The pitch drift manifests itself when the octave buffer shifts - for example, if playing a high note causes the DC octave buffer to shift from 2 and end at 4 volts, the held down bass note will drift. If the octave buffer goes from 4 and end at 2 volts, the bass note goes back to where it started. Also, if you play all 8 keys at exactly the same time, the machine has a tendency to "sag" where every note seems to drop in pitch. I still don't have the time to address this fully or post audio, sorry.
-Mike
--- In yamahacs80@yahoogroups.com, "faxiomas@..." <faxiomas@...> wrote:
>
> Hi Mike
>
> Thx for replying; actually I can have two references, one is
> Fernando's machine, the other is a 60: to be honest I didn't realise
> such a flaw until you mentioned it, I did really thought it was due to
> poor tuning in the first place, so I'd like to go deeper into it; btw,
> does the pitch drift randomly go from voice to voice (e.g., play low
> then high note, does the pitch drift to high?) or does it follow
> anything near to a logic like on the glissando?
> Also, could the bug
> originate from the idle/busy state in the KAS' FIFO shift register? As
> it is a fake poly assigner could the KAS get wrong messages perhaps?
> Let me know, I can't wait for further infos!
> :-)
>
> M
> ----Messaggio
> originale----
> Da: mborish_2000@...
> Data: 25-lug-2011 7.49 AM
> A:
> <yamahacs80@yahoogroups.com>
> Ogg: [yamahacs80] Re: KAS bug examples
>
> I'm planning on putting all of the troubleshooting results on my own
> website in the near future because I need full HTML to reference
> pictures, audio, and maybe some math. I need a better scope to catch
> everything related to the bugs on my CS-80 even though I already know
> temporary solutions for both of them. I can't really justify or afford
> an amazing deep memory scope until at least sometime next month and I
> still might not do it because, well, it's gonna cost at least a few
> thousand US $.
>
> The two bugs that I'm going to take a crack at when I
> make some posts on my website are the SH pitch drop or raise in Sustain
> I bug and the Volt/Oct Scaling bug. The SH pitch drop or raise slowly
> changes the pitch of your release tails when you have the sustain set
> high. The Volt/Oct Scaling bug doesn't quite scale the YM26700
> properly when pin 12 spits out the octave data...I think; this is what
> I need better test equipment for. Like I said in the previous post,
> when you hold down one key and then play another in a different octave,
> you can hear the held down key jump a few hertz.
>
> I'm assuming that you
> and Fernando have run into the same octave scaling problem? If so,
> please describe your problems as well as your theory related to the
> problem. A temporary fix is to slow down the Master Clock by replacing
> the 100pf cap in the oscillator loop with a 180pf cap. I'm not going
> say why I think it works yet because all I have is a theory without the
> proper test equipment. This will slow your clock down to about 70K and
> also clears up about half of the double triggering. Yes, it slows down
> the key trigger time slightly which seems like a bad idea at first,
> but, honestly, my whole machine feels more stable and most of the
> double triggering is gone.
>
> My machine is now tolerable but not quite
> right after the clock mod. The held down bass key went from about a 4
> hertz drift on octave changes in a higher register to about 3/4 hertz
> drift.
>
> Sorry, but I've been busy and haven't had the time to mess
> with my CS-80 or get further with these issues.
>
> -Mike
>
> --- In
> yamahacs80@yahoogroups.com, "Max Fazio" <faxiomas@> wrote:
> >
> > Hi
> again
> > This is for Mike: have you managed to record any example of the
> supposed KAS' bug?
> > Let me know!
> > M
> >
> > [Non-text portions of this
> message have been removed]
> >
>