Lexicon CORE2, Service Manual

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Lexicon
6-1
Chapter 6 Theory of Operat i on
Architectural Overview
The Core2 is a 28 channel hard disk recorder card for PCI-bus based PC/Windows and Macintosh
computers. It is capable of 44.1K, 48K, 88.2K, and 96K sample rates, but only 44.1K and 48K will be
supported at first customer ship. The Core2 has a daughterboard connector to support the MP-100 reverb
processor.
The Core2 features four major circuit sections: DSP56301, Xilinx XCS10 FPGA, A/D conversion, and D/A
conversion. A Motorola 66 MHz DSP56301 microprocessor provides the PCI interface and the audio move
engine. This device controls the flow of audio data between the PCI bus (for disk storage/playback) and the
A/D converters, D/A converters, and the FPGA. The Xilinx FPGA is used to implement 8 channels of ADAT
I/O and stereo S/PDIF I/O. It is also used to create an I2S receiver interface from the MP-100 reverb
daughter board. The A/D conversion section is comprised of two stereo A/D converters (AK5383), two
stereo volume control I.C.s (CS3310), and dBx type 4 tape saturation emulation. DBx type 4 is a soft knee
limiter that provides 4 dB of headroom extension and also simulates the effect of analog tape compression.
The D/A conversion section has four stereo D/A converters (AK4324) which drive single ended –10 dBV
outputs. The analog and S/PDIF connectors are mounted in an external breakout box which is connected to
the Core2 card with a cable. The ADAT optical connectors are mounted at the PCI card edge. A block
diagram of the Core2 is shown in the following figure.