[PD] Help - filters & band limited oscillators!

Martin Peach martin.peach at sympatico.ca
Thu Mar 15 05:02:01 CET 2007

Did anyone try sqosc~ yet? I'm interested to get feedback on that one.



David Powers wrote:
> Hi Roman, I get the following error from your patch, for many of the tables:
> error: 1002-square33: number of points (512) not a power of 2 plus three
> Along with this error, it seems to stop playing somewhere above 360 Hz...
> Thanks for your help, I'm sorry to sound grumpy, it's just that in
> searching the archives mostly all I found was my old query for a year
> ago. Plus everyone says to use [blosc~] but I posted in my first post,
> that [blosc~] is broken, and I believe that it's known, ie here is
> says:
> http://blog.soundsorange.net/index.php/archives/2006/09/28/exploring-pd-extended/
> "exploring pd extended
> 27/9/2006
> CPU load rating
> blosc~ - intriguing band limited oscillators, but patch is self
> referential and not working"
> Again, a reminder that this isn't really for me, but rather, it's the
> list members chance to sell other people on PD being useful, or not,
> to the outside world. [vst~] is working great so I can demonstrate
> subtractive synthesis with VST's within pure data, but that's
> suggesting to people that PD isn't really good for  traditional
> synthesis... So if you think PD is good for synthesis, let me know
> about it!!!
> ***Note: I personally don't use PD with Gem for VJing, and to make
> weird generative MIDI sequences, mostly... I never really considered
> synthesis a strong point for PD, for reasons that should now be
> obvious.
> ~David
> On 3/14/07, Roman Haefeli <reduzierer at yahoo.de> wrote:
>> hello again
>> i improved guenter's bandlimited square a bit. i noticed that it is
>> hardcoded to 48kHz and accidently i was running pd at 48kHz, that's why
>> it sounded quite good here. however, how far i can see it, the part,
>> that selects the appropriate table, is not working as it should. i
>> couldn't completely follow, how it works, but it seems to switch only
>> correct from tab1 to tab2. for other tabs it switches at too high
>> frequencies, which might introduce a bit aliasing.
>> in my version the tables are generated on loadbang, which makes the file
>> much smaller and easier to adapt for other waveforms. the tabselector is
>> now dependent on the sampling rate, so it should sound well at different
>> rates now.  in order to provide the full spectrum even in low
>> frequencies, i added a raw square generator. below a certain frequency,
>> the oscillator switches to the raw square version, so that it should
>> sound good at arbitrary low frequencies. the number of tables generated
>> on loadbang can be changed. a bigger value lowers the frequency, at
>> which the oscillator switches to the raw version and vice versa.
>> i hope you'll have fun with it.
>> roman
>> On Wed, 2007-03-14 at 04:46 -0600, David Powers wrote:
>>> I found those, but are they really band-limited? I'm fairly sure I
>>> hear ugly digital artifacts in the saw. The square appears to be
>>> broken, unless I made a mistake cutting and pasting those 1500 lines
>>> of code into my text editor (kinda hard to tell).
>>> It's 5 30 am here and I've not slept yet :-(
>>> I can't believe there's STILL no readily available
>>> external/abstraction for such a common synthesis task, I just want a
>>> "nice sounding" example that will compare with the VST's which I will
>>> be hosting from within PD; right now "ASynth" sounds about 100x better
>>> than anything made in PD itself ...
>>> Oh and I don't see any "J" example PD patches, my PD patches don't go
>>> that high.
>>>  ~David
>>> On 3/14/07, Roman Haefeli <reduzierer at yahoo.de> wrote:
>>>> hello david
>>>> i found examples for a bandlimited saw and bandlimited square by g.
>>>> geiger in the archives. might this is what you are looking for.
>>>> http://lists.puredata.info/pipermail/pd-list/2006-05/038681.html
>>>> cheers
>>>> roman
>>>> On Wed, 2007-03-14 at 03:05 -0600, David Powers wrote:
>>>>> Hello everyone,
>>>>> I tried google and it was no help, and the server for the list archive
>>>>> seems to be down temporarily.
>>>>> Anyway, I'm giving a free (as in free beer) workshop in Chicago in
>>>>> about 16 hours, on the basics of digital synthesis. I have decided to
>>>>> use Pure Data to give my presentation, and use mostly non-commercial
>>>>> software.
>>>>> However, I'm still missing the following for demonstrating "proper"
>>>>> subtractive synthesis:
>>>>> 1. Good, out of the box "analog-sounding" filters. I'm using [moog~]
>>>>> right now, but I'm not all that satisfied with the sound compared to
>>>>> the filters in my favorite VST's ...
>>>>> 2. Band-limited square and sawtooth waveforms.
>>>>> For teaching purposes PD is great, and ideal for my demonstrations.
>>>>> But as it is, I'm having to use VST's within PD in order to
>>>>> demonstrate a "nice sounding" synth. It would be nice to show that PD
>>>>> can do it without using stuff built in Steinberg's format. That would
>>>>> also let the Mac people replicate my work, if they are interested.
>>>>> Note, nobody in the workshop has ever tried Linux, except me, so Linux
>>>>> plugins are not helpful in this case.
>>>>> I will post my patches after I give the workshop, though they are
>>>>> nothing fancy ... just basic:
>>>>> sequencer - oscillator - vca - filter. Good for demoing though, I'm
>>>>> starting with additive first, then subtractive.
>>>>> ~David
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