Modules A-180-1 and A-180-2 are simple multi-connectors. They have eight inter-connected sockets, so that you can “multiply” any audio or control signal. From the factory the modules come as two four-fold multiples. But they can be modified as an eight-fold multiple (solder bridge on the pcb). Though these modules are very “primitive” they are required very often in patches (e.g. to distribute a clock signal or a control voltage). Within a big A-100 system sufficient multiples should be planned. The function of A-180-1 and A-180-2 is the same. The modules differ only in the front panel width.

For the distribution of control voltages used for pitch control of several VCOs the buffered multiple A-185-2 is recommended. This module has a built in buffer (and a lot of additional features like CV summing) that avoids small voltage losses that may be heard in pitch control applications.

Modules A-180-1 and A-180-2 are simple multi-connectors. They have eight inter-connected sockets, so that you can “multiply” any audio or control signal. From the factory the modules come as two four-fold multiples. But they can be modified as an eight-fold multiple (solder bridge on the pcb). Though these modules are very “primitive” they are required very often in patches (e.g. to distribute a clock signal or a control voltage). Within a big A-100 system sufficient multiples should be planned. The function of A-180-1 and A-180-2 is the same. The modules differ only in the front panel width.

For the distribution of control voltages used for pitch control of several VCOs the buffered multiple A-185-2 is recommended. This module has a built in buffer (and a lot of additional features like CV summing) that avoids small voltage losses that may be heard in pitch control applications.

Module A-180-3 is a dual buffered 1-in-3 multiple. The signal applied to the input socket appears as a buffered signal at the three output sockets. Each output has it’s own buffer, i.e. the three output sockets are not simply connected to each other. The lower output of the upper unit is normalled in the factory to the input of the lower unit. That way the module works as a single 1-in-6 buffered multiple provided that no signal is applied to the input of the lower unit. But it’s also possible to pick-up the bus CV and normalize the input socket of the lower unit to the bus CV.

Application: copying/buffering of CV, gate and audio signals.

Two multiples with one 1/4 jack socket and two 3.5mm jack sockets each, upper multiple is wired monophonic, lower is wired stereophonic.

Module A-182-1 is a simple passive multi-connector similar to the multiples modules A-180-1/A-180-2. In contrast to modules A-180-1/2 each socket is equipped with a 3-position switch that allows to connect the corresponding socket to the internal bus #1 (left position), bus #2 (right position) or to turn the socket off (center position).

Examples:

all switches in left position or all switches in right position: 8-fold multiple

four switches in left position and four switches in right position: two 4-fold multiple

X switches in left position, Y switches in right position and Z switches in center position: two separate multiples with some sockets turned off

Remark: The term “bus” in the module description has nothing to do with the A-100 bus.

Module A-183-1 is a simple passive dual attenuator. Passive means, that each unit is made of two sockets and a 50k linear potentiometer only. There are no active parts like amplifiers or buffers and no power supply is required.

This is how the A-183-1 works: At the output socket appears the attenuated input signal, i.e. zero level at the fully CCW position and max. level and the fully CW position.

Applications:

Adjustable level of CV or audio signals to control other modules that do not have attenuators (e.g. Dual VCA A-132-1, Quantizer A-156, CV-to-Midi interface A-192 and modules of other manufacturers).

Module A-183-2 is a simple voltage offset generator combined with an attenuator/polarizer for the CV input. The function is similar to the vocoder slew-limiter module A-129-3. But the A-183-2 has only one channel available and does not offer the slew feature. Instead of that module A-183-2 offers another feature: switching between attenuator or polarizer function for the input control.

