Focusrite VoiceMaster Pro Mode D'emploi page 16

Q. Does the VoiceMaster Pro have the same kind of spectacular bandwidth
that has given the Red and ISA range units their reputation for 'open-ended'
sound?
A. Yes. The audio bandwidth of the VoiceMaster Pro is 10 Hz to 200 kHz!
Q. Can I take my VoiceMaster Pro with me when I travel internationally?
A. It depends. There are three versions of the VoiceMaster Pro mains transformer.
One is suitable for use in North America, one in Japan (both with mains voltages in
the 100-120V range). The third version is designed for use in the UK and Europe,
with mains voltages in the 200-240V range. If you buy a VoiceMaster Pro in a
particular territory, it will be configured for ONLY that territory's mains voltage range.
For example, if you're travelling from the USA to the UK, you CANNOT use your
US model VoiceMaster Pro. But if the mains voltage in the country you're visiting is
in the same range, you can use the VoiceMaster Pro with no problems - so taking a
VoiceMaster Pro from Germany to France, for example, would be fine.
Q. Is there an optional digital input card?
A. No, because all the processing in the VoiceMaster Pro is entirely analogue - so even
if there were a digital input, the digital signal would have to immediately pass through
a D/A converter to allow processing!
Q. Why is the 24 bit 96kHz specification important?
A. An A/D converter works by sampling the audio waveform at regular points in time,
and then quantising those values into a binary number, which relates to the number of
bits specified. The quantised signal must then be passed through a D/A converter
before it becomes audible. In simple terms, the D/A essentially 'joins the dots' plotted
by the A/D converter when the signal was first converted to digital. The number of
dots to join, combined with how little those dots have been moved, determines how
accurate the final signal will be compared to the original. The greater the sample rate
and bit rate, the more accurate the whole digital process is. So 24 bit/96 kHz
performance will ensure more accurate digital transfer of your audio information
compared to 16 bit/44.1kHz standards. This is especially important if further digital
signal processing is to be applied to the signal once converted to digital, as any
mathematical operations taking place on the data (for example as a result of a gain
change, or dynamic effect process) may result in quantisation and rounding errors. The
higher the resolution of the digital data, the smaller the audible effect of these errors.
Q. Can I retrofit a digital board to an analogue VoiceMaster Pro at a later
date?
A. Yes, and you can do it yourself - it can easily be retro-fitted by the customer
without any soldering etc, just a few screws to undo, and one clip-connector to join to
the main PCB.
Q. What is Wordclock?
A. Whenever multiple digital audio devices are connected together digitally, all the
devices must be Wordclock synchronised to avoid data transfer problems. All devices
must send and receive their data at the same sample rate (e.g. 44.1kHz) but they must
also have their internal clocks running in sync. This ensures that all units send, receive
and process their data streams simultaneously. Failure to achieve this will mean a drastic
reduction in audio quality, and other unwanted audible artefacts, such as pops and
clicks, may occur. At a sample rate of 44.1kHz for example, there are 44,100 spaces
every second that need to have samples inserted. If there is a slight drift in one of the
clocks, some of those samples will be 'missed'/will move forward one place, which
results in distortion.
To avoid such problems, every digital system needs to employ Wordclock. One unit
should be designated the 'Wordclock master', and all others should be designated
'Wordclock slaves'. Setting this up is often simple, since most digital transfer formats
include embedded Wordclock data (e.g. S/PDIF, AES/EBU, ADAT). Where this is
not the case (e.g. TDIF), Wordclock can be provided via a separate Wordclock
connection. Note that timecode synchronisation (e.g. SMPTE) is different to
Wordlock synchronisation, but equally important. Timecode enables recording and
playback devices to run in sync with one another, and carries a regular series of
absolute time values (hrs:mins:secs:frames). The two timing systems are quite
independent.
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