Wiardgroup

Does anybody know the differences, the pros, the cons of the two noise units:

Wiard noise ring versus Blacet improbability drive

- if you have the noise ring, can you do without the ID? Or does it have some sides which 
the noise ring doesn't cover?

Thanks very much,

Matthieu

Hi Matthieu
  i own a noiz ring (and a primitive ancestor to the noiz ring) and
i've built two I.D. kits for friends. Also i'm an RVG fetishist and
always tinkering with DIY RVG circuits. 
  While i realize that the I.D. and the N.R. are both considered
random voltage generators, under the hood, they are VERY different
devices. But let me ask a couple of basic questions before i spew a
bunch of information that may be of no interest to you at all...

Is the difference between analog white noise and digital noise
critical to your application? 

and...

do you already have a digital audio noise source?

The answer to those questions makes a difference in the comparison.

-doc 


--- In wiardgroup@yahoogroups.com, "matthieuvandiepen" <matthieu@...>
wrote:
>
> Does anybody know the differences, the pros, the cons of the two
noise units:
> 
> Wiard noise ring versus Blacet improbability drive
> 
> - if you have the noise ring, can you do without the ID? Or does it
have some sides which 

> the noise ring doesn't cover?
> 
> Thanks very much,
> 
> Matthieu
>

Hi Doc,

>   While i realize that the I.D. and the N.R. are both considered
> random voltage generators, under the hood, they are VERY different
> devices. But let me ask a couple of basic questions before i spew a
> bunch of information that may be of no interest to you at all...

Well i'm very interested to hear this bunch of information, so please go 
ahead!!!

> 
> Is the difference between analog white noise and digital noise
> critical to your application? 
> 
Actually difficult to say, but i understand that both the NR and the ID are 
generating analog white noise, but why could it be critical to an application?, 
i'm very interested to learn more about the possibilities of noise

> and...
> 
> do you already have a digital audio noise source?

Yes i have one, i have a Hewlett PackerD HOI-3722A Noise generator. Which 
is a scientific unit. I think it's digital. But it can make a lots of (different) noise...

> 
> The answer to those questions makes a difference in the comparison.
> 
> -doc 

Well i'm very interested to hear more about this subject,

Thanks Matthieu

> 
> 
> --- In wiardgroup@yahoogroups.com, "matthieuvandiepen" <matthieu@>
> wrote:
> >
> > Does anybody know the differences, the pros, the cons of the two
> noise units:
> > 
> > Wiard noise ring versus Blacet improbability drive
> > 
> > - if you have the noise ring, can you do without the ID? Or does it
> have some sides which 
> > the noise ring doesn't cover?
> > 
> > Thanks very much,
> > 
> > Matthieu
> >
>

After Doc responds, I will add something as well....

gary



"matthieuvandiepen" <matthieu@...> wrote:
>
> Hi Doc,
> 
> >   While i realize that the I.D. and the N.R. are both considered
> > random voltage generators, under the hood, they are VERY different
> > devices. But let me ask a couple of basic questions before i spew a
> > bunch of information that may be of no interest to you at all...
> 
> Well i'm very interested to hear this bunch of information, so
please go 
> ahead!!!
> 
> > 
> > Is the difference between analog white noise and digital noise
> > critical to your application? 
> > 
> Actually difficult to say, but i understand that both the NR and the
ID are 
> generating analog white noise, but why could it be critical to an
application?, 
> i'm very interested to learn more about the possibilities of noise
> 
> > and...
> > 
> > do you already have a digital audio noise source?
> 
> Yes i have one, i have a Hewlett PackerD HOI-3722A Noise generator.
Which 
> is a scientific unit. I think it's digital. But it can make a lots
of (different) noise...

> 
> > 
> > The answer to those questions makes a difference in the comparison.
> > 
> > -doc 
> 
> Well i'm very interested to hear more about this subject,
> 
> Thanks Matthieu
> 
> 
> 
> > 
> > 
> > --- In wiardgroup@yahoogroups.com, "matthieuvandiepen" <matthieu@>
> > wrote:
> > >
> > > Does anybody know the differences, the pros, the cons of the two
> > noise units:
> > > 
> > > Wiard noise ring versus Blacet improbability drive
> > > 
> > > - if you have the noise ring, can you do without the ID? Or does it
> > have some sides which 
> > > the noise ring doesn't cover?
> > > 
> > > Thanks very much,
> > > 
> > > Matthieu
> > >
> >
>

Hi Mathieu 
   In order to avoid re-inventing the wheel, please read the circuit
desciption Grant posted at:

http://www.wiard.com/1200/NR/Noise_Ring.html

i will be referring to the block diagram he posted.

but first....
regarding digital noise:
 If we force a feature-by-feature comparison of the I.D.  and the N.R,
 the one feature that the N.R. lacks is a 'conventional' digital noise
source. The main and aux outputs of the N.R. are both digital noise ,
to be sure, but they are both variable in spectrum and controlled by
the two CV vectors, "Change' & Chance'. This makes them a little
different from conventionally produced digital noise sources (such as
the now extinct MM5x37 chips).

In any case, your Hewlett Packard device is supplying plenty of
flavors of 'conventional'  digital noise and so you're covered there.

