Precision Electronics BX 15 User manual

Instruction Kit
BX 15
BX 30
INTEGRATED AMPLIFIER
GROMMES-PRE ISION
1-800-SIN E-46
www.grommesprecision.com

GROMMES-PRECISION 847-599-1799 F: 847-599-6178 800-SINCE-46
Thank you for purchasing from Grommes~Precision!
Grommes~Precision and its commercial audio division, Precision Electronics, has been
designing, engineering, and manufacturing quality sound equipment in the United tates
since it started operation in March of 1946. Quality, service, and flexibility as “Your Personal
Manufacturer” have made us one of the last American audio manufacturers. If you have any
questions with this or any one of our other fine products, give us a call. When you talk with a
member of the Grommes~Precision team you’ll be speaking with someone who had a hand
in concept, design, production, or testing of our products.
INSPECTION
This unit was carefully checked and packed before leaving the factory. However, it is always a good idea to
inspect the shipping container and unit for indication of improper handling. If the unit has been damaged,
make an immediate claim to the dealer or distributor from whom it was purchased. If the unit was shipped to
you, notify the transportation company without delay, saving all packing materials, in order to process the
claim.
INITIAL PERFORMANCE CHECK
Continue the inspection by running a performance check. Connect a test speaker to the 4- ohm direct output
terminals (see page 6) and a tuner, tape deck, or CD player to the auxiliary input and set the controls for
operation. CAUTION: TO PROTECT THE SPEAKER FROM DAMAGE, DO NOT TURN THE UNIT ON UNTIL
ALL CONNECTIONS HAVE BEEN MADE. IN ADDITION, MAKE SURE THE UNIT IS GROUNDED BEFORE
TESTING. If the unit should be inoperable and no damage is noted, please notify the factory at 1- 47-599-1799
and ask for Technical Support.
RACK MOUNTING
For best results use a 10-32 class UNF-2B or 12-24 class UNC-2B rack and 5/ inch machine screws (metric:
M5X -6H or M6X1-6H, 15. mm). We recommend using a Phillips head screwdriver in order to protect the
finish from unnecessary scratches. Also recommended are nylon or plastic washers which will not only help
protect the finish but also aid in retaining the screws.
CONVECTION, FAN COOLING, AND VENTILATION
This unit is cooled via convection and therefore designed for continuous operation. Do not block the unit’s heat
sink fins or vent holes located in the cover. If the unit is rack mounted, you must utilize a cooling fan that is
capable of exhausting not less than 300CFM. The fan must be mounted to the inside top of the rack above the
amplifier.
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GROMMES-PRECISION 847-599-1799 F: 847-599-6178 800-SINCE-46
TECHNICAL SUPPORT
A troubleshooting chart is located at the end of this manual for your convenience. If you are in need of further
assistance, you can reach our design engineers at 1- 47-599-1799. Grommes~Precision is based in Gurnee,
Illinois and is on Central Standard Time. Our hours of operation are Monday - Friday from 7:00am to 3:30pm.
Troubleshooting information can also be found at our website www.grommesprecision.com.
GENERAL INSTALLATION
DO NOT run microphone cables near A/C lines, data, telephone or 70V line cables.
DO NOT run outputs line cable near data, telephone or other low voltage cables.
ENSURE that all loudspeakers are in-phase.
ENSURE that there are no short circuits on the loudspeaker line before connecting to the amplifier.
GENERAL DESCRIPTION
Grommes~Precision BX 15 and BX 30 are mixer/power amplifiers, and can mix up to three signals
Rated at 15 watts (BX 15) and 30 watts (BX 30), these amplifiers are ideal for applications that
require small sound reinforcement systems Any microphone with impedance of less than 600 Ω
can be connected Setting the Mic /Tel selector switch to the “TEL” position allows the BX 15 (BX
30) to function as an amplifier for paging made from the telephone Because the Program input is
10 kΩ in impedance and is of electrically-balanced type, it can be connected to both balanced and
unbalanced type of equipment The amplifiers also come with independent bass and treble controls
for the program and AUX input, which increase and decrease specific frequencies
Transformer-isolated output terminals are provided for connection of 4Ω speakers or for 25V or 70V
line applications The BX 15 (BX 30) can be mounted in an equipment rack using the optional Rack
Mounting kit
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GROMMES-PRECISION 847-599-1799 F: 847-599-6178 800-SINCE-46
PANEL DESCRIPTION
1 Mic/Tel input volume control
Adjusts the gain of the microphone or telephone
paging. The gain, increases as the control is turned
clockwise.
