Unlocking the M-BOX
by Jeff Towne

Digidesign’s M-Box seems almost perfectly suited to the type of production that most radio producers do, offering stereo input of microphones, line level, or S/PDIF digital. The resulting mono or stereo soundfiles can be stacked in multiple tracks, in most cases 24 or more, for mixing with effects to a stereo output. Even better it’s a USB device, meaning that it can be quickly attached to almost any new-ish computer, including a laptop, by plugging-in one cable. There’s not even a power cord. While originally released for Mac OS 9.1 or 9.2, the M-Box will now run on Windows XP as well, and there is expected Mac OSX support coming early in 2003. ASIO drivers are now available, so the interface can be used with different editing programs, if one doesn’t happen to want to use ProToolsLE.

While we at Transom are especially fond of really inexpensive tools that can get the job done, there are times when spending a few extra dollars for a hardy and full-featured device is justified, and this is one of those. At about US$450, this device is still an excellent value given the high quality of the physical interface, featuring two Focusrite microphone preamps, and the professional-level software, including many useful plug-ins.

The down-side is that the M-Box must remain physically attached to the computer in order to use the ProToolsLE software, so there’s no detaching the interface and running a lean-and mean mobile rig. The M-Box itself is not dauntingly large, but it is just big enough that it’s inconvenient to lug around if all one is doing is editing and mixing, and it drags on a laptop’s batteries, as it is fully powered by the USB bus. Digidesign software design theoretically does not allow both ProToolsLE and ProToolsFree to coexist on the same computer, but there is an unofficial, unapproved, and somewhat imperfect workaround, which is detailed in a sidebar to this article. By doing a bit of file shuffling and renaming, one can switch to ProToolsFree for editing and mixing without the box attached.

Setting up the system is fairly straightforward: plug the M-Box into one of your computer’s USB ports (not a hub), run the installer from the included CDROM, and make a couple of tweaks to your system. Be sure to install OMS, even if you have no plans to incorporate MIDI devices into your sessions, ProTools needs for it to be installed and set-up.

ProTools prefers to run with specific memory settings that may seem strange, but follow the instructions in the ProTools manual and the system will work much smoother. On OS 9 Macs, Digidesign recommends that you pare down your system extensions, creating an extension set with only the minimum required. In reality, you’ll likely not have problems even with well over the absolute bare-bones set, but it’s good Mac practice to turn-off extensions that are not needed. Just be sure to turn-on any control panels and extensions having to do with Digidesign, DAE or OMS, as well as Quicktime, Sound, and USB.

Upon the first boot-up of the program, you’ll be prompted to set-up OMS. This is a utility for configuring a virtual studio, telling the software what devices are connected and how. The primary use of this is for musicians to configure MIDI devices, but even for those working with audio only, OMS needs to be set-up. Unless you have MIDI equipment that you’ll be using, let OMS search your computer for MIDI devices, and accept the default set-up, usually of quicktime music instruments, or some other built-in MIDI player. Click OK, and don't think about it any more.

In order to record your first sound into the M-Box, make a new session, and new tracks to record into. You’ll be asked what sample rate and bit-depth the soundfiles should be. Soundfiles in a ProTools Session need to all be the same bit-depth and sample rate. The M-Box supports 44.1K and 48K sample rates, and choosing between them will depend on your original material. If the final output of this project will be audio CDR, it will have to be at 44.1K eventually, so it might make sense to start at that sample rate. If you import lots of sound from CD, you should probably work consistently at 44.1K. If you have many digital sources that were recorded at 48K and will be dumped-back to a format that supports that sample rate (such as digital video) it might make sense to keep everything at that rate. It usually makes life easier to choose a sample rate and stick with it, recording in the field and in the studio at a single rate.

16-bit is still the most common, and in most cases will be perfectly sufficient for radio or internet productions. 24-bit files will give you better sound quality, but will use more disc space and put a greater processing draw on your CPU. If you have only a few tracks and you have plenty of disc space, the better resolution of 24-bit might be for you. But if you are layering lots of sound and are getting tight on disc space, 16-bit might make more sense. Remember that if your final production will be saved on a DAT or audio CDR, these formats are 16-bit, so a 24-bit session should be dithered-down to 16 before burning or play-out.

Under the "set-ups" menu, choose "hardware" to set the sync mode. Choose "internal" if you are recording an analog input from the microphone or line inputs. Choose "S/PDIF (RCA)" if you are recording via the coax SPDIF digital input. If you set the sync input to external, the digital input becomes active, and the analog inputs are disabled. Conversely, if the sync mode is set to "internal" one cannot record via the digital input. A green LED lights on the front of the M-Box when S/PDIF is the active input, and the M-Box is receiving sync. .

In almost all digital dubbing situations, it’s vital that you set the sync source to be the digital device that is playing the audio, not the one that is recording it. Otherwise, the independent clocks of the two devices will eventually drift apart, resulting in clicks, pops, or weird metallic ringing, if you are able to record at all. The M-Box is no different, so be sure to set sync to external when recording a digital source, and to internal when playing back. If your input device is connected, powered-up and still sending its original sync rate, you can leave your sync set to external while editing and mixing, but it would be safer to switch to internal sync once you are done with load-in. As with most digital transfers, there is no way to adjust the level of the incoming sound during load-in, wait until the editing and mixing phase for that.

