Analog Board Theory - Lexicon RV-8 Service Manual

RV-8 ANALOG BOARD THEORY
The analog board of the RV-8 encompasses all of the analog audio inputs and outputs, level controls and
A/D and D/A converters. This board is located below the RV-8 Video Board.
There are three separate signal paths: Main, Zone2 and Zone3. Each of the eight analog stereo inputs,
the tuner, the phono, or any of eight digital inputs can be routed to any of the three paths. The schematics
refer to Main, Rec, and Zone. Rec is named for Zone2 and Zone is named for Zone3 on the back panel.
Main Audio Paths
One of the eight analog stereo inputs, the tuner, or the phono can be routed to the main path and to the
A/D convertor(s). In addition, one of the eight digital inputs can be routed from the main board. The A/D
digitizes the analog signal (if selected) and passes it to the DSP on the main board. Digital signals from
the main board pass directly to the DSP. (Refer to the Main Audio Paths 2-Channel Input block diagram
below). The DSP creates eight different output signals from the 2-channel input. D/A converter IC's
convert each of the eight signals from the DSP to analog and then send them to their respective RCA
connectors. The outputs are also sent to the seven channels of amplification, with channels 6 and 7
having the ability to be redirected. A direct analog path is provided which passes a 2-channel analog input
signal directly to the Left and Right Front outputs via the level controls, bypassing the DSP and
converters.
1
+
2
+
3
+
Main Mux
4
+
5
+
8:1
6
+
Anlg
+
7
+
MUX
+
8
sw
+ Tuner
sw
Phono
+
Phono
sw
+
75u
Mic1/2 sw
+
Mic1/2 sw
Phono +
Preamp
Mic
Preamp
Tuner
Module
In addition, a 5.1-channel source can be selected for the Main audio path. There are two possible
methods of getting a 5.1 source into the box. Refer to the Main Audio Paths 5.1-Channel Input block
diagram on the next page)
6-4
Main Audio Paths 2-Channel Input
Front L/R Direct Analog Path
Front
L/R A/D
data
+
Level
Side
A/D
data
+
Level
DAC
data
main clks
DAC
data
to / from
Main Bd
DAC
data
DAC
data
RV-8 Service Manual
Front L/R Mux
Front L/R
sw
+
sw
+
Ctr/Sub Mux
Center/Sub
sw
+
Side L/R Mux
Side L/R
sw
+
Rear Mux
Rear L/R
sw
+
1,2
6/7 Mux
3
4,5
Amps
sw
+
6,7
Headphone
sw Amp
HDP pres
to