Audio Effects DSP Board

[EBK]

... but could you implement a phase vocoder with this board? 

Yeah good question and it sounds really interesting.  I'm not very familiar with that effect yet.

What do you think would be the requirements for the bulk of the DSP stuff?  Like would you use a sliding DFT or rather use short-time FFT's?  For reconstruction then would you then use weighted overlap and IFFT?  Is the FFT/iFFT to be done using complex math? 

If we could nail down how many FFT's/iFFT's per audio block, the audio block size, and the FFT/iFFT length, and the overlap amount and windowing approach then we'd have a good idea on whether or not this would be possible since it seems like these operations would be the majority of the processing load (true?).

More details would also give me an idea of what DSP support code I could write and optimize.

I know just enough about DSP to understand what each of your questions mean and why you are asking them but not enough to provide intelligent answers.     (it has been nearly 20 years since I studied this stuff in detail)

Perhaps I'll make an attempt to dig up something.

[elseif]

Are there any demo boards left?

-- bradley

[markseel]

I might have some ... I'll look around.  The FlexFX kit will kickstart soon though - just one more board to assemble and test to verify a few changes to the audio in/out section.

[markseel]

The C99 Digital multi-effect pedal has launched.  You could actually reprogram this with your own effects built using the FlexFX kit on GitHub.  Re-loading it with the C99 would then be accomplished using the HTML file that's used to adjust preset parameters (the C99 firmware is embedded in the HMTL file so that firmware upgrades are easy to do in the future).

https://www.indiegogo.com/projects/c99-digital-multi-effects-pedal/x/18734552#/

https://www.instagram.com/3degreesaudio/

[elseif]

One thing I find interesting about this hardware is its ability to have a secure boot using the OTP memory to store a unique ID.  This would allow an application developer to ensure that a binary, stored encrypted in NVM, could be run on only one processor, or even set of processors (for example). I expect it adds complexity to the tool chain, and could make development and debugging more complicated but it is an option for a developer concerned about protecting the IP.   I could forsee an community where a user could purchase the hardware and then purchase software from different developers keyed to that hardware.  It is an idea that might encourage application developers to invest in the hardware platform.

[markseel]

Yeah good point.  I use that feature to lock the FlexFx kit on GitHub to the FlexFX hardware module.  Same with the C99 ... the C99 FW will only run on the C99 board (the C99 board will run the C99 FW *and* the FlexFX dev kit in GitHub).

[markseel]

The C99 campaign isn't attracting much attention.  I wonder if people dislike the adjust-presets-using-USB-Google-Chrome idea.  Any thoughts?

[EBK]

The C99 campaign isn't attracting much attention.  I wonder if people dislike the adjust-presets-using-USB-Google-Chrome idea.  Any thoughts?

One tough obstacle, if you are asking me to search for one, is that the cab/amp simulator idea is basically recording studio type stuff or "church" performance stuff rather than stage stuff that needs to be in a pedal form, and once you ask people to edit the settings on a computer, it may remind them that there is free software available that does this (you can even go as far as selecting what type of tubes you want in your pre- and power amp stages with some of this free software).  With that mindset, it may look like what you are mainly offering is the A/D - D/A interfaces and CODEC, perhaps with less capability than offered elsewhere. 

Your configuration interface itself is actually quite friendly-looking and clever (I honestly love the design, and I would nominate it for an award if I could), so that is actually a big plus rather than a minus.

Personally, I love your ideas, but I'm drawn more to the DIY aspect, i.e., the platform to build stuff with, plus example code and maybe some tutorials to get started.

[Digital Larry]

The C99 campaign isn't attracting much attention.  I wonder if people dislike the adjust-presets-using-USB-Google-Chrome idea.  Any thoughts?

Sorry in advance for the TL;DR... but you did ask...

It's probably too much power to be controlled by just a couple of knobs onstage.  Even with the lowly FV-1 I can get a complex enough patch going that 3 knobs is not really enough.  And for pedals, the flip side is that more knobs is just begging for trouble because it gets more difficult to use with each knob. 

One challenge I keep harping on about is that there's an optimum way to deal with complex user interfaces for adjusting sounds.  It may be personal, but I can't relate to amp sim software on the PC, or FX editors (like for the Katana) on the PC.  I bought an Eleven Rack real cheap and it's taken the place of my Katana mostly because the UI is very accessible and it sits on top of my powered cab (Tech 21 power engine) which is where I think it belongs (near where the sound is coming out).  For some reason that makes a ton of difference to me.

