Grace Design E418, E420 Users Manual

Spacebar

Modular Microphone Positioning System

User Manual, Revision C, August, 2010

Spacebar Modular System User Manual Revision C Page 1 of 29

Table of Contents

Standard pre-configured arrays: ................................................................................................. 4

SB-SUR Surround Tree ........................................................................................................ 4

SB-DT Decca Tree .............................................................................................................. 4

SB-BL Blumlein .................................................................................................................... 4

SB-BLRA Blumlein right angle .............................................................................................. 4

SB-100 1 meter AB bar ......................................................................................................... 4

Spacebar modular components: ................................................................................................. 5

SB-AMH Adjustable Mic Holder .......................................................................................... 5

SB-MH Standard Mic Holder ................................................................................................ 5

SB-AMHRA Adjustable Mic Holder, Right Angle ................................................................... 5

SB-HB Hanging Bar .............................................................................................................. 5

SB-TJ90 90 Degree Tube Joiner .......................................................................................... 6

SB-SMA Stand Mount Adapter 5/8”- 27 thread ................................................................... 6

E407 53cm bar ..................................................................................................................... 6

E414 tube end plug .............................................................................................................. 6

E418 Tube Joiner .................................................................................................................. 6

E420 105cm bar .................................................................................................................... 7

E421 80cm bar ...................................................................................................................... 7

E422 90 degree stand mount ............................................................................................... 7

E405 42mm thumb nut w/ #10-32 x 7/8” screw .................................................................... 7

Spacebar Configurations Detail .................................................................................................. 8

Surround Tree ....................................................................................................................... 8

Decca Tree ............................................................................................................................ 9

Blumlein ................................................................................................................................ 9

AB Stereo ............................................................................................................................ 11

Hanging Arrays ................................................................................................................... 12

Setup Basics ............................................................................................................................. 12

SB-AMH/SB-MH ................................................................................................................. 12

E418 Tube Joiner ................................................................................................................ 14

SB-HB Hanging Bar ............................................................................................................ 15

Exploded Parts Diagrams ......................................................................................................... 18

SB-AMH Adjustable Mic Holder ......................................................................................... 18

SB-MH Standard Mic Holder .............................................................................................. 19

SB-TJ90 90 Degree Tube Joiner ....................................................................................... 20

SB-AMHRA Adjustabe Mic Holder, Right Angle ................................................................ 21

SB-SMA Stand Mount Adapter with 5/8”- 27 threads ........................................................ 22

SB-SUR Surround Tree ...................................................................................................... 23

SB-DT Decca Tree .............................................................................................................. 24

SB-BL Blumlein .................................................................................................................. 25

SB-BLRA Blumlein Right Angle .......................................................................................... 26

SB-100 1 Meter AB bar ....................................................................................................... 27

SB-HB Hanging Bar ............................................................................................................ 28

Revision history ......................................................................................................................... 29

Spacebar Modular System User Manual Revision C Page 2 of 29

Welcome and thanks for purchasing a Grace Design Spacebar microphone positioner. We
build all of our products to be completely reliable and easy to use, so you can concentrate on
making great recordings, not struggling with complicated equipment or difficult product
manuals. While you will find the Spacebar is completely straightforward to use, we do ask that
you familiarizie yourself with this product manual to help avoid any common user difficulties.

The Grace Design Spacebar modular microphone positioning system allows for precise and
repeatable setting of microphone capsule spacing and angle of incidence in a wide array of
microphone configurations. With precision scales for angle and distance engraved on the
Spacebar components, it becomes easy to make perfectly repeatable stereo and
multichannel microphone setups.

The Spacebar modular system components can be purchased in pre-configured assemblies
for several standard microphone arrays. As well, it is possible to build a virtually limitless
range of microphone holding structures to meet any need.

The Spacebar system is precision fabricated from machined aircraft aluminum, brass, and
stainless steel. If properly cared for it should last a lifetime. In the event that you encounter
any technical or operational difficulties with this or any Grace Design products, please feel
free to contact us at 303-443-7454, 9 to 5, Monday through Friday, MST. Or you can email
any questions to: [e-mail]

Spacebar Modular System User Manual Revision C Page 3 of 29

Standard Pre-configured Arrays:

SB-SUR Surround Tree

Holds 5 microphones

SB-DT Decca Tree

Standard 3 microphone tree 2M x 1M

SB-BL Blumlein

Holds standard large diaphragm microphones in
a vertical Blumlein configuration.

