The Musical World of USB

It's everywhere you want your music to be.No, the "U" doesn't stand for Ubiquitous, but it might as well. Ever since it was introduced a few years ago,

It's everywhere you want your music to be.

No, the "U" doesn't stand for Ubiquitous, but it might as well. Ever since it was introduced a few years ago, the Universal Serial Bus has lived up to its name, becoming standard equipment on both Macs and PCs. The music industry has embraced USB as a way to build devices with cross-platform compatibility and to reduce the reliance on what seems to be an ever-shrinking allotment of internal slots. - The past few months have seen a bumper crop of new and innovative USB devices, from simple MIDI and audio interfaces to elaborate digital audio workstation (DAW) hardware controllers and controller/interface hybrids. This critical mass of gear has inspired us to take a look at what's out there and see just how well the technology is living up to its promise. - To give you a bird's-eye view of the USB landscape, we've included a couple of tables that detail the variety of available products (see "USB MIDI Interfaces" and "USB Audio Interfaces"). Keep in mind that these lists are very fluid - some of the products may not have shipped as of press time, so specifications, prices, and driver status are subject to change. Be sure to check the manufacturers' Web sites for the latest USB developments.

THE LITTLE BUS THAT COULDUSB achieved buzzword status at about the same time as that other bus with the ever-so-catchy moniker "IEEE 1394." Both standards were portrayed in the computer press as the solution to all our connectivity hassles, and there was good reason for that kind of optimism. Both offer trim physical connectors that can fit on small computer cases and even the ultraslim profiles of modern notebooks; both let you hot-swap and daisy-chain devices; and both are capable of supplying a certain amount of power to connected devices. (If a device derives its power in this manner, it is said to be bus-powered; if it has a separate power supply and needs to be plugged into a wall outlet, it is said to be self-powered.)

USB became the bus of choice for low- to midbandwidth devices, such as mice, keyboards, scanners, and digital still cameras, whereas IEEE 1394 was reserved for more-demanding devices, such as external disk drives and digital video cameras. Many people assumed that the music industry would embrace 1394 for the next generation of MIDI and audio interfaces.

IEEE 1394 began life in the 1980s as Apple Computer's FireWire spec and was eventually adopted as an international standard by the Institute of Electrical and Electronics Engineers. Although it's found in many Macintosh computers, PC manufacturers have been slow to adopt the high-speed bus. Both platforms have widely incorporated USB, however, thanks in large part to its lower cost. Rather than freeze product development until the anointed bus of the future became clear, manufacturers of music hardware seized the opportunity to develop for the bus at hand.

With a potential bandwidth of 12 megabits per second (Mbps), USB provides a big enough pipeline to handle both audio and MIDI data even when a USB mouse and keyboard are plugged in. Developers began designing audio interfaces that took sensitive components out of the computer, and USB provides a simple plug-and-play connection for such devices.

MIDI INTERFACESPrior to the advent of USB, MIDI interfaces were connected to computers in one of several ways. The most sophisticated devices, with multiple ports and synchronization capabilities, combined an internal card with an external unit (usually rack-mountable) that required its own power cord. Simpler MIDI interfaces could use standard parallel or serial connections, which provide much less bandwidth than the internal-card connections. These simpler interfaces also required external power in most cases. The parallel and serial interfaces were portable, and the PCI and serial devices had cross-platform potential, but each arrangement compromised either convenience or performance.

One look at current MIDI-interface ads might lead you to think that USB has completely replaced other types of connections, and that isn't far from the truth. This logic is immediately apparent, for example, in Midiman's Midisport line. Available in 1-In/1-Out, 2-In/2-Out, and 4-In/4-Out configurations, the Midisports are cute little boxes containing nothing more than a USB connector and several MIDI connectors. Powered directly from the USB bus, they require no wall-wart AC adapter. They come with drivers for both Macs and PCs and are extremely portable, making them perfect for laptop use. The Midisport interfaces demonstrate the full potential of USB hardware by combining simple connections, fast data transfer, and cross-platform capabilities while eliminating external power cords.

