User's Manual HPA6 6-Channel HEADPHONE AMPLIFIER LTO www.altoproaudio.com Version 1.0 April 2002 R English SAFETY RELATED SYMBOLS CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN wire or disconnect the wiring of protective grounding terminal. Operating Conditions This apparatus shall not be exposed to dripping or splashing and that no objects filled with liquids, such as vases, shall be placed on this apparatus. To reduce the risk of fire or electric shock, do not expose this apparatus to rain or moisture. Do not use this apparatus near water. Install in accordance with the manufacturer's instructions. Do not install near any heat sources such as radiators, heat registers, stoves, or other apparatus (including amplifiers) that produce heat. Do not block any ventilation openings. No naked flame sources, such as lighted candles, should be placed on the apparatus. 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 . Read the manual . Protective grounding terminal . Alternating current /voltage . Hazardous live terminal . ON: Denotes the apparatus turns on . OFF: Denotes the apparatus turns off ,because of using the single pole switch ,be sure to unplug the AC power to prevent any electric shock before you proceed your service . WARNING: Describes precautions that should be observed to prevent the danger of injury or death to the user . CAUTION: Describes precautions that should be observed to prevent danger of the apparatus . IMPORTANT SAFETY INSTRUCTIONS Read these instructions. Follow all instructions. Keep these instructions. Heed all warnings. Only use attachments/accessories specified by the manufacturer. Power Cord and Plug 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. Protect the power cord from being walked on or pinched particularly at plugs, convenience receptacles , and the point where they exit from the apparatus. Cleaning When the apparatus needs a cleaning, you can blow off dust from the apparatus with a blower or clean with rag etc. Don't use solvents such as benzol, alcohol, or other fluids with very strong volatility and flammability for cleaning the apparatus body. Clean only with dry cloth. Servicing Refer all servicing to qualified personnel. 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 . 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. 1 WARNING Power Supply Ensure the source voltage matches the voltage of the power supply before turning ON the apparatus. Unplug this apparatus during lightning storms or when unused for long periods of time . External Connection The external wiring connected to the output hazardous live terminals requires installation by an instructed person, or the use of ready-made leads or cords. Do not Remove any Cover There are maybe some areas with high voltages inside , to reduce the risk of electric shock, do not remove any cover if the power supply is connected. The cover should be removed by the qualified personnel only. No user serviceable parts inside. Fuse To prevent a fire, make sure to use fuses with specified standard (current, voltage, type). Do not use a different fuse or short circuit the fuse holder. Before replacing the fuse, turn OFF the apparatus and disconnected the power source. Protective Grounding Make sure to connect the protective grounding to prevent any electric shock before turning ON the apparatus. Never cut off the internal or external protective grounding Preface Dear Customer: Thanks for choosing LTO HPA6 6-Channel Headphone Amplifier and thanks for choosing the one of results of LTO AUDIO TEAM job and researches. For our LTO AUDIO TEAM, music and sound are more than a job...are first of all passion and let us say... our obsession! We have been designing professional audio products for a long time in cooperation with some of the major brands in the world in the audio field. The LTO line presents unparalleled analogue and digital products made by Musicians for Musicians in our R&D Centres in Italy, Netherlands, United Kingdom and Taiwan. The core of our digital audio products is a sophisticated DSP (Digital sound processor) and a large range of state of the art algorithms which have been developed by our Software Team for the last 7 years. Because we are convinced you are the most important member of LTO AUDIO TEAM and the one confirming the quality of our job, we'd like to share with you our work and our dreams, pay attention to your suggestions and your comments. Following this idea we create our products and we will create the new ones! From our side, we guarantee you and we will guarantee you also in future the best quality, the best fruits of our continuous researches and the best prices. Our LTO HPA6 6-Channel Headphone Amplifier is the result of many hours of listening and tests involving common people, area experts, musicians and technicians. The result of this effort is a versatile Headphone Amplifier featuring 6 separated channels, each channel provides 3 push-button switches, 2 knob controls, 2 phone jacks and 4 LEDs . The common main section contains 1knob control, 1 jack and 8 LEDs. Nothing else to add, but that we would like to thank all the people that made the LTO HPA6 6-Channel Headphone Amplifier a reality available to our customers, and thank our designers and all the LTO staff, there to make possible the realization of products containing our idea of music and sound and there to support you, our customers, in the best way, conscious that you are our best richness. Thank you very much. LTO AUDIO TEAM 2 TABLE OF CONTENTS 1. Introduction ......................................................................................................................4 2. Feature List .......................................................................................................................4 3. Control Elements. .............................................................................................................4 3.1 The Front Panel 3.2 The Rear Panel 