Help in understanding how this drums circuit works (monotribe)

I want to build a drum sequencer with Arduino, and want analogue sounds. I've come across this schematic for the Korg Monotribe rhythm section (drums): http://www.korg-datastorage.jp/Manual/monotribe_sch.pdf
I think I am familiarized enough with the Arduino board to do it but I don't quite understand the drums schematic.

I know the BD, SD, HH and Noise labels on the left is where I need to send some kind of signal in order for the circuit to produce the corresponding sound (Bass Drum, Snare... etc)

A few questions:
Where it says HH Out, SD Out, etc... is the sound output? What are the nodes that say SD Decay and such, maybe you can control the decay by placing a potentiometer there? What are the labels on the right that say Rhythm and Port for? And what transistor should I use for the Qs?

Thank you!

You will get a pulse out of the HH Out/SD Out etc, not a "sound". I assume the pulse is used to trigger an internal sound or some other "noise" making circuitry.

I would expect there to be a resistor to ground on HH Decay etc - maybe that is a potentiometer or a digital potentiometer.

Keith

keith1200rs said:

I assume the pulse is used to trigger an internal sound or some other "noise" making circuitry.

Click to expand...

Really it's just a pulse? that's very dissapointing... this schematic is worthless then :-(

I would welcome other opinions but that is the way I see it. The input is from a 74xx04 gate.

Keith