As for a comparison of the approaches...

The Blacet I.D. is a very full featured implementation of a tried and
true, time-honored method of random voltage generation in analog
modulars. To wit, a noise source (continuously variable between
digital or analog) is 'snapshotted' by a sample hold at a voltage
controlled sample rate and output as random steps. The pattern of
these steps vary in amplitude according to the spectrum of the input
noise and , in duration by the clock rate. Thus, the output steps are
derived dirctly from the noise sources, analog , digital or some mix
of both.

The Wiard N.R. uses analog noise at a basic source point in it's
algorithm, but never directly. This noise is never sampled by an
sample/hold circuit, in fact there are no sample/hold circuits in the
N.R and this is a fundamental distinction. 
(It will help to consult the N.R. block diagram, at this point)
You may already know how a shift register works but for anyone who
doesn't, i'm going to use the analogy of a conveyer belt with room for
8 people....
In the  N.R. , analog noise is used to tickle the threshold of a
comparator, the comparator flips on and off producing either 'someone'
or 'no one'. depending on the state of the comparator. This
person/non-person stands OFF the conveyer belt  waiting for a signal.
The signal comes from the clock. The clock is also a 2-state device.
We'll call them 'tick' and 'tock'. Remember that the clock is not
steady. It varies with a CV. This is important. When the clock is in a
'tock' state , nothing happens. The conveyer belt doesn't move and no
one steps on. The N.R.'s output is static. But when the clock switches
to "tick" the conveyer belt moves one step and if the comparator was
tickled to it's 'someone' state, someone steps aboard. If it was in
'no one' state the conveyer moves one step with an empty place.  On
the next tick the conveyer lurches forward and if anyone was in the
last (8th) position they get dumped off. Another thing happens at each
tick, the DAC takes a snapshot of the pattern of occupied and
unoccupied places on the conveyer, and based on that pattern it sends
a voltage to the output, a different voltage for every different
pattern, Thus as the two devices, comparator and clock, go on
flickering , the conveyer gets loaded with different patterns that
SHIFT on each tick. This cycling of patterns is the heart of the
N.R.'s method, and this is very close to the classic function of a
digital shift register. 
But there are some twists!  And one of the more brilliant twists that
Grant conceived is depicted in the block digram by the line marked
'old data' feeding the "solid state switch' . This is controlled by
the 'Change' control. As the 'Change' control vector decreases, the
chances INCREASE that the passenger who was just dumped off the end of
the conveyer will get another turn and move right back to the front of
the conveyer again and prevents any 'new' passengers (from the
flickering comparator) from boarding. The effect of this is a
'circular' buffer wherein the pattern repeats ad infinitum until 'new'
passengers are re-introduced by increasing the change control. At slow
clock rates this results in cycling patterns. At audio clock rates the
effect is a clearly discernible pitch. The wonderful thing about this
(IMHO) is that the change control vector is continuous and thus, at
audio frequencies, random audio (noise) will start to organize itself
into a pitched tone. The 'between states' are sublime (to my perverse
ear, anyway) and if you descend into chaos again , when you morph to
pitch the next time there's no guarantee that you'll get the same wave
as before.
Please forgive me for editorializing, but the resulting patterns are
exquisite!!! 
i'm sorry to confess my fetish, but that's just the very definition of
my personal idea of a good time! 
=)

To drag this screed back to the issue of comparison. The method of
pattern generation just described is very different than the
sample/hold method used by the I.D. (and MANY other RVG is modular
synth history). 
Most importantly, this method yields a very different character of
output patterns than a sample/hold-based design produces. The noise
sources are never sampled directly  and thus, the output SOUNDS
different from sample/hold-based output. 
i've foolishly engaged in past disputes about whether this is can be
called 'random' or not, and if it IS randow, how random is it???...
(see ***) That's a semantic issue and a waste of time.  The bottom
line is that the noise ring yields MUSICALLY interesting patterns (to
my ear) and that's what matters.  In all fairness, Sample/holds yield
interesting patterns too (i have 9 versions of them , at last count)
but the noise ring's output is distinct from all of them. The other
very important distinction is the effect of the ability to exercise a
very fine level of control over the 'chance' and 'change' parameters.
This is a unique and VERY powerful feature.

i'm sorry for the screed, and i hope you'll think carefully before
saying it's ok for me to disgorge 'a bunch of information' ever again!
Be careful what you wish for...
;'>

best wishes,
-doc

*** a true 'Random Generator' would output a series of unpredictable
voltages, turn into Katie Couric, sternly lecture Peter Grenader his
sock choices, turn into the erased sections the white house tapes, bob
for silver apples on the moons of Mercury, ride with Elvis in a
Lincoln to the color magenta, Win the civil war in overtime and rename
everyone to "pamela" , hide a bobble-head doll of Spiro Agnew in the
ghost of Elmer Fudd's sock drawer, eradicate the letter "J",  change
your sex to 'yes', play the B3 solo from "Roundabout' and then do
nothing for 43 trillion years while simultaneously  going back in time
and derailing the Big Bang before it starts...... i think even prof.
Richter would have a tough time with THAT design....maybe the
envelooper...one can always hope 











