Crown Audio VT-15 manual Compression Section

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response, low phase shift, excellent square wave response, low distortion, and high noise immunity. The secondary of is connected directly to the grid of the first amplifier stage.

First stage

The first stage is a selected 6072 configured as a Class A voltage amplifier with a gain of approximately 30. Negative feedback from the plate of the second stage reduces distortion, flattens the frequency response, and makes the gain of the first two stages less dependent on individual vacuum tube characteristics.

Second stage

The output of the first stage is coupled to the grid of the second stage through a polystyrene capacitor. This stage operates as a Class A voltage amplifier with a gain of approximately 30. The plate is coupled through a polypropylene capacitor to the top of a potentiometer (Preamp Gain).

Third Stage

The arm of the Preamp Gain potentiometer feeds the grid of the third stage (a 6072A), which also operates Class A with a gain of approximately 30. This stage is capacitively-coupled to the grid of the output stage through a polystyrene capacitor.

Preamp Output Stage

The output stage operates as a cathode follower, presenting a comparatively low output impedance (approximately 800 ohms). The cathode output is coupled through a proprietary polypropylene capacitor to either the Equalizer or Compressor section.

Compression Section

Audio from the mic preamp is fed to the input of the pulse-width modulator (PWM) board, which provides the gain reduction. The audio output of the PWM goes through sidechain cir- cuitry which determines the control voltage and hence the amount and characteristics of the compression.

The compressor preamp consists of two stages of a 6072A dual triode, which then feeds either the Line Amp or the Equalizer circuitry.

Equalization Section

The passive LC (inductor/capacitor) equalization is inserted either at the mic preamp output or the compressor output. A 6N1P dual triode makes up the gain and then feeds either the Compressor input or the Line Amp.

Line Amp Section

Either the eq output or the compressor output feeds a 6N1P dual triode with both sections in parallel to provide line-level output. The output transformer is custom-made for us by Jensen Transformers, Inc. and is the same transformer we use on all of our products.

D.W. FEARN

VT-15 Recording Channel

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Contents Fearn How to Contact us Fearn Certificate of RoHS CompliancePage VT-15 Vacuum Tube Recording Channel Final Test Report B l e o f C o n t e n t s List of IllustrationsCopyright 2007 D.W. Fearn & Associates Limited 5-Year Warranty History of the VT-15 Vacuum Tube Recording Channel Fearn E C I F I C AT I O N S E C I F I C AT I O N S C O N T ’ D S C R I P T I O N Fearn Power S TA L L AT I O NInput and Output Connections Grounding and ShieldsVT-15 front panel controls and indicators E R AT I O NControl Set-up Mic Input OutputOntrols see Figure Compressor Controls Equalization Controls Benc h Test Initial Set-UpFearn E O RY O F O P E R AT I O N Preamp SectionCompression Section VU Meter and Meter Amplifier Fearn I N T E N a N C E VU Meter Calibration Factory Check-Out TroubleshootingWarranty Repair

VT-15 specifications

The Crown Audio VT-15 is a robust loudspeaker system that has gained recognition for its advanced technologies and impressive audio performance, making it ideal for various applications, including live events, installations, and broadcast scenarios. Built with durability and sound quality in mind, the VT-15 serves both professionals and enthusiasts in the audio industry.

One of the standout features of the VT-15 is its high-efficiency design, which is achieved through advanced driver technology. The loudspeaker is equipped with a premium 15-inch woofer that delivers powerful low-end reproduction, ensuring a solid bass presence that enhances the overall listening experience. This, combined with a high-frequency compression driver that operates at 1 inch, ensures clear and articulate treble frequencies, resulting in a balanced sound profile suitable for different musical genres.

The VT-15 incorporates Crown’s patented Waveguide technology, designed to provide consistent and controlled sound dispersion. This feature allows the loudspeaker to effectively cover large areas without experiencing significant drop-off in audio fidelity, making it a great choice for medium to large venues. The controlled directivity also means that listeners in various positions within the space can enjoy a similar audio experience, enhancing the performance of any event.

Another defining characteristic of the VT-15 is its rugged construction. Built with a reinforced enclosure, it is designed to withstand the rigors of touring and heavy use in fixed installations. The cabinet is constructed from high-quality materials that minimize vibration and resonance, further contributing to the clarity of sound. Its lightweight design allows for easier transport and setup, making it a practical choice for audio professionals on the go.

In terms of connectivity and compatibility, the VT-15 features versatile input options, allowing it to integrate seamlessly with various audio systems. Whether used in conjunction with other Crown products or compatible equipment from different brands, the VT-15 ensures flexibility in configuration.

Overall, the Crown Audio VT-15 stands out as a high-performance loudspeaker that combines advanced technologies, durability, and sound fidelity. Its powerful drivers and innovative design make it a reliable choice for any professional audio application, providing users with the quality and performance they demand. Whether for live music, presentations, or installations, the VT-15 delivers exceptional audio experiences that elevate any event or setting.
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