Wiardgroup

I really appreciate this post because it caused me to give some "deep thought" to the 
question.

I'll try to be brief.

As terminology is borrowed from one field to another, it meaning often changes.

Electronics engineering borrowed terminology from acoustics, and electronic music 
borrowed terminology from engineering.

Resonance, Q (quality), regeneration, peaking, negative feedback and positive feedback all 
have specific technical meanings. Subjectively, they can all be grouped under "resonance".

Instrument designers walk a line between two worlds and it can get confusing what to call 
something. Use the correct technical or historical name or use a popular subjective name.

The Omni-filter bandpass mode is technically correct, the Borg filter bandpass mode is 
actually a "simulated resonator". It only adds gain at the corner frequency and doesn't 
subtract anything. This is subjectively the way musicians want it. The Omni-filter subtracts 
everything but the central frequency, technically correct, but more difficult to apply 
musically.

To explain the difference I would have to get into DC response, AC response, passband 
gain, corner frequency gain and corner frequency phase response. Which I am way too 
busy to do.

Let's put it this way, when musicians talk about "subtractive synthesis" they really want to 
subtract in very specific ways. Ways that do not change the apparent "volume" of the 
sound (particularly bass volume). But mathematics is against that, and so engineers have 
to be very clever to come up with filter designs that behave subjectively correctly to 
musicians.

The Omni-filter was my first design. Later, based on what musicians told me, I designed 
filters that behave much more the way musicians prefer. Both types are "correct", but the 
later designs (Borg 1 and 2, Boogie) are specifically designed for electronic music use.

Hope that helps.

--- In wiardgroup@yahoogroups.com, "andrew dalio" <bunnyman@...> wrote:
>
> I posted a couple examples of my OmniFilter in the Files section (OmniFilter examples 
folder). 
> The filter really seems to lose a lot of output when entering the bandpass mode (very 
> noticeable in the 24dB output file). The module is processing a sawtooth wave. Coarse, 
Fine, 
> and Q are @ 12 o'clock. I'm manually turning the filter mode knob from LP to AP and 
back 
> again a few times. It worries me a bit, since my Borg I filters have a consistant output no 
> matter what mode they're in. Any comments? Or am I just not getting it? (very often the 
> case ;-)
> 
> -andrew bunny
>