Paula FM synthesis

[Joel_w]

I remember hearing that Paula is capable of FM synthesis, or at least something similar, instead of just playing samples. I’m not talking about a soft synth but an actual feature in the chip.

Are there any examples of this being used? I guess it can’t be used in a mod but maybe in a demo or game so I can hear what it sounds like.

I found this old thread talking about it, but without any examples.

https://forum.amiga.org/index.php?topic=54117.0

[Gerry]

Sonic Arranger was able to produce synthetic sounds. It was used by Matthias Steinwachs for Lionheart and Ambermoon.

[derSammler]

But that is a soft synth.

Afaik, PAULA had no FM synthesis of any kind.

[ross]

Originally Posted by Joel_w

I remember hearing that Paula is capable of FM synthesis, or at least something similar, instead of just playing samples. I’m not talking about a soft synth but an actual feature in the chip.

Are there any examples of this being used? I guess it can’t be used in a mod but maybe in a demo or game so I can hear what it sounds like.

I found this old thread talking about it, but without any examples.

https://forum.amiga.org/index.php?topic=54117.0

https://www.pouet.net/prod.php?which=65872

I didn't check if AM (volume) or FM (period) or both modulation is used, but for sure it use hardware modulation

[derSammler]

Originally Posted by ross

I didn't check if AM (volume) or FM (period) or both modulation is used, but for sure it use hardware modulation

No, it is not. That's the same you can e.g. do with the PC speaker. And you do it because there is *no* hardware FM synthesis.

The question was not if PAULA can produce beeps on its own. It can, of course.

[ross]

Originally Posted by derSammler

No, it is not. That's the same you can e.g. do with the PC speaker. And you do it because there is *no* hardware FM synthesis.

The question was not if PAULA can produce beeps on its own. It can, of course.

Oh well, give me a definition of "frequency modulation synthesis" and then let's see if Paula can't do it in hardware (and I'm not talking about a synthesis made by changing the samples in memory, or real time period, via software).

EDIT: of course it is very limited and inconvenient and eliminates one channel for each modulated channel (the reason why it is not used..), but technically it is
a feasible synthesis.
Listen carefully to the demo I linked. It doesn't do any kind of software modulation.

[Karlos]

FM synthesis, or what most people think of when they hear the term, is actually phase modulation. The instantaneous phase of the carrier wave is modified by the modulator. There's no actual change of frequency, this is the emergent property of the phase modulation. The phase adjustment is linear - take the instantaneous amplitude of the modulator, multiply it by some modulation index (intensity) and add it to the phase input for the carrier. Both carrier and modulator are both operating at some fixed sample period in a digital implementation.

What Paula offers is Period Modulation. The period register for a channel can be fetched by a different channel and poked in. The two channels are not operating at the same period, unless by coincidence. The whole arrangement is very different, but it is a genuine hardware feature.

[no9]

Originally Posted by derSammler

That's the same you can e.g. do with the PC speaker.

The uniformity of the results doesn't answer the question of whether it is capable of achieving this through its hardware features. I doubt that the 'PC speaker' has any registers to trigger that. Not to mention, it would need to have at least two channels (sources) to modulate between them. Do you think it really has these features? If not it is not the same.

[ross]

Originally Posted by Karlos

The whole arrangement is very different, but it is a genuine hardware feature.

This.
It is a surrogate of FM synthesis, but to the ear it resembles and is entirely via hardware.

Nothing to do with what you do with the "PC speaker", please...

[hitchhikr]

What Paula offers is Period Modulation.

It can also do volume modulation (even period & volume at the same time).

[Joel_w]

Originally Posted by ross

https://www.pouet.net/prod.php?which=65872

I didn't check if AM (volume) or FM (period) or both modulation is used, but for sure it use hardware modulation

Cool, thanks! Finally an example.

[Paulee_Alex_Bow]

Originally Posted by derSammler

But that is a soft synth.

Afaik, PAULA had no FM synthesis of any kind.

Paula has hardware AM & FM intermodulation between channels, though the FM is quite unpredictable. I have an assembler script that will turn it on.

[Paulee_Alex_Bow]

Originally Posted by Joel_w

I remember hearing that Paula is capable of FM synthesis, or at least something similar, instead of just playing samples. I’m not talking about a soft synth but an actual feature in the chip.

Are there any examples of this being used? I guess it can’t be used in a mod but maybe in a demo or game so I can hear what it sounds like.

I found this old thread talking about it, but without any examples.

https://forum.amiga.org/index.php?topic=54117.0

I talk about it in my Amiga softsynths video, starting at 7:16, I found the FM hard to get anything usable out of, but I LOVE the AM sound and do an example right there in the video.

