User manual ART TUBEFIRE 8

[. . . ] TubeFire 8TM 8 CHANNEL TUBE MIC-PREAMP SYSTEM 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. Do not open: Aside from four vacuum tubes, there are no user serviceable parts inside. [. . . ] The gain sensitivity is identical for both the XLR and 1/4" TRS jacks, however the XLR input impedance is 6. 4K Ohms and the 1/4" TRS input impedance is 20K Ohms. The front panel Pad switch varies the sensitivity of both inputs. Balanced Output Jacks Each channel has a low impedance 1/4" TRS balanced jack. Output Level Switch This switch optimizes the output level of the rear output jacks with your system operating level. In this case the maximum output is +22dBV when the digital level equals 0 VU. When the switch is in the "out" position, the output levels are optimized for ­10dBV systems. One way to determine how this switch should be set is to send audio through the TubeFire 8TM from a computer and run it into a line input on a mixer or signal processor. Check the meters on the mixer or signal processor to see if the level appears to be too high (clipping) or too low (barely showing any indication on the meters). Set the Output Level switch so that the level meters in the external gear do not indicate excessive clipping yet still provide good full-scale (or near full scale) deflection. FIGURE 3 - Rear Panel Wordclock Input and Thru Jacks The Wordclock input is used to externally sync the TubeFire 8TM to a master clock source. The BNC Wordclock Input jack is connected directly to the BNC Wordclock Thru jack, providing the ability to loop through the TubeFire 8TM and connect other devices to the wordclock sync source, saving the use of a BNC T­ adapter. The input is high impedance thus leaving the wordclock connection unterminated. (A 75 Ohm BNC terminator should be used on the Wordclock Thru jack if the Wordclock Input jack is used only by itself. ) Firewire Jacks The Firewire jacks are interchangable and allow both connection to your computer and to other Firewire devices including additional TubeFire 8TM units. 8 HARDWARE OPERATION How to adjust the controls for the lowest noise Start with the GAIN and OUTPUT knobs centered, and the Pad switch IN. Increase the Gain control until the Clip LED in the meter just barely comes on during the loudest peaks in level, and then back off the control slightly from that point. (The Clip LED can come on occasionally at most. ) If there is not enough level with the Gain control set fully clockwise, back off the gain to 12 o'clock and place the Pad switch in the out position. Adjust the Output control until the -10 light is on most of the time during loud passages. Increasing the input gain and decreasing the Output level control can add more tube warmth. Remember, that the Clip LED looks at both the preamp input and output peaks, whereas the -10, -20, -30 LED indicators only look at the output level which feeds to the A/D converter. How to set the Output Level switch (on the rear panel) Setting this switch correctly can lower the noise in the signal chain by optimizing the operating levels between the TubeFire 8TM and external gear. One way to determine how this switch should be set is to send audio through the TubeFire 8TM from a computer and run it into a line input on a mixer or signal processor. Check the meters on the mixer or signal processor to see if the level appears to be too high (clipping) or too low (barely showing any indication on the meters). Set the Output Level switch so that the level meters in the external gear do not indicate excessive clipping yet still provide good full-scale (or near full scale) deflection. How to use the Headphone / Line Mixer Output The TubeFire 8TM has eight D/A outputs that return audio from the computer and are assignable to the headphone output through the Output Source switches. When a switch is in the OUT position, the corresponding channel pair of D/A's (audio from computer) is selected to be mixed into the headphone output. When depressed, the corresponding channel pair of analog tube preamp outputs is mixed into the headphone output. First, determine which D/A's to use as a source from the computer. A good start would be to use channels 7 & 8, since channels 1 & 2 are the most flexible for use as inputs. [. . . ] Note that the order of devices listed is arranged by each unit's SERIAL NUMBER. We recommend using external wordclock to maintain the highest audio quality when using multiple devices. Wordclock should to be applied to EVERY unit in the audio chain including soundcards. The wordclock signal can be looped through the TubeFire 8TM units using their rear panel wordclock Input and Thru connectors, with a 75 Ohm BNC terminator applied to the last unit in the chain. Typical applications Home and Commercial Recording Studios Live Sound Recording Broadcast/Radio/TV - Multi-channel playback and recording 20 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. [. . . ]