207d
instruction Manual
Aphex Systems Ltd. Model 207D
Page 14
207d
2-ch tube mic preamp with adc
Page 15
Aphex Systems Ltd. Model 207D
closer to the peak ceiling. Although it is certainly pos-
sible to operate MicLim™ in that fashion, and often
the effect will be desirable, we recommend the use of
restraint. MicLim™ was designed to be fast and unob-
trusive for protection against accidental overloading,
especially with voices. You may find the fast speed of
this limiter too aggressive for general purpose effect
limiting. Your favorite studio compressor/limiters can
still be put to good use.
If you’re not sure about whether to use MicLim™,
just use it. If you never need it then it won’t have any
effect at all. But when that unexpected peak comes
along, Bam! You’re saved.
4.4 USING WORD CLOCK
4.4.1 External WC
Many applications require that your digital audio
source be synchronized or “clocked” by a master
clock source. The master clock may come from your
workstation’s interface electronics, house sync, or a
local stand alone word clock generator. In either case,
you need to be sure the 207D has been properly con-
nected to your word clock source. Fortunately, the
207D is provided with a highly tolerant clock input
circuit that makes level and impedance relatively
uncritical. As long as the clock source delivers from
1 to 5 volts peak-to-peak between the frequencies of
44.1 and 96kHz, the 207D will normally lock up. If
you can’t seem to get a lock, make sure the external
clock mode is selected on the front panel.
4.4.2 Internal WC
In cases where you don’t need to use an external
word clock reference, the 207D has its own low jitter
internal word clock generator. You need to select the
desired sampling rate at the 207D’s front panel. Fre-
quencies of 44.1, 48, 88.2, and 96kHz are provided.
If you are not getting any digital output, then you
should first double check this setting.
The Model 207D does not source out its internal
word clock, so you won’t be able to use it for a
master clock.
4.4.3 Multiple 207D Clocking
If several 207D’s are to be used at the same time,
you need to know whether the digital inputs to
to your mixer or workstation are synchronous or
asynchronous. Most digital consoles and recorders
require synchronization of all digital audio sources.
That means you need to distribute word clock to all
207D’s from the single word clock source. You will
need a word clock distribution amplifier to do that.
4.5 USING DIGITAL AUDIO (AES3 & S/PDIF)
The front panel meter is directly calibrated to the digi-
tal audio headroom (and analog as well). It is impor-
tant to leave some headroom at all times. Causing the
headroom meter to hit the top of the scale will result
in distortion. Even if you can’t hear the distortion in
the analog output, your digital recording medium or
workstation will almost certainly add enough digital
artifacts to make the distortion audible in the mix.
This is a lesson not so much about the 207D as about
digital editing and processing in general. It is always a
great idea to leave the top 6dB of the digital dynamic
range open to allow for overshoots that will occur
later when passing through equalization and other
processing such as codecs.
4.6 REPLACING YOUR CONSOLE’S MIC PREAMPS
The most basic application for the 207D is to provide
an upgrade over the microphone preamplifiers in
your mixing console. We are not insinuating that your
console’s preamps are no good, just that the Model
207D is better. If you did not know that, you probably
would not have bought your 207D.
Consoles are built for functionality at a target price
point. Lower priced equipment may have a huge
array of facilities rivaling more expensive equipment.
However, everything inside is designed as cheaply as
207D
207D
207D
207D
Word Clock Source
WC
Dist Amp
CLOCKING MULTIPLE 207D’S
Using the 207D