The Xor'cist released!

4/19/2016

edit 2016-04-26: Limited edition fully assembled pedals now avaliable!

Here's a new DIY project - the Xor'cist stutter fuzz and ringmod. It's now avaliable as a PCB and as a fully assembled pedal.

I have been wanting to do a CMOS based squarewave stutter fuzz (a choppy on/off type tremolo) for quite a while. I have also been thinking about doing an extended version of the Corruptor ringmod (without the over-the-top sequencer of the King Corruptor) so I decided to combine both these ideas into one circuit and this is the result. :)

It can do fuzz, ring modulation or a blend of both. With the stutter engaged it will do stuttering fuzz, stuttering ringmod or alternating between fuzz and ringmod (depending on the mix knob setting). The momentary stutter footswitch can be disengaged and the LFO can be off/on/gated.

The Xor'cist uses a CD4070 XOR chip (hence the name) to achieve both the ringmod and the stuttering effect. It's basically the bastard big brother of the Corruptor.

PCB and complete pedal avaliable in the webshop

27 Comments

Jaroslaw

12/14/2015 03:56:03 am

Is it fuzz XOR ringmod? ;) Like https://en.wikipedia.org/wiki/Exclusive_or

Fredrik Lyxzén link

12/15/2015 03:34:27 am

That's correct! Email me your adress to parasitstudio @ gmail.com and I will ship out the prototype PCB to you. :)

kahel

12/14/2015 05:28:32 am

The Xor'cist - because it uses the CD4070B Xor (Exclusive OR) gate at its heart ;-)

12/15/2015 03:36:27 am

Yes, spot on! Easy guess :P I will send one prototype PCB to you too since I have one left. Email me your adress to parasitstudio @ gmail.com :)

Ash

12/14/2015 01:56:27 pm

Not sure just want one, lol. Maybe it spins in a loop (modulates) like Linda Blairs head then spits out green soup.

12/14/2015 05:43:18 pm

Actually I agree with Jaroslaw. It can be either fuzz or ring mod or both fuzz and ring mod.

Joris Krawczyk link

12/26/2015 08:46:52 am

Oh no, too late! The answer was written on the left side of the pedal: "XOR", and because it sounds like hell! Good job guys, I'm going to follow your work and your blog, I really love it!

Shane

4/19/2016 08:11:08 am

Awww man!I just placed an order a few days ago!I knew I should have waited another few days!
Oh well,perhaps in another few weeks or so.
This is an awesome circuit!Well done sir!

Guy

5/20/2016 10:26:51 pm

What is the difference between the 2 versions of this 1 pedal?

5/30/2016 03:02:55 am

One version has the second modulation footswitch (for the stutter) as a latching soft touch switch, with one rate LED and one modulation indicator LED. The other version has a momentary soft touch switch and two alternating rate LED's

JP Rubio

10/16/2016 09:09:27 am

Awesome pedal, really unique sound. I got my kit from musikding and its worth every penny. Question tho, is it supposed to rattle when not playing or did I make a mistake? Cheers

10/16/2016 09:32:09 am

Figured it! Used the CD4069 from my unknown pedal to try, seems the other chip is damaged. Now stuff really gets real :D!

danilo

8/2/2017 05:44:08 pm

Hi,
I'm not sure I understand version 2.0, how the LFO works now without the switch ? Is it always on ? And why did you remove the tone switch ? Which kind of tone the pedal will have now ?
Anyway does musikding still sells v1 ? I think is much more interesting ! They link the 2 version without further explanations
Thank you

8/5/2017 03:01:20 am

Hi Danilo,

With the 2.0 version the LFO is either always running or gated by the guitar signal (depending on a dip switch setting on the PCB), but the modulation (stutter sounds) is only engaged when pressing the momentary footswitch which can be either latching or momentary (also depending on a dip switch setting on the PCB).

