[sdiy] They aren't sawtooths, they're ramps

[cheater cheater]

this expo saw could be possibly approximated by taking a linear ramp
osc, offsetting it so that its signal ranges from 0 to 1 V, an then
multiplying it by itself in a ring modulator. The saw will be x^2, but
that's near enough.

If anything, I would say that the way this expo saw would distort
would be different. The distortion would be brighter, I think.

Wonder how this expo saw could be done with today's oscillator designs.

D.

On Mon, Nov 2, 2009 at 18:22, Jerry Gray-Eskue <jerryge at cableone.net> wrote:
> I have references that date back to the 70s and they consider Saw and Ramp
> to be the same thing, a sharp vertical rise (or fall) and a linear slope.
>
> A (pure) sine wave has only the fundamental frequency.
> A saw or ramp wave has all the harmonic overtones of the fundamental
> frequency decreasing exponentially with the harmonic series.
>
> A triangle wave (1/9,1/25,1/49...) and square wave (1/3,1/5,1/7,1/9...) has
> all the odd harmonic overtones of the fundamental frequency.
>
> The ratios of the harmonics and odd even content define the wave shapes.
>
> <<However, original relaxation oscillators generated exponential rises and
> falls >> This would be rich in harmonics but I am not sure of the harmonic
> content.
>
>
>
> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl
> [mailto:synth-diy-bounces at dropmix.xs4all.nl]On Behalf Of Electronic
> Battle
> Sent: Monday, November 02, 2009 11:22 AM
> To: synth-diy DIY
> Subject: [sdiy] They aren't sawtooths, they're ramps
>
>
> Hello All
>
> Please can someone talk about the difference between sawtooth and ramp
> waveforms and whether they sound different?
>
> Mere nomenclature and semantics possibly, but nevertheless, most VCO cores
> these days are (as far as I have seen) integrators which provide a constant
> current charge pump into a capacitor and get a linear voltage generated at
> the op-amp output. You get a linear rise and fall of the triangle wave which
> can be processed into a ramp.
>
> However, original relaxation oscillators generated exponential rises and
> falls - these are the true sawtooths.
>
> Have a look here:
>
> http://www.eng.cam.ac.uk/DesignOffice/mdp/electric_web/Exper/05263.png
>
> The module front panel says "saw" but the waveform says "ramp"
> http://yusynth.net/Modular/index_en.html
>
> The ASM VCO core says "saw" but it is actually ramp.
>
>
> So VCOs which say "saw" on the front are actually generating ramps: what is
> the sonic difference though? Is the harmonic makeup radically different -
> what would the fourier spectrum look like and would it sound that different?
>
>
> None of this meant to sound like any kind of a criticism by the way, merely
> an observation.  IS the sonic difference i.e. an audible A:B comparison able
> to identify two distinctly different tones?
>
>
> EB
>
>
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