TASCAM digital interface
The TASCAM Digital Interface ( TDIF ) is an interface that was developed by TASCAM as a dubbing interface for direct transfer between digital tape recorders (based on high-8 video cassettes). Eight digital channels can be transmitted bidirectionally . In contrast to the ADAT format, only a 25-pin D-Sub cable is required for the forward and return lines.
The data is transmitted separately from the clock. Since the information is not channel-coded, the cables can be a maximum of a few meters in length, and special cables must be used to ensure reliable transmission. The data is transmitted serially with a maximum of 24 bit / 48 kHz on eight output and eight input channels (TDIF 1 standard). With version 1.1 a parity bit was introduced, and since the TDIF-2 standard it is also possible to use a higher data rate with a reduced number of channels (96 kHz / 4 channels, 192 kHz / 2 channels).
The synchronization takes place either internally via L / R clock, or externally via WordClock , since this clock information (in contrast to most digital formats) is not carried in the cable here. The L / R clock determines whether a signal is intended for the left or right channel. This signal has the same frequency as the sampling rate (here e.g. 48 kHz).
A serious disadvantage of the TDIF interface is the type of electrical adaptation selected. While practically all other digital audio interfaces such as AES / EBU (AES-3 and EBU Tech. 3250-E), S / PDIF and MADI use power matching with the same impedances on the source and sink side (75 ohms or 110 ohms) TDIF with voltage adjustment . With TDIF, the source has an impedance of around 50 ohms and the sink 140 ohms, which leads to reflections and interference with the signal transmission, especially with longer lines (> 5 m).
The TDIF format has hardly been able to prevail in the audio sector against the ADAT format of the American company Alesis. Besides TASCAM, there are few suppliers of devices with this interface; Examples: Soundscape, Otari, Apogee, RME, Motu, Yamaha , Sony , Digidesign .
Since digital tape recorders are rarely used nowadays, the use of the TDIF interface has shifted to digital mixers , sound cards and audio converters.