5. Bass control
Increases the low frequency response when turned
clockwise, and decreases the response when turned
counter-clockwise. The center position provides the
flat response.
2. Program input volume control
Adjusts the gain of the Program input. The gain,
increase as the control is turned clockwise.
6. Power Switch
Power is switched on and off with each depression of
this switch.
3. Aux input volume control
Adjusts the gain of the AUX input. Clockwise rotation
increases the gain.
7. Power Indicator-LED
Lights green when the power is switched on.
4. Treble control
Increases the high frequency response when turned
clockwise, and decreases the response when turned
counter-clockwise. The center position provides the
flat response.
. Output Level indicator
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GROMMES-PRECISION 847-599-1799 F: 847-599-6178 800-SINCE-46
REAR PANEL DESCRIPTION
1. AC power cord 10. Mic/Tel / Aux 2 Selector Switch*
2. Circuit Breaker – For Amplifier 11. Aux 2 Input (RCA Jack)
3. Circuit Breaker – For Convenience Outlet 12. Aux 3 Input (RCA Jack)
4. Earth Ground Connection Screw 13. Program /Aux 3 Selector Switch*
5. Speaker Output Terminals 14. Mute Switch
6. Program Input Terminals 15. MOH volume control
7. Mic/Tel input Terminals 16. MOH output terminals (transformer-isolated output)
. Aux 1 Input (RCA Jack) 17. Convenience Outlet
9. Mic/Tel selector switch
* Switch selects between RCA Line inputs and Microphone level.
POWER SOURCE
VAC
The supply transformer has been designed for use on 115V, 60Hz,
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GROMMES-PRECISION 847-599-1799 F: 847-599-6178 800-SINCE-46
MUTING
Announcements made using the Mic/Tel input take precedence, decreasing the sound volume of all current
broadcasts from equipment connected to the Program or AUX input. The interrupted broadcasts are
automatically restored gradually after Mic/Tel input announcement completion
LINE (Aux) CONNECTION
The equipment provides an auxiliary input which may be used for connecting other signal sources such as a
Radio Tuner, CD or Cassette player. A push switch is located on the rear panel for selection of, Mic1→Aux2,
Program→Aux3, Aux1 single channel ,etc. The Aux input is a dual RCA phono jack and has a stereo to mono
converter for each channel
RCA Phono plug connection
Sleeve-Shield
SLEEVE
PIN
Pin- Signal
INPUT CONNECTION
．Mic /Tel AUX2 input connections
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GROMMES-PRECISION 847-599-1799 F: 847-599-6178 800-SINCE-46
．AUX1 input connections
．AUX3 Program input connection
OUTPUT CONNECTIONS
．Output terminals
The amplifier has three speaker outputs: 4Ω, Ω, 25V and 70V. Use only one of these outputs for connection.
Class 2 wiring
Note: The impedance in the figure below represents the total impedance of the speaker system.
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GROMMES-PRECISION 847-599-1799 F: 847-599-6178 800-SINCE-46
． MOH output terminals
． The amplifier’s MOH output is 1w/ Ω
LOUDSPEAKER CONNECTION
Use only 70.7V or 25V line loudspeakers.
LOW IMPEDANCE Ω or (4Ω):
This output allows connection of standard low impedance loudspeakers. The minimum impedance must be
4Ω. When two or more loudspeakers are in use, ensure that they are wired in such a way that the impedance
load is between 4Ω and 16Ω.
BX 15 and BX 30 Technical Specifications
Type Mixer Amplifier
Model BX 15 BX 30
Supply AC 120V 60 Hz ± 10%
Output Power: 15W 30W
Outputs Speaker outputs: 4Ω, Ω, 25V, 70.7V
MOH, 1W @ Ω
Inputs Terminal (balanced)
Mic: 1mV, 600Ω
Telephone: 100mV @ 10KΩ
Program: 100mV @ 10KΩ
RCA JACK (unbalanced) Aux 1~3: 150mV, @ 10K
Frequency response 50Hz ~ 20KHz ± 3dB
Total harmonic distortion Less than 1% @ 1KHz, rated power
Signal to noise ratio 0dB
Tone Controls Bass: ± 10dB at 100Hz
Treble: ± 10dB at 10KHz
Indicators Output level
AC power consumption 50W @ RATED POWER 90W @ RATED POWER
Dimensions (mm) 212(W) x (H) x 275(D)
Weight 3.3 KGS 4 KGS
Color Black
Mounting options Free standing or 19” rack mountable
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GROMMES-PRECISION 847-599-1799 F: 847-599-6178 800-SINCE-46
IMPORTANT
The wires in the mains lead are colored
In accordance with the following code:
Green and Yellow: Earth (E)
Blue: Neutral (N)
Brown: Live (L)
As the colors of the wires in the mains lead of
this apparatus may not correspond with the
colored markings identifying the terminals in
your plug proceed as follows:
The wire, which is colored green and yellow,
must be connected to the terminal, which is
marked with the letter N or colored black. The
wire, which is marked with the letter L or
colored red.
