GRACE DESIGN SB-SUR-HD Modular Microphone Positioning System User Manual

GRACE DESIGN SB-SUR-HD Modular Microphone Positioning System User Manual

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 familiarize 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 303-823-8100, 9 to 5, Monday through Friday, MST. Or you can email any questions to: [email protected]

Note:
As of March 2023 the following systems will be available with the SB-SMA-HD Heavy Duty Stand Mount adapter.

SB-DT-HD Decca Tree
SB-SUR-HD Surround Tree
SB-3D11 2L 1M Cube

These systems can be large and heavy. The SB-SMA-HD is much stronger than the regular SB-SMA stand mount adapter that uses 5/8-27 microphone threads. The SB-SMA-HD does require a stand with a 5/8” (16mm) “baby” pin or a 1-1/8” (23mm) “junior” socket.   If you already own one of the multichannel arrays listed above we highly recommend purchasing the SB-SMA-HD

Standard Pre-configured Arrays:

SB-SUR-HD Surround Tree Holds 5 microphones

SB-3D 2L 1M Cube Holds 11 microphones

SB-Prism 2L 1M x 2M Array. Holds  11 microphones. Note, order SB-3D with additional SB-SMA or SB-SMAHD

SB-DT-HD 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 Components:

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

SB-AMHEX Adjustable Mic Holder Same as SB-AMH but with 1.5” (38mm) extension. Used to make mics on perpendicular bars have  matching vertical positions.

SB-MH Standard Mic Holder

SB-AMHRA Adjustable Mic Holder, Right Angle

SB-HB Hanging Bar

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.

SB-SMA-HD Heav Duty Stand Mount Adapter For 5/8” (16mm) “baby” pin and 1-1/8” (23mm) “junior” socket. Recommended for multichannel arrays and anytime a lighting stand is used instead of a microphone stand.

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.

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 Configurations Detail

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.

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

Meter Cube 11 Channel Array

The SB-3D11 immersive surround microphone array was developed by Grammy award winning Morten Lindberg from 2L. The array makes a 1 meter cube with a 7 channel array at the lower level and a 4 channel array at the upper level. Due to the size and weight of this array it comes with the SB-SMA-HD Stand Mount Adapter. The SB-SMA-HD can sit on a 5/8” (16mm) “baby” pin or a 1-1/8” (32mm) “junior” socket receiver.

Mounting this array using a 5/8-27 microphone mounting thread is not recommend.

See the SB-3D11 system exploded parts diagram for a list of included components.

Prism 11CH Array

The SB-Prism array is 2L’s evolution of the 1 Meter Cuba array above. The Prism configuration places the rear channels on a separate stand so that the array has the dimensions of 1M wide, 1M high, 2M deep. This system can be created from the SB-3D11 1 Meter Cube system by adding the SB-SMA or SB-SMA-HD stand mount adapter.

Decca Tree

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.

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 relative to the horizontal plane. This can be very useful when micing and ensemble from above on a tall stand.

B-BLRA Blumlein with SB-AMHRA right angle mic holders (shown with RCA 44 type mics)

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

SB-BL Blumlein with SB-MH standard mic holders
See the SB-BL system exploded parts diagram for a list of included components.

AB Stereo

The AB Stereo microphone technique typically uses two omni-directional microphones spaced apart by a distance. The SB-100 configuration is basically a 1M wide stereo bar. With the addition of another E420 tube and a E418 joiner tube, the SB-100 becomes an SB-200 2 meter stereo bar.

Hanging Arrays

For applications that require hanging a microphone array from a ceiling, the SB-HB hanging bar can be used. The SB-HB can be used with the SB-SUR surround tree, SB-DT Decca tree, and the SB-100 AB bar. The SB-HB has a 1 inch eye-bolt on one end and threads into the SB-SMA stand mount adapter at the other. The SB-HB can be ordered in two versions:

1. SB-HB-1M with a guide line yoke sized for 1 meter wide bars.
2. SB-HB-2M with a guide line yoke sized for 2 meter wide bars.
   

Decca Tree with SB-HB Hanging Bar

Setup Basics

SB-AMH/SB-MH
All of the modular microphone holder assemblies use adjustable clamping handles to tighten and loosen the holder from the tube it is mounted on. Turning the handle clockwise will tighten or “clamp” the holder in position on the tube. The clamping action is very secure and does not require extreme torque on the handle. As well, the final position of the handle can be adjusted.

by pulling on the handle while rotating. This allows the handle to be adjusted so that it can be at a convenient angle for tightening or loosening.

The angle of incidence of a mounted microphone can be precisely set by using the angle indicating protractor markings which are engraved on the front of the SB-AMH. The angle is indicated from +90 to -90 degrees in 5 degree increments. T he angle adjust thumb screw must be loosened before rotating the upper portion of the microphone holder.
SB-AMH Adjustable Mic Holder showing protractor markings and sight holeder

To calibrate the angle of incidence, follow these steps:
A) Loosen locking thumb screw and rotate mic holder so that 0 degrees is indicated. Then re-tighten the thumb screw.
B) Thread on the microphone clip and orient it so that it is perpendicular to the  Spacebar tube.
C) Lock the microphone clip in place by tightening the jam nut against it.
D) Now the angle of the microphone can be precisely adjusted by loosening the thumb screw and rotating the microphone.

