| Author |
Message |
Jerry Avins
Guest
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 Posted:
Sat Oct 08, 2005 12:55 am Post subject:
Re: Questions about FM synthesis and amplitude |
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Ben Bradley wrote:
...
| Quote: | I do believe "carrier" is a legitimate term as used in FM
music/sound synthesis, though I can see where it can trigger others to
assume it means an RF frequency.
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That's right. If I implied otherwise, I was wrong.
...
Jerry
--
Engineering is the art of making what you want from things you can get.
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ
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Radium
Guest
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| Posted:
Sat Oct 08, 2005 1:03 am Post subject:
Re: Questions about FM synthesis and amplitude |
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Ben Bradley wrote:
| Quote: | But you're certainly right that the OP shouldn't be reading about
RF FM generation if he wants to learn about FM music/sound synthesis.
|
I don't get any of info from reading about FM radio. FM radio is topic
that is toally irrelevant and boring to me. I get my thoughts from
reading about the most basic roles of modulator and the carrier in FM
synthesis.
Screw radio.
People like Real Mccoy [no offense] need to know that I have read
nothing about FM radio and don't care about it at all. Once again, I
got my thoughts [faulty as they are] from reading about FM synthesis
and what the mod and carrier does.
I repeat, I have never read about radio FM at all! At all! FM radio is
a dead-boring topic! I don't care about it! I never read it!
It is FM *Synthesis* that interests me. It is FM *synthesis* that I
read about. |
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J Ketutsalo
Guest
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| Posted:
Sat Oct 08, 2005 1:28 am Post subject:
Re: Questions about FM synthesis and amplitude |
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Ben Bradley wrote:
| Quote: |
How can a sound vary in its volume if it can't change its amplitude?
Well, that is another totally unrelated story...
Please tell me the "story"
Well, Mr. Ketutsalo?
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Well, I probably shouldn't have written what I did, but here we go. :-)
First we have to define volume and amplitude. Consider any harmonic (or
inharmonic) complex, i.e., anything but a single sinusoid. That is what
you get from FM synthesis, anyway. From signal theoretical point of
view, peak amplitude (or amplitude curve) and the power of the signal do
not have a simple relationship. By altering the phase relations of the
partials you can change the amplitude quite a bit without affecting the
signal power, or the other way around you can keep, for instance, the
peak amplitude constant and alter the power. Of course, RMS amplitude is
always related to power.
Once you enter the psychoacoustic domain, things get even trickier. The
perceived loudness (what I would like to call volume) of two or more
sinusoids depends on the absolute pitches of the sinusoids, as well as
on their frequency relations. The sensitivity of the ear is quite
different at different frequencies. Furthermore, if two sinusoids fall
into the same critical band (analysis band of the ear) the loudness is
different from the case where they fall into different critical bands.
The frequency domain behavior is pretty well understood but taking the
temporal character of sound into account is even more complicated, and
especially in this context psychoacousticians still don't understand
everything about loudness perception.
So, not really relevant for FM synthesis and I'd rather leave it there.
This is a huge topic and not exactly my field... |
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Richard Dobson
Guest
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| Posted:
Sat Oct 08, 2005 4:10 am Post subject:
Re: Questions about FM synthesis and amplitude |
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Radium wrote:
...
| Quote: | But on the web pages I read. The carrier does not change by its
amplitude ..
|
This must be the source of the problem. What web pages, exactly?
It would be a good idea in your case not to anthropomorphise these things too
much. An oscillator used as a carrier "does not change.." because it is a
machine without either consciousness or intention, devised by a human, and the
human can do what the h*** it likes, such as changing the amplitude of a signal.
A human musician is not bound by theory, and if they want to apply an oscillator
to the bandwidth control of a filter "to see what happens", they will jolly well
go ahead and do it, and leave others to come up with explanations and theories
about what happens.
