If someone takes a look at all the public available tandem rotor helicopters - he will admit that they all have only 2 combined Aileron/Collective servos each swashplate. The reason for this might be in history as the available flightcontrols for such helicopters had this limitation. It is obviously that a "full control" over all 3 axis would be way better than they can do with only 2 of them.
Some days ago Hirobo has manufactured a Tandem with 2 x 120° ECCPM Swashplate including a simple Gyro/Mixer System. Fortunately we could borrow one from a Customer (which bought it used from another one who built it with a NEO and the 2 Servo solution) with the goal to develop 2 swashplate mixers for tandem through macrocells.
First we converted it back to original 120° swashplates (changed the outer rings to the original ones) and set them up with macrocells. This has many advantages like:
Our goal was to develop a app for the VBar Control touch which sets up all the basic parameters and all the macrocells behind. It gives a nice clean user interface to set up what might be needed in addition to the normal VBar NEO Pro parameters. Even a usage with the (now outdated) Ailerion/Collective H-2 swashplates is possible.
As we do not know your helicopter it is the pilots responsibility to adjust useful throws, control loop ratios etc. in the VBar. With the Macrocells we can give you best flexibility. Please check all directions etc. after a change of the setting before a flight. The pilot is responsible for safe operation.