SB-BLRA Blumlein right angle

Holds RCA 44 type ribbon microphones in a
vertical Blumlein configuration.

SB-100 1 meter AB bar

Straight 1 meter stereo bar. Can be extended to
2 meters.

Spacebar Modular System User Manual Revision C Page 4 of 29

Spacebar Modular Components:

SB-AMH Adjustable Mic Holder

Mic holder with precision angle scale. 5 degree
markings from +90 to -90 degrees.

SB-MH Standard Mic Holder

SB-AMHRA Adjustable Mic Holder, Right Angle

SB-HB Hanging Bar

Spacebar Modular System User Manual Revision C Page 5 of 29

SB-TJ90 90 Degree Tube Joiner

Allows any two 7/8” tubes to be joined at a 90 degree
angle.

SB-SMA Stand Mount Adapter 5/8”- 27 thread

Comes with 3/8-16 European style thread adapter.

E407 53cm bar

7/8” diameter, LASER etched scale reads 25-0-25cm.

E414 tube end plug

Attaches to the end of any of the 7/8” tubes. Provides a
threaded hole for attaching hooks for guide lines or an
E414 24m thumb screw to provide a safety stop for
microphone holders.

E418 Tube Joiner

Joins any two 7/8” tubes. Made from very strong 304
stainless steel.

Spacebar Modular System User Manual Revision C Page 6 of 29

E420 105cm bar

E421 80cm bar

E422 90 degree stand mount

E405 42mm thumb nut w/ #10-32 x 7/8” screw

Note: All components which feature microphone mounts come standard with 5/8-27 American
standard threads. As well, all microphone mounts can be ordered with the European
standard 3/8-16 British Standard Whitworth threads. These part numbers will have a - BSW
suffix.

Spacebar Modular System User Manual Revision C Page 7 of 29

Spacebar Configurations Detail

105cm

105cm 53cm

Surround Tree

The SB-SUR system allows for mounting of 5 microphones. In its standard configuration three
microphones can be mounted as a “front triplet” and two microphones can be mounted as a
rear pair. All microphone spacings can be precisely adjusted using the engraved centimeter
scales on the bars. Also, all microphone angles of incidence can be precisely adjusted in 5
degree increments.

The front left and right microphone holder spacing can be adjusted from 6cm to 102cm if
using the E420 105cm bar and 6cm to 50cm E407 53cm bar.

For surround microphone arrays using the SB-SUR system we highly recommend visiting

http://www.mmad.info. This website was created by Michael Williams who has written much

about multichannel microphone array design. It contains an interactive design decision
sequence for tailoring your microphone configuration to your specific acoustic venue. The
underlying theory for this design approach is contained in a series of AES papers written by
Michael Williams.

fig 1: Surround Tree

See the SB-SUR system exploded parts diagram for a list of included components.

Spacebar Modular System User Manual Revision C Page 8 of 29

Decca Tree

105cm

210cm

This classic microphone configuration was developed by Decca Records engineers in the
1950s. The Spacebar Decca Tree configuration provides a simple, precise, and easy to set up
solution for this technique. The standard Spacebar Decca Tree comes with three E420 1
meter tubes, an SB-SMA 5/8”-27stand mount adapter and three SB-AMH adjustable mic
holders. These are configured to provide a 2 meter spacing between left and right
microphones and a center microphone 1 meter forward. Since the stand mount adapter can
move front to back on the 1 meter tube it should be located at the balance point for maximum
stability.

fig. 2: Decca Tree

See the SB-DT system exploded parts diagram for a list of included components.

Blumlein

The Blumlein stereo micing technique was pioneered by Alan Blumlein in the 1930s. The
Spacebar Blumlein configuration allows for holding two figure-8 microphones on the same
vertical axis and at a precise 90 degree angle of incidence. Two types of mic holder are
available depending on the microphones being used. For RCA 44 and RCA 77 type mics and
their derivatives the SB-AMHRA holder should be used. Most other microphones can be
mounted with the SB-MH standard mic holder.

A unique feature of the Spacebar Blumlein configuration is that the whole vertical tube
assembly can be rotated on a horizontal axis allowing the mics to be aimed up or down

Spacebar Modular System User Manual Revision C Page 9 of 29