--- In wiardgroup@yahoogroups.com, "matthieuvandiepen" <matthieu@...>
wrote:
>
> Hi Doc,
> 
> >   While i realize that the I.D. and the N.R. are both considered
> > random voltage generators, under the hood, they are VERY different
> > devices. But let me ask a couple of basic questions before i spew a
> > bunch of information that may be of no interest to you at all...
> 
> Well i'm very interested to hear this bunch of information, so
please go 
> ahead!!!
> 
> > 
> > Is the difference between analog white noise and digital noise
> > critical to your application? 
> > 
> Actually difficult to say, but i understand that both the NR and the
ID are 
> generating analog white noise, but why could it be critical to an
application?, 
> i'm very interested to learn more about the possibilities of noise
> 
> > and...
> > 
> > do you already have a digital audio noise source?
> 
> Yes i have one, i have a Hewlett PackerD HOI-3722A Noise generator.
Which 
> is a scientific unit. I think it's digital. But it can make a lots
of (different) noise...

> 
> > 
> > The answer to those questions makes a difference in the comparison.
> > 
> > -doc 
> 
> Well i'm very interested to hear more about this subject,
> 
> Thanks Matthieu
> 
> 
> 
> > 
> > 
> > --- In wiardgroup@yahoogroups.com, "matthieuvandiepen" <matthieu@>
> > wrote:
> > >
> > > Does anybody know the differences, the pros, the cons of the two
> > noise units:
> > > 
> > > Wiard noise ring versus Blacet improbability drive
> > > 
> > > - if you have the noise ring, can you do without the ID? Or does it
> > have some sides which 
> > > the noise ring doesn't cover?
> > > 
> > > Thanks very much,
> > > 
> > > Matthieu
> > >
> >
>

"drmabuce" <drmabuce@...> wrote:
>
 The method of
> pattern generation just described is very different than the
> sample/hold method used by the I.D. (and MANY other RVG is modular
> synth history). 
> Most importantly, this method yields a very different character of
> output patterns than a sample/hold-based design produces. The noise
> sources are never sampled directly  and thus, the output SOUNDS
> different from sample/hold-based output. 

The Buchla "Sources of Uncertainty' is the seminal circuit that
employs a similar use of noise (as a modulator of the sampled source,
rather than the noise being the sampled source itself), and a
recursive structure that can create suprisingly musical patterns in
the name of UNCERTAINTY, which I think is a better term than RANDOMNESS.

I think that Uncertainty is the key to Grant's Woggle Bug and Noise
Ring.  Simple randomness is found on virtually every synthesizer -
Uncertainty is found on the Buchla and the Wiard.


gary

> 
> The Buchla "Sources of Uncertainty' is the seminal circuit that
> employs a similar use of noise (as a modulator of the sampled source,
> rather than the noise being the sampled source itself), and a
> recursive structure that can create suprisingly musical patterns in
> the name of UNCERTAINTY, which I think is a better term than RANDOMNESS.
> 

To be arcanely technical about it...

When I use the term entropy I mean Shannon's measure of information entropy, not 
thermodynamic entropy (which uses a similar equation, the reason Shannon used the term 
"entropy"). Information entropy is just a histogram of the number of levels in a matrix of 
information, expressed as the number of bits needed to store that number of levels. If 
there are only two levels, you only need 1 bit to store it. If there are 4 levels, you need 2 
bits to store the information and so on.

The original Buchla 266 presented control of the level entropy of the uncertainty source 
(from  1 to 6 bits). But there was no control over the frequency spectrum entropy (if you 
calculated the information entropy of the DFT). The Buchla 265 sample and hold presented 
control of the time spectrum entropy via the recursion control, but not the level entropy.

The Noise Ring provides both types of control, level entropy via the "Chance" control, and 
frequency spectrum entropy via the "Change" control.

I don't know if this is scientifically true, but it is believeable that the ear does both types of 
entropy measurements at a very fundimental level. The ear uses a kind of "battery" system 
to supply the ear, because blood flow would be too noisy. The ear uses "hairs" to sense 
both level and frequency information. IF an excited cell uses more "current" than a non-
excited one, then the way the ear is structured, the information entropy is proportional to 
the "current draw" for the two different "hair" structures. One for levels (amplifier cells) and 
one for time spectrum entropy (cochlial cells). Higher information entropy excites more 
cells, which draw more "current".

The above may be complete scientific hog-wash. But there must be some structure that 
does this or you could not hear the difference in the tones produced.

The proof is, we know it works, because it works!

