[sdiy] AD/DA schematics? quantizers,etc woohoo

[Dan Snazelle]

well good news!!!

i think i figured something VERY important out

to get a nice quantizing sound with steps in between the notes, i think you do NOT want a clock as HIGH as i am using for audio

that was my issue. i was always using either too HIGH a clock or TOO low,. with too high a clock, the CV came out very similar to the way it went in. with a 103 cap instead of a 102  i am getting NICE stairs of notes

if i can find a good place to post a sample i will

thanks so much to all!!




--------------------------------------------
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----------------------------------------
> From: matthias.herrmann at fonik.de
> To: subjectivity at hotmail.com
> Subject: AW: AW: AW: [sdiy] AD/DA schematics? quantizers,etc
> Date: Sat, 16 May 2009 11:28:51 +0200
>
>> -----Ursprüngliche Nachricht-----
>> Von: Dan Snazelle [mailto:subjectivity at hotmail.com]
>> Gesendet: Freitag, 15. Mai 2009 19:32
>> An: matthias.herrmann at fonik.de; sdiy
>> Betreff: RE: AW: AW: [sdiy] AD/DA schematics? quantizers,etc
>>
>>
>>
>> ok this is interesting.
>>
>> right now i have the bits hooked up like this
>>
>> a1-d2
>> a2-d2
>> a3-d3
>> a4-d4
>> a5-d5
>> a6-d6
>> a7-d7
>> a8-d8
>>
>> it seems you are saying that there may be a different config i
>> need to find
>
> yep.
>
>>
>> also...i do NOT know if i am running this at the correct sample rate
>>
>> i have had NOTHING but trouble finding a clock that is both
>> stable and will go high enough
>
> yo might want to take a look at the mickey mouse logic at ray wilsons MFOS
> site. i use a simple schmitt trigger based VCO, runnig at approx. 30MHz, way
> beyond whats audible.
>
>
>>
>>
>> i am finding 2 things...that for driving this with AUDIO i need a
>> very high clock (neither of my vcos go anywhere near high enough)
>> and that for the quantizer i get some results with my vcos but
>> would probrably get better with a clock rate specified in the datasheet
>>
>>
>> anybody have schematics for a really high freq clock? maybe even
>> a a voltage controlled one?
>>
>> or do i just need to switch the cap of a vco to a really low one
>> like a 50pf?
>>
>> anyway...this has been a great learning experience.
>>
>> even if it only sounds like a sample and hold at this point, it
>> IS in tune when i move my offset pots correctly.
>>
>>
>> anyway...i am sure i will be writing more later !
>>
>> thanks
>>
>>
>>
>>>
>>>> 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
>>>
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>