Doepfer A-135-1 Voltage Controlled Mixer (8HP)

Full Description

Version 3 Additions

The Doepfer A-135-1 Voltage Controlled Mixer has undergone a few changes and updates since the first edition. Version 3 features the improvements made for version 2 which include the added individual outputs for each VCA, the more compact 18HP front panel, and DC coupled I/Os for the processing of slowly varying CVs. The revised version 3 builds on the improvements even more by normalling all signal I/Os on the module. All signal inputs are normalled, so input #1 for example, is normalled to input #2 unless a plug is inserted into socket #2. This rule applies to the other inputs, with 2 being normalled to 3, and 3 normalled to 4 (1 to 2, 2 to 3, 3 to 4). This input normalling can be interrupted by removing a jumper on the PCB. The CV inputs are also normalled in the same way. You can also choose between "All" and "Selection" for the Sum Output mode. All mode features all four VCAs mixed together. Selection mode works by removing a VCA from the sum signal if a plug is inserted into its corresponding single output socket.

Controls & Indicators

• Audio In Attenuator (x4): These four attenuators control the levels of their respective audio inputs. Adjust the controls to the desired input levels of the audio signals at the Audio Inputs. They allow you to compensate for different audio levels in the original signals, so that the same CV results in approximately the same audio level at the output
• Gain (x4): Adjusts the amplification offset for the VCA in question. Position "0" corresponds to no amplification offset, meaning that the channel in question contributes no signal to the output, provided that no positive CV is applied to the external CV input. Turning up the gain control increases the amplification, proportional to the gain control setting, even if no voltage is applied to the external CV input. With the gain control, amplification response is shifted up into the positive range. The VCAs in the A-135-1 feature a linear control response, meaning the amplification is in direct linear proportion to the CV input
• ext. CV Attenuator (x4): These four attenuators control the levels of their respective CV inputs. They control the amount of effect that the CV has on amplification

Inputs & Outputs

• Audio In (x4): Individual inputs for patching in the signals you wish to amplify
• Ext. CV IN / CV 2 (x4): Individual sockets for control voltages. The effective CV range of each VCA goes from 0V (no amplification) to approximately +5V (maximum amplification). The effective control voltage is the sum of the voltages coming from the gain control (about 0V to +5V), and the external CV that may be attenuated with the ext. CV attenuator
• Single Outputs (x4): Individual outputs for the amplified audio signals from each VCA
• Sum Output: This is the output socket for the sum of the four audio inputs amplified by the four VCAs

Specifications

• Width: 18HP / 90.3mm
• Depth: 50mm (Measured from the rear side of the front panel)
• Current:
  • +12V: +60mA
  • -12V: -50mA