So I suggest, again, stop wracking your brain with these questions, get Csound:
http://www.csounds.com/
get the Csound book (have you got any books on this stuff?):
http://csounds.com/book/index.html
and make an FM synthesizer from first principles. I predict four lines of
code, for each of two envelopes and two oscillators. In a patch diagram, all
oscillators, including the one used as a carrier for FM, show two control
inputs, for frequency and amplitude.
Richard Dobson |
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(null
Guest
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| Posted:
Sat Oct 08, 2005 4:42 am Post subject:
Re: Questions about FM synthesis and amplitude |
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Jerry Avins <jya@ieee.org> wrote:
| Quote: | Radium wrote:
It would make more sense to me, if the initial signal was a signal that
only varied by its frequency [carrier] and this initial signal
modulated the latter signal [modulator] in the following manner:
Everything would make more sense to you if you found out how they work,
instead of deciding that you know.
|
Jerry: Radium did the same thing last time it was on the group.
You're wasting your time: no way that pig's gonna learn to sing.
Francois. |
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Jerry Avins
Guest
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| Posted:
Sat Oct 08, 2005 4:42 am Post subject:
Re: Questions about FM synthesis and amplitude |
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(null) wrote:
| Quote: | Jerry Avins <jya@ieee.org> wrote:
Radium wrote:
It would make more sense to me, if the initial signal was a signal that
only varied by its frequency [carrier] and this initial signal
modulated the latter signal [modulator] in the following manner:
Everything would make more sense to you if you found out how they work,
instead of deciding that you know.
Jerry: Radium did the same thing last time it was on the group.
You're wasting your time: no way that pig's gonna learn to sing.
|
Yeah; I was there. It seemed hopeful for a while. Time to quit for a
time. (Maybe some day he'll learn what a bit is.)
Jerry
--
Engineering is the art of making what you want from things you can get.
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ |
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John L
Guest
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| Posted:
Sat Oct 08, 2005 8:55 pm Post subject:
Re: Questions about FM synthesis and amplitude |
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Hi Radium
I see this is driving you nuts, and I hope -unlike the
element whose name you've adopted- you're not decaying
under the stress; no offence intended, just couldn't
resist the urge to pun ;)
Ok.
I was deeply into my DX synths for years. I no longer
dabble, but miss it. I hope my memory serves me well
enough to help.
<politely snipped at times>
Radium wrote:
| Quote: | In FM synthesis, I have read that the sound we hear is the carrier
wave.
|
Correct. We hear only the carrier wave(S).
| Quote: | But the carrier wave can only change by its frequency. Only the
modulator can change by amplitude.
|
Not so...see below...
| Quote: | So how is it that the audio output
from the FM synth can change loudness? The carrier wave is the audio
output. It is very confusing and frustrating question for me.
|
The simplest answer is that the carrier's amplitude - its
output level, the volume of the sound you hear - is determined
by a number of factors, primarily the output level you select;
ADSR envelope; key velocity, key pressure, various controller settings.
| Quote: | It would make more sense if the carrier controlled the modulator.
|
If you reversed the situation, you'd just end up with the
"ex-modulator" becoming the very carrier that's confusing you.
| Quote: | The carrier can only change by frequency.
|
No....
You can control the amplitude of the carrier. (FM wouldn't be
much use if we couldn't.)
The carrier's output level is set by you; but this output
level can be influenced by ADSR, velocity, pressure, and LFO.
| Quote: | The modulator can change by both > frequency *and* amplitude.
|
Yes it can....see above.
| Quote: | It would make more sense if the FM signal
generated by the carrier would be convert to audio by the modulator and
the modulator signal would be what we would hear. But that isn't the
case.
|
That's not the case because what you describe wouldn't be
FM synthesis. FM gives VAST opportunities to create complex
waveforms by modulating one sinewave oscillator with one or more
other sinewaves - that is the fundamental principal of FM (Frequency
Modulation) synthesis.
