Kramer 912 User manual

KRAMER ELECTRONICS LTD.
USER MANUAL
MODEL:
912
Power Amplifier
P/N: 2900-000684 Rev 2

912 – Contents i
Contents
1Introduction 1
2Getting Started 2
2.1Achieving the Best Performance 2
3Overview 3
3.1Defining the 912 Power Amplifier 3
4Connecting the 912 5
5Technical Specifications 7
Figures
Figure 1: 912 Power Amplifier Front and Rear Panels 4
Figure 2: Connecting the 912 Power Amplifier 6

912 - Introduction 1
1 Introduction
Welcome to Kramer Electronics! Since 1981, Kramer Electronics has been
providing a world of unique, creative, and affordable solutions to the vast range of
problems that confront the video, audio, presentation, and broadcasting
professional on a daily basis. In recent years, we have redesigned and upgraded
most of our line, making the best even better!
Our 1,000-plus different models now appear in 11 groups that are clearly defined
by function: GROUP 1: Distribution Amplifiers; GROUP 2: Switchers and Matrix
Switchers; GROUP 3: Control Systems; GROUP 4: Format/Standards Converters;
GROUP 5: Range Extenders and Repeaters; GROUP 6: Specialty AV Products;
GROUP 7: Scan Converters and Scalers; GROUP 8: Cables and Connectors;
GROUP 9: Room Connectivity; GROUP 10: Accessories and Rack Adapters and
GROUP 11: Sierra Products.
Congratulations on purchasing your Kramer 912 Power Amplifier, which is ideal for
the following typical applications:
•Presentation rooms and multimedia applications for local audio amplification
•Personal audio listening (for example, a PC and portable CD player)

2 912 - Getting Started
2 Getting Started
We recommend that you:
•Unpack the equipment carefully and save the original box and packaging
materials for possible future shipment
•Review the contents of this user manual
Use Kramer high performance high resolution cables.
Use only the power cord that is supplied with this machine.
Go to http://www.kramerelectronics.com to check for up-to-date
user manuals, application programs, and to check if firmware
upgrades are available (where appropriate).
2.1 Achieving the Best Performance
To achieve the best performance:
•Use only good quality connection cables to avoid interference, deterioration
in signal quality due to poor matching, and elevated noise levels (often
associated with low quality cables)
•Avoid interference from neighboring electrical appliances that may adversely
influence signal quality
•Position your Kramer 912 away from moisture, excessive sunlight and dust
i

912 - Overview 3
3 Overview
The Kramer 912 is a high performance power amplifier that can accept a balanced
stereo audio input on a 5-pin terminal block, and an unbalanced stereo audio input
on two RCA connectors.
Both inputs can be connected simultaneously.
The balanced and unbalanced stereo audio inputs are converted to a differential
stereo audio output for speakers on a 4-pin terminal block.
The 912 Power Amplifier features:
•An audio level knob to adjust the volume
•The ability to control the volume remotely using a remote 10V volume control
•Mixing of the unbalanced and balanced inputs
•An ON LED indicating that the unit is receiving power
•A 12V power source making it ideal for field operation
•Easy-to-connect, detachable terminal blocks
The 912 Power Amplifier is housed in a Kramer TOOLS enclosure.
3.1 Defining the 912 Power Amplifier
Figure 1 defines the 912 Power Amplifier.

