Bogen GA6A Guide

© 2004 Bogen Communications, Inc.
All rights reserved.
Specifications subject to change without notice.
54-5757-03C 1101
Utility Amplifier
GA6A Model
Installation and Use Manual

CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
NOTICE: Every effort was made to ensure that the information in this guide was complete
and accurate at the time of printing. However, information is subject to change.
WARNING: To reduce the risk of Fire or Electric Shock, Do Not Expose this apparatus
to rain or moisture.
Apparatus shall not be exposed to dripping or splashing and no objects filled with liquids,
such as vases shall be placed on the apparatus.
WARNING: Only connect unit to AC mains outlet providing protective earthing connection.
NOTE: Mains plug is used as disconnect device from the mains and shall remain readily
accessible and operable.
CAUTION: These servicing instructions are for use by qualified service personnel only. To reduce the
risk of electric shock, do not perform any servicing other than that contained in the operating
instructions unless you are qualified to do so.
CAUTION: DO NOT INSTALL OR PLACE THIS UNIT IN A BOOKCASE, BUILT-IN CABINET, OR IN
ANOTHER CONFINED SPACE. ENSURE THE UNIT IS WELL VENTILATED. TO PREVENT THE RISK
OF SHOCK OR FIRE HAZARD DUE TO OVERHEATING, ENSURE THAT CURTAINS AND ANY OTHER
MATERIALS DO NOT OBSTRUCT THE VENTILATION VENTS.
Always follow these basic safety precautions when installing and using the unit:
IMPORTANT SAFETY INSTRUCTIONS
1. Read these instructions.
2. Keep these instructions.
3. Heed all warnings.
4. Follow all instructions.
5. Do not use this apparatus near water.
6. Clean unit with dry cloth.
7. Do not block any ventilation openings. Install in accordance with the manufacturer's instructions.
8. Do not install near any heat sources such as radiators, heat registers, stoves, or other apparatus
(including amplifiers) that produce heat.
9. Do not defeat the safety purpose of the polarized or grounding-type plug. A polarized plug has two
blades with one wider than the other. A grounding-type plug has two blades and a third grounding
prong. The wide blade, or the third prong, are provided for your safety. If the provided plug does not
fit into your outlet, consult an electrician for replacement of the obsolete outlet.
10. Protect the power cord from being walked on or pinched particularly at plugs, convenience receptacles,
and the point where they exit from the apparatus.
11. Only use attachments/accessories specified by the manufacturer.
12. Unplug this apparatus during lightning storms or when not used for long periods of time.
13. Refer all servicing to qualified service personnel. Servicing is required when the apparatus has been
damaged in any way, such as power-supply cord or plug is damaged, liquid has been spilled or
objects have fallen into the apparatus, the apparatus has been exposed to rain or moisture, does not
operate normally, or has been dropped.
CAUTION: TO PREVENT THE RISK OF ELECTRIC
SHOCK, DO NOT REMOVE ANY FRONT/BACK COVERS
OR PANELS. NO USER-SERVICEABLE PARTS INSIDE.
REFER SERVICING TO QUALIFIED PERSONNEL.
The exclamation point within an equilateral triangle is
intended to alert the user to the presence of important
operating and maintenance (servicing) instructions.
The lightning flash with arrowhead symbol, within an equi-
lateral triangle, is intended to alert the user to the presence
of uninsulated "dangerous voltage" within the product's
enclosure that may be of sufficient magnitude to constitute
a risk of electric shock to persons.

3
Description
The GA6A is a rugged six-watt, dual-input audio amplifier with a wide variety of smaller applications including
background music, relaying communication from one room to another, or sound reinforcement.
The GA6A delivers rated power at not more than 1% total harmonic distortion from 75-15,000 Hz into
transformer-coupled or direct low-impedance loads.
Inputs for a low-impedance balanced dynamic microphone and an auxiliary audio source (tuner, CD player, etc.)
can be mixed. Individual front-panel controls regulate the level of each input. Connections for 8-ohm and 25V or
70V speaker lines are provided on the rear panel output terminal strip. A 3-position switch is supplied to provide
9 dB of treble boost or cut at 10,000 Hz or flat response.
Package Contents
(1) GA6A
(1) Installation and Use Manual
Accessories
WMT1A
Matching Transformer
• Hi-Z, 10k-ohm primary impedance
• Lo-Z, 600-ohm secondary impedance, balanced with
center tap
• Matches high-to-low impedance or low-to-high
impedance
• Adapts line level signals to microphone inputs

