Trying to Understand the Filters in 32-Voice Mode on Prophet X/XL

[NivekReznourgensen]

Hi all,

Please help a newbie understand something. It seems that sometimes the sampled instruments are not affected by the filter when they should be.  I am on the latest Prophet XL firmware 2.2.1.  When I load up F1 P2 "PX Grand Piano32", and turn the filter cutoff knob, I hear no change like the filter is being bypassed.  So I then go into the "Inst Misc" settings to see if the LPF is bypassed, which it is not.  Next, I check the filter's "LPF Misc" page to check the bypass setting there.  It was bypassed, so I turn the bypass off, but then I still hear no change when sweeping the cutoff knob. 

Is there another way that the filter could be bypassed?

I was able to make up a 32-voice piano patch that seems like it's a clone of the "PX Grand Piano32", and it successfully goes through the filter(s).  I guess what I'm trying to understand is - am I overlooking an extra filter bypass somewhere, or is this a compatability problem with the latter-day firmware (2.2.X) and the factory patches?

Any help would be appreciated.

Thanks..

[NivekReznourgensen]

Found the issue.  I can disable all of the "bypass LPF" options all day long, but it won't let me control the filter with the knob if the VCF Amount is set to max (127)....

BTW - helpful tip for anybody new to pro-level hardware synthesizers:  it sure does help to read the user manual....       lol

That said, I don't fully understand the algorithm behind the VCF amount and the cutoff value, but that's another post I think.

[Derek Cook]

Interesting find, and thanks for reporting back.