The A-130 is a linear voltage controlled amplifier designed mainly for controlling control voltages. The VCA has two signal inputs, each with an attenuator. They are amplified by the combination of the gain control and the two CV inputs. The VCA output is then passed through a further attenuator to control the overall output level from the A-130.
A-130 History: Since the A-130 has been released, there have been three different versions: Version 1: (manufactured up until 2001) The first versions of A-130 were designed using a CEM3381 Curtis chip. This versions of the A-130 was unable to process slowly varying control voltages as it had AC coupled signal in/outputs. Version 2: (manufactured between 2001 and 2013) The second version of the A-130 was designed with the CA3080 OTA chip which was able to process slowly varying control voltages as it had DC coupled signal in/outputs. This chip is no longer manufactured. Version 3: (manufactured from 2013) The current version of the A-130 is designed with the high-end VCA SSM2164 chip. It is able to process slowly varying control voltages as it has DC coupled signal in/outputs.
Unfortunately it's not possible to upgrade older modules because the new circuitry is totally different.