modular guitar pedals idea - work in progress...

[heaterman]

Hello!

I am working on some kind of modular pedal concept. The Idea is to have VCA's LFO's envelope followers, sequencers, delays with different inputs/outputs to controll each other.
For example you could do a simple tremolo with one LFO controlling a vca. But then you can controll the first LFO with another one so that the speed changes according to the second... the LFO speed can also be controlled by an envelope so every time you hit a note the tremolo is going from fast to slow or viceversa.

Here are some videos to show what its all about:

1) This is a basic PT2399 delay. The Time is controlled by a 10 Step sequencer (CD4017 circuit). It can go from weird pitch shifting Vibrato to subtle chorusish sounds. It also has an output from the sequencer signal and an controll input for the sequencer speed.

[youtube]https://www.youtube.com/watch?v=nWvWzKZlO7M[/youtube]

2) Here's a ducking effect. It is done like that: The "Bassdrum" (coming from the boss loopstation) goes into the envelope follower (based on the mu-tron follower section) the envelope signal controls the VCA which squashes the guitar signal. The VCA is done with the Coolaudio V2164 chip using only one channel.
In the video you see these boxes from left to right: loopstation as the bassdrum source - envelope follower - one LFO - a second LFO - VCA (on breadboard) - to the far right you see a simple true bypass switch to bypass the VCA.


Link


3) Again the VCA, but now it is controlled by the first LFO, so it's a tremolo. Later, the second LFO varies the speed of the first one, so it is alternating between two pre-set speeds. In the end, the envelope follower is controlling the first LFO. Every time the bassedrum is hitting, the tremolo starts from a fast to a slow rate.


Link


It's all very prototype-ish, still a lot of work in progress... what do you think of it?

best,
David

[aishabag23]

This is very cool!

[FiveseveN]

Cool indeed. I love it when people develop tools for sonic exploration rather than the next FF or TS variant.
Are you making these for yourself or planning on a comercial series? In any case, take a look at modular synths on the off chance you are not familiar with them; following the Eurorack standard would open up a lot of options.

[heaterman]

Thank you!
At the moment i'm just doing them for myself... maybe i consider doing a small series if enough people would be interested, but that's definitely not possible in near future
And i'm not shure still how practical such a system is gonna be.
Still I have to fix stuff and experiment more. Some problem causes different control voltages. The envelope puts out a different voltage than the LFO and i'm trying two different VCA's (one with a vactrol the other with a 2164 chip) and they two need different voltages. So I'm working on getting these to work all together without having to readjust voltages every time I connect something differently.

... In any case, take a look at modular synths on the off chance you are not familiar with them; following the Eurorack standard would open up a lot of options.

Yeah! got the idea more or less from eurorack systems But I like to have these things working with 9v and like to have most stuff footswitchable. But like having the 5v standard for the control voltages would be a good idea to be somehow compatible.

Anyhow; here are the schematics so far, if anyone is interested. You can see, everything is very simple actually.

The VCA done with the Coolaudio 2164 quad vca chip. It gets quiter, if CV increases.


The vactrol-based vca. It gets louder if CV increases.


The LFO, a simple dual wave LFO, the speed can be controlled by an CV via the vactrol.


And the envelope: Inputbuffer, then a Mu-tron follower, actually. It can go from high to low or low to high CV output. It needs a dual supply...


Last but not least a delay. Just a basic PT2399 Delay but with following features/mods
-effects Loop in the feedback path
-momentary switch to select between a second delay time, this results in pitch shifting effects
-momentary switch to turn on a vactrol for bending like pitch shiffting effects
-CV input for the time setting

[calfzilla]

This looks really cool! When I opened the thread I thought maybe it was something like the CONSOLE but this is another level.

[centraleuropean]

That's cool, i've been thinking about it for a while.

I was thinking about doing the same using the eurorack standard for a few reason 1) there are already quite a few great/freaky modules 2) DIY projects are common 2) it's a great to have an existing standard for power supplies, cases, panels, general conception, etc...

It can be very compact et cheaper : less enclosures, just metal plates, less parts and pcb for LFO's in circuits ( A double VCA and a decent oscillator and you have a trem, a panner, a ring mod, etc ..)