| Quote: | In reality, the modulator controls the carrier.
|
To be more precise, the modulator *modulates* the carrier
- that's FM synthesis.
| Quote: |
The FM output signal is the frequency-varying carrier signal.
|
The carriers output frequency only "varies" if modulated by the
LFO, or by a modulator set at a low frequency. More often, we hear the
carrier's frequency as "fixed" (apart from LFO), the timbre of the
carrier being determined by the frequency and amplitude of its
modulator(s).
| Quote: | The carrier can only change by its frequency. The carrier
cannot change by its amplitude, thus the audio cannot change
by its loudness.
|
The carrier's loudness can indeed change. ADSR envelope, key
velocity, etc.
| Quote: | It would make more sense to me, if the initial signal was a signal that
only varied by its frequency [carrier] and this initial signal
Modulated the latter signal [modulator] in the following manner:
1. Depth of the change of 1st signal's frequency determined the
loudness of the 2nd signal
|
Yes, that would be handy, and would lead to better leslie
emulations, but it would further complicate the editing
process (I wouldn't mind).
But you CAN control the amplitude of the carrier
to a large degree - the envelope generators on the DX7 for
example gives you a 5-stage "ADSR" - more than you find on most
synths.
| Quote: | 2. Rate of the change of the 1st signal's frequency determined the
pitch of the 2nd signal
|
I don't know what you mean by "rate of change". You also lost me
with "1st and 2nd signal".
| Quote: | Apparently this is not the case in FM synthesis [it is the reverse].
This is why I'm confused.
If the carrier signal is what we hear, then all we should hear is tones
whose loudness remains constant. Right? This would obviously not
classify as music.
|
But you've heard the FM sounds; they ARE musical, expressive
and dynamic. The sounds you hear can only be the carriers, so that
should prove that there is something missing in your understanding
of FM. FM is basically simple, but the *wonderful* range of editable
parameters makes for painstaking effort and attention to detail -
IMO it's WELL worth the effort.
| Quote: | Any assistance would be appreciated
|
Try to find a copy of "The Complete DX7" on eBay. All will be revealed
therein. I wish I could remember more!
Good luck.
John. |
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Radium
Guest
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| Posted:
Sat Oct 08, 2005 11:02 pm Post subject:
Re: Questions about FM synthesis and amplitude |
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Thanks so much for your understanding and assistance. Its been a long
time since anyone has able/willing to answer this question of mine.
John L wrote:
| Quote: | Hi Radium
I see this is driving you nuts, and I hope -unlike the
element whose name you've adopted- you're not decaying
under the stress; no offence intended, just couldn't
resist the urge to pun ;)
Ok.
I was deeply into my DX synths for years. I no longer
dabble, but miss it. I hope my memory serves me well
enough to help.
politely snipped at times
Radium wrote:
In FM synthesis, I have read that the sound we hear is the carrier
wave.
Correct. We hear only the carrier wave(S).
But the carrier wave can only change by its frequency. Only the
modulator can change by amplitude.
Not so...see below...
So how is it that the audio output
from the FM synth can change loudness? The carrier wave is the audio
output. It is very confusing and frustrating question for me.
The simplest answer is that the carrier's amplitude - its
output level, the volume of the sound you hear - is determined
by a number of factors, primarily the output level you select;
ADSR envelope; key velocity, key pressure, various controller settings.
It would make more sense if the carrier controlled the modulator.
If you reversed the situation, you'd just end up with the
"ex-modulator" becoming the very carrier that's confusing you.
The carrier can only change by frequency.
No....
You can control the amplitude of the carrier. (FM wouldn't be
much use if we couldn't.)
The carrier's output level is set by you; but this output
level can be influenced by ADSR, velocity, pressure, and LFO.
The modulator can change by both > frequency *and* amplitude.
Yes it can....see above.
It would make more sense if the FM signal
generated by the carrier would be convert to audio by the modulator and
the modulator signal would be what we would hear. But that isn't the
case.
