A-135-3 is a  is a voltage controlled stereo mixer with four inputs. Behind a front panel with 8 HP only eight linear VCAs (voltage controlled amplifiers) and the mixer based on the VCAs are available.

Controls, Inputs and Functions of each input:

• Level (manual control of the VCA amplification), small rubberized knob (L1...L4)
• Control voltage input with associated attenuator (CV 1...4), for the full VCA control range about 0...+5V control voltage are required (attenuator fully clockwise), for higher control voltages the attenuator is used, the attenuators are without knobs, just plastic shafts with white marker
• Signal Input left/right (InL 1...4 / InR 1...4) 
• The signal inputs are not equipped with an attenuator. But the VCAs can process all signals up to 15Vpp / -7.5...+7.5V without clipping. In case of higher levels an external attenuator is required (e.g. A-183-1).

The sum of the left and right signals appear at the sockets Out L and Out R. The maximal amplification is  about 0.5 to avoid clipping at the mixer outputs (otherwise the outputs may distort with 15Vpp signals at each signal input and full amplifications). If another maximal amplification (e.g. 1) is required two resistors have to be replaced. 
All inputs and outputs are DC coupled. Consequently the module can be used to process both audio and control voltages.

Additional technical specification for each VCA (based on the specifications of the VCA circuits CEM3360/AS3360 used in the module):

• Crosstalk between two channels: better than - 80dB
• Signal attenuation at 0V CV: better than -80dB
• Total harmonic distortion: typ. 1%
• Control voltage feedthrough: max. 15mV

Merk:

Doepfer

Type:

Mixer

Nummer:

A-135-3

Diepte:

45mm

Breedte:

8HP

Power:

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

Module A-138j is a four channel mixer with an additional polarity/mute switch for each input. In the upper position of the corresponding switch the inverted signal is used. In the center position the input in question is turned off (mute) and in the lower position the "normal" (i.e. non-inverted) signal is used. The inverting of signals is used especially for control voltage signals (e.g. LFO, ADSR). But even for corellated audio signals this feature is useful. For example for feedback applications or the mixing of original and processed signals (e.g. original and filtered signal to obtain new filter types).
Channel 1 features in addition an Offset function: provided that no plug is inserted into socket Input 1 control Lev.1 generates an adjustable DC voltage (positive or negative depending upon the position of the polarity switch).
On top of that the module is equipped with two types of single outputs and a dual mix output.  All inputs and outputs are DC coupled. Consequently the VCAs can be used to mix both audio and control voltages.
Each input is  - apart from the polarity/mute switch - equipped with a linear attenuator. The amplification range is 0....1.
The single outputs offer the attenuated and possibly inverted/muted signal of the channel in question. Two version of single outputs are available:

• Single Output A: If a plug is inserted into the single output "A" socket the channel in question is removed from the sum signal.
• Single Output B: If a plug is inserted into the single output "B" socket the channel in question is not removed from the sum signal. This type of single outputs is available only for the channels 1 and 2.

Based on this flexible structure each channel can be used also individually as attenuator or inverter (i.e. without mixer function). 

The output is twice available (two sockets, hard-wired like a multiple).

The distances between the controls and sockets are smaller as for the standard A-100 modules and rubberized small-sized knobs are used. In return the front panel has 6 HP width only. The module is primarily planned for applications where only limited space is available.

Merk:

Doepfer

Type:

Mixer, Inverter, Offset

Nummer:

A-138j

Diepte:

40mm

Breedte:

6HP

Power:

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

A-138s is a simple but useful 4-in-2 mixing tool.

It has four inputs available. Each input is equipped with an attenuator (Level) and a panning control that is used to distribute the signal to the left and right output.

Beyond stereo mixing it is equally suited to create variable parallel routings.

For example: Any of the four inputs may be routed in variable intensity to feed two filters. You may regard the A-138s as a smaller version of the A-138m Matrix Mixer. Inputs and outputs are DC coupled, i.e. the module can be used for the mixing of control signals too.

