The Cyndustries List

Mark,

I'll have to disagree here, as I corraborated with more precise measurements
what Richard Brewster had provided and heard.

Here's an experiment almost any ZO owner can do.  Tune your ZO and your
master oscillator MOTM-300 or whatever to exactly 240 Hz.  Apply an envelope
to the index FM and the master oscillator sine wave to the Dynamic 2 FM
input.  Put the Index knob at around 7.  With this middle of the range
setting, I hear harse beating just one octave above the 240 Hz root note.
This beating is caused by mistracking of the ZO.  It gets worse with higher
frequencies and is downright clangorous.  That is hardly 6 great octaves, it
is not even 1.  To clarify, ZO Range is Medium, Bias is High, and Tuning
knob is almost centered within the 10 turn range, as recommended per the
manual for best pitch accuracy.

Which voltage source were used for your measurements?  Which frequency
counter was used?  The use of ratios is potentially misleading.  If you are
just showing ratios between each succeeding octave, as implied by the 2:1
ratio, then the errors are cumulative as one goes up the scale.

John Loffink
The Microtonal Synthesis Web Site
http://www.microtonal-synthesis.com
The Wavemakers Synthesizer Web Site
http://www.wavemakers-synth.com


> -----Original Message-----
> From: The_Cyndustries_List@yahoogroups.com
> 
> I should have been clearer.  I used the middle setting for Range, which
> must
> be your MEDIUM.  I did not use the LFO range.
> 
> John Loffink
> 
> > -----Original Message-----
> > From: The_Cyndustries_List@yahoogroups.com
> > [mailto:The_Cyndustries_List@yahoogroups.com] On Behalf Of tuninghead
> >
> > Hi there John and other trackers,
> >
> > John L., we repeated your measurements, but this time we used the
> > appropriate range setting for low audio which is the MEDIUM range
> > setting.  You are stretching the LFO range into boy's choir territory.
> >  For the same frequency range you used, we measured our octave ratios
> at:
> >
> > volts   ratio
> > -1
> > 0     2.009
> > 1     2.003
> > 2     2.007
> > 3     1.996
> > 4     1.999
> > 5     1.989
> > 6     1.981
> >
> > This shows 6 great octaves and a usable 7th.  Now, why aren't there 10
> > good octaves?
> >
> > The topology of the Zeroscillator core is unlike any conventional VCO
> > sawtooth or triangle core.  The current that runs the core is the
> > result of arithmetic computations that are all performed in analog --
> > most critically, a multiplication.  This multiplication (which I have
> > covered in a previous post) does not exist in conventional VCOs and
> > because of its very prescence, is a small source of error.  The
> > multiplier used for this task is the finest one available in the free
> > world, period.  Additionally, issues of dynamic range loom large in
> > the design trade-offs that must be made to bring you the absolutely
> > outrageous amount of modulation this oscillator offers.  Techniques to
> > maximize accuracy are covered in the Zeroscillator manual.
> >
> > We have 15V of power supply to work with (Euro versions have 12V).
> > Everything has to happen within that space.  Improved accuracy can
> > always be traded for modulation range.  The HIGH BIAS position
> > provides 1V of bias and the LOW BIAS position provides about 0.2, if
> > I'm remembering correctly.  This means in HIGH BIAS we can attain
> > about 1000% modulation before the multiplier will be taxed for
> > accuracy (at about 10V).  In LOW BIAS we get about 5000%.  Considering
> > that 100% is the most you can ever get from a conventional VCO (and
> > most designs restrict the range to far below that), this is pretty
> > darn exciting.  The BIAS switch is not there to change frequency
> > range.  It's there because of accuracy tradeoffs.   To get improved
> > accuracy you could pump 5V into the LINEAR FM input to give the
> > multiplier more to work with.  The accuracy will get better at the
> > expense of the modulation range being reduced to about 200% which may
> > still be enough for the sound you are looking for.
> >
> > To answer another question, yes, a precision voltage reference is used
> > for all critical internal voltages.  The power supply rejection was
> > tested and found to be superior to the Modcan oscillator.  John Ross
> > is responsible for adding to the design, the most comprehensive power
> > supply cleansing I have ever seen on an EM module.  We could have just
> > regulated down to +/-12V, but that too would have cost us range.
> >
> > There have been other attempts at thru-zero, analog VCOs in the past.
> >  None of them turned into products because although they did the FM
> > thing, none of them tracked well enough to be accepted.  I found the
> > ZO's tracking to be quite adequate to make any sound I desired along
> > with a Modcan VCO as a modulator.  Personally, as a user, I have no
> > complaints with the ZO's performance, and as an engineer, I have held
> > nothing back about the ZO's operation and design tradeoffs.  We are
> > doing something in analog that has been traditionally believed to be
> > the sole property of digital and I believe we have pulled it off well.
> >
> > In choosing an oscillator, one always compares features and specs, but
> > comparing the ZO to a traditional oscillator is like comparing apples
> > and oranges.  They're both fruits, but if you need citrus, an apple
> > isn't going to cut it.  You can be about the measuring or about the
> > music.  The Zeroscillator offers sounds that are unobtainable from any
> > other commercially available analog module in the solar system.  It's
> > up to each individual musician to decide what is important.  The units
> > are flying off the shelves and the feedback we are getting from users
> > ranges from sheer delight to ecstatic euphoria.
> >
> > --Mark Barton
> >