DCO

[Bjarne Nillson]

Well, nice to se that my erlier posting 
made some pink noice on the synt diy!

>No.  There's nothing intrinsic to the oscillator itself that's
>digital.  Why try to cover up the true nature of the sound producing
>process with jargon?

Hmm, you didn't read the last lines in my posting saying 
that this was just some small philosophying around the meaning of the 
word DCO etc.And i am absolutely not to cover upp anything, why should 
I?

>>It's nothing like an ordinary VCO.  You can't add portamento, you
>>can't modulate it with an analog signal.

>Dear Don,
>You can produce produce portamento with the 'divide-
>by-N' system. The Junos did it very nicely and more
>recently the Basstation and Pulse mono synths. Its just
>a matter of allowing small enough 'centile' increments between
>sweep does not produce noticable steps.
>
>Regards
>Steve Grainger

I can just fill in with Steve's tune here, yes you can,
its just a matter of some software coding.

And regarding to the Waldorf Pulse some year ago i had
some email correnspondance with the designer of the Pulse.
We had some small talk about OSC's and he told me that
the Pulse uses two 68HC11 one for doing the DCO thing
and the other as "in house" doing midi etc.
He told me that he had some real headaces for the
sync generation on this device ending upp with
conecting a wire from the NCO to a input pin comparator 
and solwing the rest with software!
The Pulse osc are using the internal 16 bit timer
and the pulseaccumlulator regiters and the comparators.

Does anyone know if the Pulse are using a integrator as a
solution for generating the SAW wave?
Also the Pulse have TRI wave to, regadless to the
issue of "allways to late CV" integrator issue.

>>>Now, how do we change the square wave to a saw!
>>>Easily by a odinary integrator,the same integrator used in a VCO!
>>>Now, the discussion starts to be interesting,

>>.....because, I am going to ask BJ how to keep the amplitude of
>>the saw constant with frequency!
> 
>> That's a trick I would like to learn too.
> 
> -tg

>The Juno 106 uses a nice trick - the integrator is fed with a cv 
(de-muxed
>from a dac, with a linear control law) to generate the saw, and the 
square
>wave is only used to reset the integrator. There will be a small error 
in
>amplitude due to error in the cv, but not in frequency.
>An analogue switch before the capacitor is used to select 3 different
>resistance values at the input to the integrator for octave selection.

>Colin f

As Colin says here that's the trick to use!
And the usage of 3 different resistors for 3 different integrator charge
currents for different frequencys are interesting to!
The JX3P and JX8 uses this solution to, they depend
to a demuxed CV to the integrator.

But they dont use the 3 resistor solution as the J106 uses!
Hmm all of  those machines uses 12 bit DAC for the CV.

I wonder how the Juno1 and 2 wave IC works? 

BJ[one person, one rom, one confusius!]
 

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