[sdiy] Starting a Four Pole Filter in an FPGA.....

Antti Huovilainen ajhuovil at cc.hut.fi
Sun Nov 2 17:57:22 CET 2008


On Sun, 2 Nov 2008, Jim Patchell wrote:

> Thanks for the links...if nothing else...they are both very 
> interesting...and hopefully, I will find something very useful at one of 
> those....the musicdsp site looks particularly good...

Sadly almost every non-trivial piece of code on the site is at least 
subtly wrong (most are not so subtly).

The following is better pseudocode for Moog-like filter than most you 
find on the net: http://users.tkk.fi/~ajhuovil/moog.txt

Real Moog emulation has tanh nonlinearities in different places making it 
harder to implement for a novice.

A and B constants can be replaced by A = 0.75 and B = 0.25 with slight 
changes to tuning and feedback correction polynomials.

Antti

"No boom today. Boom tomorrow. There's always a boom tomorrow"
   -- Lt. Cmdr. Ivanova



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