
terminology becomes a minefield
frequency shifting can be seen as the same thing as single sideband modulation, which is derived from amplitude modulation a/k/a ring modulation
frequency modulation is kinda like amplitude modulation in gross terms, but involves varying frequency information as opposed to amplitude (volume) information.
as i understand it, all of this stuff was developed and first used in radio transmission and telephony before it got ported over to synthesis by early electronic music pioneers. From there it gradually trickled down to guitard luddites until here we are, sorta kinda.
As far as your question, in addition to the Arcing Prisms, check out the Alexander Syntax Error (frequency shifter), EHX Ring Thing in SSB mode (frequency shifting), Catalinbread Bicycle Delay (frequency modulation on repeats), Frayed Knot Electronics Belladonna (also frequency mod on repeats) - sensing a theme here? A lot of these pedals are implementing frequency mod or frequency shifting on delay repeats, I guess because that seems like a way to make this more appealing to buyers


Also - as you probs realize, Arcing Prisms is implementing frequency shifting and comb filtering (no freqmod tho) on delay repeats....

Note: FM synthesis is frequently (haha) actually phase modulation, including in most Yamahas which are at the top of the heap in terms of FM synthesis sales and influence historically.
Iron Ether has an FM synth pedal, as I'm sure you know, the FMeron, which is basically a 2 op FM synth or, in other words, a Frequency Modulator.... While it can produce tones quite reminiscent of FM synths (especially on bass signals), it has a rep for being touchy and creating harsh noises that frustrate many users that thought they were buying the bottom two or three octaves of a DX7. :/
OTOH, I freaking love it, since these "noisy" settings are basically what you get, and I largely want, from a frequency modulator.
So, you may, or may not, want to check that one out too/instead.
Also, the Line 6 MM4 and M series pedals have an algo that sports both amplitude and frequency mod if you want to check that out (M5s go pretty damn cheap over here).

also, i can't remember if Zoom threw some freqmod in the multistomps, but maybe if i stop feeling so logy later on i'll shift myself to look in a manual, though i don't really think it's in there.
same same, i think, for Boss (though i also wouldn't be surprised if they threw it in given the synthesis lineage with Roland/Boss) and Digitech's RP series.
Did i miss anything?
Probs



