What does FM Emulation mode actually do?

Virtual instruments HALion
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On the import page of an FM Zone, one can select the FM emulation mode (Halion, FM-X, or DX7). The manual is pretty vague on what this actually does:

"In HALion mode, the oscillator works with continuous values, for maximum precision.

FM-X emulates the characteristics of Yamaha’s Montage synthesizers.

DX7 emulates the characteristics of the Yamaha DX7 synthesizer."

Not all that helpful.

From my own testing, I’ve noticed that in DX7 mode…

  • The level of an operator can’t be changed with its GUI level knob mid-note. Whatever the level is at the start is what it will be
  • Envelope decay is slower for a given value than in Halion mode.

But so far that’s all I’ve been able to figure out. Is there somewhere I can find a fuller account of what changes with this setting?

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I’d like to know this too!

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Synthopia seems to be a pretty decent FM synthesis comparison between the DX-7 and FM-X

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That makes me want to try a Yamaha Montage in real life. ^-^;

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From my understanding, the “FM-X” mode still has a small amount of quantization, while certain parameter changes in “Halion” mode are almost perfectly smooth. You could consider the Halion mode an “HD” version of FM-X, both are very similar to each other.

FM-X is a direct evolution of the FM synthesis featured in the classic Yamaha DX7, but several changes have been made (like you have noticed), necessitating the emulation modes present in Halion for accurate reproduction of old presets.

Another difference in DX7 mode is that several presets become a lot noisier due to lower parameter resolution. Both FM-X and Halion modes are nearly crystal clear in comparison.

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Thanks for the response. This is what I’d like to know more about.

Is DX mode actually using lower-res lookup tables like the DX7? Or is it just levels/envelopes that are affected? I tried looking at the sine wave of each mode in Halion’s scope and in Izotope Insight, but didn’t see or hear a difference in the waveform.

Envelope-wise, I’ve noticed that there’s also a subtly different attack behavior - if the attack time for an operator’s envelope is set to 0, the DX mode is noticeably click-ier in a way that could be useful for some sounds. A few of my own presets do sound a bit grungier (in a way that I like) when I switch to DX mode.

I’m sure at some point “just use your ears” is the way to go. But I do still wish the Steinberg folks would include more details in the manual so I can know how to best take advantage of each setting.

I’ve submitted a support request to get more information. I’ll update this thread if I hear back.

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