Three Jumpers Jumping
Let's start with the little cables that
come along with every module that we ship.
These are called "Power Jumper Cables"
and have either 3-pins going to 3-pins,
4-pins going to 4-pins, or 3-pins going
They're referred to as "three to threes"
"four to fours" or the crossover type
"three to four" Power Jumper Cables.
The latter are the most popular when combined
with our Distro Cards because they're so
versatile, however if you have a Modcan brand
of rack mount enclosure, in most cases
you should ask for 3-pin-to-3-pin or
"three to three" Power Jumpers.
They are all typically 18" inches long.
There are presently two different types of
power distribution boards that we offer...
Original Combo-Distro Card
The first was simply the Combo-Distro Card which ~combined~ the 3-Pin Modcan power headers
with the more popular 4-Pin power headers
used by other modular companies.
This facilitated the "cynthiafication" of other
brands of modular circuits to the Modcan and
Cynthia format by opening up the architecture.
The board also introduced a miniature
4-pin Auxiliary Bus to the system allowing the
easy distribution of ~pre-patched~ Gate and Trigger
signals, as well as up to two different Pitch or
Modulation (LFO) signals. The decision was made
to add the fourth pin in order to support
duophonic keyboards, such as made by Arp,
This Auxiliary Bus is used by the Cynthia
Dual ADSR modules for example, to link multiple
envelopes to a common Gate and Trigger source -
simply by pulling-out the ATTACK knob switches
on the Envelope's front panel.
The SixPac-Distro Card
Then along came our aluminum SixPac enclosures,
and a newer distro card was developed with
Duplicate sets of Screw Terminals allowing
the ability to daisy-chain a few cards together
for smaller set-ups of no more than (3) SixPacs
For obvious reasons, these new cards are called
SixPac-Distro Cards. They have six of each
power header connector type, (instead of eight
as the original Combo Distro cards do), and are
completely interchangeable with the other cards.
It does not matter which type of distro cards
you put into a SixPac. (The actual green or
beige color of the boards has to do with what
~batch~ of cards they were made in and has
nothing to do with the board type).
When developing the newer SixPac-Distro cards,
we wanted to add more current capability
fearing that someone out there might attempt
to daisy chain more than the maximum of
three boards chained together.
This limitation exists because no matter
how many boards one might chain together,
the very ~first~ board in the chain must
handle the current of *all* subsequent
boards in the chain.
On a single-layer board there was not much we
could do except to remove the solder mask itself
to allow thicker metal traces.
Kissing the Ground
Ground is an indefinite voodoo science,
talk with four engineers, and you will
hear four theories on "proper" grounding.
For this reason, the distro cards have
a bus wire LINK to one of the mounting
hole pads on the board in order to facilitate
grounding of the power supply to the chassis.
This Link is easily snipped if desired.
Theoretically, the very best method
of system grounding architecture is the
"Star Ground Configuration", where there
is only One true system ground at the
0-Volts terminal of the power supply.
(the Green Banana jack on your Cynthia
In a Star Ground Configuration, you
would never daisy-chain power from card
to card, but instead have all power and
ground emanating from a central wiring harness.
On SixPac configured systems of larger than three
SixPacs, (or WoodWork cabinets with more than
three Combo-Distro Cards inside) it is best
to wire-up a terminal block strip to fan out
power and ground from a central source.
We sell what we call a "Wiring Harness" for
this purpose, which has all of the wires and
a special little board with the proper
screw terminal strip and mounting holes.
In actual practice, we find that real world
systems out there, (as opposed to theoretical)
are usually a combination of distribution
methods. So if you have a configuration
that works... Don't "fix" it!
For example, I have Six WoodWork Cabinets
in my own system now, each with it's own
power supply. After setting-up the cabinets,
I plug all six power supplies into an AC Mains
power strip, and then I take a handfull
of green patch cords and connect the
ground jack from five different cabinets -
gathering the cables into the single green jack
on the center cabinet's power supply.
This forms a star grounding network of six
power supplies. Some are Major Supplies,
and some are Medium Supplies, that does
What would happen if I used short cables and
daisy-chained the ground from cabinet to cabinet
~instead~ of all of those long green banana
cables going to one central supply?
Probably no difference at all, but IF there were
by chance any rare noise problems, then I'd try
a star configuration as a possible cure.
Supply and Demand
Medium Power Supplies are good for up to about
(18) modules maximum. Major Power Supplies are
good for up to about (36) modules maximum.
Our Power Supplies are incredibly robust.
If there are any shorts in the wiring
for example, they will shut down instantly
to save your modules. I have to say that with
all of the experiments going on around here,
we've never had a problem. For this reason I
absolutely love these supplies!
As long as you see two Green Lights lit
- then you're Good to Go!
(The upper green LED indicates that the
Positive side of the supply is working (+15V),
and the lower green LED indicates that
the Negative side of the supply is working (-15V).
All the components of our power distribution
scheme are conservatively rated to provide
maximum current handling and protection.
We use beefy thick cable throughout for
maximum bass response and current handling.
A new third type of distro card is in development
here which may become the new standard.
We're waiting for a few test boards to return
from the PC board house to see how well the
improvements work. For example these are
multi-layer boards with more current handling
full solder mask, and larger screw terminals
that are more forgiving with large diameter
Rest assured that these are all interchangeable!
Hope this answers a few questions!