This new breed of USB microphone tends to be based around a large-diaphragm condenser microphone with a built-in A-D converter and USB port for delivering audio directly to your computer without requiring any additional outboard hardware, such as preamps or audio interfaces. USB microphones also tend to have a built-in headphone port for monitoring while you record, with audio able to be streamed to the microphone from the DAW over USB at the same time as it is being streamed back to the DAW for recording.
Convenience, however, comes at a price. With a traditional recording set-up the engineer has the option to pair mics with different preamps to get different sounds, and even different A-D converters and clocks can have an affect on the sound.
With a USB mic, however, all of this is built into the microphone itself, preventing users from experimenting with different colours. However, since everything is built into the unit, everything can be tuned to the voicing of the microphone itself, ensuring a clean and clear signal. While this might not be perfect for the professional recording studio, it will be a significant boon to travelling musicians or journalists wanting to record on the road, podcasters and anyone wanting to make a high-quality, clean recording without significant investment in equipment first.
CEntrance managing director Michael Goodman (pictured) says he is seeing some of the cheaper USB microphones "being a first purchase for people who are just starting out recording and are looking for their first microphone, it's a very simple way-in". Meanwhile, more expensive models and USB adapters are being used by professionals in radio journalism and voiceover markets.
Some manufacturers, such as sE and Samson, have developed their USB microphones using an existing analogue microphone design as the basis. The SE USB2200a, for example, is based on sE's popular sE2200a large-diaphragm condenser. It has a fixed cardioid polar pattern, 10dB pad and low-cut filter, just like its traditional sibling.
However, inside is a proprietary chip and software set that handles both A-D and D-A duties as well as dealing with the issue of capsule noise caused by transforming the 5V USB power supply to standard 48V phantom power. The sE USB2200a has another trick up its sleeve, since it is capable of simultaneously providing an analogue signal over standard XLR mic cables, enabling you to use the USB2200a with your mic preamp and A-D converter of choice alongside or instead of the USB signal should you wish.
Blue Microphones has taken the opposite approach for its range of USB microphones, putting the company's distinct approach to design to good use to produce three very different USB microphones. The Blue Yeti is a multi-pattern condenser microphone with three capsules combining to produce four polar patterns: cardioid, omni, figure-of-eight and stereo. The design includes a built-in desk stand with cable management features and a standard mic-stand mount.
However, it's not just the physical characteristics that make the Yeti stand out, the audio quality of this microphone has led to it being the first microphone to earn the distinction of being a THX Certified Microphone. The Snowball microphone follows the design characteristics of Blue's early Ball microphone, with two polar positions: cardioid and omni, while the Snowflake has been designed for extreme portablility, even packing away into its own desk stand and laptop screen mount. This cardioid microphone is ideal for podcasting, where you can clip it to the screen next to your built-in webcam.
Even some of the older, big names in microphones are getting in on the USB microphone front, with Shure adding the PG27USB and PG42USB microphones to the company's PG microphone range. The PG27USB has been designed with a clean, clear, flat frequency response for use on all manner of signal sources, while the PG42USB has been voiced for lead vocal purposes. As well as the audio quality of the microphone Shure's marketing manager Paul Crognale sees the ability to monitor audio as a key feature of USB microphones: "That's why we offer the zero-latency headphone output and the ability to mix the live track with any pre-recorded tracks."
AKG too has a USB microphone, the Perception 120 USB, which boasts 24-bit A-D conversion and 128x over-sampling.
The range of USB microphones is already impressive, but it is dwarfed by what is available from traditional analogue microphones. Thankfully, in-line adapters are now available, which convert a standard analogue mic signal into a USB signal in a device not much bigger than a couple of XLRs plugged together.
Like the USB microphones themselves, many of the USB in-line adapters provide built-in headphone jacks, and you'll also find models that provide variable gain and phantom power, in effect providing a full mic preamp and A-D converter in an innocuous device. With one of these devices you can use any microphone from your collection, connecting quickly to a DAW over USB.
One of the earliest in-line XLR-to-USB adapters was the CEntrance MicPort Pro, which provides 24-bit/96kHz A-D conversion, 48V phantom power and a built-in 1/8" headphone jack for zero-latency monitoring. This is joined by similar devices from Shure - the X2u - and three models from MXL, which also has a wide range of USB microphones.
CEntrance's Goodman boasts some big-name customers for the MicPort Pro: "One of the big customers of the MicPort Pro is the BBC. CNN and NBC also use it for radio broadcast, and we have the support of the Hollywood voiceover guys who enjoy the ability to use their favourite Neumann mics in portable applications."
Similar devices are also available for guitars, turning hi-Z guitar-level signals into digital signals across USB. The CEntrance AxePort Pro is one such example and can be used alongside the MicPort Pro, or other AxePort Pros, with a single driver on Windows to create an aggregated device of multiple MicPort and AxePort models for multi-track recording. Mac users can, of course, do this with any devices using Core Audio's built-in device driver aggregation tools.
With so much development in USB microphones and the future of USB heading towards wireless technology could we see future USB microphones and adapters that utilise wireless technology, similar to the wireless MIDI keyboards that have been appearing from M-Audio and CME?