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AB-8
8 Channel
Audio Switcher
DC BLOCKEDDC BLOCKED
A A GROUNDGROUND
CONNECTCONNECT
Green - Over threshold
Red - In release cycle
A-B switches toggle connections from A and B to COMMON.
Footswitch (momentary) toggle connections from A and B to COMMON.
Autoswitch connects B channels to COMMON until signal from CH. One A
is over threshold of trigger.
Link In connects to other AB-8 units or accepts external
control voltages. 0 VDC connects A to COMMON and
+5 VDC connects B to COMMON.
Link Out from first unit in chain makes it the Master.
MASTER CONTROL SECTION
LINK OUT
LINK IN
FOOTSWITCH
Introduction
The AB-8 is an 8-channel, balanced, bidirectional signal switcher (1 in - 2 out or 2 in -1 out). Mic level audio, line
level audio, and MIDI signals can be routed with the AB-8. The AB-8 auto-senses loss of input on the primary
inputs, and automatically switches to secondary inputs for backup in live tracking applications. It can also be used
to manually switch between inputs and outputs when multi-tracking in a studio. Channels can be switched
individually or globally and AB-8 units can be master/slaved for switching large numbers of channels.
Features
Eight channels of balanced A-B switching for line or mic level audio or MIDI signals
Each of the eight channels can be individually switched or assigned to a Master Control circuit
Master control through front panel pushbuttons, footswitch or automatically triggered
by loss of signal on channel one A input
Can be configured as two inputs to one output, one input to two outputs or a mixture of each
Multiple units can be ganged together under Master Control of the first unit or control voltage input
Indicator lights show status of each channel
Automatic switchover to redundant copy of backing tracks for live performance
Easily switch from tracking to mixing in recording setups
All signal paths are connected A to COMMON when AC power is removed
Internal DIP switches configure ground path switching and DC blocking requirements.
Auto trigger has sensitivity and hold time controls to accommodate input signal levels from -40dB to +20dB
B B GROUNDGROUND
CONNECTCONNECT
INTERNAL HEADER
INTERNAL HEADER
CONNECTS
CONNECTS
POWER GROUND
POWER GROUND
TO EARTH GROUND
TO EARTH GROUND
Internal DIP switches are provided to configure parameters for two switching options of the AB-8.
These switches are located on top of the circuit board.
Ground select switches route the shield wires from the A and B Dsub 25
jacks to be relay switched (factory setting) or permanently connected to
the Common jack. A and B shields can be routed independently.
DC blocking switches help eliminate small popping noises between the
A and B jacks and the Common by applying DC blocking circuitry
between them. This is caused when equipment being connected
through the AB-8 have small DC offset voltages between them. Factory
setting is with no DC blocking, which is the position required for passing
phantom power.
WARRANTY
This product is guaranteed to be free from defects in materials and workmanship to the
original purchaser for a period of 5 years from the date of purchase. Should service be
required, return the unit postage prepaid along with the original sales receipt to:
Whirlwind
Attention - Repair
99 Ling Road
Rochester, New York 14612
The warranty on this product shall not apply to defects or damage resulting from abuse,
abnormal use or from repairs or modifications performed by anyone other than Whirlwind. If it is
determined a manufacturing defect has occurred, Whirlwind will repair or replace the unit at our
option and pay the postage back to you.
99 Ling Road - Rochester, NY 14612
800-733-9473 / 585-663-8820 Fax: 585-865-8930
Website: http://www.whirlwindusa.com
Email: sales@whirlwindusa.com
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ON/OFF
AUTO-SWITCH
TRIGGER
THRESHOLD HOLD TIME
MASTER CONTROLS
AUTO
SWITCH
MANUAL
A B
STATUS
CH. 1
SELECT
B
A
M
CH. 2
SELECT
B
A
M
CH. 3
SELECT
B
A
M
CH. 4
SELECT
CH. 5
SELECT
B
A
M
B
A
M
CH. 6
SELECT
B
A
M
CH. 7
SELECT
B
A
M
CH. 8
SELECT
B
A
M
POWER
U.S.Audio
AB-8 8 ch Audio Switcher
1 2
3
4
5
6
1516
14
7
8 9 10
Controls and Functions
Auto-switch on/off switch engages the signal sensing circuit to control when the unit switches from A to B with
1.
the loss of signal on channel one A.
2.
Threshold control sets the level at which the signal present on channel one A will keep the A channels
connected to COMMON. When the channel one A signal falls below this threshold, the AB-8 will automatically
switch COMMON channels to the B channels. Only COMMON channels set to the M (Master) position are
switched, COMMON channels set to A or B are not switched automatically. The threshold operates through a
signal range of –40 dB to +20 dB.
3.
Trigger LED illuminates green when the signal level on channel one A is above the threshold level and stays
green until that signal is removed. It then illuminates red through the duration of the hold time.
Hold time control adjusts the length of time before the AB-8 Auto-switches the COMMON channels from A to
4.
B when the channel one A signal falls below the level set by the threshold trim pot.
Auto-switch LED illuminates when the Auto-switch function is engaged.
5.
6.
Manual A - B switches change all channels assigned to the Master Controls with a single push of either
switch.
A - B LEDs indicate whether A or B channels assigned to the Master Controls are connected to the COMMON
7.
channels.
13
1112
12.
B Female Dsub 25 connector can be either an input or output connection for eight channels of balanced audio.
The connector is wired to the Tascam DA88 standard pinout.
13.
A Female Dsub 25 connector can be either an input or output connection for eight channels of balanced audio.
The connector is wired to the Tascam DA88 standard pinout.
14.
Link In and Out jacks are standard ¼” tip- sleeve and are used for connecting multiple AB-8 units together
under Single Master Control from the first unit in the chain. The Master Control sections and footswitch
controls of all slave units are disconnected. An external control voltage can also be used to activate
switching from A to B. 0 VDC applied to the tip of the LINK IN jack connects A channels to COMMON and +5
VDC on the tip connects B channels to COMMON. Both control voltages are referenced to the sleeve
contact of the jack. In this configuration all Master Controls are deactivated.
15.
Footswitch jack allows Master Manual switching using a standard momentary N.O. footswitch in addition to
the A - B Buttons on the front panel. The jack is ¼” tip- sleeve.
16.
Power IEC inlet connects to incoming AC power with a voltage range of 90- 230 VAC at 50 or 60 Hz.
®
Tascam DA88 is a registered trademark of the TEAC corporation Toyko, Japan
®
®
8.
Channel Select switches control the A - B connection to COMMON individually for each channel. Any of the
eight channels can independently connect A or B to COMMON or assign the channel to the Master Controls
for simultaneous multi channel switching.
9.
Channel yellow and red LEDs indicate the current switching status of each individual channel and the green
LED illuminates when the channel is connected to the Master Controls.
10.
Power switch turns the power on to the AB-8. The AB-8 automatically connects A to COMMON on all eight
channels when power is turned off. However, the LEDs will show no indications.
11.
COMMON Female Dsub 25 connector can be either an input or output connection for eight channels of
balanced audio. The connector is wired to the Tascam DA88 standard pinout.
®
Pin-out for TASCAM DB25
8 Channel Balanced Connector
-
G
-
G
+
-
G
+
-
G
+
-
G
+
-
G
+
-
G
+
-
G
+
+
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