SSM2005

–14–

REV. 0

Using the SSM2005 for Karaoke

In Video mode, the SSM2005 removes centered vocal informa-

tion from the LF and RF speakers. This allows the device to be

used in Karaoke applications, where the user can sing along with

any music recording. Figure 11 shows a circuit diagram for such

an application.

The OP179 is the microphone preamplifier with a gain of +20 dB.

A 2.2 k

Ω resistor connects the microphone to the +6 V supply rail,

providing proper biasing for an electret microphone.

The SSM2402 is used as a clickless switch, connecting the

center output to either the center out from the SSM2005 or the

microphone. In Circle Surround mode, the control voltages to

the SSM2402 connect the output from the SSM2005 to the

center output.

In Karaoke Mode, this connection is opened, and the micro-

phone is directed to the center output. At the same time, the

SSM2005 should be loaded with data byte (MSB first):

1 1 1 0 1 0 1 1. This activates the center canceling circuitry in

the SSM2005, removing centered vocal information from the

left front and right front speakers.

The overall result is the microphone output comes out of the

center speaker, with the vocals-removed music coming from the

remaining speakers.

14

13

12

11

10

9

8

1

2

3

4

5

6

7

SSM2402

+6V

6V

SSM2005*

FOR KARAOKE, LOAD DATA

BYTE: 1 1 1 0 1 0 1 1

LEFT IN

RIGHT IN

10 F

10 F

CENTER

OUTPUTS

*ADDITIONAL PINS OMITTED

FOR CLARITY

+5V

KARAOKE

MODE

CIRCLE

SURROUND

MODE

SW-2

7404

6V

OP179

+6V

0.1 F 1k

MIC

2.2k

10k

+6V

48

47

46

45

44

7

10

39

Figure 11. Using the SSM2005 for Karaoke