Doepfer A-150 Dual Voltage Controlled Switch
Module A-150 (Dual VCS) contains two separate voltage-controlled switches.
Each switch has a control voltage input, a common Out / Input, and two In / Outputs. The switches are bi-directional: they can work in both directions, so can connect one input to either of two outputs, or either of two inputs to one output. Voltages in the range -8V…+8V at the O/I resp. I/O sockets can be processed by the module.
Two LEDs show which in / output is active (ie. which is connected to the common out / input).
Similar modules: A-152 Voltage Addressed Track&Hold / Switch (Multiplexer) / Digital Outputs
New: From May 2004 an improved version of the module is manufactured. The revised version allows to process voltages in the full A-100 voltage range (i.e. -12V….+12V). The previous limitation to -8…+8V is no longer valid. The new version can be distinguished from the previous version by the printing at the pcb (“A-150 DUAL VC SWITCH VERSION 2”). Another way to distinguish the two versions are the integrated circuits: “CD4053” for the old version, “DG409” for the new version. Sorry it is not possible to update the old version of the A-150 to the new one as the complete circuit has been changed.
Doepfer A-151 Quad Sequential Switch
Module A-151 (Quad Sequential Switch) is like an electronic four-position rotary switch.
It includes trigger and reset inputs, four in / outputs, and a common out / input. Each time a pulse is received at the trigger input socket, the common out / input is connected to the next in / output. After the fourth in / output, the next trigger makes it step back to the first again, and so on. A positive pulse at the reset input switches the out / input immediately back to the first in / output (see Fig. 1). Voltages in the range -8V…+8V at the O/I resp. I/O sockets can be processed by the module.
Four LEDs indicate the active in / output (ie. the on that is connected to the out / input at any particular time).
From spring 2005 a revised version of the module is available. With an additional switch the number of steps can be set to 2, 3 or 4 (thanks to Peter Grenader for this idea). Moreover the revised module allows to process voltages in the full A-100 voltage range (i.e. -12V…+12V). The limitation to -8V…+8V is no longer valid. While stocks last the user can choose between version 1 and 2. Version 1 will be no longer manufactured in the future.
The A-100 DIY page describes how to install this additional switch for the old version of A-151.
Similar modules: A-152 Voltage Addressed Track&Hold / Switch (Multiplexer) / Digital Outputs
Doepfer A-152 Voltage Addressed Switch / Analogue Shift Register
Module A152 is a very useful switching and T&H module. It combines a voltage addressed 1-to-8 multiplexer and 8 fold T&H that can be used as kind of an analog shift register too. The active in/output is displayed by a LED. The digital output of the currently addressed step outputs “high”. The remaining digital outputs are low.
Instead of voltage control even clock/reset controlled addressing of the active step is possible. The rising edge of each clock signal causes an advance to the next state. The rising edge of the reset signal resets to step 1.
Basis principles: The sum of the voltages coming from the manual Address control and the CV input define the currently addressed step of the 3 sub-devices. If the module is controlled by clock and reset the control voltage has to remain unchanged as the CV control has priority over the clock/reset control (e.g. simply turn the CV control fully counterclockwise and do not touch the Address control knob).
Sub-device #1 is the bidirectional 8-fold multiplexer (kind of an electronical 8-fold rotary switch). Bidirectional means that it works into both directions like a mechanical rotary switch: the common socket may work as an output that is connected to one of the 8 inputs that are e.g. connected to modulation or audio sources. But the common socket may even function as input. In this case the signal applied to the common socket is output to the currently addressed single socket. The voltage range of the in/outputs to be switched is the full A-100 voltage range -12V….+12V. All A-100 signals can be switched without any restrictions.
Sub-device #2 is the addressed 8-fold T&H. The signal at the common T&H input is connected to the addressed T&H output. As soon as a new output is addressed the last voltage is stored at the output (Track&Hold function). The T&H section of the A-152 allows the emulation of the “toggling T&H” function of the Buchla module 266 “Source of Uncertainty”. Only the first two T&H outputs of the A-152 are required for this application. This unit can be used also as kind of an analog (shift) register. The difference to a “real” analog shift register is that the sampled output voltages are not shifted to the next output but remain allocated to the same output. But in some cases (e.g. controlling the pitch of 3 VCOs by 3 output voltages of the A-152) the result is the same.
