ART HeadAmp6

Important Safety Instructions

? This symbol, wherever it appears, alerts you to the presence of uninsulated dangerous voltage inside the enclosure. Voltage that may be sufficient to constitute a risk of shock.

? This symbol, wherever it appears, alerts you to important operating and maintenance instructions in the accompanying literature. Please read manual.

Read Instructions: Retain these safety and operating instructions for future reference. Heed all warnings printed here and on the equipment. Follow the operating instructions printed in this user guide.

Do Not Open: There are no user serviceable parts inside. Refer any service work to qualified technical personnel only.

Power Sources: Only connect the unit to mains power of the type marked on the rear panel. The power source must provide a good ground connection.

Power Cord: Use the power cord with sealed mains plug appropriate for your local mains supply as provided with the equipment. If the provided plug does not fit into your outlet consult your service agent. Route the power cord so that it is not likely to be walked on, stretched or pinched by items placed upon or against.

Grounding: Do not defeat the grounding and polarization means of the power cord plug. Do not remove or tamper with the ground connection on the power cord.

Ventilation: Do not obstruct the ventilation slots or position the unit where the air required for ventilation is impeded. If the unit is to be operated in a rack, case or other furniture, ensure that it is constructed to allow adequate ventilation.

Moisture: To reduce the risk of fire or electrical shock do not expose the unit to rain, moisture or use in damp or wet conditions. Do not place a container of liquid on it, which may spill into any openings.

Heat: Do not locate the unit in a place close to excessive heat or direct sunlight, as this could be a fire hazard. Locate the unit away from any equipment, which produces heat such as: power supplies, power amplifiers and heaters.

Environment: Protect from excessive dirt, dust, heat, and vibration when operating and storing. Avoid tobacco ash, drink spillage and smoke, especially that associated with smoke machines.

Handling: To prevent damage to the controls and cosmetics avoid rough handling and excessive vibration. Protect the controls from damage during transit. Use adequate padding if you need to ship the unit. To avoid injury to yourself or damage to the equipment take care when lifting, moving or carrying the unit.

Servicing: Switch off the equipment and unplug the power cord immediately if it is exposed to moisture, spilled liquid, objects fallen into opening, or the power cord or plug becomes damaged during a lightning storm or if smoke odor or noise is noted. Refer servicing to qualified technical personnel only.

Installation: Install the unit in accordance with the instructions printed in the user guide.

Introduction

The HeadAmp6 is a full-featured six-channel stereo headphone amplifier that includes six auxiliary inputs to allow separate mixes on each headphone channel. Each output channel also features a dual function Balance control which will pan between Left & Right sides of the main signal bus, or vary the Mix between the main signal bus and the Auxiliary input for that respective channel.

Each output channel includes one front and two rear panel stereo 1/4-inch TRS headphone jacks for ease of installation and quick patching capability. Mono, Mute L, and Mute R buttons on each channel select between four operating modes: 1) Stereo, 2) Mono Left, 3) Mono Right, 4) Mono Both (Left & Right) for versatile monitoring solutions. Independent output level controls on each channel personalize monitoring levels.

Input options include XLR and 1/4-inch TRS balanced inputs with matching "Thru" jacks for bridging multiple units. An additional front panel stereo 1/4-inch TRS Direct In jack for quick patch override of the rear panel inputs is included for quick insertion of any stereo source. The Master Volume control sets the main signal bus level. Eight-segment precision LED level metering on the main bus and four-segment indicators on each output channel provide visual feedback of the signal level at all key points.

Installation

The HeadAmp6 may be used in a wide variety of applications and environments. Its rack-mountable steel and aluminum enclosure is both attractive and designed for continuous professional use. Mounting location is not critical. However, for better performance and greater reliability, it is recommended that the unit not be placed on top of power amps or other sources of extreme heat, or strong magnetic fields.

AC Power Hookup

The HeadAmp6 has an internal power supply. Only connect the unit to mains power of the type marked on the rear panel. The power source must provide a good ground connection, and the ground pin on the mains plug should never be defeated.

