Very Cheap DIY Patchbay for Synthi Clones

Very Cheap DIY Patchbay for Synthi Clones
For anyone who is building a Synthi clone, one of the main problems is the matrix patchbay –
Original Synthi’s use Sealectro matrixes, these are no longer made and used ones are almost
impossible to find.
Ghielmetti make similar matrix patchbays which can be used. They are probably better
quality than the Sealectro ones, but are very expensive – 300-500 euros depending on the
type.
I present here a very simple and cheap DIY solution. It provides all the functionality of the
original matrix, with a slightly smaller footprint so it can be used in true Synth clones without
affecting the original layout/design. Total component cost is less than £10! And all
components are readily available. All parts can be found on Ebay, typically for the prices
shown (at the time of writing)
Parts List:
170 Breadboard (2 required) cost £2 pair
95 x 127mm stripboard (standard size) £2
Breadboard wires/cable bundle £1.50 for 65/70 wires
2k7 5% resistors (100 pack) £1
Misc: Solid core wire, header cable and solder
Rather than explain every step of the construction, I have included a series of photos to show
how to make the patchbay, should be very easy to follow. There’s nothing difficult but there
are a few things to note –
Each Breadboard has 17 rows – the Synthi only requires 16, but the extra one can be used
for additional patching. It should be possible to use larger Breadboards to give more patching
possibilities (eg voltage control for resonance etc)
Each Breadboard requires 34 wires prepared as shown to connect to the Stripboard. Each
wire can be formed by cutting a 3cm length and pushing it into an edge hole on the
Breadboard as far as it will go, then bending it around the edge until it forms a hook shape.
The 170 breadboards have sticky foam backing, use this to fix them to the stripboard, then
solder the connecting wires, which will anchor the boards firmly.
You must break the tracks on the Stripboard between each Breadboard, as shown in the
photo.
When all the soldering is done, check that there are no shorts between adjacent strips on the
Stripboard.
The Cables are made by cutting a connector wire in half and soldering a 2k7 resistor in the
middle. This replicates the original Synthi pins. I used heat shrink sleeving for a neater
appearance.
You will notice that this patchbay only provides 8 possible conections for each row, whereas
the Synthi matrix can have up to 16 connections per row or column. In practice this should
not be a problem as it is very unlikely that a patch would be that complex, but even this
limitation can be overcome by making up a few split cables as shown. These work either way
(one source to two destinations, or two sources to one destination) so you could have up to
16 connections on one row if needed.
The final picture shows the completed patchbay size in relation to the Synthi matrix.
I have bult and electrically tested this patchbay and it works as it should. I have NOT built
my Synthi clone yet though, but I can’t see any reason why it should not work. Also it could
be used in any modular synth environment.
Hope this idea is useful and good luck with your Synthi’s
vout, Jan 2013