Owner’s Manual Model Reference 75 Stereo Power Amplifier
Contents Model Reference 75 Stereo Amplifier Illustrations 3 Preface 4 Packaging 4 Accessories 4 Warnings 4 Vacuum Tubes and Preparation for Use 5 Panel Controls 5 Installation 5 – 6 Connections 6 – 7 Remote Turn-on Connections 7 Operating Procedure 7 Output Tube Bias Adjustment 8 Servicing 8 Cleaning 9 Disposal and Recycling Guidelines 9 Limited Warranty 9 Specifications 10 2
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Preface Please take time to carefully read and understand the following instructions before you install or attempt to operate this equipment. Becoming familiar with the product and its correct operating procedures will help assure you of maximum musical enjoyment and reliable operation. The effort you invest now will be well rewarded in the years ahead. Packaging Save all packaging accompanying this product.
DO NOT ATTEMPT TO OPERATE THIS EQUIPMENT BEFORE INSTALLING THE NUMBERED VACUUM TUBES IN THEIR RESPECTIVE SOCKETS. Vacuum Tubes and Preparation for Use Your Reference 75 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.
The ‘ambient’ operating temperature should never exceed 120 F or 49 C. Improper installation will cause premature tube failure and will affect your warranty, as well as the service life of the unit. It is normal for a vacuum tube power amplifier to run quite warm, and if used for prolonged periods, hot to the touch. All components within are, however, operated at safe, conservative levels and will not be improperly affected thereby, providing the requirements outlined above are adhered to.
The Reference 75 uses a grounding system that does not require a ground-lifter adaptor plug on the A.C. power cord to minimize hum. The power cord supplied with the Reference 75 has a standard grounding plug to provide maximum safety when properly connected to a grounded wall receptacle. If there is any question regarding proper grounding procedures in your installation, seek help from a qualified technician.
Output Tube Bias Adjustment Servicing 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 approximately 27 watts of their 60 watt rating. This point of operation provides ‘enriched’ Class AB1, and will satisfy the most critical listener. For best results, operate and adjust the Reference 75 at 117.5 VAC (230 VAC).
Cleaning Limited Warranty To maintain the new appearance of this amplifier, occasionally wipe the front panel and top cover with a soft, damp (not wet) cloth to remove dust. A mild, non-alkaline soap solution may be used to remove fingerprints or similar smudges. Cleaners containing abrasives should not be used as they will damage the anodized finish of the front panel. A small, soft paintbrush is effective in removing dust from bevels, the recessed nameplate and other features of the front panel.
Specifications POWER OUTPUT: 75 watts per channel continuous from20Hz to 20kHz. 1kHz total harmonic distortion typically 0.6% at 75 watts, below 0.05% at 1 watt. Approximate actual power available at ‘clipping’ 76 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) 7Hz to 60kHz.