I found that tone switch on the first version to be kinda useless imo, with only one usable setting( the others being either muffled or too harsh). So the 2.0 tone is basically fixed at the most usable setting. A tone knob insted of a switch would have been a much better option, but I decided to omit the tone selection entirely to keep the pedal easier to build with a lower component count.

The main reason the 2.0 version has been so simplified was because alot of people were having trouble with their builds, and the 1.0 was unnessecery confusing to build with the separate daughterboard and different build options.

I still have a few 1.0 PCB's left, so email me at parasitstudio@gmail.com if you want to buy it (for a very cheap price). :) Cheers / Fredrik, Parasit Studio

Keen

12/22/2018 09:30:06 am

Hi Fredrik, I built version 2.0 and the lfo LEDs are always blinking, even if the bypass switch is off. Is this the normal behavior?

12/23/2018 03:41:18 am

By setting the DIP switch on the PCB the LFO can be either 1. free running (in that setting the LFO leds will blink even if the pedal is in bypass) or 2. Gated. In the gated setting the LFO will only run when you have a guitar signal at the input, so they should not blink when the pedal is bypassed (since a bypass grounds the input, at least if using the optional 3PDT board). Check out the build document for details about the dip switch settings. If your pedal doesn't behave like this, there's probably something wrong with your build. I hope that answers your question. Best regards / Fredrik

12/27/2018 05:30:43 am

Hey Fredrik, that did the trick the dip switch was on free running.
Now the only thing that conufses me is, that one of LFO LED is always shining even when the pedal is in bypass. But that seems to be correct?

1/4/2019 03:08:10 am

Yes, that's normal behaviour. Cheers / Fredrik

Sergio

9/26/2019 04:59:44 am

Finally, I finished the pedal and I'm happy I did my first one and it works.
The dip switch setup is latching mode and LFO turned off.

However, there are some issues that I would like to fix:

1 the rate pot doesn't do anything, regarding to sound or the alternating leds, although they turn ON.

2 I must turn the gate trimpot full clockwise, otherwise there is a continuous feedback sound.

Any thoughts?

Thank you.

9/26/2019 05:05:05 am

Could someone upload one photo of the enclosure, v2?

Thank you.

Jason

10/9/2019 11:55:49 pm

Hi, I've built the stripboard version of this and it rules!! I did have a bit of troubleshooting to do and foundbthatvI hadn't soldered pin 8 of the 4070 socket, lol!! Now it rocks except for ticking in the free running LFO mode. Is there an easy fix to get rid of it or reduce it? It goes away when the mix knob is at 50/50.

10/10/2019 03:26:37 am

I'm posting the reply here aswell so other people can see it. The gated LFO was added as a workaround to stop the ticking when not playing. It's not possible to get rid of the ticking in the free running LFO mode i'm afraid.

Davelybob

5/30/2020 09:59:49 am

Eagerly awaiting a kid from musikding.

Wondering if anybody has any ideas on modding the LFO to get a triangle or saw wave switchable from the square? I figured that can't be too difficult?

6/1/2020 04:29:36 am

Hi Davelybob,

Happy to hear that you are awaiting a kit. :)

The LFO can't be any other shape than a squarewave i'm afraid. That's because the LFO is feeding into the input of an CMOS chip that only understands a logic level input, either low or high. It has a switching threshold around half the supply voltage and can only put out a logic level aswell. So if a triangle wave LFO was used it would only change state once the threshold is crossed and not really make any difference. I hope that makes sense. :)

Thomas

7/20/2020 10:05:12 pm

hi.
I bought this as a kit on musikding. It works but the polarity on the dc jack is inverted, the - being on the outside of the barrel. Is it normal or do I switched the cable on the dc jack?

Thanks!

7/21/2020 10:21:27 am

Ok, i swapped the wire and it's working with negative ground.
But I still do have a problem : when not playing and the pedal is on, there is a strong noise that follow the rythm of the LFO. Everyting seems to be soldered correctly, is there something wrong?

DOFOLLOW Backlinks link

2/26/2023 12:02:32 am

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The Xor'cist released!

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