This is how the A-183-2 works: At the two output sockets (simply two connected sockets) appears a DC voltage that is adjusted with the Offset control in the range 0…+5V or -5V…+5V. An internal jumper is used to select the offset range (0…+5V or -5V…+5V). Other ranges are possible by changing a resistor on the pc board (e.g. 0…+10V or -10V…+10V). The DC voltage generated by the Offset control is overlaid by the attenuated voltage that is fed to the In socket. The function of the attenuator control can be set to Attenuator or Polarizer by means of a toggle switch. When the switch is in the Attenuator position the control works as an usual attenuator, i.e. zero level at the fully CCW position and max. level and the fully CW position. When the switch is in the Polarizer position the control works as a polarizer, i.e. zero level appears at the center position. Right from the center position the In signal is added to the offset voltage, left from the center position the In signal is subtracted from the offset voltage. In other words: at the fully CW position the non-inverted In signal is added with the full level to the offset voltage, at the fully CCW position the inverted In signal is added with the full level to the offset voltage. The amplification range for the input is about 0…+1 in the attenuator mode, and -1…+1 in the polarizer mode. The amplification range can be modified by replacing a resistor by another value.

Applications:

Generation of adjustable DC voltages overlaid by control voltages with adjustable level and polarity to control other modules that do not have attenuators or offset controls, e.g. Sampler A-112 (mainly for the wavetable mode), dual VCA A-132-1, Quantizer A-156, Theremin A-178, CV-to-Midi interface A-192 and modules of other manufacturers).

Technical note:
The pin header for the jumper that is used to select the offset range is located between the Offset and Attenuator control on the pcb. In the upper position of the jumper the offset range is 0…+5V, in the lower position -5V…+5V.

Module A-183-3 is a simple amplifier. It is DC coupled and can be used for both CV and audio signals. The maximal amplification can be switched between 1, 2 and 4 (in position 1 the module does not work as a real amplifier but only as attenuator). The level can be adjusted by means of the Level control between zero and the chosen maximim amplification (1/2/4). Two overload LEDs indicate if the output signal goes beyond about +10V or becomes less than about -10V. Input and output are equipped with miniature 2-fold multiples (nothing but 2 connected sockets).

The main application of this module is to adapt differing audio or CV levels between different modules or systems. For example LFO, ADSR or Gate levels between modules of different manufacturers can be increased or attenuated. But even audio signals can be attenuated or amplified up to 4. But the module cannot be used as an amplifer for external low level audio signals (e.g. microphones or electric guitars) !

Active bus access module to feed CV and Gate into the A-100 bus (e.g. when using more than one frame or with external CV/Gate interfaces). Miniature jack sockets for CV In, Gate In, 2xCV Out, 2xGate Out, 2 LEDs for CV/Gate control

In general the A-185 is recommended as soon as more than 2 VCO’s (A-110, A-111) are controlled by the same control voltage source. Without interconnection of the A-185 in this case tuning inaccuracies (scale) may occur. The A-185 is mounted close to the VCOs. The controlling voltage for all VCOs is applied to the CV In socket of the A-185. By means of the CV line of the bus board the CV is connected to all VCOs at the same bus board.

Remark: To distinguish this module from the A-185-2 Precision Adder/Bus Access the name of the “A-185” has been changed to “A-185-1”.

Module A-185-2 is a precision control voltage adder/buffer. Precision means that the amplification of the inputs without attenuators is exactly 1.00 and is suitable to add control voltages for the pitch control of VCOs (e.g. from keyboard + sequencer 1 + sequencer 2). Summing resistors matched to 0.1% are used to obtain an accuracy of 0.1% for the added voltages.

The module is equipped with four CV inputs: one with attenuator and three without attenuator. Each input is normalled to +1 V (i.e. if no plug is inserted the input contributes 1 V to the sum appearing at the output).

The input with attenuator can be used for common modulations (e.g. from an LFO, ADSR, Theremin, Pitch-Bender) for all VCOs connected to the output. The Lev.1 control is used to adjust the depth of the modulation, the first switch selects the polarity of the modulation. If no signal is connected to the first socket the attenuator works as a (fine) tuning knob because a voltage in the range 0…+1V (right position of the switch) or 0…-1V (left position of the switch) is added to the CV output.

The inputs without attenuators are planned to add control voltages coming out of keyboards, sequencers, Midi-to-CV interfaces, ribbon controllers or other CV sources that follow the 1V/oct standard. For example the CV of a keyboard can be used to transpose the CV coming from a sequencer, or the CV of a slow sequencer can be used to transpose the CV from a fast sequencer.

