In today’s blog, I have been researching the evolution of the multiple audio outputs mods available for the Roland TR-505. I particularly like the version with the TL064 (or TL074) opamp mod. To keep things need and tidy, I decided to take this mod a step further by building a PCB with a small footprint for easy installation. I have got this down to a 4cm by 6cm board. I’ve had to learn Kicad which has been good fun and opens up new possibilities for my mods, for the future.
It all started from this page (link) about the better mod for the TR-505 which explains the problem with the burnkit mods tapping outputs to early which interferes with the decay envelope. I then read about the main issues with enhanced decay mod found here (link) by Analge.de. Absolutely love analge.de’s post. This post is very clear, fantastic schematics, explanations and details about the approach. In essence, it builds on the mod. The evolution is something like this:
- burnkit –> tap the outs
- 9bit © electric gaunitz –> tap the outs later to keep the full decay
- analge.de –> tap the outs later to keep the full decay and amplify the signal
- monophreak –> tap the outs later to keep the full decay and amplify the signal and pack into a small form factor.
The only issue I need to adjust is alter a few components so I can bend the caps down a bit. This is an nice and easy fix in Kicad. I have still kept the 4cm x 6cm dimensions which means it should be very easy to fit inside the TR-505.
My latest prototype can be seen here:
So, next step – wait for a double check tomorrow and then… PCBWay. Looking forward to the project build. When I have the full board, will populate and see how it measures up. Hopefully, I have this down first time but even if there is a little modding, no big deal.