Crown Audio VT-15 manual S C R I P T I O N

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D E S C R I P T I O N

The D.W. Fearn VT-15 utilizes circuitry developed for the VT-1/VT-2 Vacuum Tube Microphone Preamplifiers, the VT-7 Stereo Compressor, and the VT-4 LC Equalizer.

The Model VT-15 Recording Channel is designed to provide recording professionals with a sonically superior input device. It is typically used in sound recording studios for recording individual tracks. A quality microphone, electric instrument, or line-level signal is connected to a VT-15 input, and the VT-15 provides a line-level output. In most situations, the VT-15 will feed directly to the input of the recorder.

The microphone preamplifier section is a recreation of the classic tube preamps of the 1960s, updated with improved modern passive components and computer-aided circuit optimiza- tion. Because of the unique qualities of vacuum tubes, the VT-15 has a clarity, transparency, and warmth that solid state preamps lack. Its modern design and construction allows the VT- 15 to exceed the performance of vintage vacuum tube preamps. It accepts all low impedance balanced microphones. It features a regulated +48 volt supply for phantom powering con- denser microphones, a switchable 20 dB input pad, a phase (polarity) reversal switch, a switchable input network to accommodate very low impedance microphones (typically trans- formerless types), and a true VU meter. The input can be switched to a front-panel quarter- inch jack for recording electric instruments.

The compressor in the VT-15 is identical to a single channel of the D.W. Fearn VT-7 Stereo Compressor. In many ways, the VT-15 compressor recreates the sound of the classic tube compressors of the 1960s, but using modern gain control circuitry. The actual gain control element is a pulse-width modulator, driven by solid-state circuitry. However, the audio path is entirely class-A triode vacuum tubes. There are controls for compression threshold, gain, attack and release times, and compression characteristics.

The equalization section of the VT-15 is based on the D.W. Fearn VT-4 Vacuum Tube LC Equalizer. It uses identical circuitry, but is limited to just one frequency each in the low boost, low cut, high boost, and high cut sections. These were the frequencies most often used on the VT-4. The low frequency boost and cut have shelving curves. The high-frequency boost is a peaking type, with adjustable Q. The high-frequency cut is shelving. All the controls are con- tinuously adjustable.

The input and output transformers are custom-made for us by Jensen Transformers, Inc. All power supplies are solid state and fully regulated. All internal switching uses sealed, gold-con- tact relays for low noise and long, quiet operation. The relays never need cleaning.

A combination of four 6072A and two 6N1P dual triodes are used in the VT-15.

A total of 12 separate power supply voltages are required internally for the VT-15 circuitry. All are solid-state and fully regulated.

The VT-15 is not mass-produced. Each one is hand-made and meticulously tested and lis- tened to before shipment to the customer. It is built with pride and precision. The VT-15 is designed and built to perform in your studio for decades to come.

VT-15 Recording Channel D.W. FEARN