Each input is equipped with a three-position switch that determines if the corresponding voltage is added (right position), subtracted (left position) or if the input has no effect (center position). If no plug is inserted the corresponding switch works as an octave switch for the lower three sections as the default 1 V are added or subtracted to the output voltage according to the switch position. The first switch can be used to add a variable voltage to the sum output. The variable voltage is adjusted with the Lev.1 control and the knob works then as kind of a (fine) tuning control.

The module is equipped with 4 outputs: three non-invertíng and one inverting ouput. An internal jumper can be used to connect the non-inverted or inverted output to the CV line of the A-100 bus. That way the module can used to control several VCOs that are connected to the same bus board as the A-185-2 (same functionality as A-185-1).

Remark for A-185-2 users: There is a pin header with three pins (labelled JP5) near the bus cable connector. If no jumper is installed there is no connection between the outputs of the A-185-2 and the CV line of the A-100 bus. In the lower position the normal CV output of the A-185-2 is connected to the CV line of the A-100 bus. In the upper position the inverted CV output of the A-185-2 is connected to the CV line of the A-100 bus.

Important Notes:

The module comes with an installed jumper, i.e. one has to remove the jumper if e.g. an A-190-1/2/3 or A-185-1 is already connected to the CV line of the same bus board! If the A-185-2 should be used as CV source for the A-100 bus the CV connection of another CV source (e.g. A-185-1 or A-190-1/2/3) has to be removed. Otherwise a short circuit is made between the outputs of the CV transmitters ! Please refer also to the technical notes concerning A-100 bus principles:

Do not insert patch cables into the CV input sockets while the other end of the cable is open. The A-185-2 features high impedance inputs. Cables with open ends will cause random voltages. The other end of each patch cable must be connected to a voltage (e.g. sequencer CV output, USB/Midi-to-CV interface CV output, LFO output, ADSR output, Theremin CV output, ribbon controller CV output and so on).

Module A-186 is a very simple, passive unit that combines up to 7 gate, trigger or analog signals by or-wiring.

Function:

if all seven inputs are low or open the output is low

if one or more of the seven inputs is “high” the output turns high

Applications:

combination (“or”-wiring) of gate and/or trigger signals (e.g. from LFOs, sequencers, keyboards, Midi-to-CV interfaces, ribbon controller, theremin, trigger delays or any other source of gate/trigger signals

Maximum extractor for analog voltages: at the output the maximum voltage (minus ~ 0.7V because of the diodes) appears, similar function as the maximum output of the A-172 Maximum/Minimum Selector module, e.g. for simple waveshaping

Module A-187-1 is a DSP based effects module. Four parameters of the selected digital effect are voltage controlled. The main effect (e.g. reverb, delay, pitch-shifter, equalizer) is selected by the two small buttons effect up/down. The upper row of the display shows the effect that is currently selected.In the lower row the four parameters are shown as well as a small bar left from the abbreviation that displays the current parameter value. Each parameter can be adjusted manually (upper potentiometer row) and modified by external control voltages (lower row of the potentiometers and upper row of the sockets). The lower row of the sockets containes the two audio inputs and outputs.

Another button (bypass) is used to turn the effect on/off. When bypass is chosen the upper line of the display shows in turn “BYPASS” and the name of the pre-selected effect. In the bypass mode another effect can be pre-selected and called-up by pressing the bypass button again. Even the effect parameters can be adjusted and are displayed with the bar graphs. But they become effective not before the bypass mode is left.
A list with all effects and the voltage controlled parameters is shown below.
The module is equipped with two audio inputs and two audio outputs because the DSP board features stereo audio processing. The audio inputs can process usual A-100 signal levels without clipping/distortion. For higher levels external attenuators (e.g.. A-183-1) or VCAs may be used.

A ready made DSP board is used inside the A-187-1 module. Consequently only these effects and parameters are available that are supported by the DSP module. Some parameters can be changed only in steps or with audible artefacts. The DSP board has 20 Bit DA and AD converter with 32 kHz sample rate available. The inter sound processing uses 24 Bit. Some audio examples can be found below.

