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User’s Guide
Introducing the DMT interface
The Kurzweil DMT interface (known henceforth as the
DMTi
) is a versatile
digital audio sample-rate and format convertor, which can synchronize the
sample-rate clocks of up to four independent stereo signals. It can work with
digital audio, bidirectionally, from Kurzweil K2500-series instruments, AES/
EBU sources, S/PDIF sources using either coaxial or optical cables, and
modular digital multitrack recorders such as the Alesis ADAT and TASCAM
DA-88. It makes working with multiple digital audio formats simple.
What’s In the Box
• The
DMTi
itself
• AC power cord
• 3-meter “KDS” interface cable for connecting the
DMTi
with a K2500. (A
longer KDS interface cable—15 meters—is available from Kurzweil.)
You should save the
DMTi
’s packaging materials, in case you ever have to ship it.
Why Do I Need It?
Anyone who has tried to combine multiple digital audio signals while keeping
them in the digital domain knows that this can be extremely difficult. Clicks,
dropouts, speed changes, and other anomalies show up with regularity, often
with no consistency, in the result.
The reason for this is that the AES/EBU digital audio standard (and its
offshoot, the “consumer” or S/PDIF standard) has no provisions for externally
clocking the samples—in other words, every digital audio signal carries its
own timing information. This means that two signals from two different
sources will have no common timing reference, so when you try to combine
them, errors will occur that cause samples to be skipped or dropped,
producing various unpleasant audible artifacts.
Since the modern audio studio uses digital audio from a variety of sources,
including hard-disk audio systems, samplers, signal processors, mixers, DAT,
CD, and digital multitrack tape decks, the problem has become acute. One
common solution has been to convert all of the signals to analog before mixing
them, and thus avoid the problem of conflicting sample rates altogether. While
this is acceptable in some situations, it obviously defeats at least some of the
purpose of using digital audio in the first place.
However, if the sample-rate clocks of these sources can be coordinated so that
they are in perfect synchronization with each other while staying in the digital
domain, these problems can be avoided without resorting to analog solutions.