Module A-102 is a reproduction of the legendary low pass filter design that uses diodes in the filter stage as frequency controlling elements resulting in "strange" resonance behaviour and frequency response as resonance and frequency are not independent from another.

• manual control of filter frequency
• 3 CV inputs (CV1, CV2, CV3), 2 of them with attenuator (CV2, CV3)
• input level control
• resonance control up to self oscillation (depends upon the frequency setting for the A-102

Merk:

Doepfer

Type:

Filter

Nummer:

A-102

Diepte:

60mm

Breedte:

8HP

Power:

30mA @ +12V, 10mA @ -12V

Module A-103 is a voltage controlled low pass filter with 18dB/octave slope.

The circuit is based on a modified transistor ladder (Moog ladder) and is a reproduction of the legendary TB303 filter.

• manual control of filter frequency
• 3 CV inputs (CV1, CV2, CV3), 2 of them with attenuator (CV2, CV3)
• input level control
• resonance control up to self oscillation

Merk:

Doepfer

Type:

Filter

Nummer:

A-103

Diepte:

55mm

Breedte:

8HP

Power:

30mA @ +12V, 10mA @ -12V

Module A-105-2 is a voltage controlled low pass filter with 24dB/octave slope.

The module has these controls and in/outputs available:

• Control Frequ: manual frequency control
• Control FCV2: attenuator for the frequency control voltage applied to socket FCV2
• Control Q: manual resonance control
• Control QCV: attenuator for the resonance control voltage applied to socket QCV
• Control Input 1 Level: attenuator for the audio input signal applied to socket Input 1
• Socket Input 1: audio input 1 (with attenuator)
• Socket Input 2: audio input 2 (without attenuator)
• Socket FCV1: frequency control voltage 1 (without attenuator, about 1V/oct scale)
• Socket FCV2: frequency control voltage 2 (with attenuator)
• Socket QCV: resonance control voltage (with attenuator)
• Socket Out: audio output

Technical notes:

• Frequency range: about 15Hz ... 15 kHz
• Resonance up to self oscillation
• Max. input voltage at Input 2 without clipping/distortion: about 15Vpp
• Max. output voltage without clipping/distortion: about 15Vpp
• The signals of both inputs are mixed before they are processed by the filter. This saves an external mixer for small setups

Merk:

Doepfer

Type:

Filter

Nummer:

A-105-2

Diepte:

45mm

Breedte:

4HP

Power:

20mA @ +12V, 20mA @ -12V

Module A-106-5 is a 12dB multimode filter that is based on the filter circuit of the Oberheim SEM module.

The filter is equipped with a band pass output and a combined low/notch/high pass output. For this output a control knob defines the relation between low and high pass signal. If both signals appear at the same level (i.e. middle position of the Mix knob) one obtains a notch filter. Otherwise the low or high pass signal predominates. The module does not feature self oscillation in contrast to most of the other filters of the A-100 system.

The module generates a distorted audio signal if the level control is set to about 50% (i.e. center position) or more with A-100 standard signals like VCOs.

Merk:

Doepfer

Type:

Filter

Nummer:

A-106-5SE

Diepte:

55mm

Breedte:

8HP

Power:

30mA @ +12V, 20mA @ -12V

Module A-120 is a voltage controlled low-pass filter, which filters out the higher parts of the sound spectrum, and lets lower frequencies pass through. The Cut-Off Frequency determines the point at which filtering takes effect. You can control this manually, or by voltage control (filter modulation, for instance by an LFO). Three CV inputs are available, and the sum of the voltages from these affects the filter cut-off. VCF1 is a co-called "transistor ladder" design, with a cut-off slope of -24 dB/octave, as in various Moog synthesizers. That's what gives it its classic, legendary Moog sound. Resonance (or Emphasis) is adjustable all the way up to self-oscillation - in which case the filter behaves like a sine wave oscillator.

Merk:

Doepfer

Type:

Filter

Nummer:

A-120

Diepte:

65mm

Breedte:

8HP

Power:

30mA @ +12V, 20mA @ -12V

Module A-121-2 is a voltage-controlled multi-mode filter with a cut-off slope of -12 dB / octave.

