User manual ART PRO MPA II

[. . . ] PRO MPA II TM ART PRO MPA II Microphone Preamplifier 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. 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 two vacuum tubes, there are no user serviceable parts inside. [. . . ] Additional gain is available via the Gain switch (+20dB) and the Analog Output control (+10dB) for a maximum of 70dB total. The combination of these controls allows the user to adjust the signal level through the tube section, providing more or less "tube" sound as needed. To obtain more "tube' sound, increase input gain, use the +20dB Gain switch, "normal" plate voltage, and less Analog output gain. Both the microphone and instrument inputs are optimized for their respective sources as far as signal levels and noise performance. Running most of the gain on the input generally provides the best performance of the PRO MPA II . Refer to the section titled "Obtaining the best noise performance 3 with the PRO MPA II " for more detailed instructions on setting the Input Gain control for the best results. Input Impedance control This knob controls the Mic/line input amplifier impedance. Refer to the application section titled "Adjusting the Input Impedance" for more information on making the most of this function. The ¼" instrument input is NOT affected by this control, and remains high (>1M Ohm) impedance. Low Cut Filter control The Low Cut Filter is a single tuned High Pass Filter that is frequency tunable. The input signal can be filtered to remove "pops" or other extraneous low frequency information. This control moves the rolloff frequency from 10 Hz (fully CCW) to 200 Hz (fully CW). Since it is single tuned, it preserves some low frequency content so its use is less obtrusive. It is especially useful in close mic'd applications. Gain switch The Gain switch is used in conjunction with the input gain control to adjust signal levels through the PRO MPA II. When depressed, the tube circuit provides 20dB more gain in the signal path. This also has the effect of driving the tube harder and making the tube the dominant source of gain and overload character. 4 Phantom switch Phantom power on the microphone input is turned on and off with this switch. Depressing the switch will power condenser microphones and other 48volt phantom powered devices. NOTE: 1) Dynamic microphones are NOT affected by Phantom power, although it should be turned off when using dynamic microphones or line level inputs. 2) Although the 48volt phantom power ramps up and down slowly it may still create a pop. Mute the output of the PRO MPA II when engaging or disengaging phantom power to prevent damage to equipment following the PRO MPA II . Phase switch The Phase switch can invert the phase of the audio signal path in either channel. It can provide from +10dB of gain (fully clockwise) to completely muted. You can see the effects of this adjustment reflected in the analog meters. STEREO/Dual switch The STEREO/Dual switch selects the operation of the output control knobs. Stereo mode gains and operation are marked with reversed out text. 6 In Stereo mode, CH1 output adjusts the output gain of both channels and CH2 output control acts as a power summed Balance control. There is a slight drop in output level in stereo mode when the Balance knob is centered vs. [. . . ] Applied Research and Technology will, without charge, repair or replace, at its option, defective product or component parts upon prepaid delivery to the factory service department or authorized service center, accompanied by proof of purchase date in the form of a valid sales receipt. Exclusions This warranty does not apply in the event of misuse or abuse of the product or as a result of unauthorized alterations or repairs. This warranty is void if the serial number is altered, defaced, or removed. A R T reserves the right to make changes in design or make additions to or improvements upon this product without any obligation to install the same on products previously manufactured. A R T shall not be liable for any consequential damages, including without limitation damages resulting from loss of use. [. . . ]