If a 13 Amp (B.S.1363) plug or any other type
of plug is used, a 5 Amp fuse must be fitted
either in the plug or at the distribution board.
SAFETY PRECAUTIONS
 Be sure to read the instructions in this section carefully before use.
 Make sure to observe the instructions in this manual as the conventions of safety symbols and messages
regarded as very important precautions are included.
 We also recommend you keep this instruction manual handy for future reference.
Safety Symbol and Message Conventions
Safety symbols and messages described below are used in this manual to prevent bodily injury and property
damage which could result from mishandling. Before operation your product, read this manual first so you are
thoroughly aware of the potential safety hazards as well as understand the safety symbols and messages.
WARING
When installing the Unit
 Do not expose the unit to rain or an environment where it may be splashed by water or other liquids, as
doing so may result in fire or electric shock.
 Use the unit only with the voltage specified on the unit. Using a voltage higher than that which is specified
may result in fire or electric shock.
 Do not cut, kink, otherwise damage nor modify the power supply cord. In addition, avoid using the power
cord in close proximity to heaters, and never place heavy objects – including the unit itself – on the power
cord, as doing so may result in fire or electric shock.
 Be sure to replace the unit’s terminal cover after connection completion. Because the voltage of up to 70V
is applied to the high impedance speaker terminals, never touch these terminals to avoid electric shock.
 Be sure to ground to the safety ground (earth) terminal to avoid electric shock.
 Avoid installing or mounting the unit in unstable locations, such as on a rickety table or a slanted surface.
Doing so may result in the unit falling down and causing personal injury and/or property damage.

GROMMES-PRECISION 847-599-1799 F: 847-599-6178 800-SINCE-46
 The AC power output is specified on the AC outlet of the unit. Never exceed the specified wattage on the
unit when connecting equipment. Doing so may cause fire or property damage.
When the Unit is in Use:
 Should the following irregularity be found during use, immediately switch off the power, disconnect the
power supply plug from the AC outlet and contact your nearest GROMMES~PRECISION dealer. Make no
further attempt to operate the unit in this condition as this may cause fire or electric shock.
If you detect smoke or a strange smell coming from the unit
If water or any metallic object gets into the unit
If the unit falls, or the unit case breaks
If the power supply cord is damaged (exposure of the core, disconnection, etc)
If it is malfunctioning (no tone sounds)
 To prevent a fire or electric shock, never open nor remove the unit chassis as there are high voltage
components inside the unit. Refer all servicing to your nearest GROMMES~PRECISION dealer.
 Do not place cups, bowls, or other containers of liquid or metallic objects on top of the unit. If they
accidentally spill into the unit, this may cause a fire or electric shock.
 Do not insert nor drop metallic objects or flammable materials in the ventilation slots of the unit’s cover, as
this may result in fire or electric shock.
 Do not touch a power supply plug during thunder and lightning, as this may result in electric shock.
CAUTION
When Installing the Unit
 Never plug in nor remove the power supply plug with wet hands, as doing so may cause electric shock.
 When unplugging the power supply cord, be sure to grasp the power supply plug; never pull on the cord
itself. Operating the unit with a damaged power supply cord may cause a fire or electric shock.
 When moving the unit, be sure to remove its power supply cord from the wall outlet. Moving the unit with
the power cord connected to the outlet may cause damage to the power cord, resulting in fire or electric shock.
When removing the power cord, be sure to hold its plug to pull.
 Do not block the upper panel ventilation slots in the unit’s cover. Doing so may cause heat to build up
inside the unit and result in fire.
 Avoid installing the unit in humid or dusty locations, in locations exposed to the direct sunlight, near the
heaters, or in locations generating sooty smoke or steam as doing otherwise may result in fire or electric
shock.
When the Unit is in Use
 Do not place heavy objects on the unit as this may cause it to fall or break which may result in personal
injury and/or property damage. In addition, the object itself may fall off and cause injury and/or damage.
 Make sure that the volume control it set to minimum position before power is switched on. Loud noise
produced at high volume when power is switched on can impair hearing.
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