Analog Devices Sigma Studio- visual environment for DSP design

[Processaurus]

This looks like an interesting way to get started in DSP, Analog Devices makes some software, Sigma Studios, that has a visual environment for picking out little audio modules, and chaining them together- could be great for guitar effects design. Looks like Pure Data, or other modular synth software, but, you can take it and put it on their chip.  Lots of options for the IC's that work with Sigma Studio, but I was looking at getting started with the ADAU1701. $10.18 at Mouser.

The ADAU1701 is a complete single-chip audio system with a 28-/56-bit audio DSP, ADCs, DACs, and microcontroller-like control interfaces. Signal processing includes equalization, cross- over, bass enhancement, multiband dynamics processing, delay compensation, speaker compensation, and stereo image widening.

This one has stereo ins, and 2x stereo outs.

What do you think? Seem like it could be good for guitar?

[free electron]

I played a little bit with Sigma and ADAU1701 a while ago. Even designed a small dev board for the chip:



Unfortunately, the programmer required to work with Sigma Studio is rather expensive, although there are ways around it. You can use an external EEPROM burner, but you loose a very convenient way of developing the firmware, that is a direct link with the hardware updating the parameters on the fly.
It seems these chips (low range 1401/1701) were designed mainly for digital filter and crossover applications. Neither they have enough RAM for any serious delays and reverbs, nor any external memory interface. For that, they are very nice. I was thinking about using them to build a stereo speaker simulator. You can construct a more complex filter responses, graphically tweak the parameters until they sound good, instantly hearing the result in the hardware.

[Processaurus]

Thanks for the response, I hear you about it not being suitable for delay's and reverbs, memory intensive effects. 40Kb is what it looks like the 1701 has in program memory (also has 32 Kb in parameter RAM, not sure what the difference is). 

Could still be quite interesting for the filters, compressors, distortion, etc. The audiophile sampling rates and bit depth is attractive. Even something fun, like a fancy EQ for an analog distortion, that could do a dozen preset EQ's, like you have on boomboxes. Classical, Jazz, Rock, heh. Throw in a noise gate, or enveloper.  You could undoubtedly make a EHX microsynth type effect.

Here is a list of the modules you can drag and drop into your projects:
https://wiki.analog.com/resources/tools-software/sigmastudio/toolbox

Seems like it has enough RAM to do chorus, and flange effects, maybe some slapback? I also saw they have Sigmastudio for SHARC, those processors have more ram, or the provision for having external ram. I'm assuming those chips don't have the onboard AD/DA, though.

Free Electron, how far did you get with the ADAU-1701? did you have the fancy development kit where you can update the program, in-circuit? That would surely be the way do go with and DSP platform, otherwise you are shooting in the dark, as far as dialing in what sounds good.

[free electron]

Yes, filtering, choruses, flanging, some synth stuff is where i'd see these chips most useful.
I didn't do much with them, though, just played a little bit with EQing the signals and trying to build a stereo speaker sim for my looping pedalboard.
My setup was the mentioned dev board + Dev_LOOP as analog IO + hacked CY7C68013A-56 FX2LP board to work as USBi dongle. I was able to make it program the onboard EEPROM and update the parameters on the fly. Editing the filter response in SigmaStudio and hearing the results instantly in the hardware was pretty cool!
What peaked my interest in these chips was series of projects in Polish "Practical Electronics" magazine:
http://serwis.avt.pl/manuals/AVT5403.pdf
http://serwis.avt.pl/manuals/AVT5403_2.pdf
http://serwis.avt.pl/manuals/AVT5403_2.pdf
http://serwis.avt.pl/manuals/AVT5442.pdf

My dev board is actually inspired by the first article. I have redone it in KiCad, changing some things and going for 4 layers.

[SeanCostello]

My understanding of the Sigma DSPs is that some of them can access off-chip memory for reverbs, delays and such...but that this functionality isn't exposed in SigmaStudio. The Source Audio pedals use a variant of the Sigma DSP, and the upcoming Ventris uses off-chip RAM for its delay lines. The Source Audio folks also worked in the Sigma DSP division at Analog Devices (they might have RUN that division at some point), so they would have access to internal documentation that was never published.

[Processaurus]

Those Source Audio pedals are really interesting, one of the few pedal makers that have dove in, to the new effects made possible by dsp. It's an encouraging vote for the sonic quality of the platform, as well.