Rounding out the Midisport line is the 858/s, which (naturally) features eight MIDI Ins and eight MIDI Outs. It also provides SMPTE read/write capabilities and a serial-port connection, so it can be used with non-USB machines. When your computer is turned off, the 858/s functions as a stand-alone MIDI patch bay.

Mark of the Unicorn has embraced USB in its latest generation of MIDI interfaces, but the company has taken a different approach to the bus's advantages. Of course, MOTU's gear will work with PCs as well as with Macs (as soon as its Windows drivers are ready), and you don't have to open your computer to install the products. But in USB, MOTU has found the vehicle to implement its MIDI Time Stamping technology, which is said to facilitate extremely accurate timing.

By taking advantage of USB's ability to perform isochronous data transfers, MOTU can guarantee timing accuracy between its interfaces and your computer down to a fraction of a millisecond. (Isochronous communication bypasses data buffering and error-checking in favor of "on-time" delivery, and it reserves a portion of the bus bandwidth to ensure that it never has to wait for another device to get out of the way.)

MOTU's flagship product is the MIDI Timepiece AV, an 8-In/8-Out unit with comprehensive sync capabilities. It's a 1U rack-mountable design that can also function as a stand-alone MIDI patch bay. It can store up to 128 user-defined setups that can be recalled by MIDI Program Changes, and it has the rare ability to be programmed from its front-panel LCD. The MIDI Express XT is an 859 design with fewer sync options and fewer programmable setups. The Micro Express is essentially a 4-In/6-Out version of the XT.

Bringing up the rear of the pack in power - but leading the way in terms of portability and cuteness - is the FastLane, MOTU's simple 2-In/2-Out box that comes in a variety of iMac-inspired colors. It features a bypass mode that allows MIDI data to pass through if the computer is turned off.

All of MOTU's USB MIDI interfaces (except the FastLane) require their own power cord, and they are designed to be mixed and matched freely as your need for MIDI connectivity grows.

Other companies, ranging from industry icons such as Yamaha and Steinberg to a Korean startup called Ego Systems, are using USB for their MIDI interfaces. Yamaha's UX256 is a dual-platform, 6-In/6-Out unit that also has two serial ports to accommodate non-USB computers (see Fig. 1). It requires external power, and it comes with MIDI-routing/patch-bay software.

Steinberg's USB-2-MIDI, an inexpensive 2-In/2-Out interface, is a bus-powered, cross-platform USB poster child - and like MOTU's FastLane, it offers a bypass mode for passing MIDI data without benefit of a computer. Steinberg will soon be offering an 8-In/8-Out interface called the Midex 8 (see Fig. 2), a 1U rack-mountable unit that employs the new Steinberg technology Linear Time Base, which the company claims has submillisecond timing accuracy. The Midex 8 will ship with Mac and Windows drivers and is bus-powered (unless you use more than one, in which case external power is required).

Roland ED's UM-4/SMPU64 and UM-2/SMPU32 are simple, bus-powered 454 and 252 interfaces, respectively. Roland ED maintains a list of compatible USB host controller chips (which are found within the host computer) on its Web site, an apparent testimony to less-than-universal adherence to the published specification for these controllers. Emagic makes a compact device called the MT4 that provides two MIDI inputs and four MIDI outputs. It's bus-powered and can be used as a stand-alone MIDI patch bay, holding up to 32 patch configurations that are accessible via Program Changes.

AUDIO INTERFACESPushing audio through a USB connection has proven to be a bit of a challenge. The bus has plenty of bandwidth for several channels of uncompressed CD-quality audio, but support for this application at the operating-system level has been slow in coming. Windows 98 introduced significant support for USB audio, with further improvements in Windows 98 Second Edition. However, Apple experienced major delays in its development process; only with the release of Mac OS 9.0.4 in April did it really become possible to build cross-platform USB audio devices.

Roland ED and Opcode blazed the trail for USB audio devices, releasing their first interfaces in late 1998 and early 1999, respectively. Theirs were the only such devices available for months; in fact, the Roland ED UA-100's little sibling, the UA-30, was the only new product until this spring's crop of gear popped up. Some of Opcode's DATport and SONICport interfaces are still available, but they're currently out of production, and their development status is in limbo as a result of the Opcode/Gibson situation.

