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SEQUENTIAL/DSI => Prophet => Sequential Prophet-6 => Topic started by: NoahK on January 31, 2016, 08:11:38 PM

Title: Oscillator shape at 5 o'clock position results in muted oscillator
Post by: NoahK on January 31, 2016, 08:11:38 PM

OK, please do not laugh if this is a stupid question although I have read the manual under the Oscillator and Shape sections and have not found the answer.

It appears that turning the shape of Osc. 1 or Osc. 2 to the 5 o'clock position with a hard panned Pulse width results in the oscillator not being audible.  What is the reasoning behind this?

The p6 manual page 15 states

Quote

Each oscillator is capable of generating triangle, sawtooth, and variable- width pulse waves. These waveshapes are continuously variable and smoothly transition from one shape to the next as you turn the shape knob. This provides a variety of “in-between” waveshapes.

and page 16 states that

"

Quote

Shape: Triangle, Sawtooth, Pulse—Used to select the waveshape generated by the oscillator. Waveshapes are continuously variable and smoothly transition from one shape to the next as you turn the shape knob. This provides a variety of “in-between” waveshapes.

There is no mention that putting the shape pot at the 5 o'clock with a hard panned pulse-width  position will result in muting of the oscillator.

What am I missing here?

Thanks so much!
Noah

Title: Re: Oscillator shape at 5 o'clock position results in muted oscillator
Post by: Paul Dither on January 31, 2016, 08:40:02 PM

The pulse width basically "thins out" when you move the PWM knob to its extreme positions (0 and 100%), which results in no sound.

Maybe this animation of a modulated duty cycle helps:

(https://upload.wikimedia.org/wikipedia/commons/0/02/PWM_duty_cycle_with_label.gif)

Title: Re: Oscillator shape at 5 o'clock position results in muted oscillator
Post by: Sacred Synthesis on January 31, 2016, 10:24:59 PM

Changing the pulse width alters the timbre of the sound in such a way that it becomes inaudible.  A high pass filter and a low pass filter can each do the same thing.  This is normal analog synthesizer behavior and allows you to achieve various effects.