Sub-device #3 is the digital output section. The digital output of the currently addressed turns to “high”. All other digital outputs are low. The digital outputs can be used to trigger e.g. envelope generators or to control the reset input in the clocked mode to reduce the number of addressed stages.
Remark: In contrast to the Sample&Hold (see S&H A-148) the output voltage follows (i.e. tracks) to the input voltage as long as the corresponding stage (1…8) is active. Just when the stage is deselected the last voltage is held.
Remark: The clock signal that is fed into the Clock In socket has to be GND referenced to the A-100 frame. The reason for this is a recognition circuit at the clock input that is used to decide if the module is clock controlled or voltage controlled. For this recognition the GND pin of the Clock In socket is used. If an external clock signal is used (i.e. not coming from a module mounted into the A-100 frame where the A-152 is mounted) the GND reference is missing and the recognition circuit does not work (with the result that the clock input does not work). But there is a simple workaround: as soon as both systems are connected by means of any other patch cable that way the GND reference is established.
The “Common T&H Input” socket can be normalled by jumpers to the “Common Switches In/Out” socket, i.e. the common T&H input is connected to the common switches In/out socket as long as no plug is inserted to the “Common T&H Input”. This allows a multiplexed T&H, i.e. each T&H output has a separate signal to be sampled.
It is also possible to modify the T&H outputs for S&H function. If S&H (Sample&Hold) is chosen the voltage applied to the common input is sampled immediately when the output in question is adressed. T&H (Track&Hold) is similar but in this case the output follows the input as long as the output in question is addressed. The voltage is stored not until another output is selected. The modifiation is described on the A-100 DIY page.
Doepfer A-154 Sequencer Controller
Module A-154 is a supplement to the A-155 Analog/Trigger Sequencer module. It offers a lot of new features that are not available in the basic control unit of the A-155. The A-154 is used to replace the control unit of one or two A-155, i.e. the section marked “Control” with Start / Stop / Step / Reset buttons and inputs in the upper left corner of the A-155 front panel. If the A-154 is used to control the A-155 the control section of the A-155 is put out of action.
These are the features of the A-154:
Several running modes: forward, backward, pendulum, random, CV controlled step adressing. All modes are available as loop or one-shot.
LED display of the 5 different current modes and one LED for loop/one-shot display
Manual and voltage controlled selection (with attenuator) of the running mode. If no external control voltage is applied one of the 10 modes (5 modes x 2 loop/one-shot) is simply selected with a rotary knob. The CV input with attenuator is used to modulate the running mode with an external control voltage (digital high/low CV to switch between two modes or continuous analog CV to sweep through different modes). With the combination of manual control and CV with attenuator it is possible e.g. to use only two neighbouring modes (e.g. forward/backward) or sweep through all possible running modes
Manual and voltage controlled selection (with attenuator) of first and last step of the sequence. The range is step 1…8 in 8 step mode resp. 1…16 in 16 step mode
If the running mode “CV Controlled Step Address” is selected the First Step section is used to determine the active sequencer step. Consequently manual and voltage controlled selection (with attenuator) of the active step is possible: the active step can be set by hand with the first step manual control and then modulated by an external control voltage (e.g. LFO, Random, S&H, Theremin, Light CV source, Joy Stick) at the first step CV input (with attenuator).
An internal voltage controlled clock generator with manual and CV control (with attenuator) is available. The output of the clock generator is displayed with a LED and is used as sequencer clock provided that no external clock signal is connected to the Clock In socket (normalled socket). If the CV input of the Clock section is connected to one of the analog outputs of the sequencer the time for each step can be set separately. Even jumps (or skipping) will be possible as we will introduce the feature that a very short clock pulse will be generated if the control voltage exceeds a certain value. For example the gate row of the A-155 can be used to obtain skipping of steps: the gate output simply has to be conneted to the CV input of the A-154 clock generator. If the corresponding switch of the A-155 is set correspondingly in the gate row the step will be skipped.
