Fluxamasynth filter

Interfacing hardware, sensors, output drivers, chips.
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quarterturn
Posts: 3
Joined: Wed Jul 06, 2011 11:44 am

Fluxamasynth filter

Post by quarterturn » Wed Jul 06, 2011 11:56 am

Does anyone know if the SAM2195 does the lowpass filter in software or is it analog in nature? I see in the datasheet a reference to "VBG pin 3 Bandgap Voltage", though this is not referenced in table 6 for the filter.

Well, I guess there is only one way to find out... I'll have to experiment with different cap values than in the datasheet.

One of the bass patches (38 or 39) is just starting to get aggressive sounding with resonance at max, but it's not yet self-oscillating.

Getting that low pass filter to self-oscillate or ring at peaks is the goal! I will update if it is possible.

quarterturn
Posts: 3
Joined: Wed Jul 06, 2011 11:44 am

Re: Fluxamasynth filter

Post by quarterturn » Wed Jul 06, 2011 12:05 pm

On further reflection, badgap voltage has to refer to the DAC. Darn!

paul
Site Admin
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Joined: Mon May 12, 2008 4:19 pm

Re: Fluxamasynth filter

Post by paul » Wed Jul 06, 2011 2:12 pm

quarterturn,

Typically you don't get that kind of fine control in a "canned" chip. I'm wondering about some of the other "Dream" chips with DSP functions though

Paul

quarterturn
Posts: 3
Joined: Wed Jul 06, 2011 11:44 am

Re: Fluxamasynth filter

Post by quarterturn » Wed Jul 06, 2011 3:10 pm

Well, that there's a resonant lowpass filter at all is pretty good. As far as I can tell "pushing" the filter just leads to clipping or heavy odd harmonics on some voices, eg. bank 0 voice 1. I have not yet figured how to get it to switch to bank 1.

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