Audio connections. MOTU 828es

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AUDIO CONNECTIONS

Here are a few things to keep in mind as you are making audio connections to your 828es interface.

Mic/line/instrument inputs with preamps

Connect a microphone, guitar or line-level analog input to the front panel XLR/quarter-inch combo jack with either a standard mic cable or a balanced cable with a quarter-inch plug.

☛

Do not connect a +4 (line level) XLR cable to the front-panel inputs (because of the preamps).

Use a quarter-inch input instead.

Phantom power

If you are connecting a condenser microphone or another device that requires phantom power, engage the corresponding front-panel phantom power switch.

Preamp gain

The 828es preamps provides 63 dB of gain. Use the front panel detented trim knobs to adjust gain as needed for each input. The LCD provides visual feedback as you turn the trim knob. Preamp gain is digitally controlled, so you can make fine-tuned adjustments in 1dB increments. You can also

adjust preamp gain in the web app. See “Device tab” on page 12.

-20 dB pad

Each mic input (XLR jack) is equipped with a

-20 dB pad switch, to accommodate input signals that could overdrive the input.

Combo jack summary

Use these guidelines for 48V phantom power, pad and trim settings on the two combo input jacks:

Input

Condenser mic

48V Pad

On

Trim

As needed As needed

Dynamic mic

Guitar

-10 dB Line level via TRS

-10 dB Line level via XLR

Off

Off

Off

Off

+4 dB line level (TRS only) Off

As needed As needed n/a As needed n/a

-20 dB

-20 dB

As needed

+12dB

Zero

TRS quarter-inch analog inputs and outputs

Quarter-inch analog inputs and outputs are balanced (TRS) connectors that can also accept an unbalanced plug. The outputs are DC-coupled, so they can be used for CV control output.

☛

Quarter-inch analog outputs are not cross-coupled. Therefore, when connecting them to an unbalanced input, use a TRS plug with the ring disconnected. Not floating the negative terminal will short it to the sleeve ground and cause distortion.

Main outs

Like all I/O on the 828es, the XLR main outputs operate as an independent pair (they don’t share signal with any other output pair). In a standard studio configuration, the main outs are intended for a pair of primary studio monitors, but they can be used as regular outputs for any purpose. With adjustable converter trim, they support a wide range of industry-standard reference levels. Main out volume is controlled by pressing the A button

on the front panel (Figure 5-14) and then

adjusting volume with the MONITOR knob.

Figure 5-14: 828es front panel

H A R D W A R E I N S T A L L A T I O N

Analog trims

All analog inputs and outputs can be trimmed.

This allows them to support a variety of standards, including EBU-R68, SMPTE RP-155, +4dBu, -

10dBV, 2vRMS, 1vRMS.

The 828es quarter-inch analog inputs are equipped with high-quality, digitally controlled analog trim that provides a range from -96 to +22 dB in 1dB steps.

Quarter-inch outputs can be trimmed in the DAC itself. Range is 24 dB.

The Main Outs and Phones provide full trim range from 0 dB to -∞ (-127).

Trim controls are most easily accessed in the web

app. See “Device tab” on page 12. Trim settings

can also be accessed in the LCD menu.

Monitor A-B outputs

From the factory, the XLR Main Outs are assigned as monitor pair A and Analog Outs 1-2 as monitor

pair B (Figure 5-15). If you have a secondary pair

of studio monitors, connect them to Analog Outs

1-2.

You can change these output assignments as desired in the A-B Monitor Setup section in the

web app Device tab (item #33 on page 14). For

more information, see “Monitor controls” on page 59.

Optical I/O

Your MOTU audio interface provides two banks of ADAT optical (“lightpipe”) connectors. Each bank provides an input and output connector.

Together, they provide 16 channels of ADAT optical digital I/O at 44.1 or 48 kHz, or 8 channels at 88.2 or 96 kHz. The optical ports are disabled when the interface is operating at a 176.4 or 192 kHz. At the high sample rates (88.2 or 96 kHz),

4-channel SMUX operation supports two modes

(item #24 on page 13):

■

Standard — for 2x optical connection to

3rd-party SMUX-compatible hardware products.

■

Type II (Legacy) — for 2x optical connection to legacy MOTU products that are equipped with optical ports and support 2x operation.

The optical ports are disabled when the interface is operating at a 176.4 or 192 kHz.

TOSLink (optical S/PDIF)

Alternately, the optical ports can be configured for stereo TOSLink (optical S/PDIF) in the web app

(item #24 on page 13). The optical IN and OUT

banks can be configured independently.

Choosing a clock source for optical connections

When connecting an optical device, make sure that its digital audio clock is phase-locked (in sync with) your MOTU interface, as explained in

“Synchronization” on page 46 and “Syncing optical devices” on page 47.

S/PDIF

The 828es provides S/PDIF digital audio input and output on the RCA jacks provided. Be sure to review the digital audio clocking issues, as

explained in “Syncing S/PDIF devices” on page 47.

Monitor pair B

Monitor pair A

Figure 5-15: 828es back panel

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H A R D W A R E I N S T A L L A T I O N