Hardware configuration for guitar effects applications?

#1

Hi all,

I'm wondering if there are other Axoloti-as-guitar-pedal folks out there who would be willing to share how they have wired up their board with knobs and switches, and how it's working out.

I'm using my Axoloti primarily for guitar effects, and so far I've been having fun playing around with just the bare circuit... but sooner rather than later I want to set it up with knobs, switches, and bypass so it can work with a regular guitar pedal chain. Rather than figure this all out from scratch, I'd love to start from someone else's guitar-oriented solutions...

#2

Hi Kat, nice to hear from another guitarist using Axo primarily as a multi effects system.
With the Axo, almost anything is possible, for me the prime setup was to be able to control everything with foot switches, but when working on a patch on the desktop, I can remove the module which has everything I need to simulate what the footswitch would do.
Additionally the controllability can be adapted to any patch.
So far build is as follows..
Yes I am a bass player, with goals way beyond a standard bass effects system.

There will be some minor updates to the module soon from 8 switches + 2 bank switches to 16 switches + 2 bank switches. It will all be done at the same time a build the foot switches, had to order more footswitches from OS, so waiting for them to arrive.
:grin:

#3

Hi Gavin,

Oh, this is really cool. Thank you for pointing me towards your post, which gives me a few things to think about. I had previously been thinking about aiming for having a lot of knobs, but I think the idea of having switches control everything has major benefits. I have been finding the more I use the Axo for making guitar effects (which, really, I am just starting), the more it becomes clear that I am ultimately making custom effects for individual songs. So thinking about it like a regular pedal isn't quite right... a switch-based interface might ultimately make sense. And actually, some of the things that I'm having the most fun with are 'dynamic control' - that is, using the thing I am playing on the guitar to itself trigger changes in the effects, so I don't need to even use my feet (an advantage, as I'm really uncoordinated with foot switches).

One thing I have been wondering about is expression control... is that something you've considered? Any idea if it would work, and if so, how?

Ok, I suspect I will have more questions for you as things go... so you will hear more from me! thanks again.

#4

Nice response Kat,
Seems we might have some similar goals.

I went through investigating the knob setup some time back, you will find I made some posts about "Rotary Encoders", but this caused some mixed thoughts because, sure you can use the encoders when you are building and testing the patch, but when I am performing the patch, keep have to get up and down for any extra changes etc.. I have had this experience with many Multi effect systems over the years, so then I came up with an idea to solve this, (someone can take it and make money out of it), it is a Rotary Encoder that you can turn with one foot. A wheel to adjust the parameters with. But as I started to design it, I found it was going to slow me down greatly, so I decided to come up with a setup that I could incorporate the foot wheel later. This will be started after I finalize the module and the footswitch unit. Knobs you can control with your feet, how does that sound !.

'dynamic control' - hmmm very interesting.. I have been focusing on some patches that do this for the last week. Currently working on a trigger event every time a string is plucked, been trying to use the increase in the envelope follower to detect this. Mixed results.

'Expression Control' - Quite a broad area, do you mean like an expression pedal, or expressive parameter control influence by what you are playing at the time ? because it is the second that I am hopping will branch off of the work I am currently doing with the envelope follower in a more complex way, small steps.. !
:grin:

#5

Have you considered a KMI Softstep ?

You can sometimes find v1 pretty cheap.
It's not quite as sensitive:subtle as I'd like (perhaps v2 is better?) but it is good, and very flexible.

#6

By 'expression control' I mean using an expression pedal to control arbitrary parameters. Basically exactly what it sounds like you were trying to do with the rotary encoder project.

With some separate analog guitar pedal projects, I've hit this point where this is the main thing I want to be able to do that doesn't exist: plug an expression pedal in instead of a random potentiometer in the circuit. Not easy because the pot values and roles vary a lot from pedal to pedal. But it seems like with the Axoloti it could actually work that the foot pedal could be used to control anything, and possibly you could switch what it controls with footswitches or whatever. If anybody out there has set this up, I'd love any help even with the basics... happy to take any shortcuts here!

And yes, this isn't the right thread for it, but the 'dynamic control' stuff is super fun ... yes, I've also had'mixed results with my ideas for using an envelope follower... but I'm still making some progress and I think some of the limitations are solvable once I get over the 'how to code an actual object' hurdle...

#7

Thanks for the Softstep recommendation... I hadn't heard of it. Does look cool... although also looks a little "fussy" compared to a straightforward expression pedal that you can literally put your weight into... but it's always good to have more ideas on the table...

#8

yeah, its main advantage is each 'pedal' has multiple axis of data, so pressure and tilt in x/y (iirc each pedal has a sensor in each corner) ... so with 10 steps, and the ability to switch 'presets' it gives you a lot of possibilities.

