SD-1 diode swapping.
Posted: Thu Dec 02, 2021 4:05 pm
Hi all. I'm new to the forum. Been a Boss fan for decades but not in any sense hardcore, but recently been obsessing over some smaller details of my all time favourite pedal. I realised recently that I have 4 SD-1 now, 2 silver label MIT versions and 2 Japanese. I'm not really sure why I have so many, I like how they sound (obviously) and I like to have a backup, and I was gifted one of the MIJ ones and the other I saw for sale for £30 and couldn't pass it up. The silver labels are (or rather were) both identical component wise and sounded all but identical. The Japanese are not identical, one has a 5812 chip and 1n1588 diodes the other is the nec4558, but.... they also sound all but identical to my ears. There's really not much to put between the MIT and MIJ ones either. You can hear verrrryyyy subtle differences, but not different enough to be able to say what recipe of chip and diodes are in there. I've always believed that any tonal differences between pedals have more to do with component tolerances than any specific recipe or combination of components. Anyhow I took the soldering iron to one of the silver labels recently, just out of curiosity. I made some capacitor changes to thicken it up a bit and the result is ... Different. I can't say I prefer it to the standard pedal, but it's changed the character so I would now use it more as an always on effect rather than a boost or for lead stuff. Anyhow now that it's already something of a mule I thought I would test my precious theory and swap out the 1n4148 diodes for some NOS 1n1588 diodes that I've found. I'm betting I will struggle to tell any difference, but will try and record some sounds before and after. FWIW the cap mods that I did were C1,2,3,6, 8,9 &12. TBH I think just changing c2 and 3 would have been plenty. I'm not a fan of clipping c6 but I did put a smaller value (0.0047) in there than, which is fine.