Four simultaneous outputs are available, each with different characteristics: low-pass, band-pass, high-pass and notch (or band reject). The cut-off frequency determines the point at which the respective filter effects appear. The frequency can be adjusted manually, or by voltage control (Filter modulation, for instance by an LFO or ADSR). Two CV inputs are available, whose control voltages are summed. Resonance (Emphasis or Q ) can be adjusted manually, or by voltage control (voltage-controlled resonance / VCQ), right up to self-oscillation, in which case it will behave like a sine wave oscillator.

Merk:

Doepfer

Type:

Filter

Nummer:

A-121-2

Diepte:

50mm

Breedte:

8HP

Power:

40mA @ +12V, 40mA @ -12V

Module A-121-3 is functionally nearly identical to module A-121-2. Only the distances between the controls and sockets are smaller and rubberized, small rotary knobs are used. Therefore the front panel width is only 4HP compared to 8HP of the A-121-2. In the first place it is planned for applications where only limited space is available. The only functional difference compared to the A-121-2 is the missing attenuator for the resonance CV input CQ. 

• voltage-controlled multi-mode filter with a cut-off slope of -12 dB / octave (idential to the filter of the Dark Energy II/III but has been expanded by the voltage controlled resonance feature)
• four simultaneous outputs are available, each with different characteristics: low-pass (LP), high-pass (HP), band-pass (BP) and notch (N) 
• manual control for the cut-off frequency of the filter (the cut-off frequency determines the point at which the respective filter effect appears)
• two inputs for frequency control by means of external control voltages (frequency modulation, e.g. by ADSR or LFO):
• control voltage input CV1 without attenuator, about 1V/octave sensitivity
• control voltage input CV2 with attenuator FCV2 for the adjustment of the modulation depth of input CV2
• frequency range about 10Hz ... 20kHz
• Manual control Q for the resonance of the filter
• control voltage input CQ without attenuator for voltage control of the resonance
• resonance up to self-oscillation, in which case the module will behave like a sine wave oscillator even without audio input signal
• audio input In with attenuator Level for the adjustment of the filter input level (beyond about pos. 5 clipping/distortion occurs with typical A-100 audio levels

Merk:

Doepfer

Type:

Filter

Nummer:

A-121-3

Diepte:

50mm

Breedte:

4HP

Power:

40mA @ +12V, 30mA @ -12V

Module A-124-2 is a special 12dB multimode filter using the "strange" filter circuit of the "EDP Wasp" (an analog synthesizer with black/yellow case built end of the seventies, manufactured by the UK company "Electronic Dream Plant"). 

The A-124-2 is the Slim Line version, which is only 4hp wide. 

This design "abuses" digital inverters as analog operational amplifiers leading to distortions and other "dirty" effects that generate the specific sound of this filter. The filter is equipped with a band pass output and a combined low/notch/high pass output. For this output a control knob defines the relation between low and high pass signal. If both signals appear at the same level (i.e. middle position of the Mix knob) one obtains a notch filter. Otherwise the low or high pass signal predominates. The module does not feature self oscillation in contrast to most of the other filters of the A-100 system.

Merk:

Doepfer

Type:

Filter

Nummer:

A-124-2SE

Diepte:

45mm

Breedte:

4HP

Power:

30mA @ +12V, 10mA @ -12V

Module A-124-2 is a special 12dB multimode filter using the "strange" filter circuit of the "EDP Wasp" (an analog synthesizer with black/yellow case built end of the seventies, manufactured by the UK company "Electronic Dream Plant"). 

The A-124-2 is the Slim Line version, which is only 4hp wide. 

This design "abuses" digital inverters as analog operational amplifiers leading to distortions and other "dirty" effects that generate the specific sound of this filter. The filter is equipped with a band pass output and a combined low/notch/high pass output. For this output a control knob defines the relation between low and high pass signal. If both signals appear at the same level (i.e. middle position of the Mix knob) one obtains a notch filter. Otherwise the low or high pass signal predominates. The module does not feature self oscillation in contrast to most of the other filters of the A-100 system.

Merk:

Doepfer

Type:

Filter

Nummer:

A-124-2SE

Diepte:

45mm

Breedte:

4HP

Power:

30mA @ +12V, 10mA @ -12V

Module A-124 is a special 12dB multimode filter using the "strange" filter circuit of the "EDP Wasp" (an analog synthesizer with black/yellow case built end of the seventies, manufactured by the UK company "Electronic Dream Plant").

