Attenuators

Overview

Another “utility” module akin tot he XT-01 Power Supply – maybe not the fanciest selection for an initial introduction of stuff, but oh so necessary. Here’s the gist – one of the goals for this overarching project is to have each module do exactly one thing. Meaning that oscillators oscillate, switches switch, etc. Meaning no Easter Eggs, no hidden features, no bells, no whistles. Or at least bells and whistles combined. The idea behind this is to view each module as a building block that can be easily built, inexpensively obtained and infinitely combined. That said, in the case of this module, I think I went a little overboard – please forgive me. The original idea was to have all modules lack a volume control ala that whole simplicity thing and then have a module that was strictly an individual volume control. However, seeing as that would be a lot of wasted space, I instead opted to upgrade this module to be a resistance mixer. However, in order to allow for individual channel use, I also added interrupts to each channel. Meaning (yeah, I’m loving that turn of phrase today) that if you only need to attenuate a single channel, you can isolate one channel of the mixer to that purpose and also still have a two-channel mixer to work with. Or at least that’s the case in theory. I’m sure things most likely get wacky in the weeds, but as one of those passive necessity-type modules, I’m sure it’ll come in handy.

BOM

• 7x “Thonkicon”-style jacks
• 3x 10k 9mm linear potentiometers
• 3x 0.1uf monolithic ceramic capacitors
• 3x 10k resistors

Please note that the capacitors are somewhat optional. The exist to add DC-coupling to parts of the instrument that lack it so that anything being output to a mixer or speakers won’t inadvertently do damage to your hi-fi. If you’d like to repurpose this to be more of a CV mixer instead of an audio mixer, just replace the capacitors with a piece of wire to bridge the connection.

Schematic

Download

Eagle files on GitHub can be found here.

For those looking for a direct link to Gerber files, here you go:

XT-08_Attenuators