Buchla 200e series, User Manual

Page: 74 / 78

296e Spectral Processor
296110930
This is a multifunction 16 channel bandpass filter with separate voltage
controlled amplifiers (VCA’s) and envelope followers associated with each
channel filter. We’ll discuss several applications forthwith – you’ll undoubtedly
come up with more of your own.
Split filter: even and odd inputs
There are 16 bands of control. While you might normally have only one gain
on an input, there are independent gain controls for the even numbered and
odd numbered bands. You will need to set both knobs.
Also in this split signal path, the
“PRE-EMPHASIS” filter accentuates the
treble frequencies that may suffer in the spectral transfers. Pre-emphasis can
be especially useful for detecting vocal activity.
With one input used,
the empty input will also receive the same signal. (Tip: If
your sound is “tinny,” –when using one input-- check that gains are equal and
your pre-emphasis is down.)
But when both inputs are connected, the left side will drive only the odd
numbered filters, while the right will drive only the even
.
Split filter: even and odd outputs
By monitoring only the odd or even outputs, we’ve effectively split the filter into
two parts, with the odd filters summed to the “
odd” outputs and the even
numbered filters directed to the “ even” outputs.
Programmable filter
Plug in a signal to either of the cross-connected inputs. It will be connected to
all 16 of the filter sections. Press the DISP switch ‘till “
A levels” is illuminated,
and turn the morph control counterclockwise, thus illuminating the orange
LED. The three “
SPEC-TRUM XFER” LED’s should be off. The “ all” output is
now the sum of all 16 filters, each of whose amplitude response is governed
by one of the 16 touch-controlled potentiometers. The unit now functions as a
simple 16 channel bandpass filter, with the spectral shape indicated by the
illuminated potentiometers. Touch a potentiometer to alter the corresponding
filter’s response.
User interface tip:
When using the interface to draw in levels with your finger from left to right, a slower swipe will
generate the most accurate result.