The M-Audio Microtrack 24/96

by Jeff Towne

12/12/2005

There’s little doubt that the future of remote recording is trending toward using flash memory. As the prices for this kind of memory continue to fall, it becomes increasingly practical to carry multiple large memory cards, allowing for many hours of recording high-quality audio. The length of possible recording times, and the ease of moving the audio files to a computer for later editing make the use of tapes and discs seem increasingly archaic.

It’s a field that’s getting more and more crowded at all price levels: there are flash-memory recorders available from Marantz, Edirol, Sounddevices, Sony, Tascam, Nagra, Maya and many more, ranging in price from $400 to well over $2,000 USD. As is always the case, there are trade-offs necessary when considering size and price, and in the end it’s a personal decision which aspects of the total package are most important. If sound quality, and professional features are absolutely crucial, there are recording devices that will fit the bill, but you will pay a lot for them.  The M-Audio Microtrack 24/96 is readily available for about $400 US, needing only a big Compact-Flash memory card, and perhaps an external mic, to make it useful.  

The M-Audio Microtrack 24/96 claims to offer high-resolution recording in a tiny package, at a reasonable price. But how well does it really work? As you might expect, it’s a mixed bag. There are necessary trade-offs for size, price, and practicality. But in the end, M-Audio seems to have done a pretty good job making a functional machine that’s good enough in most important ways.  It’s easy to use, sounds pretty good compared to other options, and is small and inexpensive enough to be a viable choice for many purposes.

The recorder is amazingly flexible given its size. It features several input options, including external mic inputs with phantom power, and the biggest surprise, an S/PDIF digital input. Outputs are limited to the mini headphone jack and a stereo pair of RCA plugs, but the very nature of these devices reduces the need for elaborate output interfacing, in most cases one will connect the unit to a computer, or remove the memory card and use a card-reader to transfer files to a computer for later editing.

The best news is that at its most basic, the machine is extremely easy to use, with all the major controls readily accessible from the top, with hardware buttons, not buried in menus or controlled by soft switches.

On the down-side the battery system is potentially problematic for extended field recording; at this time it only records in stereo, it does not have the ability to record a single channel, which would double the available record time on a CF card.

Pros and Cons

Ins and Outs

On the top of the machine there are 4 jacks.

On the left is a stereo mini mic input, which works very well with the supplied stereo T-Mic. Its input level is controlled by the up/down toggles on the front of the recorder, as well as a L-M-H switch on the left side. Unfortunately, even with the slider switch set at H for high, and the input volume turned all the way up, this jack does not provide much gain for quieter microphones, even when used with the Shure a96f impedance transformer.

Luckily the quarter-inch inputs provide more gain, when needed. These middle two jacks, marked L and R for the left and right channels, are wired as TRS jacks, a term for the type of wiring used in the cables that uses three conductors, the tip, the ring and the sleeve. You can tell these plugs by the two black bands on the shaft. This means that these jacks can take signal from the XLR outputs of balanced devices, microphones or live-level devices, retaining the balanced wiring, which reduces the potential for noise and other electronic pollution of the signal.

It is important to use TRS plugs, not the more common TS unbalanced cables, as they will not make as good of a connection, and in some circumstances, those cables could damage the recorder.

Phantom power for condenser mics requires balanced connections, so if you plan to use the phantom power you have no choice but to use cables converted from XLR on the mic end to TRS at the recorder end.

On the bottom of the recorder is a pair of RCA line-outs, which would allow you to connect the audio outputs of the device to a stereo, or powered speakers, or to another recording device. And mentioned above, that kind of analog real-time transfer is rarely needed any longer, because files can be so quickly transferred.

Next is an S/PDIF in for taking digital signals in, from a DAT machine, for example, or from the digital output of a mic preamp like the Grace Lunatek or the M-Audio Duo.

And on the right, a small USB connector. With the provided cable and a click toggle and click of the system setting, the recorder can be connected to a computer, and will act like a USB drive. The recorder charges its battery when connected via this USB connector. The Microtrack also ships with an adapter than allows the USB cable to be plugged into AC power, for direct charging of the battery without a computer.

The left side of the recorder has several hardware switches. At the top end is a Menu button, which toggles the display to various menus that control the settings of the device.

Next is a Hold button which serves to disable all controls, preventing accidental powering off, or on, of the machine, and preventing changes to any other controls while the hold switch is on.

Next is a L-M-H switch for selecting a gain range for the 1/4" TRS input. It seems like it would mean "Low-Medium-High" but it actually stands for "Line - Mic - and High" As you might guess, use the L setting for inputs from an external preamp or mixer or another recorder or other line-level source. Use the M setting when recording with microphones plugged into the TRS inputs. Many mics, especially when recording quiet sources, like an interview, will require that you switch to the H setting in order to get enough gain.

