# Low Latency Mixing

While recording, if you notice a delay between the moment you play or sing a note and when you hear it in your headphones you are experiencing latency. Maestro’s low latency mixer may help and can be configured by clicking the Mixer tab in Maestro.

Maestro Low Latency mixing

A bit of background information concerning latency and computer-based digital recording setups will help you better understand these functions.
When recording with most computer-based digital audio applications, the delay between the input and output of the recording system often disturbs the timing of the musicians performing. This delay, known as latency, means that the musician hears the notes played a few milliseconds after having actually played them. As anyone who has spoken on a phone call with echo knows, relatively short delays can confuse the timing of any conversation, spoken or musical.

To illustrate the effect of latency, figure A depicts the typical signal path of a vocal overdub session. A vocalist sings into a microphone, which is routed to an analog to digital converter then to the audio software application for recording. In the software application, the vocalist’s live signal is mixed with the playback of previously recorded tracks, routed to a digital to analog converter, and finally to the vocalist’s headphones. A slight delay accumulates at each conversion stage, while a much greater amount of delay occurs through the software application, resulting in the vocalist hearing his performance in headphones delayed by several milliseconds.

By routing the hardware input directly to the hardware output and mixing in playback as shown in Figure B, it’s possible to provide the vocalist a headphone monitoring signal with a much shorter delay.
First, the signal being recorded (in this case, a vocal mic) is split just after the A/D stage and routed to both the software application for recording and directly back to the hardware outputs without going through the latency-inducing software. This creates a low latency path from mic to headphones. Next, a stereo mix of playback tracks is routed to the low latency mixer and combined with the hardware input(s). This allows the performer to hear himself while listening to playback tracks without a confusing delay in order to comfortably record overdubs.

Note that the software application’s mixer is used to set a stereo mix of playback tracks while the low latency mixer is used to set the balance between the stereo playback mix and the hardware inputs.

Working with the Maestro Mixer
Do I need the Maestro Mixer?
The Maestro mixer serves to provide a low latency monitoring mix while recording. Therefore if you’re using Duet to listen to iTunes or audio from another program, there’s no need to use the mixer. Leave the outputs set to 1-2 or 3-4 to disable the mixer.
It’s possible that the latency of your particular recording system is low enough to be unnoticed. The system latency is determined by the recording software’s buffer setting, and if your Mac is powerful enough, it’s possible to set the buffer to a lower value (shorter latency) without encountering clicks and pops in the audio output. If the latency doesn’t pose a problem while recording, the mixer may be disabled by simply leaving the outputs set to 1-2 or 3-4.

Recording software settings

Before using the Maestro mixer, it’s necessary to change a few settings in your recording software.

Software monitoring - Because the signal to be recorded is monitored through the Maestro mixer, the outputs of software tracks actively recording should be muted - after all, that’s the source of the latency. Most software applications provide an option to turn off software monitoring of recording tracks. In Logic Pro, for example, the software monitoring option is found in the same Audio preferences window used to select Duet as the hardware device (Logic Pro menu > Preferences > Audio). Uncheck the Software Monitoring box.

Playback mix - In your recording software, set up a mix of all playback tracks and route it to Out L-R. If a master fader controls the global output of the mix, it’s suggested to set the fader to 0 dB.

Maestro Mixer Settings

Initially, set the Input, Software Return, and Mixer Master faders to 0 dB.

On the Output tab of Maestro, set the speaker, headphone, or both outputs to Mixer.

After making the input selection and setting gain, the signal should be displayed on both the Input and Mixer Master meters. If the Input’s Over LED lights, reduce the input gain in the Maestro Control window. If the Mixer Master’s Over LEDs light, reduce the Input fader.

Now start playback in your recording software. The playback signal should be displayed on the Software Return and Mixer Master’s meters. Use the Software Return and Input faders to establish your desired balance between the input and playback signals. If you’ve found a good balance but the Mixer Master’s Over LEDs light, reduce the Mixer Master fader.