Beyerdynamic A20 - Headphone Amplifier Manual

Features

• Power amplifier of a discrete design using SMD technology
• Two headphone outputs connected in parallel
• Volume control for both headphone outputs
• Looped-through input to connect signal sources (CD player, DVD player) and amplifiers
• Internal switching power supply with wide-range input for worldwide use
• Supplied with two different power cables (1 x type E+F (CEE 7/7) and 1 x type B)

Controls and Indicators

Front view

1. Backlit on-off switch.
   Red = Device is in stand-by mode.
   Green = Device is turned on.
2. Headphone sockets, connected in parallel, 1/4" stereo jack (6.35 mm). In order to connect standard headphones.
   
   As the headphone sockets are connected in parallel, the volume is controlled for both headphones.
   Therefore, we recommend using headphones of the same impedance to achieve the same volume for both headphones.
3. Volume control to adjust the volume.
   
   
   Hearing protection:
   We would like to point out that listening at high volumes over a long period of time may damage your hearing irreversibly. Therefore, reduce the volume before putting into operation and when changing the audio source, as the connected devices or reproduced audio data can have very different output levels.
   Make sure that the set volume is not too high. Rule of thumb: The higher the volume, the shorter the time of listening. According to employer's regulations for safety and health the noise exposure e.g. when working should not exceed 85 dB (low volume). This is an allowed time of listening of 8 hours at maximum. If the volume is increased by 3 dB, the allowed time of listening is halved, i.e. with 88 dB the time of listening is 4 hours, with 91 dB 2 hours and so on.

Rear View

4. Looped-through input (hard-wired), RCA phono sockets for signal sources with high levels. Input sockets = for the connection of audio sources (CD player, DVD player etc.)
   Output sockets = for the connection of devices with high level input (stereo amplifiers, active loudspeakers etc.) At the output sockets you can pick up the audio signal from the input sockets and route it to your stereo amplifier, active loudspeakers or other devices with standard inputs for high levels. As the signal of the input sockets is permanently available at the output sockets, you can listen to the looped-through audio signal via your hi-fi system, even when the A 20 is turned off.
5. Mains connection with integrated wide-range switching power supply for 100 - 240 V AC.
   Due to the integrated wide-range switching power supply, the A 20 can be operated with 110 V/60 Hz or 240 V/50 Hz.

Technical Specifications

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 only with dry cloth.
7. Do not install near any heat sources such as radiators, heat registers, stoves, or other apparatus (including amplifiers) that produce heat.
8. 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.
9. Protect the power cord from being walked on or pinched particularly at plugs, convenience receptacles, and the point where they exit from the apparatus.
10. Only use attachments/accessories specified by the manufacturer.
11. Unplug this apparatus during lightning storms or when unused for long periods of time.
12. 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.

Exemption from liability

• beyerdynamic GmbH & Co. KG will not be liable if any damage, injury or accident occurs due to negligent, incorrect or inappropriate operation of the product.

Location

• The equipment must be set up so that the mains switch, mains plug and all connections on the rear of the device are easily accessible.
• If you transport the equipment to another location take care to ensure that it is adequately secured and can never be damaged by being dropped or by impacts on the equipment.

Fire hazard

• Never place naked flames (e.g. candles) near the equipment.

Humidity / heat sources

• Never expose the equipment to rain or a high level of humidity. For this reason do not install it in the immediate vicinity of swimming pools, showers, damp basement rooms or other areas with unusually high atmospheric humidity.
• Never place objects containing liquid (e.g. vases or drinking glasses) on the equipment. Liquids in the equipment could cause a short circuit.
• Do not install near any heat sources such as radiators, heat registers, stoves or other apparatus (including amplifiers) that produce heat.

Connection

• The equipment must be connected to a mains socket that has an earth contact.
• Protect the power cord from being walked on or pinched particularly at plugs, convenience receptacles, and the point where they exit from the apparatus.
• Lay all connection cables so that they do not present a trip hazard.
• Whenever working on the inputs and outputs of the equipment switch off power.
• Check whether the connection figures comply with the existing mains supply. Serious damage could occur due to connecting the system to the wrong power supply. An incorrect mains voltage could damage the equipment or cause an electric shock.
• Please note that different operating voltages require the use of different types of power cable and plugs.

Please refer to the following table:

• If the equipment causes a blown fuse or a short circuit, disconnect it from the mains and have it checked and repaired.
• Do not hold the mains cable with wet hands. There must be no water or dust on the contact pins. In both cases you could receive an electric shock.
• The mains cable must be firmly connected. If it is loose there is a fire hazard.
• Always pull out the mains cable from the mains and/or from the equipment by the plug – never by the cable. The cable could be damaged and cause an electric shock or fire.
• Do not use the equipment if the mains plug is damaged.
• If you connect defective or unsuitable accessories, the equipment could be damaged. Only use connection cables available from or recommended by beyerdynamic. If you use cables you have made up yourself, all claim to warranty is null and void.
• In order to disconnect the receiver from AC power, switch it off and disconnect the power plug from the power socket.

Maintenance

• Only clean the equipment with a slightly damp or dry cloth. Never use solvents as these damage the surface.

Troube shooting and servicing

• Do not open the equipment without authorisation. You could receive an electric shock. There are no userserviceable parts inside.
• Leave all service work to authorised expert personnel.