And finally, the Phantom Power switch, which turns on or off the current required to power some condenser mics. Phantom power is only provided on the quarter-inch TRS jacks, and use of this will reduce battery life markedly. An FAQ on the M-Audio website warns not to unplug or replug input cables to the quarter-inch jacks while phantom power is on, one risks damaging the device if the current shorts while moving cables in or out.

On the right side of the recorder is a large slot for inserting a Compact Flash card, or microdrive (the CF card loads fully into the slot, flush with the side of the recorder, the protruding card is for illustration purposes only.

A standard Compact Flash memory card is sufficient, no need for ultra-fast cards. Microdrives often have larger capacities and lower prices, but one must keep in mind that the spinning mechanism of a microdrive will burn battery life faster, is sensitive to vibrations or shock, and can potentially create noise. The no-moving-parts of a static-memory Compact Flash card is preferable.

Conveniently, the most commonly accessed Set-up and functions are accessed by pressing the "menu" button on the Microtrack's left side, to access the various screens. One scrolls through the various options by flipping the toggle switch on the right side up or down, then pressing it in to select an option. The toggle is occasionally oversensitive, skipping over an option, but it generally works pretty smoothly and comfortably with one hand.

The main top-level categories are:

• Files, where one can audition or delete recorded files
• Record Settings, where one can select bit-depth, sampling rate and other record parameters
• Backlight, where one can control the activity of the blue backlight, which improves readability, but burns battery. It can be always-on, always-off or auto shut-off at various intervals.
• System, which selects some universal settings, formats the CF cards, and puts the Microtrack in a mode where it can connect to a computer via a USB cable.

Within the Record Settings menu, one can choose the input source, selecting between the mini TRS mic input, the 1/4" TRS, or the S/PDIF digital input.

The Input Monitor can be turned on or off, determining whether the headphone jack and RCA line-outs will be active during recording. Some battery power could be saved by turning the input monitor off, but it's generally good practice to always listen to what you're recording. At this time, the input monitor is NOT active when recording from the digital input, making recording from a digital source somewhat of an act of faith.

The 27dB TRS Boost should be turned on in most circumstances when recording with microphones connected to the 1/4" TRS jacks. Turn this boost off when recording from a line-level signal, or when recording extremely loud sources through the mic inputs. This is a digital boost, not analog input gain, so it's a little quieter to have this set to off, and the input gain set higher, but for recording interviews, and ambiences, it seems that most mics require both the H setting on the gain switch on the side, and the 27dB boost from this menu.

The Encoder setting allows you to choose between full-bandwidth .wav file recording and compressed MP3 recording. Recording to .wav files uses up significant disc space, approximately 10 megs per minute. At 16-bit, 44.1 kHz, this will allow over an hour and a half of audio in a 1 gig memory card, over three hours on a 2 gig card.

MP3 recording allows significantly longer record times, as the resulting files are much smaller. A one gig card can hold over 24 hours of audio at 96 kbps, over 7 hours of audio even at the highest sample rate. The "Bits" menu item can be used to set the bit rate of the MP3 file, in several steps from 96 kbps which will create very small, but low-quality files, to 320 kbps, which would create relatively high-quality files. This is handy functionality to have when one needs long record times for relatively non-critical recordings. But it is highly recommended to resist the urge to use MP3, or any compressed recording format for important master recordings.

The problem is not whether the MP3 sounds good on the initial playback, it's that if those files are compressed further, later in the production process, either for delivery over the internet, or over a radio satellite system, or as a podcast, or simply on the end-user's computer, those additional compressions can seriously compromise the sound quality in ways that would not occur if the original recording was done in .wav format.

Next on the menu is Sample Rate. In .wav recording, on can choose 44.1, 48, 88.2, or 96. Those numbers represent thousands of samples per second, eg 44.1 khz. It's common audio shorthand to just use the terms 44.1, 96, etc. The sample rate 44.1 is a long-used standard, on CDs, DAT machines and other digital devices. 48k is a common standard for digital video. The higher sample rates are becoming increasingly popular for high-definition audiophile recording. Those rates allow for a greater frequency response, well above the 20hz to 20khz frequencies that are generally referred to as the "audible range". There's good evidence that retaining audio information above that range improves fidelity, but at a cost: recording at higher sample rates uses more disc space. 44.1 khz is certainly sufficient for most recording tasks.

Bits refers to the bit-depth of the recording, the number of gradations of resolution if each sample. 16-bit has long been the standard for CDs and DAT recorders, but 24-bit is becoming more common. That increased resolution does indeed increase the possible detail , especially in low-level information, but once again, at a cost: recording at 24-bit reduces the number of minutes you can record on a given memory card. If the machine is set to record in MP3, this bits menu can be used to change the "bit rate" of the compression, higher numbers correlates to higher quality.

