DIY Cheap-o Looper Effect

March 23, 2008 – 2:39 pm

… I’m surprised with what I’m able to do when I’m supposed to be doing homework.

Here’s my latest project, it’s less than 24 hours old =)

I’ve always wanted a looper effect, like the boss loopstation, mainly because the online demos were so neat. Being a bass player, I though it would help me practice with drum loops, but it’s just not worth the money unless you’re going to use it live. I ended up playing drum samples on my PC and playing along on the bass.

more (and video) after the break

About 2 weeks ago, a friend asked me about creating a digital recording circuit, for a project (which will be posted here when completed, going to stay a secret for now). Some online searching brought us to a keychain digital recorder product. After comparing some models, we found one that had 60 seconds of recording time, and we got 2 of it off ebay. I then came up with the idea to use this little recorder as a guitar looping effect, and wondered how it will handle it.

Yesterday, we met and started to disassemble and test this unit. We hooked it up to the Arduino, powered it from the 3.3V supply, and tested the “button press emulation”. We later went to a friend for a BBQ. When I came back home, I decided to continue experimentation. I had desoldered the microphone and speaker from the unit, and soldered some more hook-up wire. I had some problems with getting the circuit to function properly, I think I had a short circuit somewhere. I went to sleep without getting it to work.

This morning, I had a day off work, and decided to continue this little project. I soldered some more wire to replace problematic alligator clips positioning, and everything worked again. I connected my guitar to where the mic was, changed the Arduino code a little, and fired it up. You can see it in action on the following video:

You need to a flashplayer enabled browser to view this YouTube video

And here’s the simple arduino code:

int recPin = 4;
int playPin = 2;
 
void setup()
{
    //prepare pins for output
    pinMode(recPin,OUTPUT);
    digitalWrite(recPin,HIGH);
    pinMode(playPin,OUTPUT);
    digitalWrite(playPin,HIGH);
}
 
void loop()
{
    //wait and then record a 5 second loop
    delay(5000);
    digitalWrite(recPin,LOW); //"hold down" rec button
    delay(5000);
    digitalWrite(recPin,HIGH); //release it
    delay(30); // to pass debouncing
    while(1) {
        digitalWrite(playPin,LOW);
        delay(30);
        digitalWrite(playPin,HIGH);
        delay(4970);
 
        digitalWrite(playPin,LOW); //emulate a second click, this will stop playing the sample, and will be ready to play
        //again in the next loop iteration
        delay(30);
        digitalWrite(playPin,HIGH);
        delay(30);
    }
}

When I continue working on it, I will need to build some sort of preamp for the output signal. I will also recreate the Arduino program on a PIC 12F675 (or whatever the model number is) of which I have quite a few. There’s also need for better timing, and a pushbutton to start/stop loop recording (and adjust the length of the loop accordingly).

I hope to get it to a usable state, and have some creative fun with it. Now it’s time to get back to my homework in algebraic structures.

  1. 7 Responses to “DIY Cheap-o Looper Effect”

  2. Sweet project, iv been wanting to make one of these for a while. You may want to consider using this as the recorder, http://www.winbond-usa.com/en/content/view/160/290/.
    its relatively cheap and it has up to 2 min recording time. Zeh sabbaba

    By ed on Mar 25, 2008

  3. sounds cool! And fun..
    Once i get out of this far from home army base we shall join forces!

    I’m happy to see that you make and upload things :)
    I think that next week i’ll bring my electronics box to the base.. So i can build!

    Nur.

    *post written from cellphone.

    By nur nachman eytan on Mar 25, 2008

  4. great project and nice documeted :)
    i’m also a bass player and I also wanted to create a looper… I thought about a rec, stop and a play button… not only 5 sec. record time. but till now, i have too much other projects.

    i posted your project in the free encyclopadie for diy (this is till now only in german, except your looper ;) ):
    http://de.wikiants.org/Looper_Effect

    By pat on Apr 1, 2008

  5. Thanks !

    As I tried to explain in the video, the 5 seconds recording time was only for experimentation.
    I’d like to be able to use push buttons in order to record/stop/mute etc.

    By Ben on Apr 1, 2008

  6. Great idea! I bought i voice recorder to hack to looper but it wouldnt loop. The button emulution is geniues :D

    By Intosia on Mar 11, 2009

  7. This was a very cool project. I wouldn’t know where to start disassembling things and putting them back together like you have – so respect!

    By Phil Marston on Jun 15, 2011

  1. 1 Trackback(s)

  2. Jul 16, 2012: Zoom H2, Marantz PMD 620 And Sony PCM D50 shoot-out, SlapYak's LED Bass Guitar, DIY Cheap-o Looper Effect, Altoids Tin Guitar, AVR based TDA7313 Audio processor control, and Robert Crumb on Collecting

Sorry, comments for this entry are closed at this time.