[sdiy] Noob Question: Passive Filter Design

[Oren Leavitt]

Harry Bissell wrote:
> The exercise is left up to the reader
> 
> Its possible to just replace the capacitors in a Moog
> ladder filter with inductors and make it a highpass
> filter.
> 
> Run a simulation if you like...
> 
> then try to BUY the components required.  
> 
> (you'll quickly find out that building circuits with inductors
> can require absurd values, and parts that are 'ideal' and don't
> exist in the real world).
> 
> Inductors can be used in active filter design, a good number of
> guitar 'wah' pedals used them. The overall 'sound' of the unit
> depended on the actual part selected. Some parts worked well,
> some sucked
> 
> H^) harry
> 
>

Definitely into "roll your own" territory nowadays.
Round up them ferrite cores, bobbins, and magnet wire or litz wire, and 
start windin' n measurin'.
You just might get lucky... :-)


> 
> ----- Original Message -----
> From: David G. Dixon <dixon at interchange.ubc.ca>
> To: 'Tom Ivar Helbekkmo' <tih at hamartun.priv.no>, 'Sam Ecoff' <secoff at execpc.com>
> Cc: 'sdiy DIY' <synth-diy at dropmix.xs4all.nl>
> Sent: Tue, 04 May 2010 14:49:32 -0400 (EDT)
> Subject: Re: [sdiy] Noob Question: Passive Filter Design
> 
> 
>>"An active filter needs no inductors. Instead, op amps, resistors, and
>>capacitors are used for better results. Advantages include lower cost,
>>easy tuning, simple design, and modularity."
>>
>>It's at <http://www.amazon.com/gp/product/075062986X>.  Comments, anyone?
> 
> 
> I would guess that very few souls here would ever build a synth filter with
> inductors, especially when the alternative is so easy.  My personal attitude
> is that inductors should be reserved for VHF applications.
> 
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