KVR Audio

aciddose · Post by **aciddose** » Mon Feb 23, 2015 1:58 am

How many synthesizers are "true FM" ?

Zero.

What is the difference between amplitude (two quadrant) and ring (four quadrant) modulation?

Four quadrant modulation produces no residual carrier signal.

Other than that, this is like asking what is the difference between the direction up and the direction down. Nothing, they're merely different directions and depend wholly upon the observer to define.

http://en.wikipedia.org/wiki/Analog_multiplier

Naenyn · Post by **Naenyn** » Mon Feb 23, 2015 2:56 am

BlackWinny wrote:Nothing will be better source than the datasheet itself:

http://www.dtech.lv/files_ym/ym2151.pdf

Thank you for pointing that out! I should have read more thoroughly before posting here. I was hoping someone here had experience with their chips.

AdmiralQuality wrote:
Naenyn wrote:true FM?
Here we go again...

Oh knock it off. I'm doing research. I'm here for info. I'm not trying to start an argument or beat a dead horse.

AdmiralQuality · Post by **AdmiralQuality** » Mon Feb 23, 2015 2:58 am

Naenyn wrote:
AdmiralQuality wrote:
Naenyn wrote:true FM?
Here we go again...
Oh knock it off. I'm doing research. I'm here for info. I'm not trying to start an argument or beat a dead horse.

You knock it off. We have 11 pages before this explaining why the term "true FM" is meaningless in the context of music synthesizers. (What's "false FM" then?)

aciddose · Post by **aciddose** » Mon Feb 23, 2015 3:07 am

Naenyn, be very careful doing "research" on a web forum. If you're not smart enough to intuit this, listen up: the majority of comments will provide absolutely no useful information and come from completely incredible sources.

Regarding your comment about "FM able to go up in frequency forever", you are confused.

If you phase modulate, a pulse input will produce a single-sample jump equal to the amplitude of the pulse.

If you frequency modulate, a pulse input will continuously set the frequency at the modulated position.

It is impossible for a PM algorithm to produce a continuous frequency modulation because it would require an infinite numerical range to do so.

It is possible to integrate the modulation signal, then use the integral for phase modulation. This will produce the same result as frequency modulation merely phase-shifted by the integration. Unfortunately, it should be clear now why this can not be continuous.

The integral of any continuous value is infinite. So to represent a continuous frequency modulation through phase modulation requires the ability to represent a number of infinite magnitude.

AdmiralQuality · Post by **AdmiralQuality** » Mon Feb 23, 2015 3:12 am

Somebody wants to move this to PM. But not me...

Naenyn wrote:Subject: Which "FM" synths really are FM?
AdmiralQuality wrote:You knock it off. We have 11 pages before this explaining why the term "true FM" is meaningless in the context of music synthesizers. (What's "false FM" then?)
What is your problem? I'm looking for information. I'm asking a legitimate question. The term may be meaningless to you, but it is not to me. I'm even asking a specific question about a specific chip. All I needed was a "yes/no, see <this link">. My own fault for not reading farther into what I posted.

But all of that aside, if you don't want to read about what I'm asking about, then don't read it. Why do you have to try and stir up trouble?

My problem is, your question is stupid. That's your problem too, and you should appreciate the guidance you're getting here from myself and the other "incredible sources".

aciddose · Post by **aciddose** » Mon Feb 23, 2015 3:18 am

His question isn't stupid AQ, many of the answers he has received are undeniably so.

He should have been given the explanation of integral/differential and allowed time to comprehend then that PM and FM are the same thing, exactly like AM and RM are the same.

With all the bullshit posted here there is little reason to think he'll ever benefit by visiting this forum to ask his question.

AdmiralQuality · Post by **AdmiralQuality** » Mon Feb 23, 2015 3:21 am

aciddose wrote:His question isn't stupid AQ, many of the answers he has received are undeniably so.

He should have been given the explanation of integral/differential and allowed time to comprehend then that PM and FM are the same thing, exactly like AM and RM are the same.

With all the bullshit posted here there is little reason to think he'll ever benefit by visiting this forum to ask his question.

Yeah AD, I'm sure your explanation was really helpful to him.

What you just said is FAR more helpful. "PM and FM are the same thing." There you go, layman's terms.

aciddose · Post by **aciddose** » Mon Feb 23, 2015 3:24 am

Just because you never took calculus doesn't mean he hasn't.

AdmiralQuality · Post by **AdmiralQuality** » Mon Feb 23, 2015 3:28 am

aciddose wrote:Just because you never took calculus doesn't mean he hasn't.

Gotta prove you're smarter than everybody all the time, don't you Elliot? Too bad you're a complete failure when it comes to finishing a job and getting actual, useful results.

Naenyn · Post by **Naenyn** » Mon Feb 23, 2015 3:29 am

aciddose wrote:Naenyn, be very careful doing "research" on a web forum. If you're not smart enough to intuit this, listen up: the majority of comments will provide absolutely no useful information and come from completely incredible sources.

I appreciate the advice. It is the posts that include references that I tend to give more weight to.

aciddose wrote:Regarding your comment about "FM able to go up in frequency forever", you are confused.

If you phase modulate, a pulse input will produce a single-sample jump equal to the amplitude of the pulse.

If you frequency modulate, a pulse input will continuously set the frequency at the modulated position.

It is impossible for a PM algorithm to produce a continuous frequency modulation because it would require an infinite numerical range to do so.

It is possible to integrate the modulation signal, then use the integral for phase modulation. This will produce the same result as frequency modulation merely phase-shifted by the integration. Unfortunately, it should be clear now why this can not be continuous.

The integral of any continuous value is infinite. So to represent a continuous frequency modulation through phase modulation requires the ability to represent a number of infinite magnitude.

Thanks for the interesting info. It gave me some ideas for more digging!

AdmiralQuality wrote:Somebody wants to move this to PM. But not me...

Because... you like causing a scene? I moved to PM because it didn't make sense to me to involve everyone in a discussion about a problem you clearly have with me. If you can't be civil, then I suppose there is no sense in trying to discuss this with you.

EDIT: I have a feeling this is a good time for a lock, so...