Wednesday, January 19, 2022

Apocalypse Now - Aion's Meteor (Ibanez SD-9)

The 70s and 80s saw an explosion of pedals, especially distortion pedals, hitting the market. One of these was the Maxon / Ibanez SD-9 Sonic Distortion pedal. The circuit itself has quite a bit in common with the Boss DS-1 or MXR Distortion+. For this project I used the AionFX Meteor board - which like the Plasma board I recently built - is available in legacy (no bypass board) and new formats. I went with the most recent version of the board with the 3PDT bypass daughterboard. As with many classic pedals, this one doesn't appear to be in production anymore, though you can get used models for around $200.


The Meteor project keeps the circuit true to the original SD-9 rather than the later SD-9M, although it includes a couple of modifications that are independent of the signal path and the option to change between clipping diode options. As you can see above, the pedal relies on a lot of diodes for clipping to generate the distortion effect. I'm using vintage 1N914 diodes for this, although I'm quickly running out of my stash of these vintage parts.

Because I wasn't able to track down the original 2SC1815-BL transistors, I went with the recommended substitute - 2N5088. This a common situation for a lot of vintage parts, and the 2N5088 is a fairly commonly recommended substitution. It also uses a couple of red LEDs as clipping diodes, which was really cool to watch when I was testing the pedal sans enclosure!


For the enclosure I decided to do something fun and borrow another graphic from Tee Turtle's dinosaur line. Since this is the "Meteor" - we have our stalwart T-rex facing off against, well, technically it was an asteroid (or as my son remarked "when your level 1 character tries to face off against the final boss"). The font used for the pedal title is close to the Ibanez / Maxon font, and I have the pedal name in the corner to help me keep things straight!

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