User Guide VSi75 Integrated Amplifier H I G H D E F I N I T I O N®
Contents Preface 3 Illustrations 4 Warnings 5 Installation Vacuum Tubes 6 In your System 7 Connections Rear Panel Connections 8 AC Power Connection 9 Operation Power-up Procedure 10 General Notes about Usage 11 Resetting Controls 11 Automatic Mute Function 12 Front Panel Control Functions 13 Remote Control Functions 14 Maintenance Adjusting Vacuum Tube Bias 15 Servicing 16 Cleaning 16 Disposal and Recycling Guidelines 16 Limited Warranty 17 Specifications 18
Preface Thank you for selecting the VSi75 as part of your music listening system. The engineers and designers at Audio Research have spent countless hours of listening and testing to create an Integrated Amplifier of the highest caliber for music reproduction. The VSi75 has been designed to provide you many years of playback. Please take a few minutes to read through this guide to help you better understand and optimize your new integrated amplifier.
Illustrations Front Panel POWER MUTE VOL DN VOL UP BIAS INPUT Rear Panel WARNING VSi75 INTEGRATED AMPLIFIER R 1 2 3 4 5 TO PREVENT FIRE AND SHOCK HAZARD, DO NOT EXPOSE THIS DEVICE TO RAIN OR MOISTURE. UNIT MUST BE OPERATED IN A HORIZONTAL POSITION. -DO NOT OPERATE WITH COVERS REMOVEDUNIT CONTAINS VOLTAGES WHICH MAY BE HAZARDOUS. TAPE OUT PLYMOUTH, MINNESOTA MADE IN U.S.A.
Warnings Do not touch hot tubes. Keep away from children. To prevent fire, or shock hazard, do not expose your VSi75 to rain or moisture. This unit contains voltages which can cause serious injury or death. Do not operate with top plate removed. Refer servicing to your authorized Audio Research dealer or other qualified personnel. The detachable power cord on your VSi75 is equipped with a heavy gauge, 3-conductor cable and a standard three-prong grounding plug.
Installation Vacuum Tubes Before you operate the VSi75 Your VSi75 amplifier is shipped with the vacuum tubes packed in foam blocks. These must be unpacked and installed before you attempt to operate the amplifier. Included are two matched pair of KT120 output tubes, and two 6H30 dual triodes used in the input stage. Proceed according to the following instructions.
Installation In your System To insure normal component life and safe operation this unit must be operated only in a horizontal (upright) position. Adequate airflow and proper cooling thereby can occur only if there is no restriction below, behind and above the unit. The four special non-marring elastomer feet provide adequate spacing only from a smooth, hard surface. Never operate the unit while it is sitting on a surface such as a rug or carpet.
Connections Rear Panel Connections All five sets of Single-Ended inputs are clearly marked to indicate use. 6-Output binding posts (+) and (-), L & R, for 4 or 8 ohm speaker connection 1 - Power line cord inlet 1 - Power line fuseholder MATCHING: It is important to use as close as possible an impedance match between the amplifier and speaker for optimum transfer of power to the speaker with minimum distortion.
Connections AC Power Connection It is essential that the amplifier be connected to a wall AC power receptacle, or a similar heavy-duty source. If it is connected to convenience receptacles on preamplifiers, etc., the full sonic capabilities of both the VSi75 and the preamplifier will be compromised. For the very best sonic performance, the VSi75 should be connected to its own AC power circuit branch, protected by a 15 or 20 amp breaker.
Operation Power-up Procedure Make sure you have read and complied with the Installation and Connection instructions prior to attempting operation. Press the “Power” switch. The Audio Research logo will appear for a few seconds, then “Mute” will flash and a numeric countdown will show on the LCD display while power supply stabilizes, indicating operation of automatic muting circuit.
Operation General Notes about Usage If you turn off the VSi75 wait at least five minutes before turning it on again. This brief cool down period will reduce stress on the output tubes and potential damage to them. Audio Research does not recommend leaving your VSi75 on 24 hours a day as is the custom of some listeners to achieve maximum sonic performance on demand. While this is often recommended for solid-state equipment, Audio Research does not recommend this procedure for vacuum tube power amplifiers.
Operation Automatic Mute Function The VSi75 has several provisions to help protect against misuse of the exceptional dynamic range and wide bandwidth that it offers. It is not subject to damage itself, but some speakers are more limited in their ability to withstand signal extremes. These provisions, both manual and automatic, are designed not to interfere with the listening experience, while giving reasonable protection against warm-up surges and power line interruptions.
Operation Front Panel Control Functions VOLUME CONTROL: Pressing the down or up button decreases or increases the volume level. Note that the VSi75 has 103 individual steps across the volume control adjustment range. The corresponding level is indicated on the LCD display. INPUT: Allows selection of any of five single-ended input sources 1, 2, 3, 4, and 5. Pressing the Input selector button steps through each input as indicated on the LCD display.
Operation Remote Control Functions In addition to the functions on the front panel, the handheld remote also offers the following functions: MONO: Toggles the VSi75 between Stereo and Mono mode. “STEREO” or “MONO” are displayed in the bottom right of the LCD display, indicating mode. 1-5: Provides direct access to any of the five single-ended inputs on the VSi75. DISP UP/DISP DOWN: Adjust the brightness of the backlighting on the LCD display. Fifteen levels of illumination plus off are available.
Maintenance Adjusting Vacuum Tube Bias As shipped from the factory, the output “bias” adjustments are set for a nominal 65mA per KT120 tube. Under these idle conditions the tubes are each dissipating a conservative amount of power of their total capacity. This point of operation provides “enriched” Class AB 1, and will satisfy the most critical listener. For best results, operate and adjust the VSi75 at 120V AC.
Maintenance Servicing CAUTION: Your VSi75 contains sufficient levels of voltage and current to be lethal. Do not tamper with a component or parts inside the unit. Refer any needed service to your authorized Audio Research dealer or other qualified technician. Should service be necessary, please contact your Audio Research dealer, or Audio Research Customer Service (763) 5779700.
Limited Warranty Audio Research Corporation products are covered by a 3-Year Limited Warranty, or a 90-Day Limited Warranty on vacuum tubes. This Limited Warranty initiates from the date of purchase, and is limited to the original purchaser, or in the case of demonstration equipment, limited to the balance of warranty remaining after original shipment to the retailer or importer.
Specifications Power Output: 75 watts per channel continuous from 20Hz to 20kHz. 1 kHz total harmonic distortion typically 1.5% at 75 watts, .05% at 1 watt. Approximate actual power available at “clipping” 80 watts (1kHz). (Note that actual power output is dependent upon both line voltage and “condition” i.e.: if power line has high distortion, maximum power will be affected adversely, although from a listening standpoint this is not very critical.) Power Bandwidth: (-3dB points) 12Hz to 70kHz.
