fmr wrote:aciddose wrote:When you don't understand something like "two quadrant vs. four quadrant modulation" it won't help you to just change the subject to something entirely unrelated.

I'll explain what you two are very clearly missing out on:

In an operation there are two variables: x, y

Each of these variables has two "quadrants": negative and positive.

This reduces to a simple multiplication:

1 quadrant * 2 quadrants = 2 quadrants (two quadrant multiplication / modulation)

2 quadrant * 2 quadrants = 4 quadrants (four quadrant multiplication / modulation)

Idiotic post as usual. First, you confused tremolo with vibrato (a noob mistake), and said that RM is similar to FM. Now, you come with this, maybe attempting to launch a cloud over your previous dumb assertion. I only pointed the mistakes, politely (without video links).

here is what you wrote:aciddose wrote: In fact ring mod is more like FM than AM, which is a partial (reduced depth) version of ring mod. In that sense ring mod is like FM; AM is like vibrato.

Your last answer is the usual, and as usual, nothing of what you said above adds anything useful to the discussion.

And, of course, the usual pict and video links, that "enlighten" a lot. Typical

I think that you're missing something. There's little wrong with either of his posts. I'm not clear on the analogy to AM with vibrato, but it was qualified by the prior statement and his entire post was about technical understanding and analogy so I can't say that the analogy was incorrect, per se. Please don't bang on about vibrato vs tremolo, I know what the difference is and I'm giving acidose the benefit of the doubt here and believe that he does as well. It's possible that his comment was in error, it's also possible, that he was drawing an analogy from a different perspective, I will let him comment on that. In either case, it does not dismiss the rest of his post.

On Edit: Ok, it's clear now that all he meant was that AM is like vibrato in that they both are examples of two quadrant multiplication, one in amplitude, the other in frequency. Similarly, Ring Mod is like FM in that they are both examples of four quadrant multiplication, one in amplitude, the other in frequency. Sorry for the repetition below, I'm just going to leave the post intact.

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FM is like RM in the sense that it's four quadrant multiplication applied to frequency as opposed to amplitude. That defines a sense of comparison from a technical point of view, it is not incongruent with RM is a form of AM, both statements are true.

His post above should not "launch a cloud" for anyone who understands what a quadrant is. In mathematics a quadrant is a region of the x/y plane partitioned by the axes. Since there are four of them, they are called, naturally, quadrants.

A VCA is the classic example of a two quadrant multiplier. The signal is bipolar, i.e. lies in two quadrants, whereas the CV (or modulator) is unipolar, i.e., it lies in one quadrant. Hence the result lies in two quadrants. That is, the output is a scaled version of the input signal. We don't expect a VCA to accept negative control voltages.

Now, if we use a four quadrant multiplier we could apply negative control voltages as well. Positive control voltages would behave as the VCA, negative control voltages would also scale just as positive voltages do, but would invert the signal.