FM operator Type-L, Type-N, Type-M etc... what that mean???

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Jarhmander
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FM operator Type-L, Type-N, Type-M etc... what that mean???

Post by Jarhmander »

YM2203 : FM operator Type-N(OPN)
YM2151 : FM operator Type-M(OPM)
YM3526 : FM operator Type-L(OPL)
YM2413B : FM operator Type-LL(OPLL)

I JFGI but failed to get the information many times and the datasheets doesn't mention what that mean the type... so does anyone here know?

Many thanks in advance...
lidnariq
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Post by lidnariq »

Best guess: OPLL is "OPL limited" or reduced or something, since it reduces on-chip RAM, removes the channel adder (uses an external capacitor instead), and moves a DAC onto the chip.

OPN might sound for "with noise", since they seem to include a PSG and LFSR-based noise unit.

http://www.vorc.org/text/column/hally/ymxxxx.html is enlightening but doesn't actually explain anything, sadly.
ccovell
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Post by ccovell »

Generally, the difference between OPN/OPM and OPL/OPLL is the quality of the sound. OPN/M chips have 4 "operators" (per voice) which change the qualities of the base sine/square wave from the oscillator, whereas OPL* chips have only 2 operators per voice. The waveforms that the OPN/M chips can generate are therefore much more complex.

If you want to hear what this difference sounds like, then compare the FM sound from most '80s/'90s arcade games or from the Sega Genesis (OPN/M) with the OPL FM sound from systems like the MSX, Sega Mark-III, or Lagrange Point on the Famicom.

The OPL chips sound much more primitive, less dynamic, and oftentimes, a bit boring.
tomaitheous
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Post by tomaitheous »

The 2612(OPN) on the Genesis only has one waveform for the modulators and carriers, which is sine. The algorithms (mod/carrier setup) is more than likely different between the chips. I know it is for the 2151, 2612, and 2203. 2203 is supposed to be very similar to the 2612, except with half the channels and no DAC write mode. Soundshock forum is a good place to look for FM info.
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Post by lidnariq »

ccovell wrote:Generally, the difference between OPN/OPM and OPL/OPLL is the quality of the sound. OPN/M chips have 4 "operators" (per voice) which change the qualities of the base sine/square wave from the oscillator, whereas OPL* chips have only 2 operators per voice.
Is the OPL3, then, violating this convention because the OPL2 had better name recognition?
ccovell
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Post by ccovell »

No, it's not a rule, just an observation of mine to quickly suss out OPN/OPM versus OPL(L). OPL3, as far as I can tell, is compatible with the scaled back OPL, but also capable of using 4 operators for OPN/M quality.

But then again, I'm not an expert on FM sound by any means.
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