4. Installation & Connection .................................................................................................7 4.1 Mains Connection 4.2 Audio Connection a. Wiring Configuration b. In Line Connection 4.3 Rack Mounting 5. Application........................................................................................................................8 5.1 The HPA6 as a Headphone Amplifier 5.2 The HPA6 as Independent Power Amplifiers 5.3 The HPA6 in Studio Application 5.4 The HPA6 in Mono/Stereo Application 6. Technical Specifications .................................................................................................10 7.Warranty ..........................................................................................................................12 3 1. Introduction Thank you very much for expressing your confidence in LTO products by purchasing our HPA6 6-Channel Headphone Amplifier. With the HPA6 you have acquired an extremely musical and flexible 6-Channel Headphone Amplifier. Featuring six stereo headphone amplifiers, The LTO HPA6 6-Channel Headphone Amplifier performs a number of necessary tasks, not all of which are headphone related. The HPA6 6-Channel Headphone Amplifier provides Main Inputs on the rear panel and Direct In Input on the front panel to drive any or all of the 6 stereo headphone amplifiers, when using the Direct In Input, the Main Inputs signal will be interrupted automatically, the Main Outputs on the rear panel can be used to interlink any number of HPA6s for expanding. The AUX In input on each channel is used to add an additional input signal to the master signal, with the corresponding Balanced Control to determine the mix ratio between the two signals. The Headphone Out outputs on the front panel is connected in parallel to the rear panel output connectors, and provides an additional option to monitor the individual channels, esp. in the Rack mounting application. 2. Feature List Signal Rack Unit Exceptionally rugged construction ensures long life and durability Professional , universal headphone amplification system for studio and stage 6 individual stereo high-power amplifiers Maximum audio quality even at high volume levels Stereo AUX In per channel for additional signal source 6 independent input mix sections Output level control per channel Mono and LEFT/RIGHT MUTE buttons per channel for additional flexibility 3 headphone outputs per channel on front and rear panels Precise 4-digit LED output level display per channel Direct In on the front panel for additional stereo signal source Paralleled main outputs to chain several HPA6 headphone amplifiers Servo-balanced , gold-plated XLR and 1/4" TRS connectors Manufactured Under ISO9001 Certified management system 3. Control Elements INPUT LEVEL(dBu) 24 18 12 6 0 6 12 18 OUTPUT LEVEL(dBu) 24 0 12 CLIP 3 2 4 OUTPUT LEVEL(dBu) 24 0 12 CLIP 3 2 4 OUTPUT LEVEL(dBu) 24 0 12 CLIP 3 2 4 OUTPUT LEVEL(dBu) 24 0 12 CLIP 3 2 4 OUTPUT LEVEL(dBu) 24 0 12 CLIP 3 2 4 OUTPUT LEVEL(dBu) 24 0 12 CLIP 3 2 4 3 2 R L 4 MUTE R MAIN IN AUX BALANCED AUX IN 1 6 0 OUTPUT GAIN HEADPHONE OUT 5 L MUTE R 1 MAIN IN AUX BALANCED AUX IN 6 0 OUTPUT GAIN HEADPHONE OUT 5 L MUTE R 1 AUX MAIN IN BALANCED AUX IN 6 0 OUTPUT GAIN HEADPHONE OUT 5 L MUTE R 1 AUX BALANCED AUX IN 6 0 OUTPUT GAIN HEADPHONE OUT 5 L MUTE R 1 AUX BALANCED AUX IN 6 0 OUTPUT GAIN HEADPHONE OUT 5 L MUTE R 1 AUX BALANCED AUX IN 6 0 OUTPUT GAIN HEADPHONE OUT 5 LTO DIRECT IN 1 0 6 5 MONO ON HEADPHONE 6-Channel HPA6 MONO MONO MONO MONO MONO AMPLIFIER STEREO STEREO STEREO STEREO STEREO STEREO INPUT GAIN MAIN SECTION CHANNEL 1 CHANNEL 2 CHANNEL 3 CHANNEL 4 CHANNEL 5 CHANNEL 6 OFF POWER The LTO HPA6 6-Channel Headphone Amplifier has six separated channels, each channel presents 3 Push-button switches, 2 knob controls , 2 phone jacks and 4 LEDs. The common main section contains 1 knob control,1 jack and 8 LEDs. 4 3.1 The F ront P anel 3 5 12 6 10 11 INPUT LEVEL(dBu) 24 18 12 6 0 6 12 18 OUTPUT LEVEL(dBu) 24 0 12 CLIP 3 2 4 3 2 R L MUTE R 1 5 4 MAIN IN AUX BALANCED AUX IN MONO 0 6 6 0 OUTPUT GAIN HEADPHONE OUT LTO DIRECT IN 1 5 STEREO INPUT GAIN MAIN SECTION CHANNEL 1 1 2 8 7 4 9 1.Direct In Input: The Direct In Input is used to feed the signals coming from an external source. While using the Direct In Input, the Main signal applied on the rear panel is interrupted automatically. 2.Input Gain Control: This control sets the input signal level coming from Main/Direct In. 3.Input Level Meter: This 8-digit Input Level Meter informs you about the input signal level within a range from -24dBu to +18dBu. 4.Aux In Input: The Aux In Input is used to feed the further input signal, which can be mixed with the Main/ Direct In signal via Balanced Control. 5.L Mute Switch: This push-button mutes the Left input signal. 6.R Mute Switch: This push-button mutes the Right input signal. 7.Mode Switch: This push-button switches the operational mode between Mono and Stereo. Press this button for Mono application, and the Mono LED (8) lights up. 8.Mono LED: This LED informs you the current operational mode. Press the Mode Switch(7) for Mono application, this LED lights up. 9.Headphone Out Output: This 1/4" TRS phone jack is connected in parallel to the rear panel output connectors, and provides an additional option to monitor the individual channels. When this unit is permanently installed in rack, this proves to be a useful function. 10.Balanced Control: This control sets the proportion between the Main/Direct In signal and the input signal applied to Aux In Input. 11.Output Gain Control: This control sets the volume of the individual channels and refers to both the Left & Right Channel and the Headphone Out. 12.Output Level Meter: This 4-digit Output Level Meter informs you about the output signal level within a range from 24dBu to +12dBu. If the Clip LED lights up, you should turn down the Input Gain Control or/and the individual Output Gain Control (only for the Channel in ...