200e

yes, the fundamental frequency of the principal oscillator is capped.
i'm not sure if its actually 7040 hz or not;
but to give some context, that would be an A 3 octaves above the A
above the treble clef. rather high for a musical instrument.
i personally can't hear anything at all above 11khz or so: sinewaves
or harmonics. too much rockin out.

but what i was saying is that capping the fundamental (even capping
the upper limit of fundamentals produced by FM excursion) does not
limit the frequencies created by sidebands in modulation synthesis.
those sidebands will encounter limits imposed by our processor speed,
which is orders of magnitude above the limits of hearing.

anyway, the design of the 261e potentially circumvents the method of
harmonic FM synthesis by incorporating a sweet harmonic waveshaper.
the parameters of waveshaping can themselves be modulated at audio
rates (again, use the internal mod osc to avoid jitter, if you want).
the possibilities become extreme.

pauline used radio test oscaillators for her early pieces; these can
still be found quite cheap if you wish to employ heterodyning
techniques.
but for many years it has been normal practice to restrict musical
tone generators to the designer's idea of a musical range.
goes for old buchlas, dx7's, whatever.
musical means arbitrary, in this case you get don buchla's idea of a
musically useful range of fundamental pitches... oh well.

here's some raw 261e staz, real quick, for fun...
http://music.calarts.edu/~ebuchla/mp3/ttwwoossiixxoonnee.mp3

peace,

ez b

On Mon, Sep 29, 2008 at 2:06 PM, tmeade1974 <tmeade1974@yahoo.com> wrote:
> Sorry for my misunderstanding. I was basing that assessment by observing the
> pitch
> modulation in the low frequency mode of the mod osc. It does clip at the
> top.
> --tom
>
> --- In 200e@yahoogroups.com, "ezra buchla" <ezra.buchla@...> wrote:
>>
>> >> 261e's fundamental frequency is set to the top of its range, it can
>> >> still generate harmonics above the fundamental.
>> >>
>> >
>> > Via the waveshaper, yeah? If I had one beef with the 259e/261e it would
>> > be
>> > the FM in the
>> > higher frequency range. Set the fundamental to 6000 hz and fm it, the
>> > output
>> > will clip at
>> > 7040, therefore limiting the rich sidebands you might be used to on
>> > "other"
>> > synths.
>>
>> that's just not true. there is no frequency domain "clipping" at 7k.
>> the 261e primary osc only produces fundamentals up to a certain
>> frequency (its not actually 7040 despite the silkscreen; try
>> listening); this is indeed due to processor limitations; of course we
>> actually have to compute the waveform thousands of times faster than
>> the fundamental in order to produce a clean sinewave input to the
>> waveshaper. we could produce faster fundamentals but they would begin
>> life with artifacts even before waveshaping, and you would not like
>> that (or maybe you would...?)
>>
>> anyway, the waveform is actually being computed at 50k or 100k or
>> something, so pitch modulation will still produce high-frequency
>> sidebands. use the internal pitch modulation to avoid jitter. i'm
>> sorry abuot the external FM inputl; it's not useful for high frequency
>> stuff.... sorry sorry. personally i'm used to being able to process
>> arbitrary signals with FM, but i find that the 291e scratches this
>> itch.
>>
>> and yes, of course, of course, everything after the 261e sinewave is
>> analog, and the harmonic content added by waveshaping proceeds towards
>> the infinite for as far as you might care to take your analysis....
>>
>> -eb
>>
>
>