[sdiy] Quality reverb on STM32's?

[Richie Burnett]

Wanna try reverb on dsPIC sometime, using DMA to move pages of external SPI SRAM in and out of local memory. Should mitigate some of the pin count and latency issues of using external RAM. Especially since one block of memory can be being processed whilst another is being "paged in/out" via DMA.

Would still be quite a grainy reverb with just 16-bit processing though. 

-Richie, 

Sent from my Xperia SP on O2

---- Tom Wiltshire wrote ----

>That’s very true, Richie. The FV-1 is a very specific chip for very specific jobs, so it isn’t comparable in MHz terms with other general purposes processors.
>For that, Olivier’s “6% at 168MHz and 32 or 64K” is probably a better guide.
>
>> On 14 Apr 2018, at 08:56, Richie Burnett <rburnett at richieburnett.co.uk> wrote:
>> 
>> The FV-1's instruction set is *highly* optimised for generating reverb though. It is not a general purpose DSP or microcontroller.
>> 
>> It's not really fair to benchmark algorithms in MHz alone on such a specific hardware architecture. You need more instructions to do the same stuff on general purpose DSP /Microcontroller hardware. 
>> 
>> -Richie,
>> 
>> Sent from my Xperia SP on O2
>> 
>> ---- Tom Wiltshire wrote ----
>> 
>>> +1 agree.
>>> 
>>> The FV-1 chip pulls off some decent reverb algorithms, with only 1 second of delay memory at 32KHz. The secret in that case is Keith Barr’s inside track knowledge of “good reverb for cheap” and how to get the best out of algorithms by using all pass filters and so forth to “smear” the reverb. As Eric says, a lot of it is in the “tuning”.
>>> In terms of MHz, the FV-1 uses 128 cycles per sample, so that’s 4MHz - yeah, seriously; you can do decent reverb at 4MHz. At least, Keith Barr could and the rest of us had better catch up! ;)
>>> 
>>> Example from Mick on DIYStompboxes:
>>> 
>>> https://www.youtube.com/watch?v=0k69GtDoin4
>>> 
>>> Tom
>>> 
>>> ==================
>>>      Electric Druid
>>> Synth & Stompbox DIY
>>> ==================