Notes for customers who already rown an A-187-1 module:

The USB connector is not used so far. But we added it to the board provided that there will be an update of the A-187-1 firmware in the future. We will explain how to use the USB connector as soon as new firmware is available. So far there are no plans for a new firmwire.

Module A-188-1 is a so-called Bucket Brigade Device module (abbr. BBD). BBDs have been used to delay audio signals before digital delays dethroned the BBD based effect units. But BBDs have some very unique advantages (or disadvantages dependent on the point of view) over the digital counterpart which result from the special properties of the BBDs. BBD circuits can be treated as a chain of Sample&Hold units (S&H) which pass on their voltages to the next S&H in the chain at each clock pulse. A more detailed explanation – including the different types of BBDs – can be found in following chapter.

In any case the sounds generated by module A-188-1 are very special. Typical applications are: Flanger, Chorus, Analog Delay or Karplus/Strong synthesis. But as the A-188-1 has a lot of very unique features (voltage controlled clock rate / delay time with extreme range, polarity switches for the CV inputs, feedback and BBD out/mix, clock and CV output of the high speed VCO, BBD clock input, feedback insert, feedback up to self-oscillation) a lot of unusual applications can be realized with the module (e.g. delay controlled by ADSR, envelope, random or sequencer with positive or negative effect). The A-188-1 also has no built-in anti-alisaing filter in order not to limit the possibilities of the module. For this the CV out is intended.

A more detailed description of the module can be found in the user’s manual A1881_man.pdf.

Originally A-188-1 was developed for BBD curcuits with 1024 or 2048 stages as these circuits are still in production. Bur we found a limited quantity of normally obsolete BBD devices with 128, 256, 512 and 4096 stages (MN3006, MN3009/3209, MN3204, MN3005). These are more expensive than the two standard circuits with 1024 and 2048 stages. Therefore the module versions with 128, 256, 512 or 4096 stages are more expensive and available only while stocks last. The BBD type used in the module is indicated by a dot at the front panel. These are the names of the different versions:

A-188-1X with 128 stages BBD (MN3006/MN3206), available only as long as quantities of MN3006/MN3206 last
A-188-1Y with 256 stages BBD (MN3009/MN3209), available only as long as quantities of MN3009/MN3209 last geringer Bestand / low stock !
A-188-1A with 512 stages BBD (MN3004/MN3204), available only as long as quantities of MN3004/MN3204 last geringer Bestand / low stock !
A-188-1B with 1024 stages BBD (MN3007/MN3207/BL3207), standard version, no delivery limitations
A-188-1C with 2048 stages BBD (MN3008/MN3208/BL3208), standard version, no delivery limitations
A-188-1D with 4096 stages BBD (MN3005/MN3205), available only as long as quantities of MN3005/MN3205 last
For the BBD circuits with 128 and 4096 stages the first version of the A-188-1 cannot be used without modifications (additional electronic parts and wires, interrupted pcb tracks). The revised version of the module is delivered since about June 2006 and contains several jumpers to select the desired BBD circuit. If desired we are able to modify the first version of the module for the BBD with 4096 or 128 stages (additional charge).

The above pictures shows the front panel (version 2) and the scheme of the BBD module. These controls and in/outputs are available:

