Series A-135-4 contains several modules which are used to built a voltage controlled performance mixer. The modules of the A-135-4 series can be combined with the (non voltage controlled) mixer modules A-138o/p.
A-135-4 modules in detail:
A-135-4A is the main module. It is very similar to module A-138p, but with voltage control for all parameters (except gain). Also the front panels of A-135-4A and A-138p are very similar. The only difference are the additional LEDs which are used to display the magnitudes of all voltage controlled parameters. This is necessary because the positions of the manual controls do not necessarily correspond to the resulting parameter value because these are composed by both the manual controls and the applied external control voltages (via A-135-4B). Without LEDs one would be left in the dark in regard to the actual parameter value.
This module is used to route the 16 external control voltage to the main module A-135-4A. These control voltages are available for each channel:
Each control voltage has an input socket and a polarizer control available (the polarizer function is described more detailed on the A-138c info page). That way it's possible to adjust the depth and polarity of the external control voltage which affects the parameter in question. If the same CV (e.g. LFO or ADSR) is used e.g. for two panorama control inputs the result may be the opposite if the polarizers are adjusted accordingly (i.e. one positive and the other negative). The external control voltage is added to the voltage that is generated by the manual control on the A-135-4A main module. The sum of both voltages is used to control the VCA in question and is displayed with the corresponding LED on the A-135-4A module. The picture on the left side below shows one channel of A-135-4A/B as block diagram.
The mute CV input works in principle in the same way as the level CV input but with reverse polarity and higher sensitivity (about factor -2). Typically the mute polarizer control is adjusted fully CW. Then a (gate) voltage of ~ +2.5V or more fully mutes the channel in question. If the mute function is not used the mute CV input can be used as a second CV input for level (with twice the sensitivity and inverted polarity compared to the normal level CV input).
A-135-4A and A-135-4B are connected internally via a 20 pin ribbon cable. The cable can be longer so that the CV input module A-135-4B needs not to be mounted next to the main module A-135-4A (e.g. to the row above or below).
Modules A-135-4A and A-135-4B are available only as a module combo because the single operation of each module does not make sense !
Additional technical notes
Module A-135-4A has an additional internal connector available that can be used to normalize the four audio inputs. If e.g. the position of the inputs socket at the top of the modules is unfavorable under certain conditions this internal connector may be used to connect 4 external sockets which are positioned elsewhere. If there are sufficient inquiries we may offer such a passive input module (A-135-4?).
The following document explains the internal connections between the three modules: A135_4_connection.pdf
Note: Black versions of the small grey knobs used in these modules are available as spare parts. If some of the grey knobs (e.g. Pan or Aux) should be replaced by black ones they can be swapped easily by the customer. If applicable pay attention to order the knobs with 11.5mm diameter (A-100KSB in the price list / section spare parts).
All features, specifications, prices, date of delivery are still without obligation
Breite/Width: 16TE / 16HP / 80.9 mm
Tiefe/Depth: 45 mm (gemessen ab der Rückseite der Frontplatte / measured from the rear side of the front panel)
Strombedarf/Current: + 150 mA (+12V) / - 100 mA (-12V)