[sdiy] In praise of the ATM STM32F303

[Olivier Gillet]

This is a variant of this:
https://ccrma.stanford.edu/~dattorro/EffectDesignPart1.pdf (fig. 1)

(with only one long delay instead of two in the loop). I've scaled the
delay times so that everything fits in 16384 words exactly.

There's a trade-off to be found in the amount of modulation - keep it
small and you'll hear repetitions/metallic resonances. Increase it and
it'll help smooth things out at the risk of introducing heavy pitch
modulation (unwanted on pitched material unless you like Boards of
Canada...). For percussions, it's not a big deal to increase the
amount of modulation since you care less about pitch.

There's also a CPU / RAM trade-off to be explored. Complex
modulations, such as smooth random functions, help neutralize metallic
resonance without impacting your delay time budget. But then, they use
more CPU!




On Fri, Feb 12, 2016 at 10:01 PM, Richie Burnett
<rburnett at richieburnett.co.uk> wrote:
> Did you base it on the Jon Datorro "Lexicon Plate" reverb algorithm too?  Or
> one of the Spin Semiconductor FV-1 algorithms?  Or something you designed
> yourself?
>
> I know the early Reverb pioneers had to be really clever in making their
> algorithms make the best use of what limited (expensive!) memory they had
> available to them back then.  With only a small amount of delay memory you
> have to use lots of diffusion to scatter the energy around each time it
> passes around the loop otherwise you hear audible repetitions.
>
> -Richie,
>
>
> -----Original Message----- From: Gordonjcp
> Sent: Friday, February 12, 2016 8:34 PM
> To: synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] In praise of the ATM STM32F303
>
> On Fri, Feb 12, 2016 at 07:04:11PM +0000, Richie Burnett wrote:
>>
>> I'd be interested to know how they did a decent sounding reverb with so
>> little RAM,
>>
>> -Richie,
>
>
> I've got a halfway decent sounding reverb that uses about 8K of RAM at a
> fairly low sample rate. Haven't tried porting it to an STM32 but that's the
> general idea.
>
> --
> Gordonjcp MM0YEQ
>
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