At this time, the Microtrack only records stereo files, but the manual promises that there will be a mono mode in the future, available via a firmware update. That would allow double the record time if recording with a mono microphone, which would be a great help to users that record interviews more than music and ambience. When that happens the Channels control will switch between those modes.

The Rec Time Available is pretty self-explanitory, simply displaying the time remaining on the currently installed memory card. That time is displayed in the record window as well, but this is helpful to have if one is not currently recording.

The System menu contains some important controls, many of which you will set once and ignore. The first is not one of those, the Connect to PC menu item is required to mount the Microtrack as a drive on your computer, via the supplied USB cable. This is the simplest way to move audio from the Microtrack to your computer for archiving, burning to CD or editing, but the data moves at USB1 rates. If you're moving a lot of data, it's faster to remove the CF card from the Microtrack and use an external card reader if you have one that connects via USB2 or firewire. But connecting the cable, clicking on Connect to PC and then clicking again is simple. That puts the Microtrack in host mode which disables playing or recording from the machine, but it does start charging the battery.

Like with all USB devices, it's important to properly eject the Microtrack when you're done transferring the data, simply pulling the cable might corrupt the data on the CF card.

Format Media will erase all information on the CF card.You may need to do this the first time you load a new memory card into the slot.

Link L+R gangs the left and right record controls together, very helpful when recording with a stereo microphone, or a stereo line-in. Unlink them if the input signals are at significantly different levels between the two channels.

Playback EQ allows you to shape the bass and treble response of playback, but unless your headphones really need it, it's best to leave this off to better hear what you're getting at the source.

Verify Delete is best left on, it's a little too easy to bump that delete button on the top of the unit, and without this switched on, your files will be immediately erased.

Scrub Audio supposedly allows audible scanning through the audio by pressing the toggle switch up or down. It sort-of works, but the audio is just little choppy blips, it's hard to keep track of what you're hearing. But better than nothing...

Auto Off will save battery life by shutting the Microtrack down after a specified period of time if it is running on battery and no buttons have been pushed. It will NOT shut off if the machine is in record mode.

Language refers to the language the menus will display, for now English and Spanish are the only choices, more may be added through firmware updates.

Factory Defaults resets all the system settings back to the defaults. This will be helpful if you wish to reset the file numbering. As it is set, the file names just count up sequentially, even after card reformatting. Be careful with your file management, if you reset the file numbers and then transfer a new file into a folder that has an old file with the same number, one could accidentally overwrite the older file.

Firmware Update allows the capabilities of the Microtrack to be updated. There's already been one update, less than two months after the unit's release. The firmware updates take the form of files available from the M-Audio website. Download the files, load them onto the CF card you use in the Microtrack, select this Firmware Update selection, press in the selection button. Done.

Version simply displays the current firmware.

Contrast adjusts the screen brightness.

Date and Time is logged into the soundfiles, so it can be very helpful to have this set accurately.

By pressing the red record button, the record screen is displayed, and recording starts, as indicated by a large solid circle in the top left of the screen, and the time counter rolling in the lower right. You can pause to adjust your levels, or to simply wait until the right time to start, by pressing in on the toggle/selection switch on the right. The universal sign for pause, two vertical lines will display in the upper left and the counter will stop. Press that selection switch again and recording will resume. Pausing does not make any markers or make a new track. To stop recording, just press record again. There will be a short delay, and the screen will read "writing file". To record again, just press record again.

This is one major problem with the Microtrack, there's no way to write a track mark for a new file, while recording continuously, as the Marantz recorders allow. So if one is recording a continuous event, an interview or concert or something similar, you will either end up with one big file, or there will be short gaps as the recorder writes file data to the disc before it can continue. Hopefully this can be addressed in future firmware updates.

There are two time displays at the bottom of the window, the one on the left is the time elapsed in this recorded track, the number on the right is the time remaining on the disc.

The wedge shape at the top of the window reflects the headphone output volume, as controlled by the up/down toggle marked "volume" next the to the record button. The affects only the monitoring or playback volume at the headphones, it does not influence the recorded track in any way. Unfortunately there is not loads of gain on this headphone amp, and I found myself running it at full volume most times, even with loud headphones like the Sony 7506s.

The small triangles along the meter bars indicate the input gain settings, if the triangles are all the way to the right, you are at full input gain, and there's no point to trying to turn it up any more. If you have clicked L-R link in the system menu they should be even, but if you turn that off, each channel can display different gains.

The small dark bars that appear along the meters are peak-holds and indicate the peak level of the audio being recorded. The main dark meter bars are a little sluggish, and display the average levels of the input better than the peaks. Between the averaging meters, the graphic peak indicators and the red clip indicators that light up above the volume up/down toggles when a clip is encountered, there's a pretty good amount of metering to help you set your levels. The green "signal present" indicators that light up underneath the volume buttons should be fairly consistently lit when recording.