Manual and voltage controlled (with attenuator) pulse width (PW) of the clock signal. This features can be used to obtain a different gate length for each step: e.g. one of the CV outputs of the A-155 can be used to control the PW. With a PW control voltage coming from a LFO/random/S&H the gate length will change automatically. CV coming from Theremin A-178, ribbon controller A-198, light controlled CV A-179, joy stick A-174 are other ways to control the gate length.
8/16 step mode: A toggle switch us used to select 8 or 16 steps. The “16 step” mode requires two A-155 and a voltage controlled switch A-150. The A-150 is controlled by the “A3” output of the A-154. This output remains “low” as long as the active step is in the range 1…8 and turns to “high” in the range 9…16. The A-150 is used to switch between the CV/trigger/gates outputs of the first A-155 (step 1…8) or second A-155 (step 9…16).
If two A-155 are used they can work in parallel (8 steps) or serial (16 steps). The 8/16 steps switch determines if the 8 step mode (one A-155 or two A-155 in parallel) or the 16 step mode (two A-155 serial) is chosen. Both modes work with CV controlled step addressing too (see below). In 8 step mode only the steps 1…8 are addressed, in 16 step mode the steps 1…16. For serial operation an additional VC switch (A-150) is required – as mentioned above.
The functions of the Start/Stop/Step/Reset buttons and inputs are the same as for the “old” control unit of the A-155:
A high level at the Start input or operating the Start button starts the sequence from the momentarily addressed step. Not working in “CV controlled step address” mode.
A high level at the Stop input or operating the Stop button stops the sequence (the last active step remains addressed). Not working in “CV controlled step address” mode.
A high level at the Reset input or operating the Reset button resets the sequence to step 1. The sequence remains at step 1 as long as the Reset input level is high (function is activated by high level, not by low/high transition). Not working in “CV controlled step address” mode.
A positive transition (low -> high) at the Step input or operating the Step button causes an advance to the next step. The step input is connected to the clock output of the internal clock generator provided that no plug is inserted to the step input socket. Not working in “CV controlled step address” mode.
Manual and voltage controlled selection between “old” A-155 control or A-154 control of the A-155 connected to A-154 (A-154 master on/off function)
Remark: With the One-Shot modes the A-155/A-154 combination can be used e.g. as a complex envelope generator. The Gate resp. Trigger signal is applied to the Start input of the A-154. One analog row determines the levels of the envelope. The second analog row can be used to adjust the time length for each step. The Gate row can be used to select between smooth (Glide = on) or hard (Glide = off) transition between succeeding levels. For the One-Shot version of Random the sequence continues until accidentially the last step is addressed. Then the sequence stops. The combination of One-Shot and CV Addressed Step Selection is not available as it does not make sense.
Installation of the A-154: The 10 pin ribbon cable, that was used to connect the A-155 control section with the rest of the A-155 module has to be removed and plugged to the new A-154 sequencer controller. Therefore the A-154 has to be mounted on the right side of the A-155. In case that two A-155 have to be controlled the A-155 have to be mounted one on top of the other and the A-154 on the right side of the upper or lower A-155. Attention ! In case of two A-155 the second A-155 cannot be controlled by its “old” control unit. In this case both A-155 are controlled by the A-154 or the “old” control unit of the first A-155 (depending upon the position of the A-154 master switch).