This design "abuses" digital inverters as analog operational amplifiers leading to distortions and other "dirty" effects that generate the specific sound of this filter. The filter is equipped with a band pass output and a combined low/notch/high pass output. For this output a control knob defines the relation between low and high pass signal. If both signals appear at the same level (i.e. middle position of the Mix knob) one obtains a notch filter. Otherwise the low or high pass signal predominates. The module does not feature self oscillation in contrast to most of the other filters of the A-100 system.

Merk:

Doepfer

Type:

Filter

Nummer:

A-124SE

Diepte:

40mm

Breedte:

8HP

Power:

50mA @ +12V, 50mA @ -12V

Module A-196 contains a so-called phase locked loop (PLL).

A PLL consists of three parts: voltage-controlled oscillator (VCO), phase comparator (PC), and low-pass filter (LPF). All parts are normally connected to form a closed-loop frequency-feedback system.

This is how a PLL works: The output of the internal VCO (linear CV control, rectangle output) is compared with an external signal (e.g. the rectangle output of a A-110 VCO) in the so-called phase comparator (PC). The output of the phase comparator is a digital signal (low/high/tristate) that indicates if the frequency resp. phase difference of the two input signals is negative, zero or positive. The output of the phase comparator is processed by a low pass filter (LPF) to generate a smooth voltage that is used to control the frequency of the internal VCO. The 3 units VCO, PC and LPF form a feedback loop that works like this: The control voltage (output of the LPF) increases as long as the external frequency is higher than the frequency of the internal VCO and stops increasing when both frequencies become identical.The control voltage decreases as long as the external frequency is lower than the frequency of the internal VCO and stops decreasing when both frequencies become identical.

But there are some stumbling blocks: Different types of phase comparators with advantages and disadvantages can be made. Some phase comparators e.g. even lock at harmonics, i.e. if the two frequencies to be compared are integer multiples. But for some applications this can be used to create interesting effects. The A-196 contains 3 different types of phase comparators: PC1 is a simple exclusive OR, that even locks at harmonics. PC2 is a so-called RS flipflop and PC3 a more complex digital memory network. The user can select one of the three phase comparators with a 3-position switch. When PC2 is used a LED displays the "locked" state, i.e. when the frequency of the internal VCO is identical to the external frequency.

Special attention has to be directed to the frequency of the LPF. To obtain a smooth control voltage for the VCO the frequency of the LPF has to be much smaller than the lowest frequency of the internal or external audio signal. Otherwise the frequency of the internal VCO will jitter or wobble around the correct frequency. But for special effects this frequency jitter can be used intentionally. Example: frequencies in the range 50Hz...1kHz have to be processed with the PLL. Therefore the frequency of the LPF has to be about 10Hz or even less. Such a low frequency of the LPF causes a noticeable slew of the internal VCO. When the frequency of the external signal jumps e.g. between 500Hz and 1kHz it takes about 0.1 second until the internal VCO reaches the new frequency (like portamento). So one has to find a compromise between frequency jitter and portamento. But these remarks are valid only for the "ideal" working PLL. As the A-196 is used in a musical enviroment the "problems" and disadvantages with jitter and slew time lead to additional musical applications like portamento effects, wobbling frequencies or harmonic locking according to the type of frequency comparator and time constant of the PLL low pass filter. Instead of the internal manually controlled low pass filter the voltage controlled slew limiter A-171 can be used to obtain voltage control of this parameter. Normal audio filters (e.g. A-120, A-121) cannot be used for this job as the minimum frequency is to high (down to a few Hz or even less necessary) and the signal has to be DC coupled due to the low frequencies. Audio filters are normally AC coupled.

