Kilpatrick Audio Format User manual

Kilpatrick Format
Technical Specications
Kilpatrick Format
Technical Specifications
A Specification and Guide for Module Designers
Copyright 2014: Kilpatrick Audio Andrew Kilpatrick
Written by: Andrew Kilpatrick
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Kilpatrick Format
Technical Specications
Table of Contents
Introduction................................................................................................................................................4
A Few Words of Welcome.....................................................................................................................5
Use of the Kilpatrick Format Specification...............................................................................................6
Namin Requirements...........................................................................................................................6
Keep Kilpatrick Audio Informed...........................................................................................................6
Errors, Omissions and Su estions.......................................................................................................6
Physical Specifications..............................................................................................................................7
Module Stack-up Overview...................................................................................................................7
Panel Material........................................................................................................................................8
Panel Retainin Screw...........................................................................................................................9
Module Power Plu s...........................................................................................................................10
Module Stack-up Details.....................................................................................................................11
Panel Dimensions and Thickness........................................................................................................12
PCB Dimensions and Thickness.........................................................................................................12
Panel to Top PCB Spacin ..................................................................................................................12
Top PCB to Bottom PCB Spacin .......................................................................................................13
Enclosures................................................................................................................................................14
Module Mountin Plate.......................................................................................................................15
Power Supply......................................................................................................................................16
Active / Passive Enclosure Interconnect.............................................................................................17
Connectin Multiple Active Enclosures..............................................................................................17
Power Wirin and Power Supplies...........................................................................................................18
Analo and Di ital Grounds................................................................................................................18
System Power Groundin ....................................................................................................................19
Power Supplies on Modules................................................................................................................19
Audio and Control Si nals.......................................................................................................................20
Si nal Impedance................................................................................................................................20
Input and Output Volta e Ran e.........................................................................................................20
Gates and Pulses..................................................................................................................................21
Audio and CV Si nals.........................................................................................................................21
Indicator LEDs.........................................................................................................................................21
Module Desi n Techniques......................................................................................................................22
Module Power Supply Example..........................................................................................................22
Pulse Input Circuit...............................................................................................................................23
+3.3V to +5V Pulse Amplifier.............................................................................................................24
Bi-colour LED Driver.........................................................................................................................25
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Kilpatrick Format
Technical Specications
Split Supply Usin an Opamp.............................................................................................................26
Goin Between AGND and DGND....................................................................................................27
Appendix A – Part Reference...................................................................................................................28
Appendix B – Module Reference Drawin s............................................................................................29
Appendix C – Enclosure and Power Supply Drawin s...........................................................................29
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Kilpatrick Format
Technical Specications
Introduction
The Kilpatrick Format is a unique and flexible modular synthesizer format with many useful features.
The format can be applied to modular synthesizers, audio equipment, li htin and video system, and
any system where low-power modules, strai ht-forward module desi n, hi h quality construction and
easy module installation and removal is desirable.
Main Features:
•4U (7”) panel height - makes desi nin attractive and functional modules enjoyable
•Easy Plug-in System - makes installin and removin modules easy – no panel screws used
•Simple module construction – improves desi n work flow and removes uess-work – all
modules fit all enclosures
•Improved Electrical Properties – 15V rails plus separate analo and di ital rounds provide a
better electrical environment for circuit desi ners
•Banana Cables for Patching – the use of standard banana connectors offer a hi h quality,
stackable, colour-coded connector which is low-cost and easy to assemble on PCBs
•Off-the-Shelf Components – no custom connectors or toolin means parts are available from
most distributors
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Kilpatrick Format
Technical Specications
A Few Words of Welcome
On behalf of Kilpatrick Audio I thank you for taking the time to get to know more about the Kilpatrick
Format. After many years searching for the “ultimate” format for my own designs I developed the
Kilpatrick Format to solve a number of problems I saw when designing for other modular systems.
After e perimenting with 5U Modcan style and 3U Eurorack formats and being frustrated by both, I
realized that 4U is the “right” size for modular synths. Buchla and Serge definitely had it right, and
although I could have copied their proprietary formats, there were aspects that bothered me.
I finally came up with what I feel lends itself to easy module design. Products can be built in small
quantities. (important if you want to offer a lot of modules on a built-to-order basis) It has good
electrical characteristics, feels good physically, and uses all off-the-shelf parts which should make
boutique designs somewhat future-proof. The enclosure and power supply design are low-cost and
reliable.
I hope that you are inspired to make your own modules in the Kilpatrick Format and I look forward to
seeing and hearing what you come up with!
Andrew Kilpatrick - 2014
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Kilpatrick Format
Technical Specications
Use of the Kilpatrick Format Specification
The oal of this specification is to encoura e the use the Kilpatrick Format by both commercial
manufacturers and DIY builders. Please follow the specification as closely as possible, or contact
Kilpatrick Audio if your needs are not accounted for here. With so many low-quality products available
for other formats, strict compatibility is necessary to maintain the quality of the system. If your oal is
to make the cheapest possible products then please choose a different format. However, if you want to
make excellent modules that are cost-effective and very hi h quality then you are probably in the ri ht
place!
Naming Requirements
Somewhere within your advertised specifications, you must indicate that your product is a “Kilpatrick
Format” module or accessory. Use of the name means that the module or accessory meets the
requirements set out within this specification, or whichever version of the spec is current at the time
you undertake your desi n. This help customers who purchase modules to know that they are ettin a
quality product that will work well with existin and future module desi ns from other manufacturers.
Keep Kilpatrick Audio Informed
Use of the Kilpatrick Format is free of char e, but you must tell us if you release a module so that we
can keep track of products available in the format. We will also offer a module swap service so that
builders can put to ether nice systems at low cost. When you have a module ready let us know and
we'll arran e to swap a module of similar value with yours. We hope you will extend this opportunity to
other builders as well.
If you don't want to trade modules, sendin some info that we can post on our website would be reat
also. We are interested in linkin to both commercial and DIY sites if you want to become part of the
family. Prospective buyers often ask what other modules are available.
Errors, Omissions and Suggestions
Please help to improve this specification by reportin any errors, information that is missin or difficult
to understand, and any other ideas that would help to improve it.
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Kilpatrick Format
Technical Specications
Physical Specifications
The Kilpatrick Format is built around panels which are one or more spaces wide. A space is set as 1/4
of a rack width, and 4U (7”) tall. Four spaces occupy one rack-mountable enclosure. Wider enclosures
are possible, with 5 or 6 spaces bein the most useful. Spaces are 4.250" x 7.000", but panels are
manufactured as 4.240" x 6.990" to compensate for sli ht manufacturin tolerances and also ali nment
when the modules are plu ed into the system. The dimensions should be reduced by 0.005” on each
ed e so that all holes, etc. are centered within the panel.
One and two space panels are the most useful sizes, althou h three and four spaces can be made as
well. You must not make modules wider than four spaces because all modules should fit into a
rack-mounted enclosure. The corners of modules are always rounded with a 0.125” radius to make
them less sharp and also hide small ali nment problems when the modules are sittin next to each
other. If you have an idea for a hu e module it mi ht make more sense to break it up into several
smaller desi ns.
odule Stack-up Overview
Before we o into detail on the each part of a module, have a look at the followin dia ram which
shows the components of a module as a section view. All modules are built with the same stack-up and
spacin between layers.
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Fig 1 - Module Stack-up – Side View

