Anatomy of an Mbox Interface

Lets go over the surface anatomy of a two analogue channel, ProTools LE Mbox. A green LED indicates that the Mbox is on. It is powered via USB and plugs directly into the computer. There is a ¼ inch stereo headphone jack that uses a TRS connection. On a standard ¼ inch jack, there is a tip, two rings, and a sleeve that make up this adaptor. There are 5 knobs on the front of this INTERFACE. One controls the volume of the headphones. Another controls the monitoring system such as a set of speakers or a PA. The third is a MIX dial, and it has variable control between audio that is being recorded, and audio that is already recorded and in the mix. By turning the dial all the way to one side, we hear only what is being recorded. When it is dialed all the way to the other side, we only hear the mix, and not what is currently being tracked. You can blend the two audio signals as well, getting a mix of both while recording, if necessary. There is a MONO button that you can toggle to hear a mono or stereo mix. This is a nice way to check for phasing in your mix. Another button is 48V, or phantom power. There are 3 different types of microphones: Dynamic, Condenser, and Ribbon microphones. Dynamic mics do not need phantom power, but are not harmed if it is enabled. Condenser mics always need phantom power, because they use an uncharged coil inside the capsule. Ribbon mics do not need phantom power, however some can be destroyed if they are given the 48V charge, because these are very sensitive microphones. Another knob on the front of this interface is a gain stage, and controls the amount of input received by channel 1. For a very high input that is clipping with the indication of the red PEAK LED, pushing in the button that says PAD will attenuate the overall gain by -20dB. A button for selecting DI (direct input/injection) or mic is also there. DI would be an electric guitar or bass, or electric keyboards. The mic setting is for just about any kind of microphone. On the back of the Mbox interface, there is a female XLR input for each of the 2 channels available to record on simultaneously. There are also ¼ DI and Line inputs for both channels. Two ¼ monitor outs for a right and left speaker, and a digital input (S/PDIF) for digital information. There is a MIDI input/output section for a MIDI controller to send and receive digital information as well. MIDI is not audio, and doesn’t actually become audio until it comes out of the speakers, and at that point it can’t even be called MIDI anymore. To get the first signal through the interface and talking to ProTools, set up a new session and create a mono audio track. In the insert section of the virtual channel strip and select the menus plug-in – other – signal generator. Select from the various waveforms for any tone, just to make sure audio is coming out of the headphones. On the I/O section of the channel strip, select input 1 for the audio INPUT path selector. Remove the insert from the channel strip. Plug a microphone into channel 1 and arm the track with the red R button on the channel strip. Record some audio onto the track. Create a second track and make sure input and record enable are set. Record another bit of audio. Now pan both tracks opposite ways and take a listen in the headphones. Toggle the MONO button to hear the mono/stereo effect. Let’s get MIDI into ProTools. Create a MIDI track and a stereo aux track. On the aux track, in the inserts section select: Instrument – piano. Set the input on the aux channel to the correct setting, and see if the MIDI controller is talking to ProTools.