Hz to 20 kHz ±0.3 dB / 6 Hz to 100 kHz +0 dB, -3 dB
Tone Control (Bass/Treble): ±8 dB (100 Hz) / ±8 dB (10 kHz)
Loudness Control (Volume set at -30 dB position): +10 dB (100 Hz) / +6 dB (10 kHz)
Phono Max Input (1 kHz): MM: 200 mV
Power Requirements: 120V, 60 Hz for U.S.A. and Canada; 220V, 50 Hz for Europe except UK; 240V, 50 Hz for UK and Australia; 110V/220V/240V, 50/60 Hz internally switchable for other countries.
AC Outlet: 2 switched, 1 unswitched
Power Consumption: 220W (U/T), 300W (CEE), 315W (UK, SAA)
Dimensions: 440(W) x 105(H) x 323(D) mm (17.3 x 4.1 x 12.6 inches)
Weight: 7.9 kg (17.4 lbs)

Power Amplifier Section (AM-U33J):

Rated Power Output: 25 watts per channel, minimum RMS, at 8 ohms from 20 Hz to 20,000 Hz with no more than 0.05% total harmonic distortion.
Power Bandwidth: 10 Hz to 50 kHz/8 ohms (Total harmonic distortion: 0.1%)
Signal to Noise Ratio (IHF-A) (Phono/Aux): 82 dB / 100 dB
Channel Separation (IHF): Better than 55 dB at 1 kHz
Damping Factor: More than 50 (1 kHz, 8 ohms)

Preamplifier Section (AM-U33J):

Input Sensitivity (Phono/Aux, Tuner/Tape): 3 mV / 150 mV / 400 mV
Output Level (Tape Rec): 150 mV
Frequency Response (Phono RIAA Deviation/Tuner, Aux, Tape): ±0.3 dB / 6 Hz to 100 kHz +0 dB, -3 dB
Tone Control (Bass/Treble): ±8 dB (100 Hz) / ±8 dB (10 kHz)
Power Requirement: AC 100V, 50/60 Hz
Power Consumption: 75W
Dimensions: 440(W) x 105(H) x 290(D) mm
Weight: 7.1 kg

Usage Features:

LED Bar Meters: Visual display of output power levels.
Stereo Balance Control: Adjusts the balance between left and right channels.
Power Switch: Turns the amplifier on/off.
Headphone Jack (Phones): For private listening.
Meter Selector: Selects the range for the power meters.
Bass Control: Adjusts low-frequency response.
Treble Control: Adjusts high-frequency response.
Loudness Switch: Engages loudness compensation for enhanced bass and treble at low volumes.
Mode Selector: Switches between stereo and mono modes.
Input Selector Switches and Indicators: Selects the audio source (Phono, Tuner, Aux, Tape 1, Tape 2) with corresponding indicators.
Volume Control: Adjusts the overall output volume.
Ground Terminal: For connecting a turntable ground wire.
Speaker Terminals: For connecting loudspeakers.
AC Cord/Inlet: Power connection.
AC Outlets: Switched and unswitched AC outlets for connecting other audio components.
Phono Jacks: Inputs for a turntable.
Tuner Jacks: Inputs for a tuner.
Aux Jacks: Auxiliary inputs for other audio sources.
Tape 1/2 System Recording (REC)/Play Jacks: Inputs/outputs for tape decks.
Pre Out and Main In Jacks: Allows for connecting external processors or using the preamplifier and power amplifier sections separately.
MIC Jack, MIC Volume Control, Echo Control: (AM-U33J only) For microphone input and echo effects.
Audio Mute Switch: (AM-U33J only) Mutes the audio output.

Maintenance Features:

Dismantling of Unit: Detailed photographic instructions for disassembling the unit for service.
Voltage Conversion: Instructions for internally switching power requirements for different regions.
Adjustments: Procedures for:
- Power Meter Sensitivity Adjustment: Calibrates the LED bar meters to accurately display output power.
- Center Off-Set Voltage Adjustment: Adjusts the DC offset at the speaker terminals to minimize noise.
P.C. Board Classification: Lists and identifies various printed circuit boards within the unit.

Both models are designed with safety critical components that should only be replaced with manufacturer's recommended parts for continued safety. Specifications and design are subject to change without notice for improvement purposes.