altbstaudio.logicdata is a perfect squarewave. Seems like the sound tinniness is only caused by the piezo, and not the R1 output. I think it's safe to assume that all Tiger games are like this, I won't need recordings of others.
SM510 supports a mask option for R1 output: either direct control(eg. altbeast), or automatic 4khz squarewave while R1 is high(used in G&W games). Physically, I think the mask option is over here: http://tsk-tsk.net/net/temp/ddragon_vs_mickdon.jpg On the top part of the die, near the OSC pins. Use the 'puzzlepiece' as a landmark. The left one is Tiger Double Dragon the right one is G&W Mickey & Donald
The mid-90s SM510 is different(indy500, space jam), I don't know where the R1 mask option is.