The location of the microphone holder can be precisely set by using the numeric scales engraved on the tubes. The SB-MH and SB-AMH feature a sight hole that allows microphone holder to be positioned on the centimeter indicator circles. The SB-TJ90 tube joiner also has sight holes allowing for proper centering of cross bars and measurement between cross bars and microphone holders. The scales on the various bars are indicated as follows:

• E420 indicated in centimeters and reads 0 to 105cm from left to right and 105 to0cm right to left.
• E421 indicated in centimeters and reads 40-0-40cm.
• E407 indicated in centimeters and reads 25-0-25cm from the center.

E418 Tube Joiner
The E418 tube joiner is used to connect any two of the 7/8” diameter tubes. Typically used for the 2 meter segment of the Decca Tree or for very wide stereo bars. To join two tubes simply slide the tube joiner bar into one of the tubes and secure with the 8-32 x 1/4” flat head screw. Next, slide the second tube over the joiner bar and secure with the other screw. See diagram below

SB-HB Hanging Bar
The SB-HB assembly threads into the SB-SMA stand mount adapter as shown below.

When hanging the microphone array can be aligned to the sound source by attaching the supplied guide line yoke to the ends of the 7/8” tubes. With user supplied line the yoke can be tied to an appropriate anchor point in the venue. These yoke lines are adjustable so that the microphone array can be precisely aimed. Adjustments can be made by slipping the monofilament line through the shrink tubing to shorten one side of the yoke while effectively lengthening the other.

The ends of the yoke guide lines attach to the s-hooks on the ends of whatever bar is being used. The s-hooks (supplied with your Spacebar system) must be mounted to the end plugs of the tube with the supplied #10-32 x 1/2” button head cap screw. Use a 1/8” hex wrench. Do not tighten the screw so much that it binds the s-hook. The screw has a thread locking  compound applied to its threads so it will not loosen after screw is installed.

The ends of the yoke guide lines attach to the s-hooks on the ends of whatever bar is being used. The s-hooks (supplied with your Spacebar system) must be mounted to the end plugs of the tube with the supplied #10-32 x 1/2” button head cap screw. Use a 1/8” hex wrench. Do not tighten the screw so much that it binds the s-hook. The screw has a thread locking compound applied to its threads so it will not loosen after screw is installed.

Bar end s-hook installation
guide line yoke attachment

The vertical angle of the array can be adjusted by moving the stand mount adapter forward or rearward of the balance point.

Exploded Parts Diagrams

SB-AMH Adjustable Mic Holder

SB-AMHEX A djustable Mic Holder 1.5” Extended

SB-MH Standard Mic Holder

ITEM NO.| Grace Part#| DESCRIPTION| QTY.|
---|---|---|---|---
1| E408| Mic Holder 7/8″ Tube Clamp| 1|
2| H514| 5/8-27 Threaded Boss| 1|
3| H520| Round Pin 1/16″ x .3″| 2|
4| H436| 10-32 x 7/8″ FL SC SS| 1|
5| H459| 1/4-20 Flat Washer Bronze| 1|
6| H512| Adjustable Handle 10-32 x .78″ stud| 1|
7| H515| 5/8-27 24mm Nut| 1|

SB-TJ90 90 Degree Tube Joiner

ITEM NO.

| GracePart#| DESCRIPTION| QTY.
---|---|---|---
1| E415| 90 Degree Tube Joiner| 1
2| H512| Adjustable Handle 10-32 x .78″ stud| 2
3| H459| 1/4-20 Flat Washer Bronze| 2

SB-AMHRA Adjustabe Mic Holder, Right Angle

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

ITEM NO.

| GracePart #| DESCRIPTION| QTY.
---|---|---|---
1| E416| Stand Mount 5/8-27 Threads 7/8″ Tube Clamp| 1
2| H512| Adjustable Handle 10-32 x .78″ stud| 1
3| H459| 1/4-20 Flat Washer Bronze| 1

SB-SMA-HD Heavy Duty Stand Mount Adapter

ITEM NO.

| Grace Part #| DESCRIPTION| QTY.
---|---|---|---
1| E441| Stand Mount HD| 1
2| H459| 1/4-20 Flat Washer Bronze| 2
3| H512| Adjustable Handle 10-32 x .78” stud| 2
4| H510| Knob Black 5/8”| 1
5| H443| 10-32 x 1/2″ Socket Head Cap Screw| 1

SB-SUR Surround Tree

Note: For 2L Prism Array add SB-SMA or SB-SMA-HD stand adaptor.

SB-3D11 1M Cube 11 Channel Array

Note: For 2L Prism Array add SB-SMA or SB-SMA-HD stand adaptor.

SB-DT Decca Tree

SB-BL Blumlein

SB-BLRA Blumlein Right Angle

SB-100 1 Meter AB bar

SB-HB Hanging Bar

Revision history

References

• Transfer
• Transfer
• 2L - the Nordic Sound

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