Roland ED has continued production of its UA-100 and expanded the line. The UA-100 provides stereo, 16-bit, 44.1 kHz analog I/O, and an optical S/PDIF digital audio output for Windows machines. (Mac support is likely, but no release date has been set.) Audio connections include two 11/44-inch microphone inputs, one of which can be used as a guitar input; a headphone output with volume knob; and stereo aux inputs and outputs. Two channels of MIDI I/O are also available. The UA-100 features a set of 24-bit effects ranging from amp simulation to reverb to vocal harmonization.

The UA-30 is a trimmed-down version of the UA-100, with reduced I/O and no effects. One advantage of this simplification is that the UA-30 doesn't need external power, making it better for portable use. With the release of Mac drivers in early May, the UA-30 became the first USB audio device to live up to its cross-platform promise. It provides stereo, line-level I/O at either 44.1 or 48 kHz on RCA connectors, plus S/PDIF optical and coaxial I/O, a 11/44-inch mic/guitar input, and an 11/48-inch headphone output.

For several months, Ego Systems has been teasing the industry about a tiny box called the U24 that could have been the world's first 24-bit USB audio interface. Unfortunately, problems with a critical component forced the designers to scale their plans back to 16-bit audio. Still, with analog as well as S/PDIF coaxial and optical I/O in a package that's only 9 cm square, the U2A (as it's now known) is an interesting little box. The output signal is sent to all three outputs at all times, which means you can use the U2A to convert a coaxial signal to an optical signal, or vice versa.

Sound Devices is staking a claim in the high-end USB audio interface market with its new USBPre stereo interface. The device's balanced XLR inputs are individually adjustable for microphone-, instrument-, or line-level audio signals, and +48V phantom power is available for both inputs. Its headphone output can mix the computer audio output with a direct monitor of incoming audio to eliminate internal latency problems. And even with all this power, Sound Devices estimates that the bus-powered device will reduce a typical notebook's battery life by only 10 percent. The USBPre provides 20-bit audio input for applications that support high resolution, but its output is only 16-bit. Ruggedly designed for broadcast field recording, it is also compatible with popular music-production software.

The Swissonic USB Studio is a straightforward 16-bit, 44.1 kHz stereo audio interface in the body of a well-connected line mixer. It includes two mic inputs with switchable phantom power, polarity inversion, and insert jacks; four stereo line inputs; two high-impedance instrument inputs; a stereo line input with switchable phono preamp; and separate outputs for recording, monitoring, and headphones, all with independent volume control. The Studio D model adds S/PDIF coaxial and optical I/O.

DAW FRONT ENDSThe Winter 2000 NAMM show featured a couple of items that represent a whole new category of USB gear: the digital audio workstation front end. Roland ED's U-8 Digital Studio and Tascam's US-428 each include analog and digital audio I/O, MIDI I/O, and a panel of faders, knobs, and buttons for controlling your favorite software. The appeal of hardware controllers has been demonstrated previously in products such as the Peavey/Cakewalk StudioMix and the CM Automation Motor Mix, but the U-8 and US-428 go a step further by handling the audio I/O.

The U-8 uses 20-bit DACs and delivers full-duplex 16-bit, 44.1 kHz stereo audio in the Windows 98 environment. Connections include one unbalanced XLR mic input, two 11/44-inch line inputs, one high-impedance 11/44-inch guitar input, optical S/PDIF I/O, one MIDI In/Out pair, a stereo aux input and stereo analog output on RCA connectors, and a 11/44-inch headphone output. It features more than 120 built-in 24-bit effects, including Roland Sound Space, guitar effects, reverb, chorus, noise gate, and speaker simulation.

The control surface includes eight channel faders and one master fader, a set of four knobs to control various mixer and effects parameters, a data wheel, and an assortment of other buttons and knobs to control everything from input level to transport and more. The U-8 comes bundled with a custom version of either Cakewalk's Home Studio or Steinberg's Cubasis VST (buyer's choice). Currently, the U-8 is for Windows PCs only, but Mac drivers are in the works.

