> > The graph: That's the 907's frequency response with all pots
> up. (!)
> Wow, I take it you mean all the way up, or at the center?
It means all at the same value. That's one more difference between
a graphic EQ and a FB: On the EQ, the 0dB setting (center)
means a flat frequency response (ideally), and the further you
go to positive or negative (with all pots moved at the same time),
the more peaks and dents you get.
On a FB, it doesn't matter if all pots are set to 3, to 5 or to 10:
the only difference is the overall signal gain.
And with no setting of a graphic EQ (at least not with th eones I know)
can you emulate the response of a Moog FB (or a EMS FB for that matter).
The filter banks have much "better" (higher order) filters.
EQ = make corrections, and "smooth" changes
FB = make dramatic changes
Different design goals - each has its uses.
The only filter bank I have seen which has no higher order filters
(compared with a graphic EQ), is the FB in the Paia vocoder. But
even this uses parameters that would make a poor EQ, but a fairly
decent FB.
> I'm sure the phase plot is equally bizarre. I remeber it sounding
> nice. As with most Moog modules, I usually attributed the
> "niceness" (and the noise) to the discrete circuitry. Though it
> seems a lot of vintage synth character in general has more to do
> with design quirks - in the studio I call them "happy accidents."
Absolutely.
It's a sort of evolution process: Most "odd" designs will vanish
(won't sell), but some will be liked by musicians, and so they
become the standard: Distortion of tube amplifiers, ladder
filters with frequency-dependent resonance, filter banks which
have no "neutral" setting, you name it.
> Okay, no individual outputs. How about an inverted output?
No problem.
> > I have made a clone of the EMS FB many years ago for my
> > personal use, but I would not contribute to a commercial
> > version (MOTM) of this one, or any other direct copy of EMS
> > products.
>
> Why? Are there patents still in effect,
Actually, it's just the other way round. If there is a patent, this means the
circuit is available for the public, and also protected for a certain time.
If I make a patent, I give the idea away to the public, and in return I get
some protection on my idea for several years. I'm sharing my idea, but
I get more than one decade of protected exclusive use.
OTOH, if I don't make a patent of my idea (it's expensive ...), I don't
have that protection, but my circuit is not available to the public.
Unless somebody gets hold of the schematics, reverse-enigneers a
board or a chip.
> or because EMS is still (sort of) in business?
That's the point. They are in business, I admire what they have
created in the past, they have not stopped making analog products
(unlike Korg or Roland or Emu), so I would feel uncomfortable
to clone their circuits for commercial use. It's not a matter
of law or patents, it's just a matter of what feels good and what
makes me feel uneasy.
> They don't make the filter bank anymore, do they?
I don't know.
> I notice the "D" brand is probably pulling their yet to ship
> diode filter, because of a licensing hassle.
Is this true ?
Maybe the ever-hungry-for-cheap-designs "D" brand has swallowed
one of the alleged "EMS" filter clones that float around the web,
and now they noticed it doesn't sound like the real one at all ??
I am only ∗guessing∗ here, but wow, that would be a laugh !!
(I have never seen the ∗real∗ EMS filter circuit on the web,
so this scenario is not entirely impossible. (;->) )
Or maybe they have enraged the "German EMS" (Ludwig
Rehberg), who certainly is not shy in defending his properties
against a serious infringement ?? Again, just a guess, it may
be something entirely different.
Where can I learn more about this ? Ha !
> Modcan have an
> "EMS type" filter, I wonder if it's licensed.
I have no idea. I don't even know if they have an EMS filter or not.
Maybe they are just too small to cause attraction.
> Drifting even further off
> topic, how different is the Roland diode ladder from the EMS?
I don't know.
If I look at various Roland schematics, I see an evolution of
very different filter circuits. Moog cascades, Diode ladders
and OTA filters, even state variable filters. I don't know
where they got in conflict with others (rumors go that they
got in conflict with Moog, but this is all I know), but it's
clear just from the variety of Roland filters that they have
put a lot of own work into these designs, rather than just making
a cheap copy of everything.
(But these days are long gone in Roland History - ask
Paul Perry about Roland's funny ways now,
in 2002, ....)
JH.