The output voltage to a given channel will track the energy level of
the voltage that's putting it there, if that makes any sense.
Let's go back to the model of a static five volt level as your control
voltage being panned. - let's say it's coming from a sequencer
that's motionless (not currently moving) and the active stage is
dialed at five volts. So the amplitude of that control voltage is a
constant, unchanging 5 volts. Keyword being amplitude.
And for the sake of this example, let's say it's a stereo panner
we're talking about and that the pan is full left. This would create
a situation in which the voltage coming out of the left side was 5
volts, and there would be ground out the right channel.
If we were to gradually shift the pan to full right, what would
happen? Somewhere 'right' of center panning, the 5 volt level at
the left channel would decrease until it faded to ground. By
doing this, you are changing the control voltage coming out of the
left channel because the amplitude of the 5 volt level is what's
dropping.
If we now used a slow triangle wave to pan from full left to full
right. So in this model, the pan modulator is a tri LFO. As the
voltage levels at each channel fade in and out with that LFO, the
outputs at each would fade with it. So in effect, they would slew
up to 5 volts and then back down to ground. That's the point I
was getting to and I'm realizing using the word slew was
misleading.
But in effect when panning static voltages, your channel output
BECOMES a half wave rectified equivilent of the modulator and
the static level you're panning only serves as it's maximum level,
a limiter so to speak. If the tri LFO was +/- 4 volts in amplitude,
what you'd get out the left channel would be a 0 to 5 volt replica
that tracked the modulator only when it rose about ground -
halfwave rectified. During the period when the triangle wave was
in it's negative cycle, you'd have ground out of the left.
With audio signals, it's amplitude effects volume. The greater
the amplitude, the more energy sent to the speakers, the more
air pressure fluctuation through the air which our mind hears as
it getting louder. With control voltages, changes of amplitude
also effect it's level, but depending on what that CV is controlling
it may have a lot of effect on the patch. If that channel output was
connected to the FREQ VC input of a VCO, as the level dropped
so would the frequency of the VCO.
Again, that may be what people would expect and *want* from a
CV panner, but it has a decidingly different psychoacoustic effect
than panning an audio signal.
- P
--- In PLAN_B_analog_blog@yahoogroups.com, "selfoscillate"
<synaptic_music@y...> wrote:
>
>
> so does that mean, that the 5 volts will drop
> to ground and then back to the new value, whenever
> the panning parameter is changed?
> i never discovered that on the a132.
> i guess i misunderstand something.
>
> the more i think about technical issues, the more i see
> that i don't understand what's going on electrically ;-)
>
> best wishes
>
> ingo
>
>
>
>
> --- In PLAN_B_analog_blog@yahoogroups.com, Peter
Grenader
> <peter@b...> wrote:
> > When VCAs gate the control voltage, if for instance the control
> voltage is
> > static - let's say a steady 5 volts, the attenuation effects that
> static
> > level by rising up as the CV fades into one of the output
channels
> and then
> > tapering down as it decays to another output channel. To
each of
> the output
> > channels of the panner, it would effectively be like turning a
> voltage pot
> > from ground up to 5 volts then back down again to ground,
so it
> that regard
> > it acts like a slew.
> >
> > If the pan is immediate - if it jumps instantly from one output
to
> another
> > then this slew is minimized - the net effect is like an analog
> switch. A
> > clean break if you will. But as the movement from one
channel to
> another is
> > gradual, the slewing effect will be noticeable. This may not
be a
> bad thing
> > mind you, but it is an unavoidable attribute of gating control
> voltages.
