MOTM

On 30 Apr 2000 motm@egroups.com wrote:

>    Date: Sat, 29 Apr 2000 14:17:59 +0200
>    From: "jhaible" <jhaible@...>
> Subject: Re: more pictures
> 
> 
> > ooOOoo, the "What Is This?" picture is very intreaging, or however you
> spell
> > it.  If I dare hazard a guess, I'd say a 7 band vocoder...?  It clearly
> has
> > 7 bands of something, with 2 controls per band-- carrier and source
> > frequency...?
> 
> Hmm, I won't go into more details of this as the moment.
> Only so much: Nobody would build a 7-band vocoder. Even the
> little one from Paia has 8 bands ...
> 
> JH.


Fixed filter bank?


Speaking of filterbanks,

Mother Of All Fixed Filter Bank (MoaFFB) features:

Every band has three knobs.  
1. One to control attenuate the signal coming thru that band.  
2. One to tune the band.  set the midpoint of the filter.  
3. One to set the width of the band

and of course, there's CV input for every single one of these knobs plus a
cv attenuator knob per each cv input.  so actually 6 knobs per band.

then all you need is a rack of LFOs ...


but seriously, i think it would be really great to be able to tune a ffb.


----------------------------------------------------------
celesteh@...   http://www.casaninja.com/celesteh

In a message dated 5/1/2000 3:44:59 PM, celesteh@... writes:

>Speaking of filterbanks,
>
>Mother Of All Fixed Filter Bank (MoaFFB) features:
>
>Every band has three knobs.  
>1. One to control attenuate the signal coming thru that band.  
>2. One to tune the band.  set the midpoint of the filter.  
>3. One to set the width of the band
>
>and of course, there's CV input for every single one of these knobs plus
>a
>cv attenuator knob per each cv input.  so actually 6 knobs per band.
>
>then all you need is a rack of LFOs ...

And she was such a nice girl too <g>. But seriously folks, it's good to see 
how people are "assimilated." I'm wondering if it's dealing with MOTM that 
makes everyone on the list start craving for VC everything, or is it rather 
that those with the craving for elaborate and powerful VC modules are 
inevitably driven to MOTM? 1000 MOTM module purchases can't be wrong!

BTW, I think the idea of a VCF with VC bandwidth (I guess this would be VC 
slope for a LPF and HPF) would be yet another worthwhile filter project.

>but seriously, i think it would be really great to be able to tune a ffb.

I suggested this when I first used the Moog, but someone reminded me that a 
voltage controlled fixed filter bank, would no longer be fixed.

John (if it ain't fixed, don't break it) Barlow

If you can tune the band, it's no longer a fixed filter bank. It becomes
parametric, or at least, "paragraphic." What you are describing here is
really a classic parametric equalizer---"Cut/Boost," "Freq," and "Bandwidth"
are the three controls on each channel of a parametric.

I've always wondered if a parametric *vocoder* would be interesting.

 -----Original Message-----
From: 	Celeste H [mailto:celesteh@...] 
Sent:	Monday, 01 May, 2000 6:42 PM
To:	motm@egroups.com
Subject:	Re: [motm] Digest Number 481




Fixed filter bank?


Speaking of filterbanks,

Mother Of All Fixed Filter Bank (MoaFFB) features:

Every band has three knobs.  
1. One to control attenuate the signal coming thru that band.  
2. One to tune the band.  set the midpoint of the filter.  
3. One to set the width of the band

> If you can tune the band, it's no longer a fixed filter bank. It becomes
> parametric, or at least, "paragraphic."

Yes.

>What you are describing here is
>really a classic parametric equalizer---"Cut/Boost," "Freq," and
"Bandwidth"
>are the three controls on each channel of a parametric.

And if a fixed filter bank is somewhat related to a graphic EQ (difference
being the way of attenuation), then the "filter bank" counterpart of a
parametric EQ would be - you guessed it -
the ordinary BPF. The existing MOTM triple resonant filter would be
a "semi parametric filter bank" (with external mixer), and a set of
SEM-Style
filters would be a fully parametric version. I don't want to tell more than
Paul
recently did on analogue heaven, but the SEM-style VCF to come will have
a few features that will go a little beyond your dreams of VC parameters
actually ...

> I've always wondered if a parametric *vocoder* would be interesting.

I never thought that. It's part of a Vocoder designer's hard work (;->) to
lay out the filters such that they are
- flat in passband
- steep at edges
- not overlapping
- but summing to 0dB with adjacent bands wide open.
You can never do this on the fly, with knobs for all the parameters.
It's definitely not as easy as just changing bandwidth.

I do encourage experiments like that, with individual filters and stuff
(who cares if things don't overlap as long as it sounds good ?), but
it would be sucide to design a self contained vocoder like that.
And in the end, a vocoder is a building block of its own, even if
it's full of components that would make nice stand alone modules
as well.

Just my opinion, of course.

JH.