Resurrecting the OD-1A
Everything began when I decided to modify a 1981 GE-6 of mine. The Hi-fi mod consists of replacing the old op-amp and some caps. Unlike the GE-7, two quad op-amp were inside this GE-6.
I didn't recognize the RAYTHEON RC3403ADB chips, so after a bit of googling I found out they were a couple of very expensive chips.
The very first overdrive created was the BOSS OD-1. It's also one of the very first BOSS pedals to be created. Nowadays, the OD-1 is known to be based around the RC4558 dual op-amp, but the very first version, the OD-1A was a quad op-amp design.
Turns out they used the same Raytheon chip for the GE-6 and the early OD-1.
After putting a pair of trusty TL074 in my GE-6, I decided to put these precious Raytheon chip to use. For once, I wanted to go for a fully vintage build with all the mojo parts in. Just to hear the sound of that historical pedal. For that I needed another rare component, three 1S1588 diodes. If you ask me, they are probably not that different from modern small signal diodes, but we are going full mojo here. I found a really nice chap from Netherlands selling some.
The Raytheon rc3403adb next to the 1s1588
Once every component sourced, it was a quite simple build.
The final sound is very surprising. Turns out the very first overdrive is a quite versatile pedal with a very particular sound. Not loads of volume gain, and subtle but audible clipping.
My version of the od-1a
You can hear my version of the OD-1A maxed out in the intro of "Inner Tempest" by Wild Child Charlie.