> >
> > - P
> >
> >
> >
> > selfoscillate wrote:
> >
> > >
> > >
> > >
> > > hello peter,
> > >
> > > hmm i really don't know. actually i use linear vca's
> > > like the a132 or blacet dual vca for panning of control
> > > voltages and that seems to work fine. these can process
> > > both audio and cv without problems. can you please
explain
> > > the difference between your panning vca and devices like
> > > a132 and the blacet dual vca? sorry if this is a dumb
question ;-)
> > >
> > > best wishes
> > >
> > > ingo
> > >
> > >
> > >
> > >
> > > --- In PLAN_B_analog_blog@yahoogroups.com, "(i think
you can
> figure
> > > that out)" <peter@b...> wrote:
> > >>
> > >> Well, it could, but there is a problem with this idea one
must
> > >> consider:
> > >>
> > >> In order to pan audio, to avoid clicks and dead spots one
needs
> > >> the transistion to be gradual, even if ever-so-slightly. This
is
> > > fine
> > >> for an audio signal. For a control voltge however, this
> > >> dramatically changes the control voltage being panned,
much
> > >> like the effect when one gates a DC thorugh a lowpass
gate - the
> > >> vactrol makes for a really nice ring of the audio due to the
fact
> > >> those devices close down slowly - with a CV however you
get the
> > >> very same effect as running the CV through a slew.
> > >>
> > >> Any thoughts on this?
> > >>
> > >> - P
> > >>
> > >>
> > >>
> > >>
> > >> --- In PLAN_B_analog_blog@yahoogroups.com,
"selfoscillate"
> > >> <synaptic_music@y...> wrote:
> > >>>
> > >>>
> > >>> hello peter,
> > >>>
> > >>> i'd love that vc quad panner too, but it should be
> > >>> able to handle dc voltages and not only audio.
> > >>>
> > >>> best wishes
> > >>>
> > >>> ingo
> > >>>
> > >>> p.s. nice idea to start a dedicated plan b group :-)
> > >>>
> > >>>
> > >>>
> > >>> --- In PLAN_B_analog_blog@yahoogroups.com, "(i think
you
> > >> can figure
> > >>> that out)" <peter@b...> wrote:
> > >>>>
> > >>>> VC Quad panner as a stand alone sounds like a great
idea,
> > >>>> actually. Let me give that some serious thought.
Again, if
> > >>>> enough people say 'yeah', it's a win win for everybody.
> > >>>>
> > >>>> Thanks for this (good) idea.
> > >>>>
> > >>>> - P
> > >>>>
> > >>>> --- In PLAN_B_analog_blog@yahoogroups.com,
Robert
> > >>>> Hoffman <robmix@e...> wrote:
> > >>>>> Maybe there's two separate modules, the Balanced
Stereo
> > >>>> Output, which
> > >>>>> I'm all for - sign me up, and a VC Quad panner.
> > >>>>>
> > >>>>> Rob
> > >>>>>
> > >>>>>
> > >>>>>
> > >>>>> On Monday, October 4, 2004, at 01:17 PM, Johan
Boberg
> > >> wrote:
> > >>>>>
> > >>>>>> About the proposed Balanced Stereo Output
Processor,
> > >>>>>> it looks really useful, i would really like to have one.
> > >>>>>>
> > >>>>>> But i would really love to have it somehow patchable
as a
> > >>>>>> Quad Output Processor if possible. It could still be
used
> > >>>>>> as a stereo out if this is preferred. I don't know
exactly
> > >>>>>> what it would take to convert your design into this
without
> > >>>>>> changing it too much though...
> > >>>>>>
> > >>>>>> /Johan
> > >>>>>>
> > >>>>
> > >>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > >>>> ~~~~~~~~~~
> > >>>>>> Johan Boberg
> > >>>> http://www.eam.se
> > >>>>>>
> > >>>>>>
> > >>>>>>
> > >>>>> <image.tiff>
> > >>>>>>
> > >>>>>>
> > >>>>> <image.tiff>
> > >>>>>>
> > >>>>>> Yahoo! Groups Links
> > >>>>>>
> > >>>>>> To visit your group on the web, go to:
> > >>>>>>
http://groups.yahoo.com/group/PLAN_B_analog_blog/
> > >>>>>>
> > >>>>>> To unsubscribe from this group, send an email to:
> > >>>>>>
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> > >>>>>>
> > >>>>>> Your use of Yahoo! Groups is subject to the Yahoo!
> > >>> Terms
> > >>>> of Service.
> > >>>>>>
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >
> > >
> > >