PLAN B analog blog

hello peter,

ok, now i got it. sometimes it is not that easy for me to
understand tech talk in english :-)
but after all it is just a very basic thing.
the cv behaviour you are describing is exactly what i thought
would happen when mixing/panning cv's. i'm doing this
sort of cv mixing/panning often, of course not for
feeding pitch cv's into volt/oct inputs of vco's,
but for lots of other purposes, like processing of
envelopes, sending them to filters, phasers and so on.

for me it would be a killer feature to be able to mix/pan
cv voltages. if you could implement such a functionality,
that would be absolutely great. needless to say that i'll buy
that module right away, if it could mix cv's.
i always found it a bit sad that there is no voltage controlled
mixer out there which can process dc voltages, so you can close
a real gap here.

best wishes

ingo





--- In PLAN_B_analog_blog@yahoogroups.com, "(i think you can figure 
that out)" <peter@b...> wrote:
> 
> 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>
> > > >>>>>> 
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> > > >>>>>> 
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> > > > 
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> > > > 
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> > > >