User manual ART DIGITAL MPA

[. . . ] ART Digital MPATM Microphone Preamplifier TABLE OF CONTENTS Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Front Panel Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] As the Digital Level control is used refer to the Digital level LED meter which indicates both peak and average level present at the A/D converter input. This meter helps you get the perfect level adjustment and avoid clipping the A/D. Refer to the section titled "Obtaining the perfect digital level setting" for more detail on the operation and use of these features. Dither Switch The DMPA possesses a 24-bit A/D converter. When the output of the unit goes off to a system that can handle only 16 bit data, the 8 least significant bits of data are ignored (truncated). This leaves the sound with gritty "digital" sounding signals at very low levels. Depressing the Dither switch adds a dither component that when truncated replaces this with a more musical sound as the levels trail off into the noise floor. 6 ART Digital MPATM Microphone Preamplifier Generally, keep the unit in 24-bit mode (the out position of the switch) unless you are connected to a system that will truncate the signal to 16 bits. If the unit CANNOT sync to an external source (either out of range, not connected or a system failure), the optical Output select switch will blink. (You may see this switch flash once between changing sample rates, indicating the fraction of a second it takes to settle to the new rate. NOTE: When using the ADAT Input as a sync source, the maximum sample rate is limited to about 50KHz Sample Rate (selection being set to ADA - not wordclock or any other fixed sample rate). 7 ART Digital MPATM Microphone Preamplifier Optical Switch The optical output jack of the DMPA can have one of two formats. When this switch is depressed AND lit blue, this jack will output 8 channels of ADAT. (ADAT cannot be output if the sample rate exceeds 48KHZ - the Sample Rate selection being set to an internal rate). In this case the switch cap will NOT be illuminated, and the output format will revert to 2-channel mode (TOSLINK). When ADAT output is active, The left channel of the DMPA is output on CH1, the right channel of the DMPA is CH2, and the rest of the channels consist of data received from the ADAT Input jack. When the switch is in the OUT position OR the switch cap is not lit, the output consists of two channels of digital audio in the format selected by the Sample Rate Switch. The Lighting of the optical switch cap serves a second function. If it is blinking, there is a timing problem in the digital section. This usually happens when there is not a valid external timing input selected. Front Panel Connections Instrument Inputs The 1/4" jacks on the front panel serve as an instrument input. The input impedance is always >1M Ohm and the gain can be adjusted by the Input gain control. The maximum input signal level is +17dBu (5Vrms) @ minimum input gain. When you plug into this jack it DISABLES the balanced input on the rear of the unit. This feature allows you to keep the rear input patched in, and use the instrument input to switch to a different source. [. . . ] 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. [. . . ]