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In
Out
A-170
DSL
Time
System A - 100
1. Introduction
Module A-170 (Dual Slew Limiter) contains two separate slew limiters, also known as
lers or integrators.
The
upper SL
both rise and fall times (c. 0 ...10 sec).
Dual Slew Limiter A-170
portamento control-
has just one
joint control
, which sets
In
Out
Control
- +
-
Control
+
Ï
Ð
Time
Range
The lower SL has separate controls for rise and fall
times, and can therefore be used as a simple AR
envelope generator. Over and above this, you can set
the overall range for these parameters, with a threeposition switch, as on the full ADSRs.
Both slew limiters have two LEDs each, to show the
state of the rising and falling voltages.
1
A-170
Dual Slew Limiter
System A - 100
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2. Overview
➄
A-170
DUAL SLEW LIMITER
In
0
Out
-
Control
In
Time
Range
H
L
Out
0
M
0
-
Control
DSL
Time
10
+
Ï
10
Ð
10
+
➀
➁
➂
➃
➅
Controls and indicators:
Time : rise / fall time control (input 1)
1
2, 6 - LED : negative voltage indicator
+ LED
2, 6
Ï : rise time control (lower SL)
3
Ð : fall time control (lower SL)
4
Time Range
5
: positive voltage indicator
: 3-position switch for overall rise / fall
time range (lower SL)
In / Outputs:
:Input
In
!, §
Out : Output
", $
2
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System A - 100
Dual Slew Limiter A-170
3. Controls and indicators
1 Time
This control sets the rise / fall time t
(see Fig. 1) in a range from 0 to 10 seconds.
- LED • 6 - LED
2
LEDs 2 and 6 are the status indicators for the slew
limiters’
falling edges
.
3 + LED • 7 + LED
LEDs 3 and 7 are the status indicators for the slew
limiters’ rising edges.
4
Ï
With this control you set the lower slew limiter’s rise
time t
5
(see Fig. 1), within the range set by switch 6.
A
Ð
The fall time tR of the lower slew limiter (see Fig. 1) is
set with this control, within the range set by the range
switch 6.
6 Time Range
Switch 6 sets the time range for the lower slew limiter’s rise t
and fall tR times.
A
of slew limiter 1
C
Out
In
t
C
t
C
Out
In
t
A
t
R
upper SL lower SL
: A-170 response
Fig. 1
Three time ranges are available:
• L (low): 0 ... ~ 0.5 sec
M (medium): 0 ... ~ 10 sec
•
• H (high): 0 ... some minutes
The actual times are also dependent on amount of
voltage change (0 V → 1 V goes quicker than 0 V →
10 V !).
3
A-170
Dual Slew Limiter
System A - 100
doepfer
4. In /Outputs
! In • § In
Sockets ! (upper SL) and § (lower SL) are the slew
limiters’ inputs. Patch in the voltage you want to
modify here, and use the time controls t
and/or t
fall characteristics.
, tR (lower SL) to alter the waveform’s rise and
A
" Out • $ Out
" (upper SL) and $ (lower SL) are the outputs for the
modified signal.
For precision voltage control (for instance of VCO
pitch or portamento) only use the
Because the diodes in the lower slew limiter are
voltage-dependent, there is a voltage offset of about
0.5 V. This naturally makes it unsuitable for precise
1V / octave work, but for simple voltage control or in
use as an AR envelope generator, this is no problem
at all.
upper slew limiter
(upper SL)
C
5. User examples
Portamento
The example in Fig. 2 shows the A-170 (upper SL !)
as a portamento generator. With this patch, independently controllable portamento is created every time a
note is played. Use control 1 to set the portamento
time.
MID I
.
MIDI-CV
Fig. 2: The A-170 as a portamento generator
CV
A-170
upper SL
VCO
4
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System A - 100
Dual Slew Limiter A-170
Slew limiter as AR envelope generator
You can use the lower A-170 as a simple AR envelope generator, for instance in the example in Fig. 4,
to help create a certain percussive bass sound.
CV
VCO VCF
Gate
A-170
A-170
: The A-170 as a simple AR generator
Fig. 3
VCA
“Glissando AM”
The patch in Fig. 4. produces an interesting sound.
The two VCOs are set to harmonically related intervals. A keyboard pitch control voltage is patched to
both VCOs - directly to VCO1 (the carrier), and via the
A-170 upper slew limiter to VCO2 - the modulator.
When a new note is played, the carrier VCO reacts
immediately, while the modulator VCO glides gradually to the pitch of the note, producing a complex
timbral sweep.
ADSR
Gat e
A-170
upper SL
CV
VCO 1
VCO 2
VCA 1 VCA 2
Fig. 4: "Glissando AM"
H It’s important to keep the time level of the
A-170 less than the shortest note length
played.
5
A-170
Dual Slew Limiter
System A - 100
Creating complex envelopes
A combination of the Clock Divider / Sequencer (A160/161) and a number of A-170 slew limiters can
produce complex envelopes (see Fig. 5).
A-161
Clock
Se q u e n c e r
1
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A-170
The Clock Sequencer triggers the Slew Limiters in
sequence, and their various envelopes are mixed in a
linear mixer A-138a. The result is a complex envelope
which can be patched from the mixer output to
anywhere.
P
You can further elaborate on this patch, by
adding other control voltages to the slew
limiters’ envelopes - for instance:
• an ADSR with a long envelope, triggered
by output ! on the A-161;
• an LFO output, with or without reset;
• the random output from an A-118;
• an audio signal via an envelope follower
(A-119).
6
2
3
4
5
6
7
8
A-170
A-160
: Creating complex envelopes
Fig. 5
LFO, M IDI Clock
A- 138
MIXE R
In 1
Input 1
In 2
Input 2
In 3
Input 3
In 4 Out
In pu t 4
Ou tput
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System A - 100
Dual Slew Limiter A-170
7
A-170
Dual Slew Limiter
6. Patch-Sheet
System A - 100
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The following diagrams of the module can help
you recall your own Patches. They’re designed so
that a complete 19” rack of modules will fit onto an
A4 sheet of paper.
Photocopy this page, and cut out the pictures of
this and your other modules. You can then stick
them onto another piece of paper, and create a
diagram of your own system.
Make multiple copies of your composite diagram,
and use them for remembering good patches and
set-ups.
P • Draw in patchleads with colored
pens.
• Draw or write control settings in the
little white circles.
A-170
DUAL SLEW LIMITER
In
0
Out
-
Control
In
Time
Range
H
Out
0
M
L
0
-
Control
DSL
10
+
10
10
+
Time
Ï
Ð
A-170
DUAL SLEW LIMITER
In
0
Out
-
Control
In
Time
Range
H
Out
0
M
L
0
-
Control
DSL
10
+
10
10
+
Time
Ï
Ð
A-170
DUAL SLEW LIMITER
In
0
Out
-
Control
In
Time
Range
H
Out
0
M
L
0
-
Control
DSL
Time
10
+
Ï
10
Ð
10
+
8
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