As of this writing, Tascam's US-428 (see Fig. 3) will deliver several significant firsts. For starters, it is the first USB audio interface to offer 24-bit audio, with sampling rates of 44.1 or 48 kHz. And although USB's limit is generally held to be six streams of 16-bit audio or four streams of 24-bit audio, Tascam, working in partnership with Frontier Design, has somehow managed to squeeze six 24-bit streams - four in and two out - through the pipeline.

For those of us interested in USB audio for its portable potential, this is a real breakthrough, as it makes the US-428 the only device capable of recording more than two channels into a laptop. (The Digigram VXpocket 440 PC Card, its only rival for this honor, was canceled at the last minute due to insurmountable engineering hurdles.) The Tascam US-428 trumps other notebook-compatible solutions by offering both higher resolution and more input channels.

The unit's control surface is modeled after Tascam's classic Portastudio, with a row of eight channel faders and a master fader, transport controls, data wheel, assignable buttons, and more. Two of its six balanced analog inputs are XLR, and two more are switchable to high-impedance guitar inputs. In addition to two analog outputs, it features S/PDIF I/O and 32 channels of MIDI I/O. Cubasis VST for the PC is currently shipping with the US-428; the Mac version should be available by the time you read this. Control templates for popular programs are in the works as well.

OTHER DEVICESUSB is also being used in other types of devices, such as the HHB Portadisc, a high-end portable MiniDisc recorder designed for broadcast use. It includes a USB connection for transferring recorded audio into a computer for editing. Akai has announced an optional USB board for its S5000/S6000 samplers. With the included software, you can transfer material from sampler to computer or from sampler to sampler, edit programs or multis, and move audio into your favorite audio editor for additional tweaking.

Radikal Technologies has announced the SAC-2K, a very sophisticated DAW front end with touch-sensitive, motorized 100 mm faders (see Fig. 4). In addition to transport controls, a jog/shuttle wheel, and a slew of buttons and knobs, it has three separate LCDs to help you keep track of settings as you adjust them. With editor/librarian software, the SAC-2K also becomes a synth-programming control surface.

For Mixman Studio fans, Spacetoys has designed the P-Mix, a controller that emulates the software's two-turntable display, with 16 sound-trigger buttons, 8 macro buttons, 4 parameter-control buttons, and more (see Fig. 5).

In addition to its USB MIDI- and audio-interface products, Roland ED distributes the SC-8850 and SC-8820 USB Sound Canvas synth modules and the PC-300U USB keyboard. Also, a small German company named Propagamma Kommunikation noticed the absence of ASIO drivers for many USB audio products and decided to write its own. The current version has been licensed by Swissonic for use with the USB Studio and is said to be compatible with Roland ED's UA-30 MIDI interface as well. A Mac update and a Windows version are planned for release this summer. Check it out at

TIME TO GET ON THE BUS?Is USB living up to its promise? Is it right for you? The answer is a very enthusiastic "maybe." Yes, USB solves some problems, both for developers and end users, but it introduces several challenges of its own.

When one of the biggest vendors of USB music-production hardware deems it necessary to maintain a list of compatible USB host controller chips on its Web page, you know that some issues must be considered. On the other hand, nearly every manufacturer I spoke with is planning further USB development, which indicates the power of this interface.

In any event, there are three basic issues with USB: latency, compatibility, and bandwidth.

Latency. According to some unwritten law, the term USB apparently can't be used in a sentence without the word latency. Some people fear that USB MIDI and audio devices will never achieve responsive musical timing. But tell that to MOTU, which claims sub- millisecond response for its USB MIDI interfaces. With several times the bandwidth and a faster interrupt time than traditional serial ports, USB is more than adequate for the task. So why the confusion?

First, achieving MOTU's stated low latency depends on using the latest version of Digital Performer, which communicates directly with the company's hardware. Second, some of the skepticism understandably comes from the makers of software synthesizers - the canaries in the coal mine when it comes to latency. Bear in mind that we're still in the first generation of USB drivers. You can expect things to improve after the hardware, software, and OS developers have had more time to work together.