Hi Grant

--- In wiardgroup@yahoogroups.com, "Grant Richter" <grichter@...> wrote:
> The ear uses a kind of "battery" system 
> to supply the ear, because blood flow would be too noisy. The ear
uses "hairs" to sense 
> both level and frequency information. IF an excited cell uses more
"current" than a non-
> excited one, then the way the ear is structured, the information
entropy is proportional to 
> the "current draw" for the two different "hair" structures. One for
levels (amplifier cells) and 
> one for time spectrum entropy (cochlial cells). Higher information
entropy excites more 
> cells, which draw more "current".
> 

as a lifelong sinus sufferer, my otolaryngologist is practically
family! And his description of the mechanics of audio perception
overlaps yours sufficiently to merit a 'close enough for a prototype'
rating, in my mind!
The point he always stresses is biology's affinity for
phase-discrimination in perception. That is, nature overwhelmingly
favors two sensor structures that differ in either vantage-point or
type and the neural structures they stimulate process the DIFFERENCE
between them to derive complex information. If you think about it,
this is very efficient in that the scheme includes a sort of automatic
baseline measurement thus eliminating the need for a wide calibration
pass before every perceived event to determine relative scale. 
He's even described to me how plants have been shown to use
phase-discriminated sensors to perceive their environment....sans neurons!
(we spend a lot of time together , my otolaryngologist and me.... we
have to talk about SOMETHING while he's peering up my schnozz)
;'>

-doc

drmabuce wrote:
> The point he always stresses is biology's affinity for
> phase-discrimination in perception. That is, nature overwhelmingly
> favors two sensor structures that differ in either vantage-point or type
> and the neural structures they stimulate process the DIFFERENCE between
> them to derive complex information. 

From an evolutionary standpoint, one key bit of complex information if
being able to tell whether a sound is coming towards us, or going away. 
As my favorite guitarist puts it, "remember that the human ear and brain
have amazing powers of phase discrimination. Those folks who didn't were
all eaten by bears 15,000 years ago".

cheers,
Paul
-- 
Amazing thing, the brain.  I wonder what became of mine?

This has been a great discussion!  Thanks everyone for all the details on 
these RVG modules (UVG?)

While I cannot technically dissect these units to the levels of the good 
doc and others, nor place them well within the pantheon of historical 
electronic music tools, I can offer up my personal take on these modules, 
based on my experience.

I have two Blacet Improbability Drives, as well as one Wiard Noise Ring. I 
will be buying a second Noise Ring this year without doubt.  It is 
probably the most interesting module that I own.

Other than the fact that they can both output 'noise' and 'randomish 
voltages', I find very little in common between these modules.

For me (hardly a modular synth master to be sure), I have found that the 
Blacet excels in some areas where the Wiard is weak and vise-versa as 
well. The Blacet module is exceptional for deriving 'typical' clocked 
Sample-And-Hold voltage outputs, moreso than the Noise Ring which is more 
difficult to use to obtain S&H output that is not either somewhat 
cyclical, or totally and utterly noisy (or in other words 'very 
uncertain').  Additionally, the Blacet is a better module if you are 
looking to synthesize the sound of wind, surf, rain, waves, blizzards, 
hurricanes., etc.  In fact I'd like to say that this module is absolutely 
AMAZING for work like this, and the ability to control every parameter 
with CVs allows for some shifting, morphing changes to your weather 
patterns!   Also of course when you need a burst of noise to add to the 
attack of a percussion sound, the Blacet unit has the edge.

As for the Noise Ring, it is very good at things the Blacet cannot touch. 
For one, if you would like randomish/uncertain events which are somewhat 
cyclical in nature, or slowly changing, this thing delivers the goods.  I 
believe that in the 'official' description, Grant mentions that in music 
we normally have events which slowly evolve over time, with a lot of 
repetition involved.  Well, this describes it well.  I use my Noise Ring 
to create 'uncertain' modulations that have a repetitive factor, perhaps 
that evolves slowly (or quickly!) or not at all.  One of the many great 
things about the NR is that it gives you complete control over how 
random/repetitive these things are.

Another great thing about the Noise Ring - processing external data 
thorugh the shift register!  I believe that you need the second revision 
NR to accomplish this, or you can perform a simple mod to the first 
generation NR to enable this.  For everything from serious distortion to 
completely breaking your sound apart, the ability to do this processing 
brings the NR into 'effect processor' territory, with the added bonus of 
being able to recycle the data your are putting through the shift register 
to create repetitive and evolving voltage loops, similar to the above 
paragraph, but based around whatever data you inject, not just the binary 
noise the standard NR will use for the shift register.

What else?  Someone mentioned the beauty found when the random events 
start to clock at audio rates and act like a 'tone wheel' - I cannot 
overstate how cool this is, one of my favorite things to do with this 
module.

Oh, and when your ears need a rest, the NR can still be used to create a 
pretty crazy light show!

Really, you need both in your system, in my opinion.  Probably two of 
each.


-MM

http://muffwiggler.blogspot.com






"Gary Chang" <gchang@calarts.edu> 
Sent by: wiardgroup@yahoogroups.com
29/01/2007 09:14 AM
Please respond to
wiardgroup@yahoogroups.com


To
wiardgroup@yahoogroups.com
cc

Subject
[wiardgroup] Re: Wiard noise ring versus Blacet improbability drive









"drmabuce" <drmabuce@...> wrote:
>
The method of
> pattern generation just described is very different than the
> sample/hold method used by the I.D. (and MANY other RVG is modular
> synth history). 
> Most importantly, this method yields a very different character of
> output patterns than a sample/hold-based design produces. The noise
> sources are never sampled directly and thus, the output SOUNDS
> different from sample/hold-based output. 

