X Bus

Appendix B: Connections

Digital

XLR Connectors

Mic/Line 4 cards use 3-pin female XLR connectors on the MIC inputs. They are wired as follows, according to standards specified by the AES (Audio Engineering Society).

SHIELD 2

HOT

COLD 3 1

SHIELD 1

COLD 3 2

HOT

1SHIELD

3COLD

1/4" TS Phone Plugs and Jacks

“TS” stands for Tip-Sleeve, the two connection points available on a mono 1/4" phone jack or plug. They are used for unbalanced signals.

SLEEVE

SLEEVE TIP

TIP

TIP

SLEEVE

1/4" TS Unbalanced Wiring:

Sleeve = Shield

Tip = Hot (+)

2

XLR Balanced Wiring:

Pin 1 = Shield

Pin 2 = Hot (+)

Pin 3 = Cold (–)

HOT

RCA Plugs and Jacks

RCA-type plugs (also known as phono plugs) and jacks are often used in home stereo and video equipment and in many other applications. They are unbalanced and electrically equivalent to a 1/4" TS phone plug.

1/4" TRS Phone Plugs and Jacks

“TRS” stands for Tip-Ring-Sleeve, the three connection points available on a stereo 1/4" or balanced phone jack or plug. TRS jacks and plugs are used for balanced signals and stereo headphones:

SLEEVE TIP SLEEVE TIP

RCA Unbalanced Wiring:

Sleeve = Shield

Tip = Hot (+)

Balanced Mono

RING SLEEVE

SLEEVE RING TIP

TIP

 

 

RING

 

TIP

 

SLEEVE

1/4" TRS Balanced Mono Wiring:

Sleeve = Shield

Tip = Hot (+)

Ring = Cold (–)

Stereo Headphones

RING SLEEVE

SLEEVE RING TIP

TIP

 

 

RING

 

TIP

 

SLEEVE

1/4" TRS Stereo Unbalanced Wiring:

Sleeve = Shield

Tip = Left

Ring = Right

78 X.200

Unbalancing a Line

In most studio, stage, and sound reinforcement situations, there is a combination of balanced and unbalanced inputs and outputs on the various pieces of equipment. This usually will not be a problem in making connections.

•When connecting a balanced output to an unbal- anced input, be sure the signal high (hot) con- nections are wired to each other, and that the balanced signal low (cold) goes to the ground (earth) connection at the unbalanced input. In most cases, the balanced ground (earth) will also be connected to the ground (earth) at the unbalanced input. If there are ground-loop prob- lems, this connection may be left disconnected at the balanced end.

•When connecting an unbalanced output to a balanced input, be sure that the signal high (hot) connections are wired to each other. The unbalanced ground (earth) connection should be