MOS 6581 some patches has no sound?

[vintagestar]

Hi,

I have finish building the sammichSID last week. Finally, I found out it's the USB <-> Midi cable's problem. I have install a sound blaster card in my computer and use that midi, the upload works finally. Anyway, I have put two MOS 6581 in the synth. However, there is several patches sound volume is quite low. Is the chip filter broken?

P.S A016 Filtered Poly / A017 Filt Mono Pad / A022 Filtered B 6581 / A023 Filtered B 8580 / A044 Turntable / A048 Helicopters...etc I can hear them, but the sound volume is lower than other patches

Regards,

vintagestar

Edited August 4, 2010 by vintagestar

[Digineural]

I think its briefly mentioned in somewhere in the lead engine documents that the 6581 has a defect

...the same sequence played on a 6581 - you will notice, that some mixed waveforms don't work on this older SID. And note especially the background noise, which is produced by a leackage issue in the VCA/mixer section

but under the FAQ it also states:

[13] Some mixed oscillator waveforms don't output a sound

Thats normal on a 6581, it works on a 6582/8580 - see also the demo samples in the Lead Engine chapter

Honestly, I've been able to compensate for issues with the 6581 on my MB6582 by changing a few parameters to get a similar (and by no means exactly the same) sound or I just dont use the patch at all.

If its a huge concern, maybe you can grab a 6582 or 8580 and swap out some parts in the sammichSID.

Edited August 4, 2010 by Digineural