Analog Audio Connections

Audio connections to and from the HeadAmp6 include:

• Rear Balanced Inputs and Outputs: XLR (Pin 2 = Pos(+), Pin 3 = Neg(-), Pin 1 = Ground) and 1/4-inch TRS (Tip = Pos(+), Ring = Neg(-), Sleeve = Ground).
• Front Stereo Aux 1/4-inch Inputs: Tip = Left, Ring = Right, Sleeve = Ground.
• Front Direct 1/4-inch Input: Tip = Left, Ring = Right, Sleeve = Ground.
• Front and Rear Stereo Headphone 1/4-inch Outputs: Tip = Left, Ring = Right, Sleeve = Ground.

Key Features:

• Six Independent High-Power Headphone Amplifier Channels
• Dual Function Balance/Mix Control per Channel
• Front Panel Stereo Aux Input for each Channel
• Multiple Monitoring Settings per Channel
• Individual Output Level Control per Channel
• Precision Four Segment LED Metering Per Channel
• Master Volume Control with Eight Segment LED Metering
• Front Panel Direct In Jack
• One Front and Two Rear Mounted Headphone Jacks per Channel
• Connects and Drives up to 18 Headphones Simultaneously
• XLR and 1/4" Main Inputs and Outputs
• Parallel Main Outputs for Multiple Unit Use

Controls and Jacks

Front Panel

Figure 1 - Master Volume, Direct In, and Channel One: Depicts the front panel layout.

Direct In Jack: The 1/4-inch TRS jack provides a stereo unbalanced input that overrides the rear panel balanced inputs. It's useful for temporarily inserting a different main input signal or making an unbalanced connection.

Master Volume Control: Adjusts the main signal bus level. An eight-segment LED meter to its left displays the audio level.

Mute L, Mute R, and Mono Switches: These switches set the stereo headphone outputs to one of three operating modes: Stereo (all switches out), Mono Right (Mute L in, Mute R out, Mono in), or Mono Left (Mute R in, Mute L out, Mono in). These affect only the headphone outputs after balance/mix and level controls.

Stereo Aux In Jack: Stereo TRS jacks for inserting a direct stereo signal into an individual headphone channel. When a plug is inserted, the BALANCE control for that channel becomes a mix control, blending the AUX IN signal with the main signal bus.

Out Jack: Stereo TRS 1/4-inch jack providing a connection for each of the six output channels to stereo headphones or additional headphone distribution amplifiers. Two identical output jacks are provided on the rear panel for each channel.

Rear Panel

Figure 2 - Rear Panel Inputs: Shows the rear panel input connectors.

Balanced Main Inputs: XLR and 1/4-inch TRS jacks for line level signals, feeding the main signal bus. Gain sensitivity is identical for both types. The front panel DIRECT IN jack overrides these inputs.

Balanced Main Thru: XLR and 1/4-inch TRS jacks hardwired in parallel with the BALANCED MAIN INPUT jacks. Useful for daisy-chaining multiple HeadAmp6 units.

Figure 3 - Rear Panel Headphone Outputs: Displays the rear panel headphone output jacks.

Stereo Headphone Outputs: These stereo TRS jacks are the main outputs for each channel, wired in parallel with the front panel outputs. They can be used simultaneously to drive headphones or as feeds to additional headphone amplifiers. The HeadAmp6 is optimized for headphone impedances of 32 to 600 Ohms. Driving loads lower than 16 Ohms is not recommended but possible, potentially resulting in limited output power and clipping. When paralleling multiple headphones, output power is split, and combined load impedances can also cause clipping. Modern headphones typically require only milliwatts for full output. There is no direct relationship between headphone impedance and SPL output; sensitivity is the key factor.

Operation

1. Start with MASTER VOLUME and LEVEL controls set fully counter-clockwise. Set BALANCE controls to 12 o'clock. Set all MUTE and MONO switches to the "OUT" position.

2. Connect the audio monitor signal source to the rear panel BALANCED MAIN Inputs using appropriate balanced or unbalanced cables. Alternatively, connect to the front panel DIRECT IN jack using a stereo TRS 1/4-inch plug.

