Here are my thoughts, but I stand to be corrected:

> look much like sine waves at all. Is there a user advantage or is

this

> just a trade-off design for cutting costs (i.e. lame diode tri-to-

sine

> converters)

It really amounts to a 'practical necessity' to what is a hard
problem...

> Sadly from the scope shots, I noticed even the 111-2 still

maintains

> these low-quality sine waves. What am I missing

...which is that to design analogue circuitry to produce a high-
purity sine wave voltage-controlled oscillator which will track over
many octaves is a very demanding requirement (and which is perhaps
what you are 'missing' ). Producing a fixed-frequency sine wave
oscillator is hard enough, as the gain needs to be 'just right' to
limit the amplitude, and normally some non-linearity (i.e. make the
gain 'drop off' at some point) is needed to stop the wave getting too
big, and this will inevitably introduce some distortion. Then making
the frequency voltage-variable just adds more difficulty, especially
if it is required to have the frequencies track in musically
acceptable way.

Thus most designs opt for simplicity, using a triangle wave passed
through some sine-shaping mechanism, and just accept that the
output 'sine wave' may not be very 'true'. In the case of the A-110,
the output is further 'muddied' in that the tri wave is generated
from the sawtooth oscillator core, by 'flipping' one half of the saw
(hence the little glitch you may have noticed in the tri and sine
waveshapes, especially at higher frequencies).

The CEM3340 chip at the heart of the A-111 *is* a triangle-core type
oscillator, but the sine-shaping is done by circuitry external to the
chip. I don't know whether the A-111-2 is a discrete design, or based
on same chip, but the problems will be the same.

If you want high-purity sine waves for additive or FM synthesis, then
doing it analogue is probably not a good way to go - this is
something that is far better suited to being done digitally, where
controlling purity and things like the exact ratios of frequencies is
more easily done!

(Just my thoughts, and like I said at the start, I stand to be
corrected by more knowledgeable sources!)

Tim