4
Panel Descriptions
Utility Amplifier Front Panel
1. MIC Control - Regulates the level of microphone output to speakers.
2. AUX Control - Regulates the level of the AUX source to speakers.
3. Power Switch - Controls AC power to the amplifier. Illuminates when ON.
Utility Amplifier Rear Panel
1. Speaker Output Barrier Strip - Output terminal strip provides for 8-ohm, 25V, and 70V speaker outputs.
2. Shorting Link - Used when 25V or 70V speakers are to be connected to the GA6A. Must be removed if
8-ohm speakers are to be connected to the GA6A.
3. Microphone Terminal - Input terminal strip for a balanced low-impedance dynamic microphone.
4. AC Line Cord - 120V ~, 60 Hz, 0.15A line cord terminated in a three-prong plug.
5. Treble Control Switch - A 3-position switch that controls the application of 9 dB of treble boost or cut at
10,000 Hz or flat response.
6. AUX Input - High-impedance AUX RCA jack input.

5
Connections
70V & 25V Speaker Systems
Connect the 25V or 70V speaker loads to the corresponding terminals (25V or 70V) and the common terminal.
Make sure that the total wattage of all the connected speakers is less than 6 watts.
Note: Do not use both the 25V and 70V terminals at the same time. Use only one type of speaker (25V or 70V) for all
speakers connected to the GA6A.
Link
The shorting link must be in place when using 25V or 70V speakers.
8ΩSpeaker Systems
Low-impedance 8-ohm speakers can be connected to the GA6A. When using multiple speakers, the installer must
make sure that the total speaker load is not less than 8 ohms. Higher than 8 ohm impedances are safe to connect
to the GA6A, but the GA6A will not deliver its full output power to these higher impedance loads.
Connect the 8-ohm speaker load to the GND and 8-ohm terminals and remove the shorting link. 25V and 70V
outputs will not work in this configuration.
Note: If using multiple speakers, check for
proper phasing. See Section on Phasing.
Note: If using multiple speakers, check for
proper phasing. See Section on Phasing.

6
Connections
Phasing
As the voltage on a speaker changes from plus to minus, the
speaker cone moves from pushing out to pulling in. If you
reverse the polarity, the speaker responds in the opposite man-
ner.
If a speaker is pushing out and an adjacent speaker is pulling in,
some of the pressure caused by the speaker pushing out will be
absorbed by the speaker pulling in. These two speakers are
operating out of phase.
In a paging system, all the speakers should be in phase so that
they all push out at the same time. Out of phase speakers
operate perfectly well and will not cause any harm to a paging
system, but will tend to diminish the bass response in the area
around the out of phase speaker.
The important thing is to wire all the same polarity (+ or -)
connections together. This will ensure that the speakers in the
system all work in unison. All paging speaker connections have
a polarity indicator. It may be a color code, plus (+) and minus
(-) symbols, or a red dot.
Microphone Input
Connect a low-impedance dynamic microphone (these
microphones connect using 3 wires and do not require a power
source) to the microphone terminals as shown.
Note: Condenser microphones will not work with the GA6A because
the GA6A does not supply phantom power, which is required for these
microphones to operate.
Use two-conductor shielded cable for a balanced input and
connect the shield to the ground terminal.
Auxiliary Input
Use a shielded RCA cable to connect to the high-impedance
AUX input. The center of the connector is hot and the outside
is ground.
Power and Grounding
The AC line cord should be plugged into a three-wire, grounded
outlet providing 120V ~ , 60 Hz. It is important to ground the
unit.
+

_
+

_
+

_
+

_
Out-of-phase speaker connection.

