5
tenuator position. For example, with attenu-
ators at max, a CV of 8V opens the channels
to +1dB, while closing the attenuators silenc-
es the channels to -85dB. Control voltages
above 8V are well-tolerated, although the
gain response is strongly compressed above
0dB, offering only up to +3dB to minimize
distortion. This behavior affects the sound
similar to dynamic compression; however,
lowering the attenuators' setting diminishes
the effect, bringing it down to a non-com-
pressed operation (fig. 3).
Each vol input jack is internally normalled to
a fixed 8V allowing the attenuators to operate
at full range without any CV patched in.
CHANNEL MUTING
A short press on the active|aux pre button
silences the corresponding channel. This state
is confirmed by turning off the button back-
light. The clickless muting action is achieved
by introducing a few-millisecond fade-out to
near -90dB. Pressing the button again reac-
tivates the backlight and brings the channel
back through a similar clickless fade-in. The
operation of mutes can be controlled remotely
via the Bohumin expansion module that offers
four gate inputs.
PANORAMA CONTROL
Ostrawa offers both manual and CV control
over the position of each source in the output
stereo panorama. Please keep in mind that
Ostrawa operates similarly to normal studio
mixers, i.e., it only controls the attenuation of
the left vs. right signal and will not magical-
ly rotate the auditory image of your stereo
sound source around your head.
The bal knobs act as offsets to the bal input
control voltages, which are expected in the
range of -5V to +5V. Negative and positive
CV values shift the auditory image to the left
and right, respectively. The response of the
combined manual and CV controls provides
equal loudness in a near-field monitoring
setup (3dB pan law); however, as channel
volume
& panorama
fig. 3: gain response to cv
fig. 4: balance control response
0 1 2 3 4 5
-5 -4 -3 -2 -1
0
-10
-20
-30
-40
-50
-60
-70
8
10
5
Balance response
Pan control voltage
0 1 2 3 4 5 6 7 8 9 10
10
0
-10
-20
-30
-40
-50
-60
-70
10
4
2
7
1
Gain [dB]
Volume control voltage
