It might not work very well if the ADC is not very linear. In which
case the portamento would "wobble" through the octaves.
The other thing I will have to test is changing the TG note frequency
from one octave to the next while still operating all EG's and other
parameters without interruption.
In other words, will it be possible to tell the TG to change a note
frequency at any moment and not get any glitches in the frequency
output for that particular note TG.
If the ADC is linear enough and the TG can be switched at any time
then I think it would be very possible to do portamento without any
new circuitry.
Mike.
--- In korgpolyex@yahoogroups.com, "jure zitnik" <kokoon@...> wrote:
>
> i think your original idea with the pitchbend might just work - why
wouldn't
> it? is the midi pitchbend implemented in analogue
> (midi->DAC->joystick->ADC->master OSC) or completely digital?
>
> kokoon
>
> On 4/12/07, korgpolyex800 <korgpolyex800@...> wrote:
> >
> > Hi Kokoon,
> >
> > I miss my SH-101 for just that reason.
> >
> > I spent some time thinking about how to do, as you so appropriately
> > put it, "decent portamento". At one point I was looking at using the
> > existing master DCO bend circuit to create the portamento but I fear
> > that might not give us a "decent" portamento and I just know it's
> > going take a lot of programming time to make it work. Another way to
> > do portamento would be to build a brand new master DCO that was able
> > to sweep across the entire 88 note keyboard (did I mention that I'm
> > going to provide full 88 key range as an selectable parameter?). But
> > such a master DCO will require even more circuitry so it will
> > definitely have to go into the full retrofit kit. I may try to use the
> > bend circuit first and see what sort of results I get, if they are
> > "decent" then perhaps we can avoid adding more hardware.
> >
> > Isn't this fun!
> >
> > Mike.
> >
> > --- In korgpolyex@yahoogroups.com <korgpolyex%40yahoogroups.com>,
"jure
> > zitnik" <kokoon@> wrote:
> > >
> > > all i'm interested in is a decent mono mode with portamento :)
> > >
> > > cheers,
> > > kokoon
> > >
> > > On 4/12/07, korgpolyex800 <korgpolyex800@> wrote:
> > > >
> > > > Hi all,
> > > >
> > > > Well, if there's one thing I've learned it's that you should
never use
> > > > polls to make decisions because you can be sure that poll
questions
> > > > were written and scripted by an idiot.
> > > >
> > > > OK, down to business.
> > > >
> > > > After looking at the poll results and seeing some of the
responses I
> > > > was prompted to rethink the goals of the project. Taking into
> > > > consideration all of the work I've done so far and the
progress made
> > > > it would be possible to take all of the new sysex functions
(and more)
> > > > and put them into ROM space if we could add just one additional 8K
> > > > ROM. The challenge is to add that ROM without requiring major
surgery
> > > > on the hardware. Well it turns out that a small board that
would use
> > > > two 8K ROM's and one XOR logic gate chip could be made that
would map
> > > > the second ROM into the same address space as the existing
RAM. The
> > > > second ROM would be disabled for the low 2K of address space
where the
> > > > 2K RAM exists. This would mean that we would end up with 14K
or ROM
> > > > instead of the existing 8K. The only problem with this concept
is that
> > > > we don't get any additional RAM at all. This would mean that
any new
> > > > sysex commands would have to be wedged into the existing RAM
in such
> > > > as way as to not stomp all over the existing programming. I'll
have to
> > > > do some testing to see what scratch RAM is available in that
little 2K
> > > > RAM chip.
> > > >
> > > > Then, there is the big retrofit project. This will give us so much
> > > > additional RAM, ROM and other hardware that we'll be able to
transform
> > > > the Poly 800 and EX800 into something much more than we could ever
> > > > have imagined. It requires removing one IC and adding a much
larger
> > > > plug in board. It will include two flash EEPROM's which means
we'll be
> > > > able to download new code as it becomes available. And it will
have
> > > > many new performance parameters and operational capabilities.
> > > >
> > > > I think perhaps I should go for the easier retrofit kit first
and go
> > > > from there.
> > > >
> > > > Mike.
> > > >
> > > >
> > > >
> > >
> >
> >
> >
>