With audio the jury is still out, but there's reason for optimism. Roland ED promises no more latency with software synths than what PCI audio cards exhibit, but as of this writing Tascam, Swissonic, and Ego Sys haven't done enough testing to give a definitive answer. So far, the developers are uniformly confident that audio latency will not be a problem. Still, I suggest a bit of caution in considering a USB audio interface if you depend on software synths in live performance. As far as recording is concerned, all the devices covered here feature input monitoring to eliminate internal latency problems when overdubbing.

Compatibility. There seems to be no problem getting software to recognize and respond to USB MIDI interfaces, as long as the manufacturer has written drivers for the operating system being used. As of this writing, MOTU was still working on its long-awaited Windows drivers. The delay is reportedly not due to any major technical obstacles, so perhaps PC users will have finally joined the USB MIDI party by the time you read this.

Audio compatibility is a work in progress, and now that several USB audio interfaces are out there, software developers will have an added incentive to work with the hardware folks to clear up any remaining problems. It wasn't an issue at all for developers of Mac software until OS 9.0.4 was released, and Windows developers had only the two Roland ED units to consider until recently.

Bandwidth. Bandwidth isn't a concern with MIDI. Every maker of USB MIDI interfaces touts the advantages of being able to add another interface or two as your needs expand. MOTU's gear is designed around a mix-and-match approach, and the company says you should be able to use several of its 858 units at once without clogging the pipeline.

By contrast, nobody expects you to use multiple USB audio interfaces simultaneously. Well, almost nobody: Sound Devices claims that you can use more than one USBPre as long as each is on a different host controller. Check your computer's specifications carefully before trying this, because as a convenience many machines provide two USB connections on the same host. Nevertheless, audio interfaces consume enough bandwidth that you have to wonder whether your MIDI and audio interfaces will get along.

By all reports, there's no reason to worry. Even with all the control, audio, and MIDI data kicked back and forth by a complex device such as Roland ED's U-8, you have enough pipe left over for multiport MIDI interfaces, mice, and keyboards. The only manufacturer that has expressed some doubts about sharing the bus with other devices is Tascam - and given the fact that its US-428 exceeds the generally accepted audio limitations of USB, this is understandable. In Tascam's testing so far, an iMac's USB keyboard and mouse have not presented any problems, so there's apparently a bit of headroom.

Beyond these three issues, the standard rules apply. What appears to be a problem with your shiny new USB device might be fixed by optimizing your system, checking your cables, and using the latest OS patches, audio drivers, and even video drivers. I've had extremely good luck with the handful of USB devices I've installed, but I've heard some tales of hellish installations. (Of course, the same can be said about any other category of computer gear.)

Check out the manufacturer's Web site for the latest word about specifications and compatibility before you buy. The USB Implementers' Forum ( limits the use of the official USB logo to devices that have passed its compliance testing, so keep that in mind when you shop for a new computer or USB device.

Use only high-quality cables, with the not-quite-square "A" connector on one end and the flat "B" connector on the other, and never use an extension cable. Before installing a new piece of USB gear, back up your entire system, taking special care to back up configuration files so that they can be restored in case of disaster. If this sounds familiar, it should. These procedures are standard with any kind of new gear, especially for those of us who habitually push our computers to their limits.

By the end of the year, you should see computers shipping with USB 2.0 ports, which will increase the maximum data-transfer rate to 480 Mbps. This rate exceeds the current IEEE 1394 maximum bandwidth by 20 percent (although that rate will soon reach 800 Mbps, followed shortly thereafter by 1.6 Gbps). USB 2.0 is fully backward-compatible and will continue to support hot-swapping.

A year from now, will you be pumping multichannel, high-resolution audio through your notebook's USB 2.0 port? Nobody's officially saying so yet, but the company representatives I spoke with are excited by the possibilities.

It's clear that USB is changing the landscape of desktop music hardware, and the trend is likely to continue. The whole idea of gear that can be used on both Windows and Mac platforms and moved from one system to another without requiring computer surgery is attractive for both consumers and developers.

Whether USB 2.0 will render IEEE 1394 moot, or vice versa, remains to be seen. Conventional wisdom has 1394 coming out on top, but USB has already defied the conventional wisdom. While we wait for the dust to settle, there's more than enough interesting USB gear to keep us busy.