Korg Poly800/EX800 Users

On 4/5/06, Atom Smasher <atom@...> wrote:
>
>  On Wed, 5 Apr 2006, jure zitnik wrote:
>
>  > hello, i'd just like to ask how much difference would it make if i used
>  > 47k pots instead of 50k ones? 50k pots are quite difficult to get here.
>  > maybe if i wire a resistor in serial?
>  ===============
>
>  47K pots should be fine.
>
>
>  --
>           ...atom
>
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>
>
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> then i was trying to make DCO->VCF modulation but i found out that the
> DCO outputs are offset by +5VDC or so... i kinda figured that out
> without an oscilloscope - just with a multimeter and
> wires->mixer->soundcard and trial and error. is that true? what's the
> easiest way to drop that signal down 5VDC? i think it can make quite a
> nice mod.

On 4/6/06, austeritygirlone <ziggystar@...> wrote:
>  I don't own an oscilloscope myself. But if the DCO outputs are offset
>  by +5V, thus oscillating around +5V you can make a symmetrical signal,
>  thus one that oscillates around +0V, simply by running it serially
>  through a capacitor, removing the very low frequencies. Select it
>  large enough to let all desired frequencies pass nicely. Then you
>  could control the voltage range by a potentiometer. This would most
>  probably be a nice mod. I'm not looking at the schematics, but since
>  you now have two drivers for one input (VCF-Cutoff), you should
>  connect them through a resistor or something, so that you don't create
>  any short circuit.
>
>  I'm new to this stuff, so please correct me if something is wrong. :)
>
>
>  > then i was trying to make DCO->VCF modulation but i found out that the
>  > DCO outputs are offset by +5VDC or so... i kinda figured that out
>  > without an oscilloscope - just with a multimeter and
>  > wires->mixer->soundcard and trial and error. is that true? what's the
>  > easiest way to drop that signal down 5VDC? i think it can make quite a
>  > nice mod.
>
>
>
>
>
>
>  ________________________________
>  YAHOO! GROUPS LINKS
>
>
>  Visit your group "korgpolyex" on the web.
>
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>

> hehe i'm even more new to this stuff and i really don't understand how
> running AC signal through a cap eliminates the DC offset... shouldn't
> that eliminate the high frequencies (and thus the oscillation)?
> 
> jure

On 4/6/06, austeritygirlone <ziggystar@...> wrote:
>  A cap can be considered as a frequency dependant resistor. High freqs
>  can pass and low freqs can't.
>
>  Have a look at this picture:
>
>  http://www.elecdesign.com/Files/29/1478/Figure_01.gif
>
>  The +5V offset can be considered a very, very low frequency (f->0).
>
>  On the other hand you can construct a lp filter, by "shortening" the
>  high frequencies through a cap. Then you have to take the signal from
>  before the cap, because the low frequencies stay there.
>
>
>  > hehe i'm even more new to this stuff and i really don't understand how
>  > running AC signal through a cap eliminates the DC offset... shouldn't
>  > that eliminate the high frequencies (and thus the oscillation)?
>  >
>  > jure
>
>
>
>
>
>
>
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>  Visit your group "korgpolyex" on the web.
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On 4/8/06, Atom Smasher <atom@...> wrote:
>
>  On Thu, 6 Apr 2006, jure zitnik wrote:
>
>  > yeah i did it yesterday and it's fine. the only thing i'll change is to
>  > replace the resonance pot with a linear one. the lower half of resonance
>  > range has practically zero effect and at ~3 o'clock it jumps straight
>  > into self-oscillation. anyone using a linear pot for resonance?
>  =================
>
>  try using different resonance settings in the DCF (parameter 42). you may
>  want to change some settings after the mod to find the range of the knob
>  that works best.
>
>
>
>  > i also did the filter 2/4pole switch and i LOVE the 12db/oct response! i
>  > like it TONS better than the original 24db/oct! i really recommend that
>  > to everyone.
>  ===================
>
>  does that sound more like an oberheim?
>
>
>  --
>
>           ...atom
>
>    ________________________
>    http://atom.smasher.org/
>    762A 3B98 A3C3 96C9 C6B7 582A B88D 52E4 D9F5 7808
>    -------------------------------------------------
>
>        "I recognize that a class of criminals and juvenile
>        delinquents has taken to calling themselves
>        'hackers', but I consider them irrelevant to the
>        true meaning of the word; just as the Mafia calls
>        themselves 'businessmen' but nobody pays that fact
>        any attention."
>              -- Robert Bickford
>
>
>
>
>
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