That's not the case because what you describe wouldn't be
FM synthesis. FM gives VAST opportunities to create complex
waveforms by modulating one sinewave oscillator with one or more
other sinewaves - that is the fundamental principal of FM (Frequency
Modulation) synthesis.
In reality, the modulator controls the carrier.
To be more precise, the modulator *modulates* the carrier
- that's FM synthesis.
The FM output signal is the frequency-varying carrier signal.
The carriers output frequency only "varies" if modulated by the
LFO, or by a modulator set at a low frequency. More often, we hear the
carrier's frequency as "fixed" (apart from LFO), the timbre of the
carrier being determined by the frequency and amplitude of its
modulator(s).
The carrier can only change by its frequency. The carrier
cannot change by its amplitude, thus the audio cannot change
by its loudness.
The carrier's loudness can indeed change. ADSR envelope, key
velocity, etc.
It would make more sense to me, if the initial signal was a signal that
only varied by its frequency [carrier] and this initial signal
Modulated the latter signal [modulator] in the following manner:
1. Depth of the change of 1st signal's frequency determined the
loudness of the 2nd signal
Yes, that would be handy, and would lead to better leslie
emulations, but it would further complicate the editing
process (I wouldn't mind).
But you CAN control the amplitude of the carrier
to a large degree - the envelope generators on the DX7 for
example gives you a 5-stage "ADSR" - more than you find on most
synths.
2. Rate of the change of the 1st signal's frequency determined the
pitch of the 2nd signal
I don't know what you mean by "rate of change". You also lost me
with "1st and 2nd signal".
Apparently this is not the case in FM synthesis [it is the reverse].
This is why I'm confused.
If the carrier signal is what we hear, then all we should hear is tones
whose loudness remains constant. Right? This would obviously not
classify as music.
But you've heard the FM sounds; they ARE musical, expressive
and dynamic. The sounds you hear can only be the carriers, so that
should prove that there is something missing in your understanding
of FM. FM is basically simple, but the *wonderful* range of editable
parameters makes for painstaking effort and attention to detail -
IMO it's WELL worth the effort.
Any assistance would be appreciated
Try to find a copy of "The Complete DX7" on eBay. All will be revealed
therein. I wish I could remember more!
Good luck.
John. |
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Radium
Guest
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| Posted:
Sat Oct 08, 2005 11:16 pm Post subject:
Re: Questions about FM synthesis and amplitude |
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John L wrote:
| Quote: | But you've heard the FM sounds; they ARE musical, expressive
and dynamic. The sounds you hear can only be the carriers, so that
should prove that there is something missing in your understanding
of FM. FM is basically simple, but the *wonderful* range of editable
parameters makes for painstaking effort and attention to detail -
IMO it's WELL worth the effort.
|
Yes. I love my SB16 FM synth [Creative Music Synth]. IMHO all MIDI
synths other than Creative Music Synth [220] suck badly. |
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Jerry Avins
Guest
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| Posted:
Sun Oct 09, 2005 4:42 am Post subject:
Re: Questions about FM synthesis and amplitude |
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Mr.T wrote:
| Quote: | "Radium" <glucegen1@excite.com> wrote in message
news:1128795415.995011.149870@f14g2000cwb.googlegroups.com...
Yes. I love my SB16 FM synth [Creative Music Synth]. IMHO all MIDI
synths other than Creative Music Synth [220] suck badly.
Did you forget the smiley? I assume you were being sarcastic.
The SB16 FM synth sure did suck badly! Even the better PC games gave you the
option of using the Roland MT32 FM synth instead.
Fortunately things have moved on, and we can forget about all that crap.
MrT.
|
He's serious. His taste is as deficient as his arithmetic.
Jerry
--
Engineering is the art of making what you want from things you can get.
