JFET BUFFER AND RECORD OUTPUT
DRIVER
TAPE MONITOR
SWITCHING
VOLUME AND
BALANCE CONTROLS
LINE AMPLIFIER
TONE CONTROL SYSTEM
MUTING
SYSTEM
POWER SUPPLY
The output of the Selector System is followed by a very high
The Tape Monitor Switch drives a relay to break the line input path to insert tape input signals. The relay employs gold plated contacts, and allows optimum signal routing by placing the relay close to the Tape Input jacks and the Input Selector System.
The Volume Control is a precision detented potentiometer employing
The 915 Line Amplifier is a
The feedback loop contains two user selectable paths: one conventional path for flat response, and another path allowing insertion of a tone control network. This arrangement allows maximally
flat response and the shortest, cleanest signal path when tone control action is not required.
The output of the Line Amplifier is capacitor coupled to the outputs of the preamplifier.
The Tone In Switch allows complete removal of the tone controls from the signal path. This switching is accomplished with the same type of
The Bass Control is of a moving inflection, variable turnover type, and the Treble Control is of a shelving, variable turnover type. These types of tone controls offer the best “tools” for modifying tonal balance without introducing unwanted side effects.
The Muting System monitors the difference between the raw (unregulated) power supply voltage and the regulated power supply voltage. During the
The muting is accomplished by grounding the output of the Line Amplifier, using a relay with gold contacts.
The printed circuit board mounted power transformer utilizes dual primaries for worldwide operation. Internal jumpers configure the power supply for rated operation from 100 to 120 VAC, or 200 to 240 VAC, at 50 or 60 Hz. A generous amount of power supply headroom allows actual operation over much wider ranges of 85 to 130 VAC, or 170 to 260 VAC.
The power transformer feeds a conventional split full wave bridge rectifier system. Power supply capacitance is 4700 pF per rail. Stable and consistent ± l5 volt power for the amplifier circuits is
provided by