D.W. FEARN
VT-7 Compression Amplifier
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D E S C R I P T I O N
The Model VT-7 Vacuum Tube Compression Amplifier is designed to provide recording pro-
fessionals with a sonically superior signal processing device. It is typically used in sound
recording studios for processing individual tracks or, when the channels are linked, as a
stereo compressor. The inputs and outputs are at line level.
The VT-7 in many ways recreates the sound of the classic tube compressors of the 1960s, but
using modern gain control circuitry. The audio path is entirely Class-A triode vacuum tubes,
similar to classic designs but updated with improved modern passive components and com-
puter-aided circuit optimization. Because of the unique qualities of vacuum tubes, the VT-7
has a clarity, transparency, and warmth that solid state compressors lack. Its modern design
and construction allows the VT-7 to exceed the performance of vintage vacuum tube com-
pressors.
The VT-7 is capable of over 30dB of gain reduction, but all units above serial number 19 are
limited to 15dB of compression to provide greater resolution in the Threshold control for set-
ting moderate amounts of compression. The VT-7 can be special-ordered with the full 30dB
range. Although a VT-7 could be modified after construction, it is rather involved.
It is designed for use in the professional recording environment. It accepts a low impedance
(600 ohm nominal source impedance) balanced or unbalanced line level (n4dBm)
signal. It features two independent channels, which can be linked to provide precise gain
reduction tracking of a stereo signal. There are controls for compression threshold, gain,
attack and release times, and compression curve. Additional controls are used to link the two
channels and to switch the true VU meter between measuring gain reduction and output
level. It is built to sound great for a long time, with top quality parts used throughout; the out-
put transformers and many other components are custom-made for the VT-7.
All five power supplies (filament, B+, and three voltages for the solid-state control circuitry
and meter amp) are solid state and fully regulated.
The VT-7 is not mass-produced. Each one is hand-made and meticulously tested and listened
to before shipment to the customer.
