I "solved" the problem by using Maelstrom's implementation from the same thread. Whatever differences there may be in the sound are in no way greater than the fact that the synth actually works now, as I'm performing this evening! :)

However, as this is an interesting issue possibly indicating some sort of regression between Pd 0.38 and 0.48, I've attached the relevant part of the patch. I'm not very good with nuts and bolts DSP stuff, so I barely understand what's going on, I'm just a good black-box programmer who knows how to connect things up based on allegations. ;-)

The relevant bit is in [pd fm_cos].

On Sat, Sep 2, 2017 at 11:10 PM, Alexandre Torres Porres porres@gmail.com wrote:

well, you don't need to do it with fexpr~ i guess, can I see your patch?

2017-09-02 22:35 GMT-03:00 John Swartz graphographer@gmail.com:

...

I implemented the FM feedback algorithm described here by acreil: https://forum.pdpatchrepo.info/topic/6185/feedback-fm-algorithm/10

On my Raspberry Pi 2 setup running Jack in real-time mode, Pd 0.35 handled it fine.

Updating to Pd 0.48, it pegs the cpu meter and the sound is garbled, until I remove the feedback part.

Any ideas?

! john

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