The Direct Connection

Apr 1, 2007 12:00 PM, By Gino Robair

Six USB microphones that make recording easier.

Thanks in part to the popularity of Podcasting and of consumer-friendly recording applications, a number of manufacturers have added USB microphones to their product lines. This class of products brings the allegedly esoteric concept of the “digital mic” (which is really just an analog mic with a built-in A/D converter) into the realm of the personal studio.

The plug-and-play convenience of a USB mic makes it desirable for someone who wants a good-sounding, cost-effective transducer for Web-bound programs or demo use but doesn't know anything about studio technology. Such simplicity is also good for recordists and multimedia creators who want to forgo preamps, mixers, and outboard digital interfaces in mobile applications yet want a higher level of fidelity and features than an inexpensive, consumer mic offers.

Although the USB mic's list price may be comparable to that of an XLR version, the street price is often more aggressive. That's because manufacturers are aiming for the prosumer market. Prosumers are hobbyists and nonspecialists who buy inexpensive and easy-to-use products that include some pro-level features. A company can tap into this growth area by simply repurposing the technology from its regular line into a product with mass appeal. However, the question for those of us who think seriously about audio quality remains, do USB mics sacrifice sound and useful features for convenience?

In this article, I will cover six USB mics that are intended for personal-studio use, are available on their own (rather than being available only as part of a Podcasting package), and are priced between $90 and $350. At the 2007 Winter NAMM show, I saw several additional models, some of which will be available by the time you read this (see the sidebar “USB Mics on the Horizon”).

Getting on the Bus

The USB (Universal Serial Bus) protocol is used worldwide for data transfer between peripheral devices and computers. The original 1.0 specification, which offered a transfer speed of 1.5 Mb per second, was later superseded by 1.1 (12 Mbps) and finally by 2.0 (480 Mbps). You can hot-swap USB devices, and the appropriate drivers will load and unload dynamically.

Like other USB devices, these mics have a square-shaped USB B port. This means you can use a standard cable with a USB B connector on one end and the flat USB A connector, which always goes to the host, on the other (see Fig. 1). As a result, replacing a lost or malfunctioning USB mic cable is relatively easy — an important point if you're traveling.

Internally, the USB connector uses four pins: two for data, one for ground, and one providing +5 VDC of power. It's good to keep this last spec in mind because the amount of power a microphone receives is critical to how it sounds. And because many of the products in this roundup are based on mics that require phantom power, how a manufacturer steps up the voltage and implements power conditioning, buffering, and noise filtering — USB power is notoriously dirty — will have a major impact on a mic's overall sound. Unfortunately for the consumer, manufacturers keep this information proprietary, as well as any details about the built-in A/D converter, which plays an equally important role sonically.

The Main Players

The mics in this roundup are marketed as being convenient to use and having a level of sound quality that is enough above that of consumer-grade mics to warrant the extra cost. Besides sound quality and ease of use, however, I was also interested in the differences between the sizes and shapes of the mics. Portability is a big asset if you're planning to work while on the road (as some of the EM editors do).

Blue Microphones Snowball
With an attractive Mac-centric look, the Snowball contains a pair of electret condenser capsules and offers two polar patterns, each with a slightly different sonic signature (see Fig. 2). Although the Snowball's cardioid capsule is similar to that of Blue's 8-Ball, it uses a different amplification circuit in order to add presence, according to the manufacturer. Blue also says that the omni capsule is unique to this mic.

Besides the USB connector, the back of the mic includes a 3-position switch to select a cardioid pattern, a cardioid pattern with a -10 dB pad, or an omnidirectional pattern. A red LED on the front glows when the mic is fully powered.

On the bottom of the Snowball is a swivelmount that, when attached to the stand, allows you to position the mic roughly 45 degrees forward or backward. That's handy if you want to avoid recording plosives by facing the mic up or down, and out of the direction of the mouth. The Snowball comes with a telescoping tripod table stand (6.75 inches at full height) and a USB cable.

The published frequency response graph shows the omni pattern with a flat response up to about 5 kHz, with a 6 dB rise at around 10 to 11 kHz, then a drop to 0 dB again around 18 kHz. The cardioid pattern bumps up 5 dB around 1 kHz, drops down, then goes up 4 dB at 10 kHz before dropping off at 18 kHz.

Blue intended the Snowball to be simple and easy to use, and it is. Like most of the other USB mics, the Snowball's A/D converter has a 16-bit, 44.1 kHz resolution. However, the Snowball doesn't give you the option of selecting a lower bit depth or sampling rate. A company spokesman noted that although there are newer USB chips offering a greater bit depth, it wouldn't be of interest to the typical Snowball user: anyone wanting a higher resolution would use a regular mic with a dedicated converter.

However, Blue offers a pair of downloadable firmware applets — high gain and low gain — that give you control over the Snowball's output level. With the Snowball plugged in, simply launch one of the applets and it will download the data to the mic's converter chip in about five seconds. Once downloaded, unplug the mic from your computer and then reattach it to hear the new gain level. Prior to March 1, 2007, the Snowball shipped with the lower gain setting, but by the time you read this, the mic will be shipping with the higher gain setting.

Marshall Electronics MXL USB.006
The MXL USB.006 is a side-address cardioid condenser with the same 0.79-inch diaphragm used in the MXL 990 condenser (see Fig. 3). The mic includes a 3-position switch to control the amount of gain before the A/D converter: Hi (no pad), Medium (-5 dB pad), and Lo (-10 dB pad). You'll notice a gentle thump as you switch between levels.

The microphone's frequency response is 20 Hz to 20 kHz. Although the manual includes no other specs, it does offer instructions on using the mic in a Windows and Mac environment, including GarageBand in particular. A red LED illuminates from behind the grille when the mic receives power.

The MXL USB.006 comes with a nontelescoping tripod stand, a USB cable, a lightweight plastic mic clip, a thin foam windscreen, and a vinyl case that includes a separate compartment for the mic. The clip is attached by unscrewing the ring at the base of the mic, setting the mic into the clip, and then reattaching the base ring. Overall, the MXL USB.006 doesn't feel as solid as the other mics in the roundup, although its lighter weight can be a plus if portability is an issue. In a desktop situation, the clip and tripod held the mic securely.

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