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ |
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Mr.T
Guest
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| Posted:
Sun Oct 09, 2005 4:42 am Post subject:
Re: Questions about FM synthesis and amplitude |
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"Radium" <glucegen1@excite.com> wrote in message
news:1128795415.995011.149870@f14g2000cwb.googlegroups.com...
| Quote: | Yes. I love my SB16 FM synth [Creative Music Synth]. IMHO all MIDI
synths other than Creative Music Synth [220] suck badly.
|
Did you forget the smiley? I assume you were being sarcastic.
The SB16 FM synth sure did suck badly! Even the better PC games gave you the
option of using the Roland MT32 FM synth instead.
Fortunately things have moved on, and we can forget about all that crap.
MrT. |
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Radium
Guest
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| Posted:
Sun Oct 09, 2005 4:42 am Post subject:
Re: Questions about FM synthesis and amplitude |
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Mr.T wrote:
| Quote: | Did you forget the smiley? I assume you were being sarcastic.
|
No f--king way!
| Quote: | The SB16 FM synth sure did suck badly!
|
In what universe?
| Quote: | Even the better PC games gave you the
option of using the Roland MT32 FM synth instead.
|
LOL! Roland MT["empty"]32 was probably a steenking FM-emulator. F--k
that crap.
| Quote: | Fortunately things have moved on, and we can forget about all that crap.
|
You think stale rotten sample-playback synthesis is superior to the
fresh lively FM synthesis of SB16. What you smokin dude?!
I feel like making some nanobots that will specifically invade the
sample-playback synths of all synths and pollute the already polluted
sample-playback audio with audible magnetic interference.
Sample-playback = human kaka |
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Radium
Guest
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| Posted:
Sun Oct 09, 2005 4:42 am Post subject:
Re: Questions about FM synthesis and amplitude |
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Radium wrote:
| Quote: | I feel like making some nanobots that will specifically invade the
sample-playback synths of all synths and pollute the already polluted
sample-playback audio with audible magnetic interference.
|
CORRECTION:
I feel like making some nanobots that will specifically invade the
chips of all sample-playback synths and pollute the already polluted
sample-playback audio with audible magnetic interference. |
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Mr.T
Guest
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| Posted:
Sun Oct 09, 2005 11:36 am Post subject:
Re: Questions about FM synthesis and amplitude |
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"Radium" <glucegen1@excite.com> wrote in message
news:1128826463.062989.77660@g14g2000cwa.googlegroups.com...
| Quote: | LOL! Roland MT["empty"]32 was probably a steenking FM-emulator. F--k
that crap.
|
It was a lot better than the SB16 FM, but I did make a mistake. I meant the
Yamaha FB01 which *WAS* an FM synth, or cut down version of the DX7 that
Yamaha used to make FM sythesis famous in the first place. Yamaha made the
DX7, long before the cheap crappy chips made by Yamaha, that creative used
on their crappy sound cards.
The FB01 was also a real FM synth module with less performance, but FAR more
than the Soundblaster. It was supported by all the early Sierra games,
amongst others.
The MT32 was much better than the FB01 though. Thankfully things have really
moved forward in the *many* years since then though.
| Quote: | Fortunately things have moved on, and we can forget about all that crap.
You think stale rotten sample-playback synthesis is superior to the
fresh lively FM synthesis of SB16.
|
Yes I do think so, as does anybody with knowledge of sampling quality based
in THIS century.
| Quote: | What you smokin dude?
|
Obviously not what YOU are.
You are only further proving your total ignorance of music synthesizers,
sound cards, and sample players.
MrT. |
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Radium
Guest
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| Posted:
Sun Oct 09, 2005 8:04 pm Post subject:
Re: Questions about FM synthesis and amplitude |
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Mr.T wrote:
| Quote: | Yamaha made the
DX7, long before the cheap crappy chips made by Yamaha, that creative used
on their crappy sound cards.
|
Didn't Creative also make its own FM chip? |
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