Yes, it doesn’t matter if you use that LFO (running at low audio rate) to do phase modulation, linear through zero frequency modulation, amplitude modulation, ring modulation, or filter cutoff modulation - they will all produce the same beat frequency, though totally different timbres.
It seems like the cutoff modulation ought to be most similar to amplitude modulation, but they sound quite different.
You will hear a similar wavy effect indeed. It’s only called “beating” when it happens because of detuning between oscillators though.
100% amplitude modulation (output levels between zero and twice the carrier amplitude) with a let’s say 5Hz sine LFO is exactly the same und indistinguishable from two sines with a 10 Hz frequency difference. Both produce the exact same beating effect.
In the specific case of pure sine waves, the sounding result would be the same indeed. In most (probably all) other cases it wouldn’t.
In any case, the point was that the term “beating” in particular isn’t commonly used to describe LFO modulation of a filter or such, not is it “the same thing that happens” as per the original question.
In particular low audio rate lfo into filter is a huge part of the “acid sound” is it not?
A saw or square into a moving resonant filter is the Acid thing indeed. In the early days of the style the movement would come from the musician physically playing with the cutoff dial on a TB303. But an LFO (or any other method of moving the cutoff around) will do the thing too.
Here I tried to patch it so that it seems as it is the kick that is causing the instability of the squarewave drone. I could only make it works because by the clock setting i knew i have a kick every two seconds, so i had assistance from that frame when i dialed in the trigger delay at 0.22892 that opens the gate which is open for 0.054848 and lets thru the random modulation. It woul be useful to patch it somehow so the relation is that the modulation starts shortly after the kick starts by default or automation. Maybe also the problem her is that for some hits it appears as the kick makes the drone weaker, that is when the random modulation starts by lowering the filter instead of increasing it.
kick is causing the modulation.vcv (3.6 KB)
Also i find it hard to dial in a believable setting on the random scourse itself, it tends to output to much of the small movements that has a “scratching effect” instead of a vibrating effect.
Like when you are at a venue and the kick from the speaker makes the speaker grills and everythign else arond it vibrate. That effect. 
