[sdiy] more-pole filter

[Richard Wentk]

On 10 Aug 2008, at 23:42, Antti Huovilainen wrote:

> On Sun, 10 Aug 2008, Richard Wentk wrote:
>
>> Surprisingly, also not a huge difference in sound between a 4 pole  
>> and 8 pole. Obviously there's *some* difference, but it's not as  
>> musically distinctive as you might expect.
>>
>> Considering the huge extra complexity involved in making an  
>> accurate 8 pole design, it's never been worth the time, money or  
>> effort.
>
> What would be the problem with the accuracy for higher filter orders?
> I don't see how a Moog filter (for example) would be complicated by  
> adding more stages.

Higher orders are more susceptible to variations from component  
tolerances and thermal issues.

So if you duplicate a four pole, you'll get an eight-ish pole filter,  
because the poles will start to smear out from their ideal positions.  
This is most obvious with higher Q.

It's probably not obvious enough to make a big sonic difference. But  
it depends how picky you want to be.

Richard