Digital Connections for Home Recording
Digital audio equipment is a recent invention, and as such, no one standard has emerged. Because of this lack of standardization, a variety of digital connection methods are on the market, only a few (or one) of which may be on the equipment that you own or intend to purchase.
ADAT Lightpipe Digital Connections
The ADAT (Alesis Digital Audio Tape) Lightpipe format allows eight tracks of digital audio to be sent at once. Developed by Alesis, ADAT Lightpipe (or simply Lightpipe for short) has become a standard among digital audio products. It consists of a fiber-optic cable that uses a special connector developed by Alesis.
TDIF Digital Connections
TDIF (Teac Digital Interface Format) is Teac’s return volley to the ADAT Lightpipe format. TDIF uses a standard computer cable with a 25-pin connector. Like the ADAT Lightpipe, TDIF cables can transmit eight channels of digital data at a time. TDIF isn’t nearly as common as ADAT Lightpipe because Alesis made its Lightpipe technology available to other companies to use for free. Alesis encouraged these companies to adopt it as a standard because the Alesis ADAT recorders were so common.
USB Digital Connections
USB, which stands for Universal Serial Bus, is a common component in nearly all modern computers. In fact, your computer probably has more than one USB port. In case it’s been a while since you’ve had to use your USB connection, take a look at the following illustration. As you can see, USB has the following different plugs that fit different jacks:
Rectangular connector: This is called the A connector and is for any receiving device, such as your PC or a USB hub.
Square connector: Called the B connector, this is used for a sending device, such as your USB audio interface or printer.
Aside from having two different types of jacks and plugs, USB also has different standards, as follows:
USB 1.1: This standard (the original) can handle a data rate of up to 12 Mbps (megabits per second).
USB 2.0: Also called Hi-speed USB, this standard can handle 40 times the data flow of the earlier standard — 480 Mbps.
USB 3.0: This is also referred to as SuperSpeed USB. This connection transfers data at an astounding 5 Gbps, tens times as fast as even USB 2.0.
You’ll still find some USB 1.1 audio interfaces on the market, but most have migrated to the faster, 2.0 version. As of mid-2011 there are no USB 3.0 audio interfaces out yet. Expect this to change soon.
FireWire Digital Connections
Developed by Apple, FireWire (also known as IEEE 1394 or iLink) is a high-speed connection that is used by many audio interfaces, hard drives, digital cameras, and other devices. Even though FireWire was developed by Apple, you can find FireWire ports on devices from many manufacturers. FireWire cables, unlike USB cables, have the same connector on both ends.
Like USB, FireWire comes in two flavors, which are described as follows:
FireWire 400: This standard supports data-transfer speeds of up to 400 Mbps. Many audio interfaces currently use FireWire 400 as a way to connect with your computer. These interfaces can handle quite a few inputs and outputs.
FireWire 800: Yep, you guessed it — this standard can handle data-transfer rates of 800 Mbps. A couple of FireWire 800 devices are available now, but you should see many more interfaces supported by FireWire 800 soon.