Doepfer A-155 Analogue / Trigger Sequencer
Features of the analog rows (knobs):
8 potentiometers (knobs)
lower row: Scale (knob), voltage output range 0 … ~ +6,5V
upper row: 1V/2V/4V (octave range switch for exact VCO control), voltage output ranges 0 …1.0V / 0 …2.0V / 0 …4.0V
Glide time (knob), same as portamento or slew limiter
Glide Control (control input for switching glide on/off)
S&H Control (control input for internal S&H, works like A-148)
Pre Glide/S&H-Out (analog output before S&H and glide unit, especially required when external audio signals are used as inputs of the lower row)
Post Glide/S&H-Out (analog output after S&H and glide unit)
lower row: external inputs for the 8 steps (switched jack sockets), control signals or audio signals may be used as inputs (allowed voltage range -5V…+12V), the knobs of the lower row are working in this case as attenuators
Features of the trigger rows (switches):
4 Trigger/Gate tracks with 2 rows of switches
toggle switches of 1-0-1 type (with middle position), which can be used to send a trigger/gate to the track above or below or to send no trigger/gate (middle position)
3 trigger rows (i.e. short pulse for each step set, pulse width corresponds to the pulse width of the clock/step input signal)
1 gate row (i.e. a high signal is applied during the length of the step set)
Control inputs and buttons:
Step (defines the tempo of the sequence, same as clock or trigger input)
Reset (resets all rows to step 1)
Start (starts the sequence at the momentary position)
Stop (stops the sequence at the momentary position)
Step and Reset are compatible to the MIDI interface A-190, i.e. in combination with the A-190 the A-155 may be synchronized via MIDI. The quantizing module A-156 can be used to quantize the infinite analog voltages coming from A-155 into discrete semitone steps (multiples of 1/12V). Without MIDI interface e.g. a LFO rectangle output can be used to define the tempo of the sequence.
The sequencer controller A-154 adds a lot of new functions to the A-155 (e.g. voltage controlled addressing, forward/backward/pendulum/random mode, voltage control of first and last step, voltage controlled clock and gate length, step skipping, combination of several A-155 in parallel/serial mode and many more).
Doepfer A-156
Module A-156 is a Dual Control Voltage Quantizer. A quantizer converts a continous control voltage in the range 0…+10V into a stepped output voltage in the same voltage range (i.e. only certain voltages occur). Normally 1/12 V steps are used to obtain semitone steps. Quantizer 2 of the A-156 allows has more sophisticated quantizing modes like major scale (i.e. only voltages corresponding to the major scale), minor scale, major chord, minor chord, fundamental+fifth and addition of seventh or sixth when chords are selected. Only those voltages appear at the CV output which comply with the selection rule (e.g. minor chord with seventh). The mode setting of quantizer 2 is done with 3 switches (1-0-1 type with middle position). From the factory quantizer 1 is working in the semitone mode. But there is a jumper on the pc board that can be changed so that even quantizer 1 uses the same scale as quantizer 2.
For each quantizer the following in/outputs are available:
Control voltage input (CV In): The input for the contiuous voltage to be quantized
Control voltage output (CV Out): The output of the quantized voltage
Trigger input (Trig.In): If this jack is left open the quantizer is working permanently. If a rectangle voltage is applied quantisation happens only at the rising edge of the signal (e.g. from an LFO or MIDI-to-Sync interface). Thus the quantizing can be synchronized with other events.
Trigger output (Trig.Out): Whenever a quantisation happens (i.e. a new voltage is generated at the CV Out) a positive pulse occurs at this output. It may be used to trigger an envelope generator (ADSR) or for triggering other modules (sequential switch A-151, trigger divider/sequencer A-160/161, trigger delay A-162, …). If none of these functions are used the jack is left open.
On top of that the A-156 is provided with a common transpose CV input having an additive effect on both quantizers. This input is quantized in semitone steps. A typical application is the transposition of a sequence generated by the A-155 by a second control voltage (e.g. coming from the MIDI-CV interface A-190).
Typical applications:
Quantizing the CV sequence generated by an A-155 (semitone, onyl major scale, only minor scale and so on)
quantizing the voltage coming from the Trautonium Manual / Ribbon Controller A-198, Theremin A-178 or Light-to-CV module A-179 to get accurate semitones or major/minor scale tones
arpeggio-like effects with LFO, random, noise, envelope generators as CV sources (for negative or symmetrical voltages an offset must be added, e.g. with the offset/attenuator module A-129-3, to obtain positive voltages for the A-156 input).