Voice Channel™ Tube Channel Strip with Digital Connectivity USER’S GUIDE
IMPORTANT SAFETY INSTRUCTIONS – READ FIRST This symbol, wherever it appears, alerts you to the presence of uninsulated dangerous voltage inside the enclosure. Voltage that may be sufficient to constitute a risk of shock. This symbol, wherever it appears, alerts you to important operating and maintenance instructions in the accompanying literature. Please read manual. Read instructions: Retain these safety and operating instructions for future reference.
Voice Channel Tube Channel Strip with Digital Connectivity IMPORTANT SAFETY INSTRUCTIONS – READ FIRST .......................................................................... 1 INTRODUCTION .................................................................................................................................... 4 INSTALLATION ..................................................................................................................................... 4 AC Power Hookup....................
LIST OF FIGURES FIGURE FIGURE FIGURE FIGURE FIGURE FIGURE FIGURE 1 2 3 4 5 6 7 – – – – – – – Preamp section ................................................................................................................. 6 Dynamics Section.............................................................................................................. 6 Equalizer Section ..............................................................................................................
INTRODUCTION The ART Voice Channel™ is the answer to your recording and computer audio interface needs. Our secondgeneration discrete Class-A microphone preamp provides clean quiet gain while maintaining incredible transparency. A powerful dynamics processor subtly controls transients and noise of the most demanding sources. The ART Voice Channel’s semi-parametric EQ offers wide tune-ability and can be patched before OR after the dynamics processor.
FRONT PANEL CONTROLS and JACKS Mic Preamp Controls The Voice Channel™ input consists of a discrete Class-A differential preamp. The circuit is optimized for low impedance microphones as well as line level signals. Up to 60dB of gain is available from this stage. The output can be inverted using the INVERT switch. The impedance of the front and rear XLR inputs is continuously variable for fine-tuning the preamp to a wide variety of mics. Phantom power is available on the XLR inputs as well.
FIGURE 1 – Preamp section Tube Voltage Switch The vacuum tube preamp section can be adjusted to run at two different plate voltages. Refer to Figure 2 for the location of the switch. Choose the “NORMAL” setting for adding warmth to the input signal. This setting has an increased amount of tube saturation at higher signal levels. Choose the “HIGH” setting to increase overall gain, headroom, and bandwidth. NOTE: The change between tube voltage modes is gradual, taking 10 to 20 seconds to be fully activated.
Dynamic Processor Controls The ART Voice Channel™ dynamics section consists of an above threshold Compressor/Limiter with Deesser plus a selectable Expander/Gate. The attack and release controls allow a wide range of adjustment while the complex detector assures fast response without distortion. The De-esser is frequency tunable. Threshold Control This control sets the level, above which the Compressor/Limiter in the Voice Channel™ starts to act on the input signal.
Release Control The RELEASE control sets the time the Compressor/Limiter takes to increase the gain after the input level drops. Longer settings maintain the dynamics of the input signal, while shorter settings reduce the dynamics. Shorter settings will also increase the apparent reverberation, and at extreme gain reduction settings, lead to “breathing” artifacts2 Gain Reduction LED Meter The GAIN REDUCTION meter displays the Compressor/Limiter’s attenuation action.
Semi-Parametric EQ The ART Voice Channel™ offers a four-band semi-parametric equalizer. The EQ can be bypassed as well as positioned before or after the dynamics processing section. Each band has + 15dB of control range. The High and Low EQ bands are shelving type with a switch selectable turnover point. The two Mid bands can be continuously tuned over a five octave range.
FIGURE 4 – Signal Flow Block Diagram Output Level Control The OUTPUT LEVEL control provides gain or attenuation to adjust for a variety of system operating levels. This control affects the levels sent to the A/D converter and to the balanced analog OUTPUT jacks. Output Level Meters The ART Voice Channel™ provides both analog and digital output meters. The meters monitor the signal level just after the output control. This signal is sent to both the analog and digital outputs.
FIGURE 5 – Output Section Sample Rate/Dither Control The SAMPLE RATE/DITHER knob selects the sample rate for the AES/EBU, S/PDIF, and optical outputs. It also selects the dither applied. Set the switch appropriately to match up with 16 or 24 bit encoding. NOTE: This control does NOT affect the USB output. Optical Output Switch The OPTICAL OUTPUT switch sets the signal format of the rear panel OPTICAL OUTPUT connector.
REAR PANEL CONNECTIONS Mic/Line Input This “combo” jack provides balanced inputs to the microphone preamplifier. The XLR connection is in parallel with the front input jack XLR. The input impedance of both XLR connections is variable by the front panel Impedance knob. The rear 1/4” input of the combo jack overrides the front panel XLR input when used. This input’s impedance is NOT affected by the front panel Impedance control and is fixed at 20K Ohms.
FIGURE 7 – Wordclock Termination ADAT Input Jack The optical ADAT input allows the Voice Channel™ A/D converter to synchronize to systems using ADAT optical connections. The Voice Channel™ inserts its output in channels 1 and 2 of the ADAT stream while passing through channels 3 thru 8. Select ADAT/16 or ADAT/24 with the Sample Rate control on the front panel to enable this mode.
APPLICATIONS Bypassing Components Of The Voice Channel™ To bypass the vacuum tube microphone preamp: Use the preamp INSERT INPUT jack. To bypass the Compressor/Limiter: Set the RATIO control fully counterclockwise to 1:1. To bypass the Expander/Gate: Set the EXPANDER/GATE THRESHOLD control fully counterclockwise to OFF. To bypass the EQ: Use the EQ bypass switch.
WARRANTY INFORMATION Limited Warranty: Applied Research and Technology will provide warranty and service for this unit in accordance with the following warrants: Applied Research and Technology, (A R T) warrants to the original purchaser that this product and the components thereof will be free from defects in workmanship and materials for a period of three years from the date of purchase.
SERVICE The following information is provided in the unlikely event that your unit requires service. 1) Be sure that the unit is the cause of the problem. Check to make sure the unit has the proper power supplied, all cables are connected correctly, and the cables themselves are in working condition. 2) If you find the unit to be at fault, write down a complete description of the problem, including how and when the problem occurs.
SPECIFICATIONS Input Impedance Mic........................................................................................................... 150 to 3.4K Ohms, variable Line ......................................................................................................... 20K Ohms Instrument ............................................................................................... 2.5M Ohms Preamp Insert.......................................................................................... 7.
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