Another very important application of a PLL is frequency multiplication in combination with an external frequency divider. For this the output of the PLL-VCO is processed through an external frequency divider (e.g. A-163, A-160, A-161, A-115) before it is fed to In1 of the phase comparator. In this case the frequency of the PLL-VCO will be a multiple of the master frequency. E.g if the the A-163 is used and adjusted to dividing factor 5 the frequency of the PLL-VCO will be 5 times the frequency of the master VCO. Consequently frequency division (A-163) leads to frequency multiplication with the PLL circuit. In combination with the PLL low pass frequency several effects can be realized (frequency multiplication with portamento or wobbling). The frequency multiplication can even be used to drive a graphic VCO. If your graphic VCO e.g. has 8 steps (e.g. A-155) and you use a frequency divider with factor 8 in the PLL feedback the output of the graphic VCO has the same frequency as the master VCO. Another application is the generation of pseudo-harmonics (not real harmonics as only rectangle waves are available) or clock generation for switched-capacitor filters.

The PLL components are available as separate building blocks in the A-196 module. The standard PLL patch is realized by means of normalized sockets. But it is also possible to use each component separately. E.g. the VCO can be used as a simple VCO with linear control input and rectangle output. For this an external voltage has to be fed into the CV input socket. The VCO has two controls: Offset and range (switch). As the VCO has a linear control input the frequency will go down to zero (i.e. the VCO stops) if the input CV is 0V. The offset control is used to adjust the lowest frequency (i.e. the frequency for CV = 0V). The range switch is used to switch between 3 frequency ranges. The position of the switch defines the max. available frequency. For other treatments of the phase comparator output (e.g. with an external voltage controlled filter or any other processing module) the output of the phase comparator is available. Same applies to the LPF output and input 1 of the phase comparator.

It has to be pointed out that the A-196 is a very experimental module and its functions cannot be described straight forward as for other modules. Rather the user should try out the possibilities by trial and error.

Applications: frequency multiplication, special sound effects, generation of clock signals for graphic VCO (high speed VCO, e.g. for A-155 as graphic VCO), clocked audio delays or switched-capacitor filter.

Merk:

Doepfer

Type:

VCO, Phase Comparator, LPF

Nummer:

A-196

Diepte:

40mm

Breedte:

8HP

Power:

40mA @ +12V, 0mA @ -12V

C4RBN is a 4/2-pole state variable filter with input saturation, output wavefolding and more. It offers a wide range of characters, from nice and clean filter sounds to screaming, squeaky, sounds.

An innovative input saturation circuit and the output wavefolder of WMD's classic SYNCHRODYNE filter bring great sonic flexibility.

Features:

• 3 independent 2 pole outputs for High Pass, Low Pass, and Bandpass 
• Inverting Attenuator (attenuverter) for FM allows for positive and negative CV control over the cutoff frequency
• Independent 4 Pole output with switchable frequency response
• Input Saturation with 3 switchable levels and CV input for additional fine control
• PING circuit generates a fast decay envelope emulating the response of a vactrol
• Output wavefolder for extra bite and screaming character 
• Resonance with self oscillation
• Temperature compensated 1V/Oct tracking.
• Performance focused control scheme allows for on-the-fly changes of filter types with intention

Merk:

WMD

Type:

Filter

Naam:

C4RBN

Diepte:

38mm

Breedte:

4HP

Power:

92mA @ +12V, 82mA @ -12V

The Graphic Resonant Filterbank (FB) is a ten-band analogue filterbank with digital control over each bands’ boost or cut. Each band can be controlled individually via CV or manually, while complex control configurations turn the filterbank into an unconventional multimode filter and even an instrument in its own right when played with various resonance settings. The Expander module (works exclusively with the Graphic Resonant Filterbank and is available separately) provides hands-on adjustment of boost and cut for all bands.

Features

• Analogue 10 band filterbank 
• Saveable presets for filterbank, filter modes, dynamic EQ, and resonance settings 
• Main, even and odd outputs 
• Manual and voltage-controlled band boost/cut 
• Configurable resonance feedback loops 
• Manual and voltage-controlled resonance 
• Clock input for synchronization of events with a master clock source 
• Multimode filter mode 
• Spectral analyzer mode 
• Dynamic spectral compressor mode 
• Discrete and morphing pattern change 
• Configurable CV inputs 
• Expander module for immediate access to band levels
• Skiff-friendly design

Merk:

Erica Synths

Type:

Filter

Naam:

Graphic Resonant FB

Diepte:

30mm

Breedte:

20HP

Power:

138mA @ +12V (145 with Expander), 50mA @ -12V