Appendix B: Connections

“XLR” Connectors

Mackie mixers use 3-pin female “XLR” connectors on all microphone inputs, with pin 1 wired to the grounded (earthed) shield, pin 2 wired to the “high” (”hot” or positive polarity) side of the audio signal and pin 3 wired to the “low” (“cold” or negative polarity) side of the signal. See Figure A. This is all totally aboveboard and in full accord with the hallowed standards dictated by the AES (Audio Engineering Society).

Use a male “XLR”-type connector, usually found on the nether end of what is called a “mic cable,” to connect to a female XLR jack.

SHIELD 2

HOT

COLD 3 1

SHIELD 1

COLD 3 2

HOT

1SHIELD

3COLD

You can cook up your own adapter for a stereo microphone adapter. “Y” two cables out of a female 1⁄4" TRS jack to two male XLR plugs, one for the Right signal and one for the Left.

•Balanced mono circuits. When wired as a bal- anced connector, a 1⁄4" TRS jack or plug is con- nected tip to signal high (hot), ring to signal low (cold), and sleeve to ground (earth).

•Unbalanced Send/Return circuits. When wired as send/return “Y” connector, a 1⁄4" TRS jack or plug is connected tip to signal send (output from mixer), ring to signal return (input back into mixer), and sleeve to ground (earth).

1⁄4" TS Phone Plugs and Jacks

“TS” stands for Tip-Sleeve, the two connections available on a “mono” 1⁄4" phone jack or plug. See Figure C.

SLEEVE

SLEEVE

TIP

TIP

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Figure A: XLR Connectors

HOT

TIP

SLEEVE

Figure C: TS Plug

1⁄4" TRS Phone Plugs and Jacks

“TRS” stands for Tip-Ring-Sleeve, the three connections available on a “stereo” 1⁄4" or “balanced” phone jack or plug. See Figure B.

RING SLEEVE

SLEEVE RING TIP

TIP

RING

TIP

SLEEVE

Figure B: " TRS Plugs

TRS jacks and plugs are used in several different ap- plications:

•Stereo Headphones, and rarely, stereo micro- phones and stereo line connections.

When wired for stereo, a 1⁄4" TRS jack or plug is connected tip to left, ring to right and sleeve to ground (earth). Mackie mixers do not directly accept 1-plug-type stereo microphones. They must be separated into a left cord and a right cord, which are plugged into the two mic preamps.

TS jacks and plugs are used in many different applications, always unbalanced. The tip is connected to the audio signal and the sleeve to ground (earth). Some examples:

•Unbalanced microphones

•Electric guitars and electronic instruments

•Unbalanced line-level connections

Switched 1⁄4" Phone Jacks

Switches can be incorporated into 1⁄4" phone jacks, which are activated by inserting the plug. These switches may open an insert loop in a circuit, change the input routing of the signal or serve other functions. Mackie uses switches in the channel insert and bus insert jacks, input jacks and AUX returns. We also use these switches to ground the line-level inputs when nothing is plugged into them.

In most cases, the plug must be inserted fully to activate the switch. Mackie takes advantage of this in some circuits, specifying circumstances where you are to insert the plug only partially. See Special Mackie Connections, on the next page.

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