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Frequency Drifting w/ Multiple Value ?!?

I checked this multpile times to make sure this was truly occuring -- the frequency of the Operators gets slightly sharp as you increate the Multiplier value. The discrepency increases with higher multiplier values.

Take the init patch & configure as Op 3->2->1(carrier) Set Op 3, 2 waves to Saw2, Op1 to Sine. Op 3 Vol= 22, Op 2 Vol = 30 Op1 = 127. Turn off all velocity sensitivity.

Play the C one or two octaves below middle C. With all Ops at Multiplier = 1, the timbre is absolutely static. Change the Multiple for Op 3 = 2. Hold the note, you'll hear the timbre harmonics start to drift very slowly. Change Op 3 Mult = 3 and the drift is faster. Gets proportionally faster the higher the multiplier.

It can almost, but not quite, be corrected by setting the Freq Fine value of (negative) Multiplier - 1, i.e. if Multiplier=3, set Freq fine =-2

It appears that the Ops lose their Freq lock when the Multiplier vale.

Can you please confirm? All Ops are Fixed phase...


This is normal, this is due to the way frequencies are handled in the FM engine, it has been discussed here:

That will happen or not depending on the note frequency and ratios between operators.
Thnx for the link reference... Interesting behavior, not something I've seen in other FM implementations.

Is this something that will be just be a characteristic of the Essense? Or is it something that can be addressed in the future?

In some cases it is a nice variation from the normal, in other cases it 'breaks' a sound.

It will most likely stay as a characteristic of the EssenceFM.
Playing static tones for seconds is almost never wanted, and if you really want that you can simply use a custom waveform with the harmonic content of your choice.
The fact the the beating gets faster as the multiplier value is increased looks more like a rounding error that gets amplified rather than an unavoidable one...imho this should deserve a full investigation :/