The Buchla "Sources of Uncertainty' is the seminal circuit that
employs a similar use of noise (as a modulator of the sampled source,
rather than the noise being the sampled source itself), and a
recursive structure that can create suprisingly musical patterns in
the name of UNCERTAINTY, which I think is a better term than RANDOMNESS.

I think that Uncertainty is the key to Grant's Woggle Bug and Noise
Ring. Simple randomness is found on virtually every synthesizer -
Uncertainty is found on the Buchla and the Wiard.

gary

 

This e-mail is confidential and may be privileged and/or proprietary.  If you are not the intended recipient, any review, disclosure, copying, or use of this e-mail is prohibited.

Thank you all very much for the response! Especially Doc,still i'm 
wondering one thing: both modules use analog and digital noise, why 
is that? What is the difference? And why both use these different 
noise sources for different applications?

Thanks Matthieu











--- In wiardgroup@yahoogroups.com, "matthieuvandiepen" 
<matthieu@...> wrote:
>
> Does anybody know the differences, the pros, the cons of the two 
noise units:
> 
> Wiard noise ring versus Blacet improbability drive
> 
> - if you have the noise ring, can you do without the ID? Or does 
it have some sides which 

> the noise ring doesn't cover?
> 
> Thanks very much,
> 
> Matthieu
>

Hi Mike

... a quibble to keep the record straight, based on your post, i
suspect that, like me, you have a REV 1 noise ring. As I understand
it, all new customers would get the REV 2 , which bears on one of your
points...
 to wit: 

--- In wiardgroup@yahoogroups.com, mmcgrath@... wrote:
> Also of course when you need a burst of noise to add to the 
> attack of a percussion sound, the Blacet unit has the edge.

the REV 2 noise ring has a full-spectrum analog
 white noise output jack (not implemented on mine)which could be used
for percussive bursts

but to keep the game, on the level, your comment:

--- In wiardgroup@yahoogroups.com, mmcgrath@... wrote:
>  Additionally, the Blacet is a better module if you are 
> looking to synthesize the sound of wind, surf, rain, waves, blizzards, 
> hurricanes., etc.  In fact I'd like to say that this module is
absolutely 
> AMAZING for work like this, and the ability to control every parameter 
> with CVs allows for some shifting, morphing changes to your weather 
> patterns!  
> 

..is quite accurate
John Blacet implemented a switchable multimode filter on the noise
output of the Improbablility Drive and this can do double-duty,
varying the character of available CV's steps and , as Mike points
out, providing CV controlled filtered audio noise. The noise ring does
not feature onboard audio filtering 
(thanx for your comments, Mike)

-doc

> Thank you all very much for the response! Especially Doc,still i'm 
> wondering one thing: both modules use analog and digital noise, why 
> is that? What is the difference? And why both use these different 
> noise sources for different applications?
> 

Because analog and digital noise generators sound different. Analog noise is "hiss" and has a 
gaussian level distribution. Digital noise can sound like "hiss" under some circumstances, but 
can be changed a lot, it has a uniform level distribution.

Here is a chart from Federal Scientific, which shows statistical properties of waveforms 
including analog and digital noise:

http://www.musicsynthesizer.com/Circuitry/probability.htm

The Noise Ring outptus waveforms 6 and two different versions of 10. The "Change" control 
essentially controls auto-correlation.

Hi Matthieu
--- In wiardgroup@yahoogroups.com, "matthieuvandiepen" <matthieu@...>
wrote:
>
> Thank you all very much for the response! Especially Doc,still i'm 
> wondering one thing: both modules use analog and digital noise, why 
> is that? What is the difference? And why both use these different 
> noise sources for different applications?
>

i was trying to avoid this...
;'>
this is a very loaded subject, and it can go in about 50 directions at
once!
;'>
and because it is one of my fetishes, i could embark on at least 25 of
them! but i'd love to hear what some of the other eminent experts
especially Prof Richter, on this group have to say about this subject. 
Furthermore.... the Laurie Anderson restriction, "Writing about music
is like dancing about architecture" applies heavily to discussion
group  posts. 
   There are just some qualities that have to be demonstrated live in
order to be easily grasped. i guest-lecture at a local college and one
of my standard presentations covers random parameters as applied to
music. This effort started-out as one 2-hour class in the Electronic
Music Lab but the faculty expanded it to two 2-hour sessions because
the class consistently returned the following week with 2-hours worth
of follow-up questions. So now i cover the subject in TWO sessions.

Suffice to say, this will only scratch the surface and before i begin
i want to point you to some REAL authorities on the subject:

first,
http://www.musicsynthesizer.com/Circuitry/probability.htm

Grant put up a really nifty chart that sums up the differences between
 probablility distibutions in a column of blindingly practical and
succinct graphs from an old test equipment reference. God Bless our
parents generation of crusty old HAM radio veterans!!!!

next,
http://en.wikipedia.org/wiki/Information_entropy

Wiki put up a fairly decent (for once) overview and explanation of
Claude Shannon's definitive work on the subject  

In hard copy,
 
Thomas Henry put out a really nice practical book  with some great
insights into analog noise called the "The Noise Generator Cookbook"
but it's out of print

and finally, i personally, learned a hell of a lot from the very nuts
and bolts treatment of digital noise and shift registers in Don
Lancaster's wonderful "CMOS Cookbook", still in print, and still a
GREAT reference.