You could even do something like the Monome Isms (case with utilities) and a serie of foot switches that could be used for any task with patching cables (each module having a "On/off" trigger input , Tap tempo input, etc etc)

[izikg]

cool idea.
i also have similar idea running in my head
most pedal have the pre section . its midle magic and post section including mix and equlizer buffer.
so what if on the middle magic section we will put multiple stomp box like overdrive distortion . maybe add a time section including chorus deley etc.

few questions i still have to answer are
will a jfet switch be acceptable . i know people dont like jfet switch for low signla true bypass but since here it is a high signal amplitude after the pre section it might just be acceptable?

can we use few foot switch for multiple function by useing double click or long clicks. or is it just to complicated to handle (for the guitar player)?

since there will be multipe vca( or programed resitors or whatever) will a guitar player be willing to use a smartphone app to control the stomp box? this will reduce the numver of pontentiomenters or control on the stampbox

hope some thing good will grow out of these ideas

[heaterman]

thanks for your comments, it did some progress, here is a photo so far: (hope i can do a small video soon...)
From left to right there is: splitter - VCA (vactrol based) - LFO (w/ footswitch) - LFO - Distortion (rat-like) - Delay (pt2399; cv input for the time) - 8step sequencer - double VCA (2164 based) - and a mixer

i'm almost finished with this, i will add an envelope follower and one more delay but with an feedback loop insert.
for the switches i decided to do all standard true bypass, except for the next delay which will be buffered for tails...
all audio connections are standard guitar jacks, all control connections (cv) are small jacks.

i really like the eurorack format for this. its smaller cheaper easy to add things, modify etc.
But i didn't really follow the eurorack standard in terms on voltages and connectors, this one runs on 9v... so i dont think its possible to just add some cool erorack module... so its more like modular guitar pedals in eurorack cases.
also the case i did is very low, so a bigger modules with a big circuit board won't fit anyway.

@izikg i never really looked into jfet switching, since true bypass is so easy and always worked good for what i wanted to do. but i like your idea with the double/long click etc but i think that requires some programming or at least seems complicated... but i will do some research in this direction could open up some nice options. and also the idea with the app... i just have no clue about programming... and i don't think thats my route... too complicated for me
...i think i will stick with the good old shitty 3pdt switches. adding some latching switches for cv will be usefull ithink...

open questions for me are still:
-9v or eurorack voltages (+/-15v)?
-the switching concept (footswitches on the modules or a separate patchable switch box) or both?
-6,4mm jack for audio? pro: easy to implement a standard guitar pedal. contra: needs more space
-and i still wonder how useful it will be in the end
-and some minor problems like different cv voltages, LFO/Timer ticking, sometimes small useful ranges for some pots etc...

and thank you all for your inputs and checking it out, i will try to make an update here every now and then... and feel free to ask anything, i already posted some schematics but changed some minor things meanwhile... will post the new ones too when they are at a usefull point

all the best
david

[izikg]

looks grate
what is the chassis form factor/size?
do you use common power?

[heaterman]

I use 9v, everything is powered with one 1spot power supply. No hum or noise problems so far...

The chassis is made out of 2 doepfer A-100 84HP rails, so it's ~42cm wide. the plates are standard eurorack, so ~13cm high. depht is only 4cm, so it lies relatively flat on the ground (good for the stompswitching), but not much space for big circuit bords on the modules...

[Zokk]

Hi

that's very nice!
What about adding a VCF (with VC resonance), a sample and hold/noise/clock generator, a real ADSR (with bipolar outputs) and a ring modulator (to process CV or Audio)?
You may need some multiples and attenuverters if you play a lot with CV routing, and you may need an AC-DC option on your VCAs.
You may also need a trigger/gate output from your enveloppe follower, and an audio rate LFO.

You can add a CV panner as main output module (even add line drivers and speaker simulator) with two ouputs to have a real stereo.

If you look for other cool simple single supply circuits you may already know these:
http://electro-music.com/forum/topic-34550.html
http://electro-music.com/forum/forum-160.html

I'd say the best idea in a modular is to keep all the circuits at the same voltage, you'll avoid many problems.
If you stick to 9V single supply you may have a very limited headroom, and limited range for the LFO. It won't accept easily CVs from other modules except 0/+5V.
The eurorack standard psu is +/-12V, but the Dotcom/Moog standard is +/-15V... Of course you can have all the desired voltages by adding regulators after a classic +/-15V psu.

Modular is a never ending project...

edit: have you normalled some connections? like a "pre-patch".
And you can simply have 6.35mm jacks on an input/output interface, and keep all the other connectors 3.5mm.

[GrantGrand]

Wow, man, good job. Waiting for the final. If it is possible I would like to see the video of the end of the proccess.

[heaterman]

took me quite a while but finally i made a video:


Link


It is a bit long... hope it is not too boring, i learned that it's not so easy to do a exciting demo video
It just shows some possible patches, many more might be possible... a modular project is really endless...
hope you enjoy it!

[Zokk]

Congrats!
Crazy CVDelay!

What is your power supply? Did you choose the euro format too?

[microbailey]

Been watching this. Its a cool idea.
Borrow from the world of synths. If you ever commercialize this idea you can sell each module separately!
Of course the idea could get out of hand

Moog_modular.JPG

imagine changing pedal settings between songs Saving patches is the way forward.

[heaterman]

hey!
power supply is still all 9v. Still stuck to that.
euro standard would be really nice to have the possibility to easely implement other modules...
and as you said, getting other voltages is easy with regulators...
all modules run on 9v, except the envelope follower wic runs on +9/-9 volt (with a charge pump).