I programmed a few wave shaper and wave folder modules for my digital modular synthesizer. Because these modules can add lots of harmonics, they all use oversampling (implemented with poly~). They all work, except the most simple one.

See the attached ZIP file:
1. download the ZIP file
2. extract the ZIP file
3. open “test_power_shaper~.maxpat” in Max
4. see the instructions in the patch

What’s the problem?

Surprisingly, some other shapers I programmed use several pow~ objects and work normally (when tested one by one)

Tested with Max 6.0.7 on Windows 7 64-bit

Cheers

This reminds me this old topic:
http://cycling74.com/forums/topic.php?id=36397#post-176724
and after one year, it doesn’t sound to have been corrected…

p

But when the resampling attribute is set to zero, there are no more resampling filters. As far as I understand, these filters are anti-aliasing filters, though this is not clearly stated in the manual. I am using oversampling ONLY for reducing the aliasing when the synthesis introduces some frequencies that are higher than sample_rate/2, so turning these filters off is not really possible. Or do I have to program my own anti-aliasing filter, as you do in Pure Data? In this case, which kind of filter is recommended?

About the problem you mentioned with groove~, I confirm it still does not work either :(

To complicate things, I had some other problems with oversampling in Max (still when using poly~), but I don’t really want to post them immediately because it may confuse things a lot.

Seriously, removing aliasing can improve the sound a lot, and in some cases, I don’t know how to reduce aliasing besides “hardcore” oversampling and anti-aliasing filters.

From a musical result’s point of view, something is missing in the shaper I posted: the input signal (from -1 to 1) should be scaled between 0 and 1 before the shaper processing, and re-scaled between -1 and 1 after the shaper.

But this does not correct the problem

and as I said I found other problems related to oversampling

makes me think it’s actually not possible to use oversampling in Max :(

because to me it seems like a weird pow~ bug. all my other up/down antialiasing sampling works perfectly, but i cannot get your examples to work at all, just as you say.

no idea what it could be.