High speed VCO (HSVCO) section:
manual delay control
delay CV input (CV1) without attenuator (about 1V/oct) and polarity switch (negative/off/positive)
delay CV input (CV2) with attenuator and polarity switch (negative/off/positive)
turning the manual delay knob clockwise or an increasing the external CV with polarity switch in positive position increases the clock and consequently decreases the delay time (similar to a VCF or VCO, especially because of Karplus-Strong synthesis applications)
clock output (e.g. to control another BBD, SC-Filter or delay module)
CV output (e.g. to control a VCF that follows the BBD clock), this voltage is composed of the manual delay control, CV1 and CV2
BBD/audio section:
standard versions of the module: 1024 or 2048 stage BBD (choice at order, a mark at the front panel identifies the type of BBD, similar to A-138a/b)
special versions of the module: 128, 256, 512 or 4096 stage BBD (additional charge, available only while stocks of these special BBD chips last)
delay range for 1024 stage BBD module: ~ 2.5 ms to ??? (corresponds to max. a clock frequency of ~ 200 kHz)
delay range for 2048 stage BBD module: ~ 7 ms to ??? (corresponds to max. a clock frequency of ~ 150 kHz)
the delay ranges for the 128, 256, 512 and 4096 stage versions can be found in the user’s manual A1881_man.pdf.
the max. delay time (???) is not specified as it depends upon the desired quality of the delayed audio signal. The signal becomes more and more poor as the clock frequency is reduced (please refer to the corresponding note below and listen to the audio examples for details)
external clock input (used to control the module e.g. from an external HSVCO or from another BBD module). The socket is normalled to the output of the internal clock oscillator.
two audio inputs (connected as a miniature multiple) with attenuator
BBD output (raw delayed output without original signal, e.g. for external feedback control via other A-100 modules, e.g VCA or VCF), the BBD output is affected by the feedback polarity switch to obtain the polarity function even for external feedback loops
manual feedback control
feedback polarity switch (positive/off/negative), affects even the BBD output socket
external feedback input (the socket is normalled to BBD output)
BBD signal polarity switch (positive/off/negative)
mix control (relation between original signal and positive or negative BBD signal)
mixed audio output
Links to some audio examples are available below (with 2048 and 1024 stage BBD devices). The main difference between the two types of BBDs is the delay time range. The maximum clock frequency mentioned in the data sheet of the 2048 stage BBD is 100kHz. This leads to a minimum delay time of about 10ms. But we found that the device is able to operate even a bit beyond this spec (up to ~ 150kHz) causing a minimum delay time of about 7ms. The maximum clock frequency mentioned in the data sheet of the 1024 stage BBD is 200kHz. This leads to a minimum delay time of about 2,5ms. Overclocking is not possible for the 1024 stage BBD.

The maximum (useful) delay time is hard to define. The output becomes more and more crunchy as the clock frequency goes down because the number of samples per second taken from the original signal decreases as the clock frequency is reduced. But this is only one aspect. Indeed several effects occur simultaneously:

kind of bit crunching because of the increasing time between samples taken from the audio signal
aliasing effect as the sample rate becomes less than twice the max. audio frequency
BBD losses: the BBDs are not specified for clock frequencies less than 10 kHz (this value is valid for both 1024 and 2048 stage BBDs). The BBDs can be treated like a chain of sample&hold units with very small capacitors (the capacitors are integrated on the BBD chip). Clock frequencies below 10kHz cause voltage losses as the holding times of the S&Hs are no longer sufficient to pass on the voltages to the succeeding stage without errors/losses.

A-188-2 is another module that is based on a so-called Bucket Brigade Device (BBD). If you are not familiar with BBDs please refer to the A-188-1. There you can find some details about this special type of circuits.

The main difference between A-188-1 and A-188-2 is the type of BBD circuit that leads to completely different module principles and sounds. The A-188-1 uses different single BBD chips with one signal input and one signal output only. In contrast the A-188-2 uses as so-called tapped BBD that has available six outputs – the so-called taps after the BBD stages 396, 662, 1194, 1726, 2790 and 3328. In the A-188-2 we use this special BBD circuit (MN3011) to obtain these module features:

The module has available two separate mixing sub-units. For both mixers the levels and polarities of each BBD output can be adjusted to obtain two different mixtures of the BBD outputs. A new type of potentiometers with center detent and center terminal is used for the BBD mixing controls to have a better feel for the neutral position. Each mixer has a wet/dry control at its output that allows choosing between the pure input signal (original), the BBD mix or anything in between. The two outputs can be treated as stereo outputs but it is also possible to use one of the outputs for other applications (details in the next paragraph).

