[sdiy] AD/DA schematics? quantizers,etc

mark verbos mverbos at earthlink.net
Thu May 14 02:34:58 CEST 2009 

Dan,

I'd power your opamp from +/-15 as normal, but after the opamp/before  
the AthD put a low valued resistor followed by a diode to +5 and one  
to ground. That will limit the signal swing, preventing the AtoD from  
being hit too hard. That's standard stuff, a bit like what's inside of  
CMOS chips to protect their inputs.

Mark





On May 13, 2009, at 7:39 PM, Dan Snazelle wrote:

>
> oh and what should my in and out opamps be powered off of? i usually  
> use + or - 15 or 12
>
> will that still work in this system?
>
> it gets confusing with all the vrefs and swing limitations
>
> thanks
>
>>
>>
>>
>> i know this is a simple question but to gurantee a 0 to 5 volt  
>> swing on the input, is it best to limit the swing with a voltage  
>> divider or to just use an opamp with the signal on the non- 
>> inverting side and an offset with one side going to +V through a  
>> resistor and the other side going to ground?
>>
>> i have never had to limit the swing of a signal before
>>
>> thanks
>>
>> --------------------------------------------
>> check out various dan music at:
>>
>> http://www.myspace.com/lossnyc
>>
>> (updated monthly)
>>
>> http://www.soundclick.com/lossnyc.htm
>>
>>
>>
>> http://www.indie911.com/dan-snazelle
>>
>> (or for techno) http://www.myspace.com/snazelle
>>
>> ALSO check out Dan synth/Fx projects:
>>
>> AUDIO ARK:
>>
>> www.youtube.com/watch?v=TJRpvaOcUic
>>
>> www.youtube.com/watch?v=BqIa_lXQNTA&feature=channel_page
>>
>> www.youtube.com/watch?v=V4nJPjGgOcU&feature=channel_page
>>
>> and soundtrack/design work:
>>
>> NEW: check out Dan's sound design from the 1998 award winning film  
>> SAFARI by catherine chalmers
>>
>> http://www.catherinechalmers.com/videos.cfm
>>
>>
>>
>>
>>
>>
>> ----------------------------------------
>>> From: jerryge at cableone.net
>>> To: subjectivity at hotmail.com
>>> Subject: RE: [sdiy] AD/DA schematics? quantizers,etc
>>> Date: Wed, 13 May 2009 11:48:56 -0500
>>>
>>> Oh and you can get another effect by varying the Clock rate, the  
>>> slower it
>>> runs the more Chucky the conversions sort of like a bad low pass  
>>> filter as
>>> lower rates will kill of higher frequencies.
>>>
>>> -----Original Message-----
>>> From: synth-diy-bounces at dropmix.xs4all.nl
>>> [mailto:synth-diy-bounces at dropmix.xs4all.nl]On Behalf Of Dan  
>>> Snazelle
>>> Sent: Wednesday, May 13, 2009 11:27 AM
>>> To: gsn10 at hotmail.com; sdiy
>>> Subject: RE: [sdiy] AD/DA schematics? quantizers,etc
>>>
>>>
>>>
>>> oh and by the way, if i want to use switches to turn on and off  
>>> each out of
>>> the ADC, what should i do? leave it floating instead of to ground?
>>>
>>> thanks
>>>
>>>
>>>
>>> --------------------------------------------
>>> check out various dan music at:
>>>
>>> http://www.myspace.com/lossnyc
>>>
>>> (updated monthly)
>>>
>>> http://www.soundclick.com/lossnyc.htm
>>>
>>>
>>>
>>> http://www.indie911.com/dan-snazelle
>>>
>>> (or for techno) http://www.myspace.com/snazelle
>>>
>>> ALSO check out Dan synth/Fx projects:
>>>
>>> AUDIO ARK:
>>>
>>> www.youtube.com/watch?v=TJRpvaOcUic
>>>
>>> www.youtube.com/watch?v=BqIa_lXQNTA&feature=channel_page
>>>
>>> www.youtube.com/watch?v=V4nJPjGgOcU&feature=channel_page
>>>
>>> and soundtrack/design work:
>>>
>>> NEW: check out Dan's sound design from the 1998 award winning film  
>>> SAFARI by
>>> catherine chalmers
>>>
>>> http://www.catherinechalmers.com/videos.cfm
>>>
>>>
>>>
>>>
>>>
>>>
>>> ----------------------------------------
>>>> From: gsn10 at hotmail.com
>>>> To: synth-diy at dropmix.xs4all.nl
>>>> Subject: RE: [sdiy] AD/DA schematics? quantizers,etc
>>>> Date: Wed, 13 May 2009 11:58:43 -0400
>>>>
>>>>
>>>> That doesn't look like a good circuit design anyway, since it  
>>>> appears to
>>> short the ADC outputs to ground while leaving the DAC inputs  
>>> floating.
>>> Circuit bending really hasn't done the world any favors...
>>>>
>>>> Anyway, a properly-designed variant of that wouldn't be a bad  
>>>> idea, you
>>> could even add a "patch bay" between the inputs and outputs and  
>>> map the
