[sdiy] FPGA Synth Music

[Scott Gravenhorst]

cheater cheater <cheater00 at gmail.com> wrote:
>Scott,
>to put this topic back on rails, I would like to say that after
>listening to the demo I am very impressed. It sounds great. 

heh, thanks.

>What do you mean with '4x 2-op'? 

Each voice uses up to 8 voices in pairs,  So there are four 2 operator FM sound generators
per voice.  These four 2 op generators are amplitude modulated by an ADSR and then they
are summed as the voice's output.

>Is it only just ever one oscillator affecting just one other one, no chaining? 

Not in this design.

>If so, what stops you from doing that? 

I get 16 polyphonic voices because the fixed structure is easily repeated 16 times.  It
fits into the small FPGA I have.

>In fact what stops you from gong all-out and making, say, 32-operator schemes? 

I don't know this from experience, but I understand from reading that more and more
operators tend to produce more and more noise or noise-like sounds and that the most
useful chains are 2, 3 and perhaps 4 operator chains.  Not saying that more aren't useful.
 I do have plans for a synth that has the ability to chain up to 8 operators, or make
smaller chains out of 8 operators (per voice).  So something like 5-op and 3-op mixed
would be possible.

>BTW, can you use arbitrary waves for the operators in your synth?

Well, the design can be resynthesized with a ROM other then the sine ROM I have.  So in
that regard, yes.  It's a pretty standard 1/4 cycle deal.

I need to get back on this project...

>Cheers
>D.
>
>On Sat, Feb 27, 2010 at 21:56, Scott Gravenhorst <music.maker at gte.net> wrote:
>> http://electro-music.com/forum/download.php?id=21668
>>
>> A modified version of my 16 voice eight operator (4 x 2-op) bell synth.
>> The modifications accomodate an alternative scale of 96ET.
>>
>> This piece was recorded using one $49 FPGA development board and Eric
>> Brombaugh's Cirrus DAC board.  No effects were used.
>>
>> -- ScottG
>> ________________________________________________________________________
>> -- Scott Gravenhorst
>> -- FPGA MIDI Synthesizer Information: home1.gte.net/res0658s/FPGA_synth/
>> -- FatMan: home1.gte.net/res0658s/fatman/
>> -- NonFatMan: home1.gte.net/res0658s/electronics/
>> -- When the going gets tough, the tough use the command line.
>>
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>

-- ScottG
________________________________________________________________________
-- Scott Gravenhorst
-- FPGA MIDI Synthesizer Information: home1.gte.net/res0658s/FPGA_synth/
-- FatMan: home1.gte.net/res0658s/fatman/
-- NonFatMan: home1.gte.net/res0658s/electronics/
-- When the going gets tough, the tough use the command line.