My budding interest in Eurorack modular synthesizers has lead me to consider the ambition of building a replica of the venerable Roland System 700 modular synthesizer, which was released in 1976. Unsure of my patience and capability for soldering together PCB’s, I initially pre-ordered two of the most simple modules as a test to see if this idea was feasible.
My boards and faceplates arrived for the 709 Sample & Hold and the 716 3 Channel Mixer, made by Pharmasonic, yesterday, and I had already attempted to order all the parts needed to build them, so I dove right in.
As this is my 1st encounter with the Eurorack format, I have some initial thoughts. First, modular is getting easier to get started in all the time, but the bar is still pretty high. Just getting set up to START putting together a rig is expensive, as a power supply and some sort of case or rack must be obtained. I purchased a 4ms Row Power 30 power supply and a 2hp MIDI module so I could have some sort of control signal input, and a pair of 84hp rails, and threw together a fairly horrible looking wooden frame to mount the rails in (my first and possibly last attempt at dovetails). Several parts are still needed, such as a headphone monitor, line out, etc before this will even begin to be useful.
Getting all the parts together for a project such as this appears to be the biggest challenge. Pharmasonic was gracious enough to provide Mouser project links for each module, which allows for easily adding all the parts for a project to a shopping cart at mouser.com, but none of these lists are complete, due to certain IC’s, transistors, and other bits just not being available, and things like pots and switches were not included, probably to allow the builder to select those according to their own tastes.
This quickly turned into a very international project. The jacks are only available from Thonk in the UK, the boards came from Japan, and I wound up ordering 3 types of transistors from China off eBay, as well as parts from the US.
I managed to fail to order IC and transistor sockets and bought the wrong power connectors. I also bought the wrong size switch and
a knob that was too large for the S&H unit. Pharmasonic suggested purchasing parts after the boards have arrived to avoid improperly-sized bits such as this in the future– lesson learned.
I started with the mixer, as that is the simpler of the two modules, and the whole idea with starting with these fairly useless-by-themselves modules was to re-familiarize myself with soldering and build some confidence on my part. It came together quite quickly, and I felt comfortable soldering things together after some initial attempts, realizing that I was using solid core solder which was performing horribly, and stopped to find some rosin core solder, which made things MUCH easier. The wire cutters I had on hand didn’t do a terribly good job of cutting the leads flush with the bottom of the board. Since I didn’t have IC sockets, I didn’t bother with the 2 IC’s, and will add those as soon as sockets arrive for the job.
The S&H was also pretty simple, just a few more parts on the board than the mixer, and no real surprises there other than finding that my switch didn’t fit the PCB holes and the knob was big enough to cover its label and markings. Again, no IC sockets so those were not added, and also no transistors were put in as I am a little paranoid about what I had ordered and want to use sockets so I can easily pull them out if I need to.
Overall, the two boards took maybe 3 hours of leisurely looking over boards, placing parts, soldering, and attaching the faceplate, and was a very rewarding experience other than dealing with missing or mis-sized parts.
I don’t have enough Eurorack equipment to be able to test these modules once they’re complete at this time, as I lack some key bits such as a sound source, but I hope to be able to plug in some other audio devices to at least be able to confirm that things work as expected.
Feeling good about my success thus far, I went ahead and ordered 13 more modules from Pharmasonic, which should be enough to build out a clone of the System 700 “Block 1”.
