[sdiy] NICs, GICs, NLOs and all that

[Magnus Danielson]

From: "Osamu (Sam) HOSHUYAMA" <houshu at rogers.com>
Subject: Re: [sdiy] NICs, GICs, NLOs and all that
Date: Sun, 05 Jan 2003 00:14:28 +0900

> Hello Ian, Magnus, and List,

Hi Osamu,

> Ian Fritz wrote:
> > It seems that there has not been much use of NICs and GICs (negative and
> > generalized impedance converters) and related circuits in the synth-diy
> > arena.  Recently JH reminded us that synthetic inductors constructed from
> > classical gyrator circuitry may have important advantages in constructing
> > fixed-frequency filter banks.  I've collected some interesting general
> > information and circuit ideas in this area from the web and thought I would
> > pass them along.  Of course, much of the basic information is also
> > available in textbooks on network theory.
> 
> Orban uses gyrators in their products, not DIY though.  Their schematics
> could be inspiring.
> 
>   Orban manuals (pdf):
>            ftp://ftp.orban.com/

This IS the way it should be done. Complete manuals online even on acient
products. RRRRESPECT! ;O)

> 672 and 674 are parametric equalizers with unusual gyrators (NIC based).

Both graphical and parametric equalizers is where I would expect gyrators to
show up. If I recall things correctly, gyrators is a very good option when
good dynamics is of interest.

> FYI:
> Other schematics are interesting as well.  However, most of the files 
> are over 2 M bytes.  To choose the files to check, this short summary 
> may be helpful.
> 
>    1xx: Reverberators
>    2xx--3xx: Stereo synthesizers
>    4xx: Compressors
>    5xx: Sibilance controllers
>    6xx: Equalizers
>    8xxx--9xxx: Broadcasting systems
> 
> Especially, the followings are interesting for me:
> 
>    300: Stereo synthesizer  (2 pole fixed APFs are used)
>    418: FET based compressor
>    622: Parametric equalizer with unusual biquad filters
>    642: Parametric equalizer with unusual filters
>    672, 674: Equalizers with unusual gyrators

Many thanks for the Orban link!

What sits in the top of the rack just left of my computerscreen?
An Orban 418A Stereo Limiter! ;O)

This is an interesting device, since it's actually two stereo limiters in
series, first a broadband limiter, which is followed by a HF limiter, so the
high end can be further processed. Also, that then in Stereo, so even if only
one channel missbehaves, both get the same treatment so that the balance
between them is kept. Exactly what you want for a mastering line, and that's
where this one was once salvaged.

Cheers,
Magnus