Doepfer

hi andreas,
there is an old poll...it was a module proposed by
florian a long time ago...
bakis.


--- Andreas Lindholm <andreas.k.lindholm@telia.com>
wrote:
> That sounds interesting to me although I don't
> completey grasap it, but the
> wobbling and inaccuracy in this case could be more
> advatageous as an effect
> than a pure VCO it seems to me... when did this
> module come up on the
> agenda? I didn't even know it was something Doepfer
> had in mind....
> 
> 
> ----- Original Message ----- 
> From: "Bakis Sirros" <synth_freak_2000@yahoo.com>
> To: "Doepfer_a100 group"
> <doepfer_a100@yahoogroups.com>
> Sent: Thursday, June 26, 2003 6:06 PM
> Subject: [Doepfer_a100] a brief explanation about
> the uses of a PLL
> VCO.(from doepfer.)
> 
> 
> > dieter says:
> > "a PLL and it's application is not very easy to
> > understand. I will try to write an explanation and
> > publish it on our web site as soon as we publish
> the
> > preliminary page for the PLL module (no A-100
> number
> > so far).
> > Here is a simplified explanation: A PLL is a
> linear
> > rectangle VCO with a frequency comparator that
> > compares the frequency of the internal PLL-VCO
> with an
> > external frequency (master frequency) - e.g. the
> > rectangle output of  "normal" A-100 VCO - and
> makes
> > the the internal VCO frequency equal to the
> external
> > frequency. Or better said: it tries to adjust the
> > internal frequency so that it becomes equal to the
> > external frequency. The problem is the frequency
> > comparator - even called phase comparator - that
> > generates a kind of a correction voltage that
> becomes
> > zero if both frequencies are identical. Different
> > versions with different advantages/disadvantages
> of
> > frequency comparators are available. Some types of
> > comparators e.g. will "lock" even at multiples of
> the
> > frequencies. Another problem is the time that is
> > necessary until the PLL-VCO is adjusted. It will
> > always take some time until the new frequency of
> the
> > PLL-VCO is reached (similar to portamento). The
> time
> > constant of the internal low pass filter (not an
> audio
> > low pass but a low pass/slew limiter for the
> > correction CV) defines the time until the new
> > frequency is reached. But this time has not to be
> too
> > short otherwise the frequency of the PLL-VCO will
> > "wobble" around the master frequency. These
> > "disadvantages" lead to additional musical
> > applications like portamento effects or wobbling
> > frequencies according to the type of frequency
> > comparator and time constant of the PLL low pass
> > filter.
> > Another application is frequency multiplication in
> > combination with an external frequency divider.
> For
> > this the output of the PLL-VCO is processed
> through a
> > frequency divider (e.g. A-160, A-161, A-163)
> before it
> > is fed to the PLL frequency comparator. In this
> case
> > the frequency of the PLL-VCO will be a multiple of
> the
> > master frequency. E.g if the the A-163 is used and
> > adjusted to dividing factor 5 the frequency of the
> > PLL-VCO will be 5 times the frequency of the
> master
> > VCO. Consequently frequency division (A-163) leads
> to
> > frequency multiplication with the PLL circuit. In
> > combination with the PLL low pass frequency
> several
> > effects can be realized (frequency multiplication
> with
> > portamento or wobbling). The frequency
> multiplication
> > can even be used to drive a graphic VCO. If your
> > graphic VCO e.g. has 8 steps (e.g. A-155) and you
> use
> > a frequency divider with factor 8 in the PLL
> feedback
> > the output of the graphic VCO has the same
> frequency
> > as the master VCO. Another application is the
> > generation of pseudo-harmonics (not real harmonics
> as
> > only rectangle waves are available).
> >
> > I hope this explanation will help and not cause
> more
> > confusion. I know that the PLL is not very easy to
> > understand.
> > Best wishes
> > Dieter Doepfer"
> >
> >
> >
> > INTERESTING???????OF COURSE,YES!
> > bakis.
> >
> >
> >
> >
> > =====
> > synthfreak(parallel worlds)
> > athens-greece
> > [Doepfer_a100] group owner
> >
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> >
> >
> 
> 
> 


=====
synthfreak(parallel worlds)
athens-greece
[Doepfer_a100] group owner

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