Ok... here goes...

To the EE faction, the difference is pretty basic. They tend to view
the phenomena in terms of the origin and the output. In their
shorthand, they told me that the difference is that analog noise is a
back-biased Zener junction, and digital noise is a just a big-ass
shift register.

to expand :
Analog noise originates as a sort of avalanche of electrons spilling
over a semiconductor barrier. It reminds me of a heavily loaded
Pachinko machine***1. In technical terms, the noise is generated by
the Zener breakdown phenomenon in an inversely polarized
base-collector junction. It exploits the shot noise of electrons at a
'choked' semiconducting gate. This physical phenomenon manifests
itself electrically as statistical fluctuations in current flow
present at the base of a reverse-biased bipolar transistor. (It is
also possible to use a reverse-biased Zener diode instead of a transistor)
The current fluctuations go VERY fast and when you amplify them a lot.
It makes a very fast wiggly line on the O'scope. To an EE, that's
analog noise.

Digital noise originates with a shift register that is clocked at a
very fast rate in the audio range. The old MM5437 and MM5837 chips
used as a one-chip noise source in many 80's era synths were
essentially big self-clocking shift registers on a single chip. If you
refer to my earlier post i explain how a shift-register works using a
conveyer-belt analogy. In the case of most conventional digital noise
sources, just consider a conveyer belt with room for many more people,
a steady and very fast clock, and no feedback. That's how the
randomness originates, and the output is not as wiggly as analog
noise. It jumps very fast from step to step rather than rising or
falling from point-to-point as analog noise does. Digital noise is
often called 'peseudorandom' because it's randomness is finite and
limited to the number of bits in the shift register. (spaces on the
conveyer belt imy little analogy) As a result at some point the shift
register method has to 'start over' and it will repeat itself. This
manifests itself in the output audio as the infamous digital noise
'thunk'. The larger the number of bits in the register the longer the
interval between thunks***2 

So...
so far we have Wiggly, point-to-point Analog Noise generated by a
semiconductor wired backwards, 
and Digital Noise, hissing along in fast discrete steps with a 'bump'
every time it runs out of bits and has to start over.

if you're listening at the output jack, the ear just kind of shrugs
and declares that it all just kind of sounds like a hiss.... so what's
the big deal? 

A sample hold is a sort of time-lapse photography it 'takes pictures'
at (ostensibly) a slower rate than the change-rate of the phenomenon
being sampled.....
Now at this point, i bid farewell to my respected EE friends and put
on my (rather silly and impractical) artiste hat. From here on ,my
declarations are PURELY subjective and not only defiantly unproven but
unprovABLE!!!!
  When i sample analog noise at some arbitrarily fixed rate and map
the resulting steps to pitch, my mind's melodic memory notes a
'character' this quality becomes clearer to me over time (and i am
notorious and oft-chided amongst the other residents of Mabuse Manor
for listening to this kind of crap for HOURS!!!).
(ahem)
But if i sample DIGITAL noise at the same clock rate my (perhaps
arguably addled and insane) mind registers not only a higher degree of
repetition (hmmmm THAT pitch sounded familiar!) but also a different 
melodic character.
Call me a head-case (and it wouldn't be the first time) but my
artistic conclusion is that both are 'good' and i need both in my
compositions.

That is an overall survey of 'la difference'
and Vive Ca Difference!!!!



...and to anybody still reading (what's WRONG with you???) i apologize
again, but that's about as small a nutshell into which i can put a
full answer to Mathieu's question.

-doc

***1 Pachinko is a kind of small pinball machine that was (is?)
popular in Japan. Unlike their American counterparts lots of balls
(50-100) are in play at once and there are no flippers (at least on
the ones i played) it's just a sort of barely controlled cascade of
little silver balls


***2 On the MM5437, the interval was minutes long, the MM5837 beat the
problem to a degree. Theres a good explanation at
http://www.vego.nl/8/08/03/08_08_03.htm
if you read German

Hi Mathieu
after reading Prof. Richter's comment (below) a sensible clarification
 occurred to me. We have been discussing noise in two contexts:
1) as an AUDIO signal
and
2) as a source for derivation of CONTROL VOLTAGES (ie via a sample/hold)  

and as i read back over the discussions i notice that i jump back and
forth between these two contexts very freely and this is prone to
cause confusion. So please allow me to restate a couple of points clearly.

As an AUDIO signal, analog and digital noise are different but to my
ear, the difference is not well defined and with processing the two
forms of noise can 'cross-dress' pretty convincingly (at least in a
dark bar when i'm drunk)
;'>
As the professor points out, digital noise has sonic parameters that
are easily changed (especially on the N.R.) and shifting these
parameters will change the AUDIBLE characteristics of the noise quite
a lot. But i would add that Analog white noise ('hiss') can be changed
quite easily too with processes like filtering and balanced modulation.
The point is that in the AUDIO realm the difference can be very blurry.