>>> inputs to the outputs any way you want, resulting in some sort of  
>>> primitive
>>> waveshaper that could probably do some sort of frequency  
>>> multiplication or
>>> something. For audio purposes it's probably way too nasty but it  
>>> might be
>>> interesting for CV signals.
>>>>
>>>> ----------------------------------------
>>>>> From: subjectivity at hotmail.com
>>>>> To: synth-diy at dropmix.xs4all.nl
>>>>> Subject: RE: [sdiy] AD/DA schematics? quantizers,etc
>>>>> Date: Wed, 13 May 2009 14:45:44 +0000
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> check this out:
>>>>>
>>>>>
>>> http://experimentalistsanonymous.com/diy/Schematics/Fuzz%20and%20Fuzzy%20Noi
>>> semakers/Digital%20fuzz.bmp
>>>>>
>>>>> i was going to try and build it as it uses an ADC0808 but he  
>>>>> only labels
>>> pins up to 20!....so now i dont know if he just didnt touch pins  
>>> 21-28 or if
>>> i have a totally different chip
>>>>>
>>>>> this is all very confusing!
>>>>>
>>>>>
>>>>>
>>>>> i found another schematic that uses an ADC0804 for the input and  
>>>>> it seems
>>> VERY different than an adc0808 in that it only has a + and a -  
>>> input instead
>>> of 8 multiplexed inputs.
>>>>>
>>>>>
>>>>> in general are the ADC08xxx chips pretty easy to switch for  
>>>>> another one
>>> in the series? or do i need to just go out and order the ADC0804  
>>> if thats
>>> what it calls for?
>>>>>
>>>>> can anyone recommend a good book on AD/DA converters?
>>>>>
>>>>> thanks
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --------------------------------------------
>>>>> check out various dan music at:
>>>>>
>>>>> http://www.myspace.com/lossnyc
>>>>>
>>>>> (updated monthly)
>>>>>
>>>>> http://www.soundclick.com/lossnyc.htm
>>>>>
>>>>>
>>>>>
>>>>> http://www.indie911.com/dan-snazelle
>>>>>
>>>>> (or for techno) http://www.myspace.com/snazelle
>>>>>
>>>>> ALSO check out Dan synth/Fx projects:
>>>>>
>>>>> AUDIO ARK:
>>>>>
>>>>> www.youtube.com/watch?v=TJRpvaOcUic
>>>>>
>>>>> www.youtube.com/watch?v=BqIa_lXQNTA&feature=channel_page
>>>>>
>>>>> www.youtube.com/watch?v=V4nJPjGgOcU&feature=channel_page
>>>>>
>>>>> and soundtrack/design work:
>>>>>
>>>>> NEW: check out Dan's sound design from the 1998 award winning  
>>>>> film SAFARI
>>> by catherine chalmers
>>>>>
>>>>> http://www.catherinechalmers.com/videos.cfm
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> ----------------------------------------
>>>>>> From: subjectivity at hotmail.com
>>>>>> To: tom at electricdruid.net
>>>>>> Subject: RE: [sdiy] AD/DA schematics? quantizers,etc
>>>>>> Date: Wed, 13 May 2009 13:23:39 +0000
>>>>>> CC: synth-diy at dropmix.xs4all.nl
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> yes i have actually built quite a few crushers , some of my own  
>>>>>> design.
>>> they are cool but i am looking for something a bit different
>>>>>>
>>>>>> i suppose what i meant was i was interested in changing BOTH  
>>>>>> the sample
>>> rate AND bit rate of the incoming audio with an AD/DA setup
>>>>>>
>>>>>> thanks!
>>>>>>
>>>>>>
>>>>>>
>>>>>>> Dan,
>>>>>>>
>>>>>>> One quick comment;
>>>>>>>
>>>>>>>> i am really trying at first to make:
>>>>>>>>
>>>>>>>> a sample rate reducer or crusher
>>>>>>>
>>>>>>> These are quite different, reducing the amount of digital data  
>>>>>>> in
>>>>>>> either the X or the Y direction.
>>>>>>> For a sample-rate reduction type effect, you should have a  
>>>>>>> look at
>>>>>>> Tom Bugs' bugcrusher, although it isn't actually reducing any  
>>>>>>> sample
>>>>>>> rates. Rather it's an audio-rate S&H. Still, similar sound.
>>>>>>>
>>>>>>> A real bitcrusher effect would be generated by sampling the  
>>>>>>> input
>>>>>>> with an A/D, then feeding only the most significant bits (you  
>>>>>>> choose
>>>>>>> how many) to the output D/A.
>>>>>>>
>>>>>>> I've got this effect in software on my digital oscillator. It  
>>>>>>> allows
>>>>>>> you to reduce the output resolution from 16-bit down to 1-bit.  
>>>>>>> This
>>>>>>> is further than anyone really needs to go, but it made the  
>>>>>>> control
>>>>>>> easier to do!
>>>>>>>
>>>>>>> HTH,
>>>>>>> Tom
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
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