Overview
MU10 Synth Architecture
XG: The new generation after SY/TG era
YAMAHA was a late comer to PCM synthesis, as they had proudly stuck to their FM synthesis.
(See DX7 and SY99 page).
SY and TG series are the first YAMAHA PCM-related synths, which first came out in 1989.
(See TG33, TG55 ,
SY99 and TG100 page).
Some of them had ground-breaking synthesis abilities beyond a mere rompler,
but as they were their early attempts,
some features, especially modulation controls, were implemented incompletely.
All YAMAHA PCM synths have come to adopt XG standard since 1994.
That was the beginning of YAMAHA's new PCM Rompler era after SY/TG.
SY's weaknesses (realtime control, etc.) are fixed in XG,
though their interesting synthetic features are gone.
The synthesis architecture
MU10 (and most XG modules) is made of the familiar combination of PCM oscillator, filter, amplifier, LFO and effects -
it's a simple Rompler.
One big advancement from SY is that its filer LFO and filter envelope can be used at the same time.
MU10 can layer up to 2 oscillators in a Voice.
QS300 uses the same synthesis engine, but can layer up to 4 oscillators.
MU10 and compatibles has over 200 PCM waves in 4MB ROM.
MU10 and SW60XG can be used as a multi-effector thanks to the A/D input.
QS300 were much more expensive than MU10, though they are almost the same synth.
I don't know if difference in audio quality is involved.
Please tell me if you have any information.
The filter
Most low-end sound modules use 2-pole, -12db/oct filter, and I have believed that MU10 also uses 2-pole.
But YAMAHA says:
DB50XG (MU10 compatible) "has a full 24db per octave 4 pole fully resonant set of filters...."
As far as I know, a "fully resonant" 4-pole filter can (nearly or fully) oscillate by itself.
MU10's Filter does not sound like other 4-pole Filters that I know, and sounds much more like 2-pole.
MU10's resonance at max. (28KB)
Roland Super JX's 4-pole filter (204KB)
YAMAHA TG55's 4-pole Filter Self-Oscillation (504KB)
Roland SoundCanvas' 2-pole filter (300KB)
Next 
XG editable
Deep Synthesis: Home
8. 18. 2003