[sdiy] Filterbank, part deux

[Tim Ressel]

Yo,

Now that the CSound filterbank experiment was
successful, it is time for phase II: Program a DSP
board with the filterbank. This involves dusting off
my DSP neurons as well as my DSP boards. I have an old
Motorola 56002 EVM, 2 ex-kit lites (adsp 2181), and a
Sharc which I am saving for a special occasion, like a
soft-synth. Rumor has it that CSound was ported to the
Sharc, that would be a kick-butt thing indeed.

DSP programming is fun. Each line of assembly code can
have up to 3 operations going on: an ALU/MAC
operation, and a move operation in both X and Y space.
As one MAC operation is being done, you can be loading
data for the next operation. This is called
pipelining, and was origionaly intended to torture
prisoners of war. Now it's called a major breakthrough
in computation. Isn't marketing wonderful?

The filters I used in CSound were the PAREQ filters,
which were meant for parametric EQ application, hence
the name. The nice folk that maintain CSound provide
the source code for it, so I able to determine that
the PAREQ filters are acually 2nd order biquads. Since
I already have code for the ezkit-lite to do cascaded
biquads, I'll probably use it for this application.

My grand plan is to have several global configurations
available via a front panel control. Extra stuff can
be downloaded or something. If this is all successful,
I will make a module out of it. The easy part is doing
the programming, the hard part is interfacing the DSP
baord to front panel controls.

Other DSP module ideas I have are a reverb module and
a table-driven distortion module. 

Thanks for listening, you've been a great audience 
;-)

--tr


__________________________________________________
Do you Yahoo!?
Yahoo! Mail Plus - Powerful. Affordable. Sign up now.
http://mailplus.yahoo.com