If one is recording an analog source, there are three choices of inputs: mic, line and instrument. All plug into the combination XLR/quarter-inch jacks on the back of the M-Box. Microphones plug into the XLR jacks, which can provide phantom power to condenser mics. Line level signals should be plugged into the 1/4" hole in the center of each combo jack, which will accept TRS balanced connectors or two-conductor unbalanced. That same 1/4" jack will accept an instrument-level input, such as from an electric guitar. When connecting a small portable device to the analog inputs, one would use an adapter cable with a stereo mini on one end and left and right mono quarter-inch plugs on the other. Plug the stereo mini into the line-out or headphone out of the minidisc or DAT recorder, and the 1/4" jacks into the left and right combo jacks on the back of the M-Box. Don’t use the quarter-inch jacks above the combo jacks, those are outputs or insert points.

Which input is active is selected via a small white button to the left of each input gain knob on the front of the M-Box. Pressing the button repeatedly will toggle between the available inputs, a green LED will light up indicating mic, line or instrument. Instrument levels are lower than line level, so be careful not to select "instrument" when loading sound from a line-level input, such as a DAT machine or minidisc, the signal may be too loud and could distort. Each channel can be set independently, so one can have a mic plugged into one channel and the (mono) output of a DAT into the other. You cannot record analog and digital signals simultaneously.

Analog Input Gain is controlled by the top two knobs on the front of the M-Box. Create or open a ProTools session, create tracks to record into, or put existing tracks into record-ready by clicking the red record indicator on the channel strip, either in the mixer window or the edit window of your session. Adjust the knobs so that your input signal is strong on the input meters on your computer screen, with peaks hitting the yellow (but no red.) There is also a red "clip" light next to each input knob, if you see those light up, turn your inputs down until the clip lights stop flashing. If you have clips at very low volumes, make sure you have selected the proper input (mic, line, or instrument) or turn down the playback device's volume if possible.

There is a clever zero-latency monitoring option controlled by the second knob from the bottom. It’s often helpful to avoid hearing the delay (latency) that results from audio travelling to the computer and back: that small echo can be maddening when recording voice-overs or musical performances. When the second knob from the bottom is turned fully clock-wise, only the computer playback is routed to the headphones and main monitor outs. With the knob turned fully counter-clockwise, only the inputs will be routed directly to the headphones and main outs. In many circumstances some intermediate position will be best, to allow some of the existing tracks to be monitored while hearing some of the new take. Be careful to pull down the on-screen fader for the record track when monitoring both the computer playback and the direct input (when the balance knob is somewhere between full left or right), or the combined delayed and direct signal will sound metallic and phasey. Try not to use the balance knob as a volume control, use your amplifier’s volume knob, or the sensitivity controls on powered monitors instead. If you have no active inputs, but the knob is turned less than fully clockwise, you can pick-up scratchy noises from the empty input channels, which can be annoying, or worse, could ruin your mix if you are dumping out of the analog outputs.

If recording a single channel, such as a mono announce mic, the direct, zero-latency input will be panned hard to one side, because channels one and two are routed directly to the left and right monitor inputs, respectively. It can be distracting to hear one’s voice in only one ear, but never fear, the M-Box has a handy mono button right next to the balance knob that switches the headphones to mono, for this very purpose. Keep in mind this only switches the headphones, not the line outputs, to mono, and only combines the inputs to mono, not the tracks being played back.   The bottom knob is the headphone volume control, which controls the mini jack on the front, and the 1/4" jack on the rear. Sadly, only one of the jacks can be used at one time.

There are two "insert" jacks on the rear of the M-Box that can be used to integrate analog processing before the analog inputs’ signal gets to the computer. With the flexibility of plug-in effects on mixdown, inserts are less important at the input stage, but if you have a compressor or some other device that you just love to record with, you can take advantage of the M-Box’s Focusrite mic preamps and still route your signal through your old gear before it is digitized. The jacks are standard, so a classic insert cable with a three-conductor TRS 1/4" on one end that splits to mono send and return cables will send the signal to your processor after the mic preamp, and return it to the M-Box before the A/D converters.

Connecting the M-Box to speakers is pretty straightforward: the 1/4" line-out jacks on the back can send a balanced or unbalanced signal, depending on the cable you use. Connect those outputs to an amplifier, a mixer, or directly to powered monitors. Remember, this is line-level, these outputs will not drive speakers without an amplifier. As is conventional, line 1 corresponds to the left output of ProTools, andd Line 2 to right.

Editing in ProTools LE 5.2 for the Mac, or 5.3 for Windows XP, is much the same as other versions of ProTools, with a few notable improvements over ProToolsFree especially its support of more than eight tracks, and those tracks can be stereo or mono. If moving a session from ProTools 5.2/3 to a system with an earlier version of the software, one must choose "save a session copy in" under the file menu. You can pick a destination disc, and select various software versions (5.0 for ProTooslFree) and what aspects of the session to save: just the session file, or also all sound files, fades and plug-in settings. If one is simply changing the software version but using the same hard drive for the soundfiles, there's no need to copy the soundfiles. But if one is saving to a removeable drive to transfer the whole session to a new computer, copying all soundfiles and settings along with the session file is a quick and easy way to be sure you have everything you'll need.

More info on the M-Box at digidesign.com

For more on WHAT TO BUY, check here on Transom