The A-188-2 has a feedback section available that is very similar to the one in the A-188-1. But as we now have 6 different BBD outputs available 6 different feedback types are possible. The feedback input socket is normalled to the “396” output (not to “1194” as shown in the scheme, the front panel is correct). But by patching the feedback socket to any of the single output sockets another BBD tap can be used for the feedback to obtain different sounds. Even external feedback processing is possible (e.g. with a VCA for voltage controlled feedback). The feedback control has polarizer function, i.e. the neutral position is at the center. Left from the center the feedback signal is subtracted from the input signal, right from the center it’s added (negative/positive feedback). Even for this potentiometer the new version with center detent is used.
A special feedback can be obtained if one of the mix outputs is used for the feedback function. In this case for each tap the positive or negative feedback share can be adjusted. This leads to multiple peaks and/or notches in the frequency response of the module.

For each tap of the BBD a separate output socket is available. These sockets can be used for changing the feedback loop – as mentioned above -, for voltage controlled mixing of the taps – e.g. with the voltage controlled mixer A-135 or other applications that require access to each single tap.

The A-188-2 uses the same high speed VCO (HSVCO) for the BBD clock as the A-188-1. The clock and consequently the delay time can be controlled manually (delay control) and by the two control voltage inputs CV1 and CV2. The sensitivity of CV1 is approximately 1V/oct. CV2 is equipped with a polarizer (a new type of potentiometers with center detent). The HSVCO has a clock output available that is normalled to the clock input socket. These sockets can be used to link different BBD modules and to run them with the same clock. But even other applications with frequency dividers (e.g. A-163) or PLL (e.g. A-196) are conceivable. A voltage composed of the manual delay control, CV1 and CV2 is available at the CV out socket, e.g. to control an external clock suppression filter as the A-188-2 is not equipped with such a filter (same as for the A-188-1).

Important note (especially for A-188-1 users): The A-188-1 uses single BBD circuits, which can be adjusted to minimize the clock noise as the outputs of the used BBD circuits are symmetrical (for details please refer to A1881_adjustment.pdf, trimming potentiometer P10). By way of contrast the BBD circuit used in the A-188-2 (MN3011) has six asymmetrical outputs that cannot be adjusted to minimize the clock noise. In addition the clock noise of the six outputs adds up. From there the clock noise of the A-188-2 is more intense than of the A-188-1. This is caused by the properties of the MN3011 but not a mistake of the module ! If you feel that the clock noise is too much you have the right to return the unused module within 14 days (i.e. the module has no scratches or prints, e.g. from srewing into the frame).

Module A-189-1 is a voltage controlled bit modifier. It offers several voltage controlled algorithmic functions like voltage controlled bit crunching, bit shifting (with/without carry over), bit exchange, rectifying, absolute value and calculating operations like addition, subtraction, multiplication or division.

The module has two control units both with manual control and CV input with attenuator:

one for the algorithmic function according to the selected mode (e.g. number of shifted bits): BC and BC CV

and one for the sampling rate (SR and SR CV).

The signal input is equipped with an attenuator. As the module is DC coupled even control voltages can be processed.

The mode (e.g. bit crunching, bit shifting, bit exchange) is selected by a 16-position rotary switch:

Switch position Function Remark
1 bit crushing BC controls the number of bits (bit reduction)
2 AND Signal AND BC
3 OR Signal OR BC
4 XOR Signal XOR BC
5 bit shift right BC controls the number of bit shifts
6 bit shift left BC controls the number of bit shifts
7 multiplication Signal x BC
8 compare & complement if signal > BC then output = bit complement of the input signal, otherwise unchanged
9 compare & absolute if signal > BC then output = absolute value of the input signal, otherwise unchanged
10 addition output = signal + BC (with overflow/clipping)
11 addition with BC swap same as 10 but with nibble swap of BC (nibble = half byte, i.e. four bits)
12 short delay 1 with dynamic normalization BC controls the length of the delay memory
13 short delay 2 same as 12 but different length/feedback
14 short delay 3 same as 12 but different length/feedback
15 short delay 4 same as 12 but different length/feedback
16 four stages FIR filter BC controls the filter coefficient

Remark: Module A-189-1 is the first derivative of the universal AD/DA module. More modules derived from this basic idea are planned for the future (e.g. CV delay, CV modifier including Hz/V-to-V/Oct, digital waveshaper/multiplier, clocked audio delay).