Monday, April 8, 2013

BOSS CH-1 mod (digital version) Super Duper Chorus

Boss CH-1 super chorus pedal.  This is the less popular digital version of the CH-1.  The older super chorus pedals are analog and sound much better.  This pedal uses a digital processor chip to create the "chorus" effects.  I opened this guy up and found some useful mods.  I changed the resistor in parallel with the rate pot.  The effect rate now speeds up to almost infinity.  One of the added toggle switch cuts the clean signal out, only allowing the modulated signal to pass ( sounds like a vibrato ).  The other toggle switch changes the chorus setting in the digital chip.  This switch makes the effect more intense and almost square-wave sounding.  To give you an idea of what the mods sound like, below is a sound clip of me playing guitar, badly, while messing with the settings. 

I wouldn't call this pedal warm or lush.  More like corny, or cheesy sci-fi.  It's almost more suited for Casio keyboards then it is for guitar. 

Upon request here's some gut shots to display the mod I did.

The two toggles squeezed in there 

Rate resistor reduced to 1.8 K. you could solder bridge this if you wanted.

Tremolo switch.  Theres probably a better way to cut out the clean signal.

Pin 13 of the echo processor lifted.  The switch ties pin 13 to pins 11 &12.  This basically add more modulation depth.  In hindsight you might not need the switch.  Just lift pin 13 so it's no longer grounded and solder it to pin 12.  With pin 13 enabled, the depth control at about 11 o'clock sounds like the stock pedal would with the depth control maxed out.  

Here's the echo processor's data sheet for reference ES56028.pdf


  1. hola! yo estoy interesado en esta mod,podrias detallarla paso a paso con fotos?

    un abrazo!

  2. Great mods! thank you very much, a more simple way to cut the dry signal is to conect the blue wire coming from the dual jack board (STEREO-MONO) to ground, acts the same way as plugin a dummy cable to the output B. I also jumpered r63. Cheers!

  3. Thanks, nice mod. Not easy for newbie like me, I'll try to get ultra-Chorus mod. regards Alex

  4. Replies
    1. Thanks for the heads up. I think I got the Mp3 working again, for what it's worth :]

  5. I've been poking around trying to find what cap controls the delay time. The old analog versions you could mod the C10 cap. That doesn't seem to be the same on this newer version. Any help would be great. Your R63 mod worked great. I ended up using around a 5.2K.

    1. Hey, It's been a minute since I've looked at this pedals circuit. I think what I called the 'ultra chorus switch' changes the delay time. If you look at the ES56028.pdf you can see the delay time is preset inside the main processor chip. Pins 11, 12 and 13 control delay time. The echo application circuit has all three of those pins on switches, which is interesting. I think my mod just bridges pin 13.