AW: AW: [sdiy] AD/DA schematics? quantizers,etc

[Matthias Herrmann]

> Von: synth-diy-bounces at dropmix.xs4all.nl
> [mailto:synth-diy-bounces at dropmix.xs4all.nl]Im Auftrag von Dan Snazelle
> Gesendet: Freitag, 15. Mai 2009 17:38
> An: jerryge at cableone.net; sdiy
> Betreff: RE: AW: [sdiy] AD/DA schematics? quantizers,etc
>
> ok
>
> in the current setup, the quantatizing (sp?) seems to be working
> better BUT and this is a big BUT....
> When DRIVING a VCO....it is sounding more like a sample and hold
> than a quantizer.
>
> and what i mean by this is that if i feed in a very low freq
> sawtooth what i get out of the vco sounds like  a series of notes
> with steps in between very very similar to a sample and hold fed
> by a white noise and fed into a vco
>

1st thing that comes to my mind is: you wired the input bits of DAC in the
wrong order.

if wired correctly you should see a staircase as result of your sawtooth.
the datasheet should give you a table that shows the combination of the bits
resulting in what output voltages.
i.e. 0100000 for 0.04V and 01111111 for 9.96V (7 bits used, 10Vref). so what
would 01001100 be? you should verify that.

hope i did not misunderstood the whole issue!?

cheers,
matthias
___
www.fonitronik.de



>
>
> is this due to what fonik was mentioning? he noted that he needed
> to put latches on the output of the DAC so that there was a
> smooth flow between notes
>
>
> or maybe i have done something wrong again
>
>
> all in all it is a cool sounding effect but not quite the sound i
> had been going for.
>
>
> i do not know even how to setup a latch on the out...what would
> control it?
>
> the clock? a bit from the A to D?
>
> thanks