To my ear, the most apparent differences between analog and digital
noise are exposed when the two forms of noise are sampled by a
sample/hold circuit and output as patterns of control voltages. That
context is what yields the 'character' difference to which i was
referring in my earlier posts.

-doc

PS: i want to state for the record that Grant & i did NOT collude on
referring you to the Federal Scientific chart on musicsynthesizer.com
. It's just that little chart is such a gem in it's succinctness and 
thoroughness that it's hard to beat as a resource.... Kudos to Grant
for noticing that chart in the back of some cast-off technical
reference in  the 2nd-hand bookstores he haunts, and giving it a new
lease on life as a billboard on the information highway! Bravo Professore!


--- In wiardgroup@yahoogroups.com, "Grant Richter" <grichter@...> 
> Because analog and digital noise generators sound different. Analog
noise is "hiss" and has a 
> gaussian level distribution. Digital noise can sound like "hiss"
under some circumstances, but 
> can be changed a lot, it has a uniform level distribution.
> 
> Here is a chart from Federal Scientific, which shows statistical
properties of waveforms 
> including analog and digital noise:
> 
> http://www.musicsynthesizer.com/Circuitry/probability.htm
> 
> The Noise Ring outptus waveforms 6 and two different versions of 10.
The "Change" control 
> essentially controls auto-correlation.
>

Hi Doc,

thanks very much for your wonderfull lecture on analog/digital noise.

yes i am indeed from the noisy netherlands. And i agree with you, Dutch isn't 
that different from German. It just has some more distortion in the 
pronunciation.

So i guess we now are all a lot wiser on the noise subject. I really would like 
to learn more of your other (music related) fetishes.

Some Wiard usergroup subjects i have on my wishlist are:
- vocoders (how to make a patch with a modular)
- control processors
- sequencers

Anyway, until now i want to thank you very much,

Matthieu van Diepen




--- In wiardgroup@yahoogroups.com, "drmabuce" <drmabuce@...> wrote:

>
> Hi Matthieu
> --- In wiardgroup@yahoogroups.com, "matthieuvandiepen" <matthieu@>
> wrote:
> >
> > Thank you all very much for the response! Especially Doc,still i'm 
> > wondering one thing: both modules use analog and digital noise, why 
> > is that? What is the difference? And why both use these different 
> > noise sources for different applications?
> >
> 
> i was trying to avoid this...
> ;'>
> this is a very loaded subject, and it can go in about 50 directions at
> once!
> ;'>
> and because it is one of my fetishes, i could embark on at least 25 of
> them! but i'd love to hear what some of the other eminent experts
> especially Prof Richter, on this group have to say about this subject. 
> Furthermore.... the Laurie Anderson restriction, "Writing about music
> is like dancing about architecture" applies heavily to discussion
> group  posts. 
>    There are just some qualities that have to be demonstrated live in
> order to be easily grasped. i guest-lecture at a local college and one
> of my standard presentations covers random parameters as applied to
> music. This effort started-out as one 2-hour class in the Electronic
> Music Lab but the faculty expanded it to two 2-hour sessions because
> the class consistently returned the following week with 2-hours worth
> of follow-up questions. So now i cover the subject in TWO sessions.
> 
> Suffice to say, this will only scratch the surface and before i begin
> i want to point you to some REAL authorities on the subject:
> 
> first,
> http://www.musicsynthesizer.com/Circuitry/probability.htm
> 
> Grant put up a really nifty chart that sums up the differences between
>  probablility distibutions in a column of blindingly practical and
> succinct graphs from an old test equipment reference. God Bless our
> parents generation of crusty old HAM radio veterans!!!!
> 
> next,
> http://en.wikipedia.org/wiki/Information_entropy
> 
> Wiki put up a fairly decent (for once) overview and explanation of
> Claude Shannon's definitive work on the subject  
> 
> In hard copy,
>  
> Thomas Henry put out a really nice practical book  with some great
> insights into analog noise called the "The Noise Generator Cookbook"
> but it's out of print
> 
> and finally, i personally, learned a hell of a lot from the very nuts
> and bolts treatment of digital noise and shift registers in Don
> Lancaster's wonderful "CMOS Cookbook", still in print, and still a
> GREAT reference.
> 
> Ok... here goes...
> 
> To the EE faction, the difference is pretty basic. They tend to view
> the phenomena in terms of the origin and the output. In their
> shorthand, they told me that the difference is that analog noise is a
> back-biased Zener junction, and digital noise is a just a big-ass
> shift register.
> 
> to expand :
> Analog noise originates as a sort of avalanche of electrons spilling
> over a semiconductor barrier. It reminds me of a heavily loaded
> Pachinko machine***1. In technical terms, the noise is generated by
> the Zener breakdown phenomenon in an inversely polarized
> base-collector junction. It exploits the shot noise of electrons at a
> 'choked' semiconducting gate. This physical phenomenon manifests
> itself electrically as statistical fluctuations in current flow
> present at the base of a reverse-biased bipolar transistor. (It is
> also possible to use a reverse-biased Zener diode instead of a transistor)
> The current fluctuations go VERY fast and when you amplify them a lot.
> It makes a very fast wiggly line on the O'scope. To an EE, that's
> analog noise.
> 
> Digital noise originates with a shift register that is clocked at a
> very fast rate in the audio range. The old MM5437 and MM5837 chips
> used as a one-chip noise source in many 80's era synths were
> essentially big self-clocking shift registers on a single chip. If you
> refer to my earlier post i explain how a shift-register works using a
> conveyer-belt analogy. In the case of most conventional digital noise
> sources, just consider a conveyer belt with room for many more people,
> a steady and very fast clock, and no feedback. That's how the
> randomness originates, and the output is not as wiggly as analog
> noise. It jumps very fast from step to step rather than rising or
> falling from point-to-point as analog noise does. Digital noise is
> often called 'peseudorandom' because it's randomness is finite and
> limited to the number of bits in the shift register. (spaces on the
> conveyer belt imy little analogy) As a result at some point the shift
> register method has to 'start over' and it will repeat itself. This
> manifests itself in the output audio as the infamous digital noise
> 'thunk'. The larger the number of bits in the register the longer the
> interval between thunks***2 
> 
> So...
> so far we have Wiggly, point-to-point Analog Noise generated by a
> semiconductor wired backwards, 
> and Digital Noise, hissing along in fast discrete steps with a 'bump'
> every time it runs out of bits and has to start over.
> 
> if you're listening at the output jack, the ear just kind of shrugs
> and declares that it all just kind of sounds like a hiss.... so what's
> the big deal? 
> 
> A sample hold is a sort of time-lapse photography it 'takes pictures'
> at (ostensibly) a slower rate than the change-rate of the phenomenon
> being sampled.....
> Now at this point, i bid farewell to my respected EE friends and put
> on my (rather silly and impractical) artiste hat. From here on ,my
> declarations are PURELY subjective and not only defiantly unproven but
> unprovABLE!!!!
>   When i sample analog noise at some arbitrarily fixed rate and map
> the resulting steps to pitch, my mind's melodic memory notes a
> 'character' this quality becomes clearer to me over time (and i am
> notorious and oft-chided amongst the other residents of Mabuse Manor
> for listening to this kind of crap for HOURS!!!).
> (ahem)
> But if i sample DIGITAL noise at the same clock rate my (perhaps
> arguably addled and insane) mind registers not only a higher degree of
> repetition (hmmmm THAT pitch sounded familiar!) but also a different 
> melodic character.
> Call me a head-case (and it wouldn't be the first time) but my
> artistic conclusion is that both are 'good' and i need both in my
> compositions.
> 
> That is an overall survey of 'la difference'
> and Vive Ca Difference!!!!
> 
> 
> 
> ...and to anybody still reading (what's WRONG with you???) i apologize
> again, but that's about as small a nutshell into which i can put a
> full answer to Mathieu's question.
> 
> -doc
> 
> ***1 Pachinko is a kind of small pinball machine that was (is?)
> popular in Japan. Unlike their American counterparts lots of balls
> (50-100) are in play at once and there are no flippers (at least on
> the ones i played) it's just a sort of barely controlled cascade of
> little silver balls
> 
> 
> ***2 On the MM5437, the interval was minutes long, the MM5837 beat the
> problem to a degree. Theres a good explanation at
> http://www.vego.nl/8/08/03/08_08_03.htm
> if you read German
>

