[sdiy] continuous tuning of analog oscillators

sines sines_list at scale.la
Thu Jul 11 16:22:14 CEST 2019


Deckard’s Dream and Kijimi [and probably Xerxes as well] tune each card just like you’re proposing with the digital solution. It’s digital control over analogue oscillators. The widely used STM is on board all of these afaik. A “listener” scheme listens for fader adjustment [there are over 80 values to listen to per patch]. Unfortunately due to non-motorized faders, you need to “wake up” each slider by adjusting each slider slightly to modify that part of the patch.

The software development is not trivial, and [most likely] may be outside the realm of your project.

This may be obvious, but this should get you started thinking in this direction:
http://www.rhodeschroma.com/?id=circuitdescriptions
http://www.rhodeschroma.com/?id=tuning
http://prophet600.blogspot.com/2012/09/tuning-and-frequency-counting.html


Todd

> On Jul 11, 2019, at 10:05 AM, ulfur hansson <ulfurh at gmail.com> wrote:
> 
> DCO’s might be a good enough solution, but also has a host of problems to work through on its own... are there any good modern DCO examples/implementations out there?
> 
> also - looks like korg figured out a way to pack the micros into a tiny enough space to be worth the trouble - i wonder how the new moog one handles tuning, perhaps a similar approach?
> 
> Sent from outer space
> 
> On Jul 11, 2019, at 13:28, Jacob Watters <jacobwatters at gmail.com <mailto:jacobwatters at gmail.com>> wrote:
> 
>> If you want to tune the oscillators continuously anyway, then why not use DCOs? The signal is still analog, and the pitch is perfectly controlled without the extra sampling and tuning code.
>> 
>> Jacob Watters
>> JacobWatters.com <http://jacobwatters.com/>
>> Tel: 226-886-3526
>> 
>> 
>> On Wed, Jul 10, 2019 at 5:03 PM ulfur hansson <ulfurh at gmail.com <mailto:ulfurh at gmail.com>> wrote:
>> hello list,
>> 
>> I have a really nice synth voice up and running on my bench, and have always dreamt of making my own poly.
>> 
>> all parameters are voltage controlled, but the tuning is... well... not perfect.
>> 
>> currently I'm quite happy to omit oscillator FM, so in theory the oscillators would not "need" any modulation other than PWM.
>> 
>> autotune feels a bit archaic at this point, so i'm wondering - a tiny microcontroller listening for zero crossings should be able to adjust the frequency of each oscillator for near perfect tuning, no?
>> 
>> so far, i sadly haven't developed the skills required for digital solutions - but I wonder how crazy it would really be to implement something like this - can anyone think of a project / reading material that could help guide the way towards creating a tiny (preferably REALLY small) ADC/DAC listener circuit that could correct the resulting frequency of a sawtooth oscillator?
>> 
>> it would be amazing to put 8 of these voices together with perfect tuning without any divide down or stepped interval solutions...... but then again it would also mean i'd need at least 16 micros to listen to all the oscillators at once!!
>> 
>> any thoughts would be greatly appreciated, or even better yet - if someone would be interested in a collaborative effort, i'd be happy to send hand soldered smd prototypes between continents if necessary!
>> 
>> many thanks,
>> -úlfur
>> 
>> -- 
>>>> ulfurhansson.com <http://ulfurhansson.com/>
>> cargocollective.com/ulfur <http://cargocollective.com/ulfur>
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