User's Manual

6-Channel HEADPHONE AMPLIFIER
LTO www.altoproaudio.com Version 2.3 September 2005

English

SAFETY RELATED SYMBOLS

CAUTION

RISK OF ELECTRIC SHOCK DO NOT OPEN
This symbol, wherever used, alerts you to the presence of un-insulated and dangerous voltages within the product enclosure. These are voltages that may be sufficient to constitute the risk of electric shock or death. This symbol, wherever used, alerts you to important operating and maintenance instructions. Please read. Protective Ground Terminal AC mains (Alternating Current) Hazardous Live Terminal ON: Denotes the product is turned on.
To prevent fire and damage to the product, use only the recommended fuse type as indicated in this manual. Do not short-circuit the fuse holder. Before replacing the fuse, make sure that the product is OFF and disconnected from the AC outlet.

Protective Ground

Before turning the product ON, make sure that it is connected to Ground. This is to prevent the risk of electric shock. Never cut internal or external Ground wires. Likewise, never remove Ground wiring from the Protective Ground Terminal.

Operating Conditions

Always