[ Show youtube player ]

[Karlos]

Originally Posted by Paulee_Alex_Bow

I talk about it in my Amiga softsynths video, starting at 7:16, I found the FM hard to get anything usable out of, but I LOVE the AM sound and do an example right there in the video.

[ Show youtube player ]

I designed an alternative to 14-bit replay that instead uses Paula volume modulation to gain adjust a preprocessed 8 bit stream (generated from a 16-bit source) composed of frames where the volume of a frame is set by the modulator channel running at some fixed divisor. I mocked it up in software (encode/decode) but someone here - grond maybe? - actually implemented the replay proof of concept on hardware.

[Paulee_Alex_Bow]

Originally Posted by Karlos

I designed an alternative to 14-bit replay that instead uses Paula volume modulation to gain adjust a preprocessed 8 bit stream (generated from a 16-bit source) composed of frames where the volume of a frame is set by the modulator channel running at some fixed divisor. I mocked it up in software (encode/decode) but someone here - grond maybe? - actually implemented the replay proof of concept on hardware.

Wow that sounds ingenious, kinda not a million miles from how AM radio works right?

[Karlos]

Originally Posted by Paulee_Alex_Bow

Wow that sounds ingenious, kinda not a million miles from how AM radio works right?

I think NICAM night be a better analogy, if you can remember that. Each 8 bit frame is made of samples that have been normalised from the 16 bit originals, to be played back at the correct (well, as close as possible given the 8-bit resolution) amplitude when attenuated by whatever the hardware channel volume is set to for that frame, by the modulator.

https://github.com/0xABADCAFE/paula-hdr

[Paulee_Alex_Bow]

Originally Posted by Karlos

I think NICAM night be a better analogy, if you can remember that. Each 8 bit frame is made of samples that have been normalised from the 16 bit originals, to be played back at the correct (well, as close as possible given the 8-bit resolution) amplitude when attenuated by whatever the hardware channel volume is set to for that frame, by the modulator.

https://github.com/0xABADCAFE/paula-hdr

Amazing stuff. A kind of companding then, I believe that Roland used a similar scheme in their JV range (1080 etc) of playback sample+synthesis modules to get more fidelity out of modest hardware

[Karlos]

Yeah, comparing. I considered delta encoding the 8-bit data and compressing that using more conventional techniques but that wasn't really the goal. Didn't stop me thinking about it though.

[Photon]

Originally Posted by Joel_w

I remember hearing that Paula is capable of FM synthesis

Yes, according to this definition by Wikipedia, and in hardware. Set up one channel to amplitude module another's frequency, and you're done. Reduces the number of channels by half, but 4 channels can be kept if the AM is done with the CPU, which is possible on all Amiga CPUs.

If by FM you mean "Sounds like Yamaha" (FM was their bid for a patentable synth engine), remember that the overall sound character is mostly up to the filter, and the waves and the treatment of them in the engine affects the overall sound minorly in comparison - to the point of even filter and circuitry artifacts being celebrated for giving a synth "a unique sound".

My definition of FM is if that almost every sound sounds like a variation of a metallic bell if R is set to fade out fast, and it does the "FM Bass" fart, it's === Yamaha.

---

The Amiga is a wonderful machine. <3 On it, rather uniquely, any synthesis and sample/wavetable/synth engine hybrid engines can be imagined with full support of the hardware. You're not limited to make something like what's already been. It obviously takes roughly the amount of work of coding a VA or other digital synthesis engine and minds knowledgeable of sound theory, which is why engines are not so advanced - e.g. Sonix, MusicLine, and not much else that has gained traction (FC and SID are as simple as Yamaha Y series, just waves+ADSR.)

You also need someone tasked with programming lots of parameters for impressive instruments, and the synthesizer companies employed them. If the coder is supposed to do that work also, that's a lot of talent in, and hours out of, a select few key personnel.

[Karlos]

FM (Phase modulation) can sound amazing. You just have to know how it works and how to wield it. It's not a very intuitive model, unlike additive or subtractive.

It gets especially interesting when you realise you don't have to be restricted to sine waves. Any periodic function, by definition, can be phase modulated.

So, if you use triangle or saw waves carriers and a triangle for the modulator, you can create a sort of resonant sweep that you'd normally end up using filters for. Or you can replicate behaviours like oscillator sync and various other conceptually "subtractive" ideas.

Many of the sound in this experiment were created using phase modulation of one form or another

[ Show youtube player ]