Hi Matieu (et all)

--- In wiardgroup@yahoogroups.com, "matthieuvandiepen" <matthieu@...>
wrote:

> thanks very much for your wonderfull lecture on analog/digital noise.
> 

Thank YOU for raising an issue about what's BEHIND the panel. That's
my FAVORITE part of the synthesizer!
;]


> yes i am indeed from the noisy netherlands. And i agree with you,
Dutch isn't 
> that different from German. It just has some more distortion in the 
> pronunciation.
> 

You're gracious to say so, but i really have no excuse. i've used that
article in the footnote many times before and knew perfectly well that
it was in Dutch. i was in a hurry when i typed it and my mind slipped
from "Dutch" to "Deutsch" .... (sigh) .... as Romeo aptly chided: i'm
an "Alter Mann",....losing ground to senility.

But more importantly, my faux pas embarrasses me more because i marvel
at, and am constantly humbled by, the command of my native language
that you Wiardos in other countries constantly demonstrate.
We Americans are spoiled. Imagine the bedlam that would ensue if i
tried to talk about the difference between Gaussian and uniform
probablility distributions in DUTCH. 
(shudder)
Hat's off to you tolerant folks in other lands!


> So i guess we now are all a lot wiser on the noise subject. I really
would like 
> to learn more of your other (music related) fetishes.
> 
> Some Wiard usergroup subjects i have on my wishlist are:
> - vocoders (how to make a patch with a modular)
> - control processors
> - sequencers
> 

There are many Wiardos on this group with deeper expertise in these
subjects than mine. i -can- tell you that assembling a vocoder using
individual mudules is not cost effective. It requires a dozen (or
more) of fixed filters, VCF's and envelope-followers. This is much
more efficiently accomplished in an integrated design, but even then
it is still expensiveto build and thus, expensive to buy . There
appear to be few shortcuts to that function.


> Anyway, until now i want to thank you very much,
> 

It was my pleasure.

Happy Patching
-doc