4 912 - Overview
Figure 1: 912 Power Amplifier Front and Rear Panels
Front and Rear Panel Features
# Feature Function
1 CONTROL Button Press in for remote volume control using the 10V
Control connection, release to control the volume
using the front panel Volume knob (see item 2).
Warning: When a remote volume control is
connected, switching between the volume controls
may cause a sudden, large volume level change
2 VOLUME Control Knob Turn clockwise to increase the volume,
anticlockwise to decrease the volume
3 OVER LED Lights red when the amplifier overheats
Overheating causes the amplifier to automatically
reduce power to protect the unit from damage. Once
the unit cools down, full power is restored
4 ON LED Lights green when the unit receives power
5 IN 1
Unbalanced
Stereo Audio
Input
LEFT RCA
Connector
Connect to the unbalanced stereo audio source
You can connect both the unbalanced and the
balanced inputs simultaneously—the inputs will be
mixed
RIGHT RCA
Connector
6 IN 2 (L+ L- G R+ R-) Balanced
Stereo Audio Input Removable
Terminal Block
Connect to the balanced stereo audio source
You can connect both the unbalanced and the
balanced inputs simultaneously—the inputs will be
mixed
7 OUT (L+ L- R+ R-)Stereo
Output Terminal Block
Connector
Connect to the speakers
8 10V CONTROL (GND VOL V+)
Control Removable Terminal
Block
Connect to a remote 10V volume control (see
Section 4). Connect G to one end of the
potentiometer, VOL to the wiper, V+ to the
opposite end of the potentiometer
9 12V DC Connect to the supplied power adapter, center pin
positive

912 - Connecting the 912 5
4 Connecting the 912
This section explains how to connect and operate your 912.
Always switch off the power to each device before connecting it to your
912. After connecting your 912, connect its power and then switch on
the power to each device.
To connect the 912, as illustrated in the example in Figure 2:
1. Connect the unbalanced stereo audio source (for example, a stereo audio
player) to the LEFT and RIGHT IN 1 RCA connectors.
Or alternatively, connect the balanced stereo audio source to the GND, left (L+ L-) and
right (R+ R-) input terminal block
2. Connect the OUT speaker terminal block to a pair of speakers. Connect the
left speaker to the L+ and L- pins, and the right speaker to the R+ and R-
pins.
Note: Do not ground the speakers.
3. Optional—Connect the G, 2 and V+ pins on the 10V CONTROL terminal
block connector to a remote 10V volume control.
4. Select the volume control method using the CONTROL button on the front
panel. Press CONTROL (10V position) to select the remote 10V volume
control.
5. Connect the 12V DC power adapter to the 912 power socket and to the
mains electricity (not shown in Figure 2).
6. Adjust the volume using the method selected in Step 4.
i

6 912 - Connecting the 912
Figure 2: Connecting the 912 Power Amplifier

912 - Technical Specifications 7
5 Technical Specifications
INPUTS: 1 unbalanced stereo 1Vpp/10kΩon 2 RCA connectors
1 balanced stereo +4dBu/10kΩon a 5-pin removable
terminal block
OUTPUT: 1 stereo speaker output on a 4-pin removable large
terminal block
INPUT SENSITIVITY: Unbalanced: 440mVpp
Balanced: 105mVpp
OUTPUT POWER: 5.5W RMS power per channel into a 8Ωload
8.4W RMS power per channel into a 4Ωload
AMPLIFIER TYPE: Class D
MAXIMUM VOLTAGE
GAIN:
Unbalanced: 32.6dB (x43)
Balanced: 36.2dB (x65)
BANDWIDTH (-3dB): >20kHz
S/N RATIO: Unbalanced 60dB
Balanced 63dB
CONTROLS: 8Ω: Unbalanced <-68 to 33dB, Balanced -60 to 36dB
4Ω: Unbalanced -48 to 40dB, Balanced -60 to 38dB
COUPLING: Input: Unbalanced DC (internal AC path), Balanced AC
Output: DC
AUDIO THD + NOISE: 8Ω: Unbalanced 2.3%, Balanced 2.5%
4Ω: Unbalanced 3.1%, Balanced 4.3%
AUDIO 2nd HARMONIC: 8Ω: Unbalanced 1.4%, Balanced 1.4%
4Ω: Unbalanced 2.7%, Balanced 3.5%
POWER SOURCE: 12V DC, 2.8A Full load 4Ω@10% THD+N
DIMENSIONS: 12cm x 8.5cm x 2.5cm (4.7" x 3.4" x 1") W, D, H
WEIGHT: 0.3kg (0.67lbs) approx.
ACCESSORIES: Power supply, mounting bracket
OPTIONS: RK-3T 19” rack adapter
Specifications are subject to change without notice at http://www.kramerelectronics.com