Default bassline patch left-handed?

MIDIbox SID
1

Hi all,

I was wondering if there was a reason to set the left-right oscillators with a different wave type (left is Pulse, right is Sawtooth) in the default bassline patch.

I discovered this thing when I checked my gear after expansion (now it has 2 stereo 8580’s and one mono 6581) and noticed that in the default bassline patch the left channel’s VU meter in my mixer was clearly higher than the right one.

I started checking thoroughly all the audio wires and SID modules with no results. It was when I connected an oscilloscope to both outputs when I noticed the (quite obvious) difference in the wave shape.

I can confirm this in the source code (sid_preset_bassline.inc, ca. line 45):

;; Voice #1
	;;	Flgs  Wave  AD    SR  PW_L  PW_H  Acc  Delay Trns  Fine  PRng  Port. ArpM  A.S/D A.G/R Res2
	db	0x01, 0x04, 0x00, 0xc0, 0x00, 0x09, 0x10, 0x00, 0x28, 0x80, 0x02, 0x28, 0x00, 0x1f, 0x05, 0x00
[...]
	;; Voice #2
	;;	Flgs  Wave  AD    SR  PW_L  PW_H  Acc  Delay Trns  Fine  PRng  Port. ArpM  A.S/D A.G/R Res2
	db	0x01, 0x02, 0x00, 0xc0, 0x00, 0x09, 0x10, 0x00, 0x28, 0x80, 0x02, 0x28, 0x00, 0x1f, 0x05, 0x00

	        ^^^^ HERE IT IS

Bug or feature? :wink:

Many thanks,

RAZ

2

This is an intended default configuration. You will notice, that most of my bassline patches are using the right-channel bassline with saw waveform in upper range.

Best Regards, Thorsten.

3

Now it’s all clear. Thanks!!!

RAZ