7
Operation
Power
The AC line cord should be plugged into a three-wire, grounded out-
let providing 120V ~, 60 Hz. The power switch illuminates when unit
is switched ON.
MIC Control
Controls the amount of MIC signal heard at the output. Clockwise
increases the signal.
AUX Control
Controls the amount of AUX signal heard at the output. Clockwise
increases the signal.
Treble Control Switch
Provides a stepped increase or decrease in high frequency (above
10 kHz) heard at the output. The “Cut” position can help reduce high
frequency feedback. The “Flat” position provides no modification to
high frequency response. The “Boost” position provides more clairty
and intelligibility to speech.
Overload Protection
The amplifier output is protected against overload and shorted speaker
lines by a thermostat enclosed in the power transformer. If the break-
er opens, the amplifier will have no output. Set the Power switch to
OFF and wait a reasonable time for the breaker to reset. If the break-
er trips again, have the trouble investigated by a qualified technician.

Warranty
Power Output: 6 watts RMS
Frequency Response: 30 Hz to 12 kHz +0 dB, -3 dB
Total Harmonic Distortion: 1% @ rated output
Power Bandwidth: 75 Hz to 15 kHz
Inputs: Lo-Z MIC, balanced or unbalanced; AUX
Sensitivity: MIC 0.3 mV;AUX 0.2 V
MIC Dynamic Range: 46 dB
Hum and Noise: MIC -50 dB;AUX -64 dB below rated output
Output Impedance/Voltage: 8 ohms; 25V & 70V line
Tone Control: 9 dB treble boost at 10 kHz, 9 dB treble cut at 10 kHz
Protection: Internal Thermostat
Controls: MIC,AUX, illuminated POWER switch
Terminations: Outputs and Microphone — terminal strip
Auxiliary — RCA-type phono plug
Power Consumption: 16W, 120V ~, 60 Hz
Dimensions: 8-1/2" W x 2-3/4" H x 6" D
Shipping Weight: 6 lb.
Specifications
50 Spring Street, Ramsey, New Jersey 07446, U.S.A.
Tel. [phone] • Fax: [phone]
www.bogen.com
Limited Warranty; Exclusion of Certain Damages
The Bogen GA6A Utility Amplifier is warranted to be free from defects in material or workmanship for two (2) years from
the date of sale to the original purchaser. Any part of the product covered by this warranty that, with normal installation
and use, becomes defective will be repaired or replaced by Bogen, at our option, provided the product is shipped insured
and prepaid to: Bogen Factory Service Department, 50 Spring Street, Ramsey, NJ 07446, USA. The product will be
returned to you freight prepaid. This warranty does not extend to any of our products that have been subjected to abuse,
misuse, improper storage, neglect, accident, improper installation or have been modified or repaired or altered in any man-
ner whatsoever, or where the serial number or date code has been removed or defaced.
THE FOREGOING LIMITED WARRANTY IS BOGEN’S SOLE AND EXCLUSIVE WARRANTY AND
THE PURCHASER’S SOLE AND EXCLUSIVE REMEDY. BOGEN MAKES NO OTHER WARRANTIES
OF ANY KIND, EITHER EXPRESS OR IMPLIED, AND ALL IMPLIED WARRANTIES OF MER-
CHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE ARE HEREBY DISCLAIMED AND
EXCLUDED TO THE MAXIMUM EXTENT ALLOWABLE BY LAW. Bogen’s liability arising out of the manu-
facture, sale or supplying of products or their use or disposition, whether based upon warranty, contract, tort or other-
wise, shall be limited to the price of the product. IN NO EVENT SHALL BOGEN BE LIABLE FOR SPECIAL,
INCIDENTAL OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, LOSS OF
PROFITS, LOSS OF DATA OR LOSS OF USE DAMAGES) ARISING OUT OF THE MANUFACTURE,
SALE OR SUPPLYING OF PRODUCTS, EVEN IF BOGEN HAS BEEN ADVISED OF THE POSSIBILITY
OF SUCH DAMAGES OR LOSSES. Some States do not allow the exclusion or limitation of incidental or conse-
quential damages, so the above limitation or exclusion may not apply to you. This warranty gives you specific legal rights,
and you may also have other rights which vary from State to State.
7/22/2008