In Phobos there are four Source units. You can see them numbered 1 - 4 at the top of the interface. Each Source unit can load either a Loop or a Tonal sound.
When a loop is loaded into a Source unit the same sound plays regardless of which key is pressed. The pitch of Loop sounds is not directly affected by the key used to trigger the sound.
When a Tonal sound is loaded into a Source unit its maximum polyphony is determined by the number of keys in its key range and any overall polyphony limits that have been configured in the Settings page. The pitch of Tonal sounds is adjusted to match the key that was used to trigger the sound.
There are three Convolver units which appear in Phobos at the three points of the central triangle. Each Convolver unit can load any of the same Loop or Tonal sounds.
These Convolver units are slightly different from conventional convolution reverb-like effects. In a similar way to the Source units, the Convolver units are polyphonic. This means that for each key that triggers one of the Convolver units a separate and new impulse response is created. This impulse response will be generated on the fly. This is what we mean by the ‘polyconvolution’ engine in BT Phobos.