Xaoc Devices Sewastopol - Manual (Page 3)

EXTERNAL FX ADAPTOR
Arrange an external chain of
desired processors (rack, pedals,
etc.) to be included in your patch.
Route the “dry” signal outside
using the
export
socket 1 , care-
fully attenuating it 2 and send it
out to the external devices via
fx
send
socket 3 . Remember that
modular signals are way too hot
for typical studio gear so you can
easily cause a damage, so attenu-
ation is important! The “wet” sig-
nal returns via
fx return
socket
4 and needs to be amplified 5
to reach the usual modular level.
Now, you can use the effected
signal available from the
import
socket 6 . There are
overload
indicator LEDs to help you with
adjustments. If distortion is your
thing, there’s a soft clipping avail-
able (jumper
17 selected).
AUDIO INTERFACE
Same way as above, Sewastopol
provides comfortable way of
importing the external signal
from a standalone synth, drum
machine, any other instrument
or microphone into your modular
system – and process it (as
described below). Simultane-
ously you can use the module as
a general output to an outboard
mixer, amp, computer interface
etc.
caution
: the
import
path
offers a huge range of gain in
order to allow amplifying very
weak signals. Thus, at high gain
settings, the input stage may be
extremely sensitive to all kinds of
noises from other devices. This
was a deliberate design choice
to offer more functionality at the
price of audio purity.
ENVELOPE FOLLOWER
Sewastopol features an unique
envelope follower circuit which
accurately detects all positive
and negative peaks of the input
audio signal, and offers both
rapid response to transients and
smoothed response to amplitude
fluctuations.
As opposed to common follow-
ers based on rectification and
simple smoothing (which result
in unwanted ripples in the output
voltage), the module implements
a novel bipolar peak detec-
tor whose output is held until
a subsequent waveform peak
arrives. This results in a stable,
ripple-free output voltage for a
constant amplitude input signal.
On the other hand, the response
for a rapid increase of amplitude
(often associated with transients)
is near instantaneous. Additional
smoothing is possible which may
be effective for complex signals
with varying amplitude (e.g.
chords from a guitar).
The
import
socket 6 is nor-
malled to the envelope follower
section for the imported signal
but you can use that section inde-
pendently by patching the signal
to be analyzed into the
follower
in
socket 10 . An envelope voltage
is extracted to follow the signal
amplitude and is available from
the
envelope out
socket 11 . The
LED below indicates the envelope
voltage range. You can set the
envelope snappiness with the
envelope release
knob 7 . The
intelligent smoothing circuit al-
lows adjusting the release time in
two wide ranges (jumper
8 se-
lected) without affecting transient
response. On top of that, there is
a switchable input highpass filter
9 aimed at attenuating very
low frequencies (below 33 Hz or
3 kHz). It makes the follower less
sensitive to bass which usually
dominates much softer percussive
sounds, and improves the overall
response to mixed music.
VOLTAGE COMPARATOR
The comparator input is nor-
malled to the envelope follower,
but you can use it directly by
patching the signal into the
com
-
parator in
13 socket. The trigger
and gate signals are generated
by comparing the output of the
envelope follower with an adjust-
able
threshold
12 level, and are
available consecutively from
gate
out
14 and trigger out
15 sock-
ets. In order to prevent multiple
triggering in case of small am-
plitude fluctuations, an optional
hysteresis is offered (jumper
16
selected). With hysteresis on, dif-
ferent thresholds are applied for
increasing and decreasing volt-
age, so that any changes within a
small range are ignored.
AUDIO SIGNAL
GATE threshold
level
AUDIO SIGNAL
ENVELOPE release
time
AUDIO SIGNAL
TRIGGER threshold
level