Now somewhere this thing might be more suitable esp. with the IRs and stuff, is as a recording interface to hang off of a speaker load.  I'm building a couple tube amps at the moment but I just play in the back room like most other senior citizen former wanna be rockers so I'm not going to want a 4x12 stack and in fact I'm thinking of buying a Suhr reactive load with built in IRs (just came out late 2018).

Because of this tube amp project, I just started looking into all the reactive loads and variations thereupon.  Boss has a Waza thing which is $1299 that combines a reactive load, IRs, effects, and a class D amp to drive your speakers back again.  No way am I going to spend that much.  But I might spend $600 on this Suhr thing (which lets you select 1 or 16 IRs from the front panel).  Or, I might spend $300 on a plain reactive load and some money on something else (like a variation on your gizmo) designed to work with that type of device to add IRs and effects to the signal to send out either to a board or powered speaker like the Tech 21.

Here's another crazy idea that would be a lot of work, but I just took an online course in "Faust" which is a way to easily create DSP algorithms (effects/synths) that can target multiple platforms by simply regenerating the code. 
Although you write Faust code (rather than drawing a picture), it is very compact and drives a block diagram based structure, sort of like SpinCAD but about a billion times as powerful.

https://ccrma.stanford.edu/~rmichon/faust2api/

There is a "faust2api" builder that lets you adapt the Faust code generation to different targets.  Another possibility with Faust is that it can support OSC (control messages over the network).  It also lets you write apps that use smartphone sensors for continuous control.

You might find uptake in that experimenter (i.e. not strictly guitar focused) community (e.g. I'm pretty sure Hoxton Owl can use Faust generated code) and focus on things that lower powered devices cannot do well.  For example, I wrote a very simple 3 oscillator synth in Faust that ran on my Android phone.  If I played more than 6 notes at once it started to glitch because it was running out of CPU.  If I added the reverb patch it started glitching with only 3 or 4 at a time.

It's possible that the product as presented seems too geared towards a guitar pedal rather than something that could do all this other stuff.  I know people are using Raspberry Pis and the like for networked interactive music installations, and those are great because they are ubiquitous but they also are a little underpowered IMO to create complex synth voices and reverb algorithms all at the same time.

Sorry I didn't have a shorter answer like "you need to paint it green".  I think your invention has lots of potential and maybe it needs to be also targeted at a different group of people such as Faust nerds or the modular synth world where they are really going to do things you never even thought about and squeeze as much power out of the thing as it's got.

[markseel]

Yep I asked!  Keep the feedback coming.  Really don't want to paint this thing green though ;-)

One challenge I keep harping on about is that there's an optimum way to deal with complex user interfaces for adjusting sounds.  It may be personal, but I can't relate to amp sim software on the PC, or FX editors (like for the Katana) on the PC.

I'm not following you, can you clarify?  The C99 is the cab sim (plus effects) - the PC isn't used for audio processing.  Maybe I misinterpreted your feedback?

[Digital Larry]

Yep I asked!  Keep the feedback coming.  Really don't want to paint this thing green though ;-)

One challenge I keep harping on about is that there's an optimum way to deal with complex user interfaces for adjusting sounds.  It may be personal, but I can't relate to amp sim software on the PC, or FX editors (like for the Katana) on the PC.

I'm not following you, can you clarify?  The C99 is the cab sim (plus effects) - the PC isn't used for audio processing.  Maybe I misinterpreted your feedback?

Yeah, no problem, I was not talking about the C99.  I meant that in general I like to interact with something other than a mouse.  Even touchscreen is better IMO than using a mouse.

[markseel]

OK that makes sense :-)

[MetalGuy]

Because of this tube amp project, I just started looking into all the reactive loads and variations thereupon. 
Boss has a Waza thing which is $1299 that combines a reactive load, IRs, effects, and a class D amp to drive your
speakers back again.  No way am I going to spend that much.  But I might spend $600 on this Suhr thing (which lets you select 1 or 16 IRs from the front panel). 
Or, I might spend $300 on a plain reactive load and some money on something else (like a variation on your gizmo)
designed to work with that type of device to add IRs and effects to the signal to send out either to a board or powered speaker like the Tech 21.

You can build your own fine tuned reactive load with quality components for around 200 bucks. This has been very well documented in the following thread:

https://www.thegearpage.net/board/index.php?threads/aikens-reactive-dummy-load.1072793/

Unfortunately most pics are gone but it's an informative read.

Many commercial loads are lower quality than that. Also some of the very famous don't have the low resonance circuit.
It's well known the tube amp will start distorting at the reactive resonance frequencies first producing harmonics to the low fundamental which no EQ can add after that. One downside is once you tune your reactive load to your favorite cabinet that's it. It's possible of course to build a variable resonance version but then you'll need some custom inductors which makes the task somewhat more complicated.


