Is FM-X emulation or a dedicated FM circuit?

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iixorbiusii
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Is FM-X emulation or a dedicated FM circuit?

Unread post by iixorbiusii » Wed May 29, 2019 9:17 pm

Hi,

Just curious as to whether the MODX / Montage FM-X engine, is a dedicated circuit / chip, or just some kind of virtual emulation run within the same DSP responsible for the AWM2 synth engine?

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Stevie18
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Re: Is FM-X emulation or a dedicated FM circuit?

Unread post by Stevie18 » Thu May 30, 2019 7:33 am

I think there is ample evidence that it is running on a DSP in the synth. Running in dedicated hardware is really not necessary anymore these days, people have implemented FM on really cheap microcontrollers. Using dedicated hardware would not give any advantage and would be expensive and inflexible. Some people think it would sound different: but even in the DX it was just digital calculations which can be implemented in software with 100% accuracy. Any perceived sound differences would then be the DSP and analog circuits after the DSP.

For the Montage there is this article which describes the hardware: http://sandsoftwaresound.net/montage-hardware-platform/

The guy writes that the second DSP is used for FM-X. Sounds very plausible for me.
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Re: Is FM-X emulation or a dedicated FM circuit?

Unread post by iixorbiusii » Thu May 30, 2019 9:44 am

Thanks for the reply, and link to an interesting article.

Whilst I have found the built in FM-X sounds to be 'good', what I have really been impressed with, are how great my converted DX7 patches sound in the MODX. They sound very full and dynamic, and somewhat 'ballsier' than they do in VST land !

Hence I was wondering if they somehow dedicated some circuitry somewhere, as it sounds amazing with my DX7 library. I hope they one day allow immediate import of DX7 sysex banks.
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Re: Is FM-X emulation or a dedicated FM circuit?

Unread post by Derek » Thu May 30, 2019 1:14 pm

FM would have to be quite well suited for computer generation (and DSP is only a special form of computer) as Chowning was experiment with FM on university mainframes! ;)
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Re: Is FM-X emulation or a dedicated FM circuit?

Unread post by vertig0spin » Fri May 31, 2019 2:03 pm

iixorbiusii wrote:
Thu May 30, 2019 9:44 am
Whilst I have found the built in FM-X sounds to be 'good', what I have really been impressed with, are how great my converted DX7 patches sound in the MODX. They sound very full and dynamic, and somewhat 'ballsier' than they do in VST land !

Hence I was wondering if they somehow dedicated some circuitry somewhere, as it sounds amazing with my DX7 library. I hope they one day allow immediate import of DX7 sysex banks.
I have found that the converted sounds are pretty good, but not identical and not quite as good as they sound on the DX7. I have my DX7II-FD synth connected to the Montage input and so I can now compare the differences in real time. After a few adjustments on the Montage they are basically identical, at least for non-Unison sounds. And it seems like the adjustments are the same for each operator, which makes it quick & easy to fix. Regarding unison based sounds (which are most of my best/favorites on the DX7), I don't want to use up 4 PARTs on the Montage to get that same sound, so after digging on forums for a solution, I found an Insert effect (Pitch Changer) that adds 4 layers & detunes them similar to DX7 Unison, but it also allows me to stereoize & enhance the original sound, all in one single PART, which is a double bonus!

Plus for every sound I use that's FM-X based, it uses the second internal DSP processor, thus providing double the polyphony on the Montage (and 1.5 times polyphony on the MODX, which is still great)! :dance:
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Re: Is FM-X emulation or a dedicated FM circuit?

Unread post by iixorbiusii » Fri May 31, 2019 3:07 pm

/\ what I have found, is there is more expression to the converted DX7 patches when played on the MODX, than on either my mk1 or mkii DX7's. The FM-X 'DX7' patches built in as presets sound a bit less dynamic, for me. I don't really care about that though, as I'm really pleased with how my converted DX patches sound.

This could perhaps be because the 'cheaper' keybed of the MODX(6) doesn't need to be played quite so hard as a DX7, to get higher velocity effects? I haven't played a Montage but I know it has a more robust Keybed which possibly needs to be played harder - like on an original DX? I recall as well that the original DX7 keybed didn't transmit the full velocity range and would only really give about 4/5ths of what could be available within the synth engine.

I have found a few patches which don't quite convert properly - ones with quite ambitious PEG parameter data. But this is no different to any of my DX vsts. And if I recall correctly, there were even some patches i made years ago on MK1 DX7's, which behaved differently on my DX7-IIfd and vice versa.
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