(its also standalone, so just plug it directly into Axoloti, and its very durable... as no moving parts etc)

I don't know if my 'issues' with it are partly related to the fact I don't use pedals much (over simple sustain and expression), so my coordination around the steps is not very good :slight_smile:

#9

I remember reading through the specs etc on the softstep a while ago, at 6 foot 3 and 100kgs I am convinced I would be far too clumsy for a device like that. It looks like it requires rather sensitive control, not something I could provide.

Regarding expression pedals, very easy to setup on the axo, I guess the question is, how many do you want. To save a bit of money, I might make something like a 5 expression pedal board.
The problem with adjusting the parameters with an expression pedal, when you change the patch, anything you have connected to the expression pedal will default to the current position the expression pedal is in. But with a rotary controller, it begins from the preset position.
I believe there is definitely room for both, its just a matter of getting the right hardware and patch configurations to meet your needs.
My current setup will already take to expression pedals that I have to the Axo, so this gives me a start on how far I want to go.
as far as adding expression to pots in your pedals, it can work, I remember trying it years ago with the tone on an overdrive pedal, I loved it. But I have also wondered if it is possible to find a way to mount a servo to a pedal to control a pot, which is connected to the Axo or some other micro controller, then the servo could easily be controlled by an expression pedal or even an LFO in an Axo patch.
:grin:
My problem is the more I think about trying new things, the further away I get from progressing with my core setup etc.. very frustrating..
:unamused:

#10

Nah, they drove cars over them :wink:

Yeah important that you remain focused, easy to get sidetracked - I'm having to refocus myself for the same reason.

#11

Ah, I see your point about the rotary controller. Hm... I will have to think about this.

In pursuit of my expression-pedal-for-everything ambitions, someone tipped me off to a thing called the "Third Hand" by Tone in Progress. I'm not sure these are actually available anywhere, but it's an example of a mechanical knob-turning pedal.

Working digitally, it has to be possible to be 'smart' enough not to need this, though, in my opinion!

#12

The KMI softstep is somehow the only choice if you want a usb class compliant midi pedalboard that is also USB powered, and it's reliable and roadworthy, BUT using it as ten expression pedals is very hard, and believe me I'm very much used to small pedals and foot jugglery... I was aiming myself at something like

but I ended up sticking rubber buttons on the pad corners and use it mostly as switches

Stompbox version of Axoloti
#13

Yeah, the "third hand", I saw that for the first time just the other day, in fact I spent several hours today in hardware stores etc,, looking for inspiration if it can be done DIY.
Reason being, I like the cable peice, not the pedal peice, if the cable peice could be connected to a servo instead of an expression pedal, Axo could control it.
Still investigating, but got a few ideas to try out..
:grin:

#14

OK, have done some testing, was able to get the concept working rather crudely using the cable that is used on bycicles to activate the break mechanism.
The cable is quite thin, so as it twists it doesn't maintain shape, with some further testing with cable thincknesses should be able to nail it.

Capture.PNG1144x453 362 KB

:grin:

#15

so your intention is to control existing guitar effects with Axoloti, rather than build an effect with Axoloti?

would it not be possible to open up the existing pedal, and make the pots in the pedal be controller via 'CV', Ive seen this discussed a few times on muffwiggler.

usually, the solution is based around using a homemade vactoral - such that the pot is replaced (or possibly done in parallel) with an LDR, and then the incoming voltage (in this case from Axoloti) drives an LED. (the LDR and LED are put inside a small tube, and sealed).
its quite a simple solution, and keeps the circuits electrically isolated... if you search on MW, you will find lots of improvements on this design.

#16

Actually, my intention is, if the cable is designed right, it could control any rotary pot or possibly more.
I will always consider having an additional external pedal or two (only boosters, overdrives, distortions) that I will want to add to the effects chain through the Axo, only because these are areas where it appears DSP is lacking, but time and experimenting will tell, but once again the flexibility to add as desired is the goal here.
Further to this, something I have been thinking about quite a lot for the last 6 months is a kind of mixer for guitar pedals, think of something like a simple mixer connecting an effects pedal input and output per channel rather then being mixed into a master output. By connecting pots as faders I could create a very crude passive version which could in turn be controlled by this flexi shaft. So rather then controlling the effect itself, I am controlling which effect is on, off, and its mix in the chain. I have looked at a plethora of looping units, I do believe in some ways they are extremely over engineered. I have also looked into digital pots, multiplexors and switching systems etc.. None of them feel worthy of what I am wanting to achieve. This is all mostly long term goals, and I only think and talk about them when I know its not going to slow me down.
:grin:

#17

I always just figured expression pedals (like wah or volume) were an effect pedal, but instead of just a switch, they have a potentiometer rigged into the axis of the pedal...if that's the case, it shouldn't be hard to create one at all...you could probably buy whatever mechanism they use online by now for cheap and throw them into an own sewing machine pedal (which is what they used in the beginning I believe..)