[sdiy] Chris Synths polysynth

[Roman Sowa]

That trick was widely used in many Yamaha PS synths. They had special 
keyboard scanner chip for that, using 2 resistor strings for octaves and 
semitones.

Roman

W dniu 2021-10-21 o 11:53, Richie Burnett pisze:
> Neat trick Tom
>
> -Richie,
>
> Sent from my Xperia SP on O2
>
> ---- Tom Wiltshire wrote ----
>
>> Here’s the correction:
>>
>> Imagine you have a DAC with 4-bit resolution. If we use one with a step-between-values of 1V, and then add the output of another with a step-between-values of 1/16th of a volt, we can make an 8-bit DAC. That’s basically what you do with the PWM. The process is helped by the very good linearity of digital-counter-based PWM as a method of producing a voltage.
>>
>> I’ve used a 3-bit PWM scaled to produce 1V per step and a 4-bit PWM scaled to produce 83mV per step to produce Pitch CVs. It worked very well and produced good CVs across the 8 octaves. The reduced bit depth of each PWM DAC means that the output frequency can be higher without the PWM clock frequency having to be super-high, and this improves the effect of filtering and the responsiveness of the CV to changes.
>>
>>> On 21 Oct 2021, at 09:54, cheater cheater via Synth-diy <synth-diy at synth-diy.org> wrote:
>>>
>>> Correct me if I'm wrong, but I think summing two PWMs will just add 1
>>> bit of depth.
>>
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
>> Selling or trading? Use marketplace at synth-diy.org
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
> Selling or trading? Use marketplace at synth-diy.org