Roland TR-505 Individual Output Mod and Replacement Rear Panel

The Roland TR-505 Individual Output Mod

Recently I received a Roland TR-505 as a gift. It’s a curious gift for an analog enthusiast like me because the 505 is a digital, sample based drum machine from 1986 which sounds (let’s say) unique, and while never proved to be a marvelous instrument, it has become a darling for circuit benders and people interested in modification. It has a bigger brother, the TR-626, which allows for panning, tuning, and makes a fantastic midi controller for other percussion instruments, but the TR-505 is essentially basic. There’s not a lot more you can do with it straight out of the box.

Personally, the TR-505 was my second drum machine. I “upgraded” from a TR-707, and in 1986 the world was very different. This is the drum machine which solicited the calls of “Get a real drummer!” because in 1986 somehow using drum machines was a big threat to musicians and the idea of “bands”. I was cornered more than once after my early performances and once surrounded and beaten up for using such an instrument. The reason why I played the rest of a show with blood streaming down my face, the very provocateur of this violence, the instrument which solidified my love of electronic music, and the power it had culturally, was now back in my possession.

But the trouble is it sounded even worse than I remembered it to sound (it was not at all an “upgrade” in the end). It’s not terrible per se, but it isn’t wonderful either, and the lack of controls over the unmodified sounds (circuit bending not accounted for here, those sounds are bonkers!) make it pretty static, and lifeless.

So I decided to modify this TR-505 and give it individual outputs for the Bass Drum, Snare Drum, Hand Clap/Rim Shot, Hi Hats and the Congas. I chose these sounds because, first, those are the sounds which I felt with some EQ and external processing would make the biggest variety of sounds for the end results, and second, because the other sounds would be just fine coming out the main outputs, and work appropriately with overall dynamics and EQ or effect.

METHOD
I chose the “easy way”, tap into the voice section and create a loop between the circuit board and the jack. This interrupts the sound when you connect a cable to the jack, and it is removed from the main output.

What’s good about this method is that it’s raw, and in takes the sound out of the main mix.
What’s bad about this method is that it is raw. The envelope, panning, and level controls are lost.

Using an additional board and more wiring, it is possible to tap into the voice board after the VCA, and get the full stock sound out of the individual outputs. This may or may not cut the sound from the main mix. I didn’t choose to do it this way. I liked the raw sound, and felt that since I was looking to post process these drums that it was just as well to take them rough and ready than to mess around trying to get the sounds to sound like they did out of the mains (which I didn’t really like).

Further, you don’t have to tap the sounds I chose. You can tap any of the sounds you want individual outputs for. You can also tap them all if you like, but my modification guide only covers the ones I chose, and my replacement panels only accommodate those outs, with those labels. Typically, folks who go for all the sounds tend to drill holes onto the side of the TR-505 and take their outputs from there. I wanted mine to all come out the back, and to still be able to use it normally if I wanted to.

VERY IMPORTANT NOTES
If you do decide to follow my guide, or explore modification of your TR-505, or any other instrument I wholeheartedly support your curiosity and courage. However, I am not responsible for any problems you encounter, instruments which get ruined, or for technical support of any kind. I’m a really nice person, and I love to discuss these things, but I can’t accept responsibility for what you have decided to do or not do. Also, this is important, I am not a technician. I am not a service or repair person of any kind. I am a very busy musician, and in my down time, I explore these things because I love them. I share this information to help make a better world where things are done for love, and adventure, and not for profit, or personal importance. That said, I encourage you to ask all of your questions before you dive in or mess something up. This stuff can be hard, and even discouraging. But when we learn, when it works, it’s wonderful.

REAR PANEL REPLACEMENT

The story of the rear panel is well known. Its a slender bit of plastic that is glued to the back of the TR-505, and over time the glue has become brittle, and it comes off. Many TR-505’s don’t have their rear panels anymore, and others have been re glued and are a mess. Whether you are planning to modify your drum machine or not, we have a file for you to enable you to make a new rear panel.

The Modified Panel
This is a replacement panel for my version of the individual output modification. It makes space for an individual Kick, Snare, Clap/Rim, Hi Hats, and Conga outputs and is labeled as such. If you want different sounds to be labeled, you’ll need to edit the gerber file and make your personal changes before printing.

The Stock Panel
This is a replica of the original panel. It’s source file will allow you to print with whichever materials you like, and restore or replace the missing or manky panel from your drum machine. There are two screw holes added on either side for secure mounting. You may want to add some glue, just to keep it flat and nice, but you don’t have to.

Where to print it?
There are many services nowadays which print both panels and PCB’s. Some are elaborate, and offer many options, others are quick and dirty. This one was printed by JLC3DP in Hong Kong, and it was inexpensive, and they came out great.

Notes and Credits

This modification, despite much information about them all across the inter-web, would not have been possible if it weren’t for the help and kindness of the very talented Harry Axten. Harry’s patience, and generosity with me helped to avoid more than one baffling bungle of this effort, and also provided the source gerber files for printing the panels.

Without the expertise and friendship of Ahmad from San Francisco Synthworks I would not have been able to edit these files to produce these panels (nor to have included the important quote by Nelson Mandela on the inside).

I thank you both so deeply for your kindness and friendship.

“We know too well that our freedom is incomplete without the freedom of the Palestinians.”
– Nelson Mandela

LOVE