Rainbow Electronics MAX5406 - Manual (Page 19)

MAX5406
Audio Processor with Pushbutton Interface
______________________________________________________________________________________ 19
Ambience Control
Use the ambience function for boom boxes, head-
phones, desktop speakers, or other audio products
where the speakers are physically close together. A
stereo signal is designed to be played over speakers
that have a wide physical separation. The ears and
brain combine the sound from these two sources to
create a perception of sounds distributed in space. In
the case of headphones, this wide physical separation
does not exist, resulting in the sound apparently com-
ing from somewhere inside the head. A similar situation
exists when the speakers are not widely separated, for
example when they are located on a desk or inside a
single enclosure. One way to compensate for this is to
increase the apparent separation of the L and R signals
arithmetically. The L and R signals can be modeled as
a channel-specific component added to a monocompo-
nent. To emphasize the channel-specific component,
one needs to remove the opposite channel-specific
component from the monocomponent.
This function is accomplished with circuitry inside the
MAX5406 and external network. Control the ambience
effect with the AMB button that toggles between wide
(full effect) and normal (no ambience effect). Use the fol-
lowing equations for matrix surround (fixed ambience):
1
0
SWITCH
CONTACT
IS BOUNCING
SWITCH
CONTACT
IS STABLE
SWITCH
CONTACT
IS BOUNCING
READY TO ACCEPT
ANOTHER BUTTON PRESS
INPUT ACCEPTED
PUSHBUTTON PRESSED
t LPW t WS
t HPW
DEBOUNCE BY
WAITING FOR
STABLE LOW,
t LPW
WAIT FOR
FIRST ZERO
CROSSING OR
TIMEOUT, t WS
DEBOUNCE BY
WAITING FOR
STABLE HIGH, t HPW
L1_H
L1_L
WIPER MOVES HERE
(t LPW + t WS )
Figure 11a. Wiper Transition Timing Diagram (No Zero Crossing Detected)