THE ART TUBE MP
Owner's Manual

The Phase Switch allows you to invert or reverse the phase of the output signal. In the normal position, output signals are in phase with the input signal on all jacks. When engaged, both the XLR and ¼� outputs have their signals changed to 180 degrees out of phase. This function comes in handy to prevent a hollow sound, due to phase cancellations, when using multiple microphones on a single source or when using a combination of direct and microphone pickups on the same source. In a Live Sound application you may be able to get more gain before feedback by reversing the phase of the vocal microphone. The Output Control adjusts overall level just after the tube and metering and before the output amplifiers. This allows you to scale the output to the system you are driving. Typically you would set this about mid way for going into a line level input. When directly plugging into an instrument amp or the microphone inputs on another piece of equipment you may find that a 9 o�clock position gives you plenty of output. The LED metering circuitry covers a wide 30dB range and has a fast attack to help indicate any clipping. It is located in the signal chain just after the tube. The Output control comes after the meter so that you can use the meter to set the overall input gain for best dynamic range then trim the output signal level to the system you are driving. The red �Clip� LED comes on just before clipping and should light on extreme musical peaks only. The yellow �0dB� LED is set to 15dB below the �Clip� LED. If the �0dB� LED is on half the time then you have about 15dB of headroom on the average. The green �-7� and �-15� LEDs indicate how far below the nominal �0dB� LED your signal is. They have a long release time. These LEDs should be on much of the time during performance and if not it indicates that your signal or input gain is too low for best results. The FET limiter has its output level set to be at the �0dB� LED point so if the limiter is engaged and the �0dB� LED is on then you are in limiting. This helps in setting output level for your system. To do this you would start with the limiter off, apply a signal and increase the gain until the red �Clip� LED comes on occasionally, then engage the limiter. At this point the signal at the tubes output will be in limiting most of the time. You can then adjust the Output control so you are just below clipping at your A/D, computer, recorder, or amplifiers input. Now you can back off on the Gain control. At this point, as long as the Output control is at the current position, you can use the �0dB� LED to indicate that you are at full signal level for your equipment that follows. Note: All front panel push switches are lit when in the active position to aid in setup and operation.

A brief note from customer service: Once in a while a customer will call and say: I think my ART preamp is "noisy". What's wrong? If you experience unwanted "noise" in your system when you use a stand-alone preamp, please consider what your signal is and where you're sending it. Some people send the signal from their preamp to a mic input (they figure, "well, I'm using a mic!") on the board or recorder. This is in fact incorrect and could be the problem. ART preamps are actually intended to output a nice fat LINE LEVEL signal. If you send that line level signal to a recorder or mixer's Mic input, that circuit will usually add more gain to the signal. Gain on top of gain will indeed result in noise. Please treat the output signal as line level and you'll be pleasantly surprised at your new clean and warm sound. The same rule applies for guitar and bass players that use ART preamps as their front end. Send the signal from your preamp to a low gain input on your amp, or even a "loop return" jack which allows you to bypass the amp's solid state preamp altogether.
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