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A-170

DOEPFER A-170, A-170 Dual Slew Limiter User manual

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  • What is the purpose of the DOEPFER A-170 module?
    How many slew limiters does the A-170 have?
    What is the range of the rise and fall times on the A-170?
    What are the different time ranges available on the lower slew limiter?
    Can the A-170 be used as a simple AR envelope generator?
    What is the voltage offset of the lower slew limiter?
    Can the A-170 be used for precise voltage control?
doepfer
System A - 100
Dual Slew Limiter A-170
1
1. Introduction
Module A-170 (Dual Slew Limiter) contains two sepa-
rate slew limiters, also known as
portamento control-
lers or integrators.
The
upper SL
has just one
joint control
, which sets
both rise and fall times (c. 0 ...10 sec).
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 three-
position switch, as on the full ADSRs.
Both slew limiters have two LEDs each, to show the
state of the rising and falling voltages.
In
Control
Time
A-170
DSL
Ï
Out
In
Control
Time
Range
Out
Ð
- +
-
+
A-170
Dual Slew Limiter
System A - 100
doepfer
2
2. Overview
Controls and indicators:
1
Time : rise / fall time control (input 1)
2, 6 - LED : negative voltage indicator
2
,
6
+ LED
: positive voltage indicator
3
Ï
: rise time control (lower SL)
4
Ð
: fall time control (lower SL)
5
Time Range
: 3-position switch for overall rise / fall
time range (lower SL)
In / Outputs:
!
,
§
In
:Input
"
,
$
Out : Output
A-170
DSL
Out
Control
Ï
Time
In
➀
➁
➂
➃
➅
DUAL SLEW LIMITER
0
10
0
10
0
10
Control
Out
In
M
H
L
Time
Range
➄
-
+
-
+
Ð
doepfer
System A - 100
Dual Slew Limiter A-170
3
3. Controls and indicators
1 Time
This control sets the rise / fall time t
C
of slew limiter 1
(see Fig. 1) in a range from 0 to 10 seconds.
2
- LED •
6
- LED
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
A
(see Fig. 1), within the range set by switch
6
.
5
Ð
The fall time t
R
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 li-
miter’s rise t
A
and fall t
R
times.
upper SL lower SL
Fig. 1
: A-170 response
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 !).
t
C
t
C
Out
In
t
A
t
R
Out
In
A-170
Dual Slew Limiter
System A - 100
doepfer
4
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
C
(upper SL)
and/or t
A
, t
R
(lower SL) to alter the waveform’s rise and
fall characteristics.
" 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
upper slew limiter
.
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.
5. User examples
Portamento
The example in Fig. 2 shows the A-170 (upper SL !)
as a portamento generator. With this patch, indepen-
dently controllable portamento is created every time a
note is played. Use control
1
to set the portamento
time.
Fig. 2: The A-170 as a portamento generator
CV
MID I
A-170
MIDI-CV
VCO
upper SL
doepfer
System A - 100
Dual Slew Limiter A-170
5
Slew limiter as AR envelope generator
You can use the lower A-170 as a simple AR enve-
lope generator, for instance in the example in Fig. 4,
to help create a certain percussive bass sound.
Fig. 3
: The A-170 as a simple AR generator
“Glissando AM”
The patch in Fig. 4. produces an interesting sound.
The two VCOs are set to harmonically related inter-
vals. 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 gra-
dually to the pitch of the note, producing a complex
timbral sweep.
Fig. 4: "Glissando AM"
H It’s important to keep the time level of the
A-170 less than the shortest note length
played.
CV
Gat e
VCO VCF
A-170
A-170
VCA
CV
VCA 1 VCA 2
A-170
VCO 1
VCO 2
ADSR
Gat e
upper SL
A-170
Dual Slew Limiter
System A - 100
doepfer
6
Creating complex envelopes
A combination of the Clock Divider / Sequencer (A-
160/161) and a number of A-170 slew limiters can
produce complex envelopes (see Fig. 5).
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).
Fig. 5
: Creating complex envelopes
A-161
1
2
3
4
5
6
7
8
Clock
Se q u e n c e r
A-170
A-160
A-170
LFO, M IDI Clock
Inp ut 1
Output
A- 138
MIX ER
Inp ut 2
In pu t 4
Inp ut 3
In 1
In 2
In 3
In 4 Ou t
doepfer
System A - 100
Dual Slew Limiter A-170
7
A-170
Dual Slew Limiter
System A - 100
doepfer
8
6. Patch-Sheet
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
DSL
Out
Control
Ï
Time
In
DUAL SLEW LIMITER
0
10
0
10
0
10
Control
Out
In
M
H
L
Time
Range
-
+
-
+
Ð
A-170
DSL
Out
Control
Ï
Time
In
DUAL SLEW LIMITER
0
10
0
10
0
10
Control
Out
In
M
H
L
Time
Range
-
+
-
+
Ð
A-170
DSL
Out
Control
Ï
Time
In
DUAL SLEW LIMITER
0
10
0
10
0
10
Control
Out
In
M
H
L
Time
Range
-
+
-
+
Ð
/