The Microtrack does NOT have a built-in limiter or automatic gain control. I rarely like how those sound on inexpensive recorders, so having easily-adjustable manual input controls is a better choice, in my opinion. But as a result, you need to be very careful about your levels, there is no limiter or AGC to compensate for you if you have your volume set poorly.

The Microtrack ships with a little T-microphone that attaches to the 1/8" input on the top of the recorder. It records surprisingly good sounding audio, with a decent stereo size. Despite the foam covers, the mics distort a bit in the wind, as any mic would, but they are amazingly useable mics for something that just comes free with the recorder.

It's obviously a bit unergonomic for interviews, sticking the whole recorder in someone's face is not the best situation, and you'd need to tilt the recorder a bit to get someone's voice directly into a mic.

Audio Samples

	Ambience of an urban farm market, exiting onto the street with idling trucks using the included stereo T-Mic MP3 Download | MP3 Stream
	Rode NTG2 short shotgun mic in a very quiet soundbooth MP3 Download | MP3 Stream
	EV 635A dynamic omni mic in a very quiet soundbooth MP3 Download | MP3 Stream

Audio Quality

There have been some concerns stated in internet discussions about the self-noise of the Microtrack, and indeed, there is some audible hiss and general noise when the inputs are cranked up very high, as they often need to be. The noise will be fairly negligible when recording loud sources, but for a person speaking a conversational levels, the input gains will need to be cranked pretty high, especially with dynamic mics. It's a personal choice whether the hiss and noise is too much, I find it to be subjectively less than the Marantz PMD660 under similar conditions. There are way too many ways to test this noise, but the most real-world that I could think of was to set the microtrack's gains for proper levels for recording an interview. With both a condenser shotgun mic and a dynamic omni mic, the gain settings were pretty high, switched to H on the side, the 27dB boost applied to the TRS inputs, the hardware gain controls set to halfway for the shotgun, full-up for the omni. Here's a plot of the noise recorded by leaving the machine running in a well-isolated voice booth. Recordings were at 16-bit, 44.1 khz.

The noise floor is down at almost -70dBfs for the condenser mic, and not so much worse, maybe about -62dBfs for the omni mic. It's not perfect, but not a huge problem for most applications. Recording louder sources will allow the gain controls to be reduced, which will lower the noise floor. Recording with hotter mics, like condensers, clearly makes the noise less of a problem, yet the Microtrack does not seem to suffer from input clipping as the Marantz 660 sometimes does.

One of the bigger problems with the Microtrack is the powering scheme: there's no field-swappable battery, so if the battery dies, there's no inserting new batteries, the machine needs to be recharged. The internal battery's run-time seems to range widely depending on the unit, and the usage, but my experience was a maximum record time of about 3.5 hours, recording with no phantom power. If you need more operating time than that, the best solution seems to be an external device that can provide the required 5-volt power via a mini-USB connector. Here are two examples: http://www.bixnet.com/usbbatterybox.html and http://www.dealsonic.com/usbbapabapof.html there may be some other powering options, we'll discuss those in talk as we discover them.

There have been reports of different behavior, but when I recorded with the unit right up until the batteries failed, I lost the last soundfile that I recorded, apparently the track information was not recorded because the battery died. Earlier tracks were unaffected, but I had to transfer those files off of the CF card and reformat the card before I could record again, despite apparently deleting files, which should have freed-up space. So... don't let the batteries run out!

When connected to a computer or to AC power, or to one of those USB battery boxes, the Microtrack by default enters a charge mode that disables all the controls. If you want to operate the machine while plugged-in, have the machine booted-up before plugging the USB cable into the computer or wall power. If it's in operating mode first, the power will still run the machine and charge the battery, you'll see a small CHG indicator in the upper right of the main window, but if you attach the USB cable before starting up, it will enter a special charge mode that does not allow the machine to record or play.

In conclusion, the M-Audio Microtrack 24/96 is a very easy-to use machine, with some helpful professional features, and pretty good sound quality. There are a few downsides for field reporters, like the fixed battery, and the inability to make track marks during continuous recording. Some audiophiles might find the inputs to be too noisy, but they seem remarkably good for a recorder that sells for under $400 US, and is about the size and weight of a deck of cards. The machine's ability to record at 24 bit and 96 khz is a boon for those who desire such features, although depending on the circumstances, the mic preamp's specs won't always deliver clean sound down to those lower bits.

It's not a perfect machine, but delivers surprisingly good sound and ease of use at a decent price. There are more flash-memory recorders hitting the market, at various price points and at various levels of sophistication. I think this recorder offers a good balance of price and performance, and the convenience of the small size and weight and quality of the provided mini mics, make it a good choice for independent audio producers

More information about the M-Audio Microtrack at the M-Audio website.

Related links

• Transom digital recorder comparison chart

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