AC-Coupled module inputs

[Martin Czech]

> There's a school of synth design that says VCOs should be universal,
> we don't want to impose preconceptions or restrictions on their use,
> they cost enough as it is and they should be able to be used for
> either application.  Like on the ARP 2600.
> 
> I'll claim that approach is misguided and you really do want separate
> audio and low frequency VCOs.  (Heck, lots of different types of
> VCOs!)  And with separate classes of VCOs you can have dc-coupled
> inputs throughout.
> 
> (This same issue also applies to waveshapers and ring modulators I
> guess.)
> 


I think the situation depends on the style of music you want to do.

But even in synth pop a la Jarre, you'll find interesting "noises"
that are interesting because they live in the twilight zone between low
frequency and audio. These are the areas of sound that are hard to obtain
without a modular analog system, even today.

I think it is very usefull if e.g. a vco covers much more then audio range,
so you can sweep up some modulation into audio, ie. one should be able
to travel between low frequency and audio. Most vco designs naturally do
this, but they are designed for best accuracy in the "usefull" audio range,
of course.

Of course, if this desire would impose serious problems or erros
to circuits I would agree with you: Design only for a narower band.
E.g. some features a lfo could have could possibly lead to bad tracking
if the cicuit was used for audio. (E.g. symmetry adjust)

m.c.