the 606 and 808 are kind of specific the way they work internally. The trigger signals come from a common bus and are then ‘anded’ with a common trigger and accent signal.
At any given moment, even when the 606 is stopped the signal at each voice is either high or low and there is no way of knowing which. So if you supply an external trigger and a common trigger, you usually trigger multiple voices.
Together with a 3rd party we designed a nice little circuit ‘the additional hardware’ that supplies ‘inhibitor signals’ when a voice is triggered. It Plugs on the unipulse board and works very well in an 808. It was going to be produced and available in our shop, but so far the 3rd party has not done that unfortunately.
Additional notes: Even with the additional hardware:
– You can not fit the unipulse inside the TR-606, there just is no space.
– You need to signals per voice: one trigger and one inhibitor
Of course if you have a broken 606 and only want to trigger it via midi, you can desolder a few components and trigger it directly with the unipulse