|サウンド||低||解決済み||修正済み||2010-02-10 20:36||2014-02-04 21:12|
popeye - ポパイ (revision D)
|概 要||AY-3-8910 Voice A（ベース音）のフィルタリングがかかっていない。|
|詳 細||On the original Popeye board, sound channel A from AY-3-8910 is run through a discrete filter, producing a smoothed wave form. On MAME, the channel is reproduced without filtering, resulting in a harsher square wave sound.|
Note: this only affects sound channel A.
|再現手順||Turn on your original Popeye machine, and listen to the title melody. You'll notice that the 2 channels playing the leading melody sound sharp, but the channel playing the backgound beat is much more smooth and not a square wave.|
Start the game, hear the introduction music, same pattern: leading melody is a sharp square wave, background beat is smooth.
Now play the game. All sound effects are sharp square waves. The background melody however is smooth.
See also Popeye schematics sheet 2, upper right corner. When I am taking the sound directly at resistor R52, bypassing the whole circuit, voice A is sounding as sharp as wrongly emulated in MAME.
Probable cause for filtered sound: capacitor C4, 0.047uF, resistor R51, 20KOhm
Circuit has been verified with original board.
See picture for circuit.
|追加情報||I am going to provide some sound samples during the day.|
EDIT: Sample has been uploaded.
EDIT: Part of schematic has been uploaded.
|添付ファイル||popeye_sound.mp3 (2010-02-10 21:46)|
|popeye_sound.jpg (2010-02-10 22:21) |