[sdiy] Novation peak NCOs

[Scott Gravenhorst]

Oh my yes, I used ISE to do that...  And I've now abandoned the PC on which I did that
development (tho the projects are all on a network volume).  I have a new 64 bit
machine and I see that I did install ISE, but I have not yet tried it and programmed a
board.  Need to do that ...

Mike HEQX <mike at heqx.com> wrote:
>This is a multi-part message in MIME format.
>--===============5032824130407797237==
>Content-Type: multipart/alternative;
>This is a multi-part message in MIME format.
>Content-Transfer-Encoding: 7bit
>
>Xilinx says this about direct Digital Synthesis . "The core has optional 
>phase offset capability, providing support for multiple synthesizers 
>with precisely controlled phase differences." IS this something that can 
>be changed in realtime through software or is it like a preset value. If 
>it were changeable then it seems like it could be used for waveshaping.
>
>I'm trying to get their ISE package running so I can mess with the 
>technology . I have a long , long way to go before I understand what the 
>heck is going on.
>
>
>Mike
>
>
>On 4/20/2017 7:45 PM, Scott Gravenhorst wrote:
>> Interesting discussion.
>>
>> My first FPGA subtractive synth was a 4 osc with naive 
>waveforms. I did that because the > DAC was capable of 1 MHz 
>sample rate which I used. Harmonics above 500 kHz are so low in > 
>amplitude as to be negligible. I could portamento without siren 
>fear. The drawback was > that it's 1 MHz DAC was also only 12 
>bits (the Spartan 3E Starter Kit board). However, the > 12 
>bit-ness didn't really seem to degrade it's sound. But still, 
>aliasing is aliasing and > a good high sample rate is one of the 
>cures. It allows the simplicity of generating > waveforms in a 
>naive manner. > > Tom Wiltshire <tom at electricdruid.net> wrote: >> 
>Ok, so let's just have a look at that for a moment. >> >> Assume 
>a highest output frequency of 20KHz (I wouldn't even be >> able 
>to hear this). We've got a nyquist frequency of 12MHz. That >> 
>means that only anything that goes far enough over 12MHz to alias 
>>> all the way back down below 20KHz is actually going to be >> 
>audible. So that's 23.98MHz before we get audible aliasing. >> 
>That's equivalent to the 1199th harmonic of 20KHz ramp wave. >> 
>>> It's a high enough frequency they can ignore aliasing, even 
>for >> naive waveforms, and even for tough cases like ramps and 
>squares. >> >> It does seem like overkill, but FPGAs are cheap 
>these days, and >> running a few (or a lot of) NCOs isn't even 
>going to make one >> break a sweat. >> >> Yeah, why not? I like 
>it. Simple, direct, does the job. >> >> Tom >> >> On 20 Apr 2017, 
>at 18:20, Richie Burnett <rburnett at richieburnett.co.uk> wrote: >> 
>>>> An interesting direction Novation are taking with the use of 
>>> FPGA based NCO oscillators on their new hybrid polysynth. 
>There's >> a video from Superbooth about it on sonicstate. It 
>uses a sample >> rate of 24MHz to generate classic analog saw, 
>pulse, tri waves, >> etc, then feeds them through conventional 
>analog VCF, VCA, etc. > >>> Seems like a bit of a brute force way 
>to crack the old aliasing >> nut, but I guess it gives them the 
>ability to do some wacky audio >> rate modulation stuff with 
>reduced aliasing too. > > -Richie, > > >> Sent from my Xperia SP 
>on O2 > > >> _______________________________________________ > 
>Synth-diy >> mailing list > Synth-diy at synth-diy.org > >> 
>http://synth-diy.org/mailman/listinfo/synth-diy >> >> >> 
>_______________________________________________ >> Synth-diy 
>mailing list >> Synth-diy at synth-diy.org >> 
>http://synth-diy.org/mailman/listinfo/synth-diy >> > -- ScottG > 
>________________________________________________________________________ 
>> -- Scott Gravenhorst > -- http://scott.joviansynth.com/ > -- 
>When the going gets tough, the tough use the command line. > -- 
>Matt 21:22 > > _______________________________________________ > 
>Synth-diy mailing list > Synth-diy at synth-diy.org > 
>http://synth-diy.org/mailman/listinfo/synth-diy 
>
>

-- ScottG
________________________________________________________________________
-- Scott Gravenhorst
-- http://scott.joviansynth.com/
-- When the going gets tough, the tough use the command line.
-- Matt 21:22