Computers are wonderful, but using one with guitar has two “gotchas”: latency (the delay between hitting a note and hearing it after it goes through the computer) and connectivity (you can’t plug your guitar into the average computer). Although guitars with USB aren’t new, recent developments make USB more attractive than ever.
Minimizing latency. Apple’s OS X introduced native low-latency Core Audio drivers. Windows relied on Steinberg’s ASIO drivers to attain low latency. However, Windows 10 greatly improves its native audio. I measured around 7ms total input-to-output latency with Windows’ WASAPI Exclusive mode—which is on a par with better USB audio interfaces. (To provide perspective on 7ms of delay, it’s about the same delay as being seven feet from your amp.) Although not yet supported universally, Acoustica Mixcraft—as well as all editions of Cakewalk Sonar—already offer compatible recording software, with others certainly to follow.
Ubisoft’s Rocksmith Real Tone Cable provides compatibility with their Rocksmith software, but also serves as a general-purpose guitar-to-USB converter.
Typically, with either Mac or Windows, you plug your guitar into an audio interface that connects to a computer’s digital port via USB, FireWire, or Thunderbolt. Although compact, mobile, high-quality interfaces are available from companies like Line 6, CEntrance, and IK Multimedia, when using laptops or next-generation computers like the Surface Pro, the interface is one more thing to carry around—and you also need cables to patch it to your guitar and computer’s USB port.
To feed directly into a computer’s USB port, some guitars have USB outputs (Squier USB Stratocaster, Epiphone Les Paul Ultra III and Ultra 339, Behringer iAex393, etc.). However, a guitar-to-USB converter works with any guitar or bass. Typical models built into guitar cables (1/4" plug for your guitar, UBS plug for your computer) include the ProSound Guitar to USB Adapter, Behringer Guitar2USB, Hosa Technology TrackLink, and Ubisoft Rocksmith Real Tone Cable (all are under $30-$40).
What about quality? Audio-interface quality depends on preamps and analog-to-digital converters, so the low cost of audio-to-USB converters built into cables may be suspect. However, guitars get a bit of a pass—they generate higher levels than microphones, so they don���t need high-gain preamps. Also, digital-audio technology has progressed to the point where even inexpensive converters give good performance. Although higher-priced audio-to-USB converters like the CEntrance AxePort ($180) have excellent specs—especially noise, which matters if you’re using high-gain distortion and similar processors—whether you’ll hear any difference after going through effects and amp sims is debatable. I measured a high-gain amp sim’s noise output. A standard cable was -44dB, and the Rocksmith cable was -41dB.
Is it really “plug and play”? Yes. And no. You still need to know how to select the correct input, set the sample rate, and verify that the cable is compatible with low-latency drivers (most are). But it’s no different from using any audio interface. Once you get it running, you’ll likely not have to think about it again. And if you’re a mobile musician with a laptop, the convenience is off the hook.