analog synths & microtuning

Anyone here care to give a succint explanation about how microtuning works
on analog synths for Equal Temperaments ? I'd really appreciate it !

I've never laid my paws on a real one, only read a few bits of info & just
checked out the demo of Koblo's Vibra 9000 software synth
(http://www.koblo.com), but couldn't quite figure it out.

On Waldorf's page for the MicroWaveXT there's this snippet of info :
----------------------------------------------------------------------

Both Oscillators can have individual keytracking, from -100%, which means
that a played scale is inverted, through 0% where no pitch change occurs up
to 200%, meaning, that every semitone interval is interpreted as 2
semitones. The resolution of this parameter is very fine to also allow, for
example, 25% or 33% scalings.

You can set the Pitch Bend Range of both Oscillators individually. And in a
range of 10 octaves (120 semitones)!

----------------------------------------------------------------------

BTW, Nord's MicroModular retails for $650. All the power of the big one, but
only one DSP chip & max. 4 voice polyphony. http://www.clavia.se

Thanks in advance !

- Drew

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> From: "Drew Skyfyre" <drew_skyfyre@yahoo.com>
>
> Anyone here care to give a succint explanation about how microtuning works
> on analog synths for Equal Temperaments ? I'd really appreciate it !
>
Many analog synths operate on the one volt per octave specification. This means
that if a control signal of five volts sent to the oscillator causes it to
produce 440 Hz (I don't know if that truly is the frequency you would get for
5v, just imagine it is for the sake of this example), then six volts would give
880 Hz and four volts would give 220 Hz.

Keyboards for analog synths (true analog, not analog modelling) produce a
control signal voltage of one twelfth of a volt per key. This voltage is added
to other control signals from LFOs and the pitch-bend wheel before reaching the
frequency control input of the oscillator. Circuitry for keyboard tracking
produces a _new_ control voltage under the control of the 1/12 volt per key
from the keyboard. The new control voltage could be set to decrease when its
input increases (inverted), or it could be adjusted to increase by one
nineteenth of a volt when its input increases by one twelfth of a volt. If the
oscillator was to receive this new control signal instead of the one directly
from the keyboard, you have infinitely tweakable microtonal equal temperaments.

>> Anyone here care to give a succint explanation about how microtuning
works
>> on analog synths for Equal Temperaments ? I'd really appreciate it !
>>
>Many analog synths operate on the one volt per octave specification. This
means
>that if a control signal of five volts sent to the oscillator causes it to
>produce 440 Hz (I don't know if that truly is the frequency you would get
for
>5v, just imagine it is for the sake of this example), then six volts would
give
>880 Hz and four volts would give 220 Hz.
>
>Keyboards for analog synths (true analog, not analog modelling) produce a
>control signal voltage of one twelfth of a volt per key...

Note that digitally controlled analog synths and digitally emulated analog
synths may quantize the "voltage control" or keyboard tracking so that nET
scales of any degree are not possible.

John Loffink
microtonal@worldnet.att.net
The Microtonal Synthesis Web site
http://home.att.net/~microtonal/

Darren, John L., Thanks !

I understand now. I also found some interesting, related articles on John
Allen's pages (http://web0.tiac.net/users/jsallen/music/ [I think]).

> Note that digitally controlled analog synths and digitally emulated analog
> synths may quantize the "voltage control" or keyboard tracking so that nET
> scales of any degree are not possible.

Most likely, as fas as the info from a controller(keyboard,etc. goes,
but the "key tracking" parameter that exists in many digi-analog synths
is documented by all the companies I've seen as capable of of true nET
microtuning. I've checked at Waldorf, Doepfer, Access, Nord.
Oberheim's OB-Mx, I don't know (too expensive even for my fantasies :-),
but I know it DOES have tuning tables.

Quasimidi's Polymorph ( http://www.quasimidi.com/englisch/polymorp.htm )
is a groovy synth, but I was unable to determine if it has key tracking.

My curiousity got me looking around & many (but not all) of the
analog/digital modelling, etc. synths currently available offer
key-tracking, allowing the exploration of myriad Equal Temperaments.
Waldorf's implementation appears to be the best, with the widest range :
-100% to +200%, with +100% yielding divisions of 1 semitone (100cents),
being 12EDO (12tET). What's nice is these companies actually include this
feature, & actually document the potential microtonal use, rather than just
an "effect".

The synths that don't offer key tracking seem to be mostly the monophonic
Roland 303 clones, made by numerous companies.

Funny thing is, the non-analog Ensoniq ASR-X pro has a parameter called
"key track", with a range of fractional negative & positive options :

" Off, 1/8, 1/4, 3/8, 1/2, 5/8, 3/4, 7/8, normal,
9/8, 5/4, 11/8, 3/2, 13/8, 7/4, 15/8, 2, Pitch Table "

With 1/1 (8/8) being "normal", & the option to just select the pitch table
(tuning table) of the synth.

I suppose this means that there's a whole bunch of ET options available, in
addition to the presets in the tuning table ?

___________________________________________________________________________
Virus Access "analog" synth
http://www.access-music.de/index.html

From the PDF manual :

KEY FOLLOW (EX)
Determines the intensity of the pitch control via the keyboard: At the value
+32 (standard setting) the oscillator is controlled normally, i.e. the
octave you play is identical to the octave of the oscillator; at +63 every
ascending octave you play transposes the oscillator upwards by two octaves
(whole tone scale); +15 transposes the oscillator upwards by one octave for
every two ascending octaves you play (quarter tone scale); at 0 the keyboard
control option is off.
Negative values generate opposite control intensities.
____________________________________________________________________________

BTW, I've been looking at the demo of the latest SuperCollider release
(2.2.1), http://www.audiosynth.com , & it just gets better all the time !
PowerMac only, btw.

It is so easy to work microtonally & in real time ! There r a few microtonal
examples included. James, I don't know if you're on this list, but trust me,
if I had the money, I'd have sent you the $250 a while ago ! Meantime, I'll
try to learn how to use it.

Personally I believe SC2 is the ONLY software synth worth using, with the
exception of the icon-based Max-MSP, though SC is more powerful & is more
efficient.
____________________________________________________________________________

Salut,
Drew

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