Merk:

Doepfer

Type:

Stereo Mixer

Nummer:

A-138s

Diepte:

30mm

Breedte:

8HP

Power:

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

Module A-183-5 is a simple passive quad attenuator. Passive means in this context, 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-183-5 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.

Merk:

Doepfer

Type:

Attenuator

Nummer:

A-183-5

Diepte:

20mm

Breedte:

4HP

Power:

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

4Atten is a four channel attenuator and offset generator.

It can be used with any CV or audio signal, but the clever thing about the 4Atten is that when no input is connected, each channel can be used as an offset generator. 

This module can come in handy in many patches. For example, a channel of the 4Atten can be used to modulate the CV input of a filter without an internal attenuator. 

Features:

• 4 independent attenuators for Control Voltage and Audio signals
• 4 individual offset generators (0 to +5V)
• Performance friendly sliders

Attention:

4TTEN's PCB is 113mm tall and may be a tight fit in some cases

Merk:

WMD

Type:

Attenuator

Naam:

4TTEN

Diepte:

30mm

Breedte:

4HP

Power:

5mA @ +12V, 5mA @ -12V

Erica Synths Drum Mixer with extended headroom and a dedicated drum compressor of unique design keeps each drum sound clearly distinguishable and adds power to the final mix. Bonus feature - effects send output allows to apply external effects to the signals on the first three inputs. LEDs next to each input give visual feedback on the signal level.

Features

• 7 inputs
• Built in vactrol based drum compressor with Amount and Decay control
• +6dB signal boosting
• Three inputs assignable to main or aux send outputs
• Main and Aux Send outputs
• Signal level indicator LEDs

Merk:

Erica Synths

Type:

Drum/percussion, Mixer/attenuator

Naam:

Drum Mixer

Diepte:

35mm

Breedte:

14HP

Power:

65mA @ +12V, 41mA @ -12V

Erica Synths Drum Mixer Lite is compact version of Drum Mixer. It features extended headroom and a dedicated drum compressor of unique design keeps each drum sound clearly distinguishable and add power to the final mix. Bonus feature - effects send output allows to apply external effects to the signals on the first three inputs. LEDs next to each input give visual feedback on the signal level.

Features

• 6 inputs
• Built in vactrol based drum compressor with Amount and Decay control
• Three inputs assignable to main or aux send outputs
• Main and Aux Send outputs
• Signal level indicator LEDs

Merk:

Erica Synths

Type:

Drum/percussion, Mixer/attenuator

Naam:

Drum Mixer Lite

Diepte:

35mm

Breedte:

10HP

Power:

59mA @ +12V, 36mA @ -12V

Erica Synths Black Mixer is a compact, high quality audio mixer with a bonus feature – three buffered outputs.

Features

• 3 AC coupled inputs
• 3 buffered outputs
• Input and output protection
• Protection against reverse PSU connection

The buffered outputs allow you to send signals to several signal processing devices simultaneously, for example, split the output signal to LP and HP VCFs and create advanced bandpass and notch filters.

Erica Black series are high-end modules with unique functionality. Only the highest quality components are used and all inputs and outputs are protected against undesired overvoltage. When designing the Black Series, they did not economise on the module width, but put design and usability first. Big knobs are assigned to functions that make difference in sound. Together the Erica Black series are a range of modules that make an entire synthesizer.

Merk:

Erica Synths

Type:

Mixer

Naam:

Black Mixer v2

Diepte:

25mm

Breedte:

6HP

Power:

8mA @ +12V, 8mA @ -12V

Pico Mixer is simple 3 channel DC coupled mixer intended to mix AUDIO SIGNALS AND CV SIGNALS in order to obtain complex modulations. Also it may serve as CV AND AUDIO attenuator.

Features

• 3 inputs 
• Diode protection against overvoltage

Pico Series: is to possible to make ANY superior functionality synth module 3HP wide and affordable? Yes.

Merk:

Erica Synths

Type:

Mixer, attenuator

Naam:

Pico Mixer

Diepte:

35mm

Breedte:

3HP

Power:

4mA @ +12V, 4mA @ -12V