Mackie 1620i AUX SEND, AUX SEND 1-2TO FW, AUX RETURN, RETURN to AUX, PRE or POST, Modiﬁcation: Pre-EQAux Sends

Aux 1-4

AUX SEND 1-4

The four mono 1/4" TRS aux sends on the rear panel allow you to send balanced or unbalanced line-level outputs to external effects devices or stage monitors, independent of the main mix.

Aux sends 1-4 are independent of each other, so you can set up four separate aux mixes. The aux 1 send output signal is the sum of all the channels whose aux 1 send control is set to more than minimum. Similarly, aux 4 send is the sum of all the channels whose aux 4 send control is set to more than minimum. The overall aux output level can be adjusted with the aux send master controls.

AUX SEND 1-2 TO FW 13-14

When this button is engaged, aux send 1 and 2 are available as FireWire signals 13 and 14 to send to a computer. For example, you can use a computer with audio production software and effects plugins, as an effects host. This substitutes wonderfully for an outboard hardware effects processor. (Mixer channels 13-14 have no direct FW output when this button is engaged.)

See page 16 for an example of setting up a software effects processor using the aux sends and FireWire. Performance will vary based on system hardware.

will not be affected by any channel EQ adjustments. This modiﬁcation can be done by an authorized service center. Contact our technical support chaps for details.

AUX RETURN 1-4

These 1/4" TRS stereo input connectors allow you to add the stereo processed output from external effects processors or other devices to the main mix. Adjust the level of the incoming signals with the aux return master controls.

Alternatively, you can use these inputs to add any stereo line-level signals to your main mix, so it could be another line-level source, not just an effects processor.

If you are connecting a mono source, use the left (mono) aux return input, and the mono signals will appear on both sides of the main mix.

RETURN to AUX 1

The signals going into aux return 3 can also be added to aux send 1 by engaging the return to aux 1 switch. When engaged, the aux return 3 signal to the main mix will be interrupted.

For example, you could add the effects returned from an external effects processor fed by aux send 3, to your stage monitors fed by aux 1.

Aux Sends

PRE or POST

The aux sends can either be pre-channel-fader or post-channel-fader, depending on the position of the pre/post switches in the aux master section.

Aux Returns

For stage monitor work, use PRE, so the stage monitors do not increase in volume when the channel fader is adjusted. This allows you to set up the monitor mix and levels just right, and not have it change every time a channel fader is adjusted. Stage monitors can either be passive speakers powered by an external ampliﬁer, or powered speakers with their own ampliﬁer.

For external processors, use POST. In this way, the feed to external processors will vary in level if the channel fader is adjusted. For example, the level of any returned effect (like an echo) will also change if the channel fader is changed, keeping them in the same ratio (wet/dry).

Modiﬁcation: Pre-EQ Aux Sends

The pre-fader aux sends are post-EQ, so they are affected by the channel EQ controls. The circuit boards can be modiﬁed so the pre-fader aux sends are pre-EQ instead of post-EQ. For example, your stage monitors

10Onyx 1620i

48V

Aux 1

Aux 2

Aux 3

Aux 4