Hi Mike --
I think I understand what you want -- the ability to play any voice (preset or expansion) through both tone generator (TG) chips thereby getting full 256 voice polyphony for any Genos voice. Did I get that right?
Here's a highly simplified diagram of the two tone generator integrated circuits (SWP70) in the Genos (Source: Genos service manual):
SWP70 <----> Wave memory (2GBytes) [Expansion]
|
+ -----> DAC -----> Output
|
SWP70 <----> Wave memory (4GBytes) [Preset]
Please think of the SWP70s as fully independent computers. Each SWP70 gets commands from the same main CPU which catches notes from the keyboard, MIDI, etc. However, each SWP70 runs as an independent hardware engine. The output from each SWP70 is mixed (digitally) and sent to a digital-to-analog converter.
The limitation in Genos -- 128 voice polyphony preset and 128 voice polyphony expansion -- is due to the memory organization. Each independent tone generator computer (SWP70) has its own
dedicated wave memory. One wave memory holds the factory preset samples and the other wave memory holds the user/expansion samples. One TG chip cannot read samples from the other TG's wave memory.
This is why there are 128 voices of polyphony for preset voices and 128 voices of polyphony for expansion voices.
Hope this helps. I avoided any discussion of Montage since that wouldn't really clarify the Genos situation. I didn't give chapter and verse about why sharing isn't possible with the Genos memory technology. Also, suffice it so say, the memory organization is different in Tyros and Motif products with dual tone generation chips. Montage and Genos are a genuine break from Yamaha's past engineering practice.
All the best -- pj
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