Filtering settings for modules

[Kagamiin]

Different systems that use the same chip have different filtering characteristics on their outputs.

A notable example is the Yamaha OPLL, where you have a myriad of MSX2+ systems that use very harsh filtering on the OPLL output, but then we have the Sega Mark-III FM sound unit which has no filtering at all on its output. There's also the case with different Mega Drive revisions which have different low-pass filters.

Modules could be made to take advantage of such system-specific filtering since it affects both timbre and mixing at the same time (especially important for OPLL rhythm in many cases), and that's why I'd like to suggest this module-specific feature.

This could be implemented as a set of presets, just like it's already being done for SN76489 variants or OPLL-based chips in the "Configure system" menu.

Suggestions:

OPLL

• Unfiltered (Sega Mark III FM Sound Unit, a lot of emulators)
• 22 KHz (???) (Japanese Sega Master System)
• 3.4 KHz 1st-order (Mega Drive + Powerbase Mini FM, also my personal favorite for most soundtracks)
• ~2.2 KHz 1st-order (Yamaha recommended, used in Yamaha home keyboards and quite a few MSX systems)
• 1.25 KHz 1st-order (Lagrange Point VRC7 filter, also close to a few MSX systems (Panasonic Turbo-R comes to mind))

YM2612

• Unfiltered (emulators)
• 3.4 KHz 1st-order (Mega Drive model 1)
• 3.4 KHz 2nd-order (Mega Drive model 2)

Other filter configurations could be added later as we figure them out. I know in the OPL3 land a lot of SoundBlaster cards have different filter settings but I haven't figured out any exact values, though I used to use 8.8 KHz 1st-order to simulate a Sound Blaster Pro 2 (completely by ear tho, not scientific at all)

[tildearrow]

Will be done through patchbay effects.