[sdiy] Novation peak NCOs

[Sarah Thompson]

24MHz isn't too hard in the FPGA world unless you're using a slow
miltary/aerospace style part (e.g., the older Actel stuff). Current Xilinx
parts would handle that before breakfast. DACs used to be super expensive
for that kind of rate, but less so these days. It's an interesting option.
FPGAs are awesome, but they can be VERY tricky to work with and a nightmare
to debug. The fallout from one of those experiences is why I own a 168
channel Tektronix logic analyzer boat anchor!

On Thu, Apr 20, 2017 at 5:01 PM, <paula at synth.net> wrote:

> Richie,
>
>   NCOs, where have I heard that before ;) ?
>
>   In all seriousness, speed comes cheaply in FPGAs and a one bit DAC
> running at 24Mhz is also not expensive in terms of resources. That aside,
> remember if you generate a fast enough wave you don't have an aliasing
> problem to start with, so no BLITs, oversampling or other things needed to
> remove it, as it's not there to start.
>
>   Where I think they'll suffer is taking the analogue output back into the
> DSP for digital effects, that said at £1200 for a 3 osc 8 voice poly is
> pretty good value for money.
>
> Paula
>
>
>
> On 2017-04-20 19:20, Richie Burnett 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
>>
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