[sdiy] Filter cut off DAC

[Scott Gravenhorst]

paula at synth.net wrote:
>Veronica,
>
>> 12 is a good number in terms of control and cost. If you were to go to
>> 16 you not only have the cost of the DAC but the cost of making the
>> signal path from the DAC match that level. Not too bad at 16 bit but
>> the costs rise.
>
>totally agree.
>
>> So what do you want to do that might push the design goal above 13 bit?
>
>Just thinking, if you add an EG to an LFO and a few other modulation 
>routings I wonder if 12 bits is enough to keep things sounding "smooth".
>
>Paula

Unless you need the values between each integer change, smoothness can be achieved with a
simple single pole IIR low pass filter.  This is how I eliminate zippers in digital
synths (and I realize you want to control an analog device with digital bits).

>
>> 
>>> On May 21, 2018, at 12:40 PM, paula at synth.net wrote:
>>> 
>>> Scott,
>>> 
>>> Thanks, I should've said, I'm more thinking in terms of things like 
>>> ADSRs/LFOs, etc
>>> 
>>> Paula
>>> 
>>>> On 2018-05-21 16:30, Scott Gravenhorst wrote:
>>>> Going from my FPGA experiences, I'd say 10 or 12 is a good starting
>>>> point if not a
>>>> good end point.  I used a 12 bit DAC and it made good quality audio
>>>> (when the level
>>>> used all 12 bits of resolution).  A VCF would probably not even need 
>>>> 12 bits of
>>>> cutoff resolution IMO.  MIDI uses 7 bits of resolution for most
>>>> things, which can
>>>> be a tad low for some things, but for filter cutoff it's probably OK
>>>> as long as you
>>>> don't need to change it during a performance (then you *might* get a
>>>> zipper effect
>>>> and that can be digitally removed).
>>>> YMMV
>>>> paula at synth.net wrote:
>>>>> Random question,
>>>>> How many bits is "enough" for controlling the filter cut off on a 
>>>>> VCF?
>>>>> I would start with say 12, but would 16 be better? or 24?
>>>>> At some point there's a cost trade off.
>>>>> Thoughts?
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>>>> -- ScottG
>>>> ________________________________________________________________________
>>>> -- Scott Gravenhorst
>>>> -- http://scott.joviansynth.com/
>>>> -- When the going gets tough, the tough use the command line.
>>>> -- Matt 21:22
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-- ScottG
________________________________________________________________________
-- Scott Gravenhorst
-- http://scott.joviansynth.com/
-- When the going gets tough, the tough use the command line.
-- Matt 21:22