VLC Microphone Preamplifier/EQ/DI
HAZELRIGG INDUSTRIES
19
Line Amp Section
The EQ output feeds a 6072 line amp stage.
The cathode output of the final stage is coupled
through a proprietary polypropylene capacitor to the primary of the output transformer.
Power Supplies
Primary power from the AC mains is connected to the VLC through a standard IEC power input
connector. The Power switch energizes all three power supplies. A fuse, accessible on the IEC
input connector, protects the VLC. The power transformer is a toroidal unit custom-made for the
VLC and has primary taps for 115 and 220-240 volt operation.
A switch on the rear makes it
quick and easy to go between voltages. Be sure to also change the fuse to the appropriate value.
Filament
supply
The power transformer output is rectified by a bridge rectifier and filtered before being regulated
to 12.0 volts by a three-terminal regulator. The negative output of this supply is grounded.
Although the tube filament is rated for 12.6 volts, utilization of 12.0 volts has no effect on the
operation of the VLC.
B+
supply
Two separate regulated voltages are required for the plates of the VLC. The B+ is filtered with
long-life, low-leakage computer-grade filter capacitors before being regulated and extensively
bypassed and decoupled. The negative side of the supply is grounded.