Kilpatrick Format
Technical Specications
The spacin s are chosen to allow the use of common components such as banana jacks, to le
switches, board to board stackin headers, etc. Some components like pushbuttons and some kinds of
jacks may require additional PCBs or different spacin s, but for most modules the su ested spacin
should offer the most flexibility.
Panel aterial
Panels are enerally made from 14GA (0.062" or 1/16” thick) anodized aluminum. Kilpatrick panels
are vertically brushed and anodized and screened with black epoxy ink. Other finishes are acceptable
such as powder coatin . Panels must be made from metal. The panel thickness must be 0.062” to
ensure that all module faces are ali ned when installed in a system.
Note: The use of PCB material or acrylic as a panel material is not acceptable. If these materials
are required for specific reasons, they should be installed within an area of a metal panel and not
used to support the banana jacks or mountin bolts.
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Fig 2 - Raw Panels

Kilpatrick Format
Technical Specications
Panel Retaining Screw
Below each module space in an enclosure is a blind M3x0.5 standoff used to secure a module to the
enclosure. Each module must contain a captive M3x0.5 x 25mm hex head cap bolt that uses a 2.5mm
hex key. The bolt is installed between the two PCB layers with a spacer between PCBs. The retainin
feature is accomplished by a nylon insert lock nut underneath the PCB. A hole in the top panel ives
access to the bolt. The module can be secured by ently ti htenin the bolt. When banana cables are
pulled out many at a time, the bolt keeps the module from pullin out of the enclosure. In production
the nut should be ti htened part way to allow some play in the bolt. The spacer prevents
over-ti htenin and dama e to the PCBs.
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Fig 3 - Retaining Screw – Side View

Kilpatrick Format
Technical Specications
odule Power Plugs
The main parts that secure a module into an enclosure are the power plu s. The plu s are male banana
plu s of the same type used for panel patchin . These are available as metal plu s supplied with #6-32
bolts which screw into the back of the plu . Four plu s are secured to the PCB usin additional internal
toothed lock washer on the top side of the lower PCB. Locktite blue (medium stren th) is used
sparin ly on each bolt to help keep the bolts from loosenin , but not enou h to prevent ood electrical
contact as the bolts are used to couple power to the lower PCB.
The plu s supply the four power si nals: +15V, -15V, AGND and DGND. Note that the AGND plu is
ali ned differently, thus providin a keyin to prevent backwards installation.
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Fig 4 - Power Plugs – Bottom PCB - Top View