3. For connecting multiple HeadAmp6 units, daisy-chain them by connecting the BALANCED MAIN THRU connectors of the first unit to the BALANCED MAIN INPUT connectors of the next. Note: Daisy-chaining only works with rear panel connectors; the front panel DIRECT IN jack is unit-specific.

4. Connect headphones or leads to additional headphone amps to the front or rear panel HEADPHONE OUTPUT jacks using stereo 1/4-inch TRS plugs.

5. If using the Auxiliary Mixer function, connect stereo signals to the appropriate AUX IN jacks. For a mono signal, use a TRS plug with Tip and Ring tied together, or use the front panel MONO buttons. The AUX IN signal is heard in the specific channel based on BALANCE and LEVEL control positions.

6. Turn on the POWER switch. With the audio monitor signal playing, increase the MASTER VOLUME control until the MASTER LED bar-graph lights green and yellow LEDs, avoiding the RED CLIP LED on peaks. This ensures a strong signal for all channels.

7. Set the LEVEL control on each channel to a comfortable listening level for the connected headphones.

Note on "More Me" Function: When using the Auxiliary Mixer to add a signal (e.g., vocals) for a specific channel, the relative phase of the AUX IN signal affects the mix. If the signals are in phase, the "More Me" effect is achieved. If they are 180 degrees out of phase (antiphase), the AUX IN signal will subtract from the main signal bus in that channel. Use a phase invert switch on consoles or preamps if needed.

Applications

Figure 4 - Headphone Distribution Application: This diagram illustrates a common use case where a mixing console's main stereo monitor mix is fed into the ART HeadAmp6. The amplifier then distributes this signal to multiple headphones connected to its front and rear output jacks. The diagram also shows how a second HeadAmp6 unit can be connected in a daisy-chain configuration to expand headphone distribution capabilities.

Block Diagram

Figure 5 - Block Diagram: A detailed schematic illustrating the internal signal flow of the HeadAmp6. It shows the path from balanced main inputs and direct inputs, through volume and balance/mix controls, mute/mono switches, individual channel level controls, and finally to the stereo headphone outputs. The diagram also depicts auxiliary inputs and the overall signal processing flow.

Warranty Information

Limited Warranty

Applied Research and Technology (ART) warrants this product and its components to the original purchaser against defects in workmanship and materials for a period of three years from the date of purchase. ART will, at its option, repair or replace defective products or component parts upon prepaid delivery to the factory service department or an authorized service center, accompanied by proof of purchase.

Exclusions

This warranty does not cover misuse, abuse, or unauthorized alterations/repairs. It is void if the serial number is altered or removed. ART reserves the right to make design changes without obligation to apply them to previously manufactured products. ART is not liable for consequential damages, including loss of use. Some states may not allow limitations on incidental or consequential damages.

For units purchased outside the United States, service is provided by an authorized ART distributor.

Service

If your unit requires service:

1. Ensure the unit is the cause of the problem. Verify power, correct cable connections, and cable condition. Consult your dealer for troubleshooting assistance.
2. If the ART unit is suspected to be faulty, visit www.artproaudio.com to contact Customer Service or request a Return Authorization (RA) for service in the "resources" area.
3. When returning the unit for service, pack it in its original carton or a suitable substitute. Place the packaged unit in another box for shipping. Print the RA number clearly on the outside of the shipping box.
4. Include a note with the RA number and your contact information (including a daytime phone number) with the unit, preferably attached to the top.

For Your Reference:

• Date of purchase: ___________________
• Purchased from: ___________________
• Serial number: ___________________

HeadAmp6 Specifications

ART maintains a policy of constant product improvement. ART reserves the right to make changes in design or make additions to or improvements upon this product without any obligation to install the same on products previously manufactured. Therefore, specifications are subject to change without notice.

Website: www.artproaudio.com

E-mail: support@artproaudio.com

© 2010 Applied Research & Technology

Model Number: HA6-5004-101