I'll make some comments from the position of an end user NOT interested in writing code and experiment with creating effects whatsoever.
I'll agree with Larry that most of time you have to keep it simple for the fellow musicians.
Having many features is good but not for everyone. Most people just get confised and you have to explain over and over what is what.
Since Larry mentioned reactive loads years ago I started looking for an affordable and
readily available IR module. In the mean time (before Marks's board was available) the AMT
Pangaea CP-16 module came out. NOTE that to this day it's still the only one such module  readily available to buy online. Since then I've used it many times with reactive loads and for embedding it into old and new equipment
and it does a pretty good job for what it is. There are of course some downsides to it like:

1/ max 20 msec mono impulses can be used. It's an ongoing debate whether 20msec IR are long
enough or you need a 500msec or even 1 sec IR. Some people swear by the longer impulses although
why you would need a 500msec "room colored" IR on stage is beyond me. Anyway people want more msecs
so maybe you should give them more. On the other side if you're recording you can use your PC and DAW to play whatever length IR's you want.

2/ no MIDi switching

3/ the software controlling the module is not "portable". You do what you do with your IRs on your
PC or Mac and after that you can only switch IRs up and down (this by the way is not solved properly either).
This means in live situations you don't have any visual control of what's going on neither you can change anything once IRs are loaded.
Because of 1/-3/ I had to add an external uCU (somebody wrote the code for me) that would do MIDI, up and down button switching and a double digit 7 segment LED display (kind of retro but simple).
From what I see Mark's DSP board is more powerful than that so maybe if these features (together with a small OLED display showing the active impulse number AND name) are included in a board version that would be a dedicated IR player I'm positive that it can become more popular. By "dedicated IR player" I mean channeling some of the current board capabilities for longer IRs.

[markseel]

Here's the next version of the FlexFX kit (used in the C99).  I'm reworking the C99 for the next campaign and that's taking most of my time ... but I could build some of these kits for folks that are interested.  Shoot me an email (markseel@protonmail.com) and I'll see how many queries I get and how I may be able to fit this option in to the C99 campaign.

[MetalGuy]

...but I could build some of these kits for folks that are interested...

Which kit is that?

[markseel]

The C99 main PCB (with jacks, OLED, encoder, etc) and the attached XMOS module (all shown in the previous pic) would end up being the kit since I have to make those boards anyway for the C99 campaign.  I suppose I could add the case as well and you could label/paint the plain case yourself.

[MetalGuy]

As I already mentioned I need a module similar to the Pangaea CP-16 that can handle longer impulses and that I can build into various equipment and or create some around it. I see that you have other plans for yours and that's OK. Good luck with the campaign.

[tcpoint]

Bump

[markseel]

https://www.indiegogo.com/projects/c99-effects-pedal#/

Can also be used with the FlexFX dev kit.
https://github.com/flexfx/flexfx.github.io

[Roboroy]

OK back at it.  It's been a really busy time with family, work, and side projects but I'm going to take another whack at a KickStarter for the FlexFX dev kit.  Speaking of side projects check these out:

The C99 Mutli-Effects pedal
https://www.kickstarter.com/projects/632112529/68367638?ref=499075&token=c082d5ce

Chase Bliss Audio Blooper
https://www.instagram.com/chaseblissaudio/p/BtAMQ5oBwyV/
https://pedals.thedelimagazine.com/new-prototype-at-namm-2019-chase-bliss-audio-blooper/
https://www.gearnews.com/namm-2019-chase-bliss-audio-blooper-prototype/

Fun stuff!!!  The C99 pedal video is being made now and the KickStarter for that should start in a couple of weeks.  The Blooper is going really well but it's going to take a while to finalize how that works.

Here's the updated FlexFX kit hardware ...



The board on the left is the main board that has connections for 8 pots, 2 foot switches, 3 LED's, stereo line out, stereo line in (buffered), 9V power jack, USB jack.

The board on the right is the core DSP/CODEC module that has the XUF216 and an AK4621 differential in/out stereo CODEC.  This board run off a single 3.3V supply and has connections for power, ground, USB signals, I2S MCLK/BCLK/WCLK, UART TX/RX, I2C SDA/SCL, 4 DAC wires, 4 ADC wires, and JTAG.

The core module simply plugs into the main board for a full system (where the red square is drawn) - just add jacks, pots, and power.  The core module could also be plugged into your own custom board.

Same software as before (https://github.com/flexfx/flexfx.github.io/blob/master/README.md).  This is the same foundation as is used in the C99 pedal and the Blooper (although the Blooper has additional DRAM chips for loop audio storage).

Hi Mark, are you interested in another project?