Filters Vcf 1 And Vcf - Schippmann ebbe und flut User Manual

8.5 Filters VCF 1 and VCF 2

Both filters VCF 1 and VCF 2 are the core of 'ebbe und flut' . They are different from each other and pro-
vide different sonic results. Both feature different selectable characteristics, but functionality is equal.
So we want to explain the following only once.
VCF 1/2 provides the control elements (7)/(28) – (16)/(37) on the frontpanel and (14)/(15), (18)/(16),
(19)/(17) on the rearpanel. The switches (11) and (32) are part of the envelopes and will be covered in
the corresponding chapter. At first a short reminder:
A VCF is a Voltage Controlled Filter. The first basic feature of a filter is its frequency characteristics. The-
se typical and easily audible characteristics describe, which frequency range is supressed and which
one passes the filter. Basically we make a distinction between lowpass, highpass, bandpasses and
notch (phaseshifter / allpass). 'ebbe und flut' features 12 different characteristics for each filter, selec-
table via the [curve]-rotary switch.
Second parameter is the position of the "cutoff"-frequency within the audiorange. A bandpass has a
center-frequency. The cutoff-frequency of a VCF can be controlled over a wide range by a single con-
trol voltage. This enables a modulation with the help of other signals.
A third parameter of a voltage controlled filter is "quality" or "resonance" . This parameter is also voltage
controlled and emphases frequencies close to the cutoff frequency. This leads to properties of an
oscillation circuit with increasing decay times, unitil it finally starts to self oscillate.
Fig. 8.5.1 shows VCF1 and VCF 2 as a block diagram with all connection capabilities.
select (15)
S&H
modulation
LFO
(14)
DYN
ENV1 (var level) depth (10)
pedal (from (5)) pedal (9)
frequency(7)
FREQ 1
(14t)
RESO 1
(14r)
resonance
select (13) (8)
S&H
modulation
(12)
ENV1 (fixed level)
Fig. 8.5.1 VCF 1 and VCF 2
VCF1 IN (19)
VCF 1
1 of 12
curve (16)
VCF1 OUT (18)
select (36)
S&H
modulation
LFO
(35)
DYN
ENV2 (var level) depth (31)
pedal (from (5)) pedal (30)
frequency(28)
FREQ 2
(15t)
RESO 2
(15r)
resonance
(29)
select (34)
S&H
modulation
(33)
ENV2 (fixed level)
user manual e b b e
u n d
VCF2 IN (17)
VCF 2
1 of 12
curve (37)
VCF2 OUT (16)
l
28
f l u t