[Fpga-synth] Digital Waveguide Samples (Magnus Wedmark)

[Scott Gravenhorst]

"The making of synthesizers in FPGAs." wrote:
>
>Nice MP3's Scott!
>
>I ported your last great Synth to suit my old Spartan-3 Starter Kit and my
>extension board. After some fiddling with input/outputs (knobs and SPI-sound
>output missing) a actually got both the MIDI-controller and the sound output
>working. But a have problems with getting the filter-setting working to get
>more than the initial clicking sound. After reading your explanation I tried
>to change the starting value of the parameter called 'value_out' located in
>the rotaryencoder_v3.v file.
>
>reg [14:0] value_out = 15'h2000; // changed start value to get a nicer
>starting sound

That is logical.  Also if your board has the same button arrangement (north, south, east,
west), if you hold the west button down, the filter BW changes far more rapidly.  The
filter BW value upper 8 bits appear in the LEDs.

>Isn't this the parameter the one you play with in your samples? 

Yes, it is.  What I find fascinating is how changing just one number makes such
interesting changes in timbre.

>Sorry for being a nerd a these more advanced projects..

Worry null...

>And another question, this sounds that your synth makes would be nice to
>play with, is it possible to get polyphony in an easy way? 

Yes, but this will take some significant amount of development time.  On the S-3Esk
board, there is a 512 megabit SDRAM.  I would like to use this RAM for my waveguides. 
The current system uses 4 block RAMs to make 1 waveguide.  With only 20 block RAMs
available, I can't expand it much.

Before I start that development, I've decided to let feature creep happen.  I've fixed
some problems with the code I posted and it's now turning into a usable monosynth.  I've
added velocity control over the excitation pulse height.  I will probably add some
selectable pulse shapes, at least ramp and tee-pee and some other stuff.  Then I'll post
the code as a monosynth and concentrate on the poly development since I will then know
more about the features I want to include.

>In my Spartan-3
>200K speed grade 4 i get 96Mhz max freq and 30% utilization without trying
>any tricks with settings. It would be really great to play some more
>advanced stuff with your pluck-sounds and maybe I could post some pieces
>too... :-) I'm not convinced that I actually can pull making it Polyphony
>myself. anyone taking on the project? Say... 6-8 simultaneous sound would
>be... NICE!!

My goal is 48, with a dream of 96.  I'll be happy with 48, especially since I have 4 of
these boards, I can make two or three 48 string harps with slightly detuned strings.

-- ScottG

-------------------------------------------------------------

-- Scott Gravenhorst
-- GateMan I - Xilinx Spartan-3E Based MIDI Synthesizer
-- FatMan: home1.gte.net/res0658s/fatman/
-- NonFatMan: home1.gte.net/res0658s/electronics/
-- When the going gets tough, the tough use the command line.