A friend of a friend contacted me in the summer of 2020 to have his EHX 16 Second Delay reissue modified. I had done some pedal mods for him in the past, so I was willing to give it a go, even though I was pretty bogged down with remodeling projects in my house. I was happy to be in my shop again and working with something other than drywall.. I didn't end up finishing the mod until the winter of 2021, but the owner didn't seem to mind the wait. Thanks Joe!
I can't remember what exactly he originally asked for, but I think he complained that the sound was too digital and he wanted to be able to switch the feedback on and off. Those were easy enough things to address, but I also came up with a bunch of other mods that I thought would compliment the pedal, and he agreed. So I spent some late hours of the nights that I wasn't too sleepy to mod this crazy beast.
The original plan was to create an analog signal path from the output of the pedal to the input with highpass and lowpass filters, but unfortunately there was just too much aliasing noise feeding back and being amplified, so I had to scrap that plan. I kept the filters, just created an alternative analog output to give the pedal a warmer sound. At least I think that's what I did... To be honest, at the time I am writing this, I am having trouble deciphering my notes and schematics, and my Kicad files are a mess from a catastrophic version change... I do not have a video to reference and the pedal got shipped home over a year ago, so I am just trying to recall from memory. I am pretty sure that the filters do NOT feed back into the delay though.
All of the controls on the pedal are 3.6 volt CV inputs so I added mod switches for most of them to be modulated by either a guitar audio triggered envelope generator or an external CV/pedal. The slope of each can be inverted independently. I drew up a pretty useful manual, so I will defer to that...
I found a pretty cool local seller of high quality toggle switches. I love the stubby little ones!
Well, I guess I'll keep this short since I cant recall too much about building this. I will say though that this pedal is powerhouse of drone! If you see one, get it! It is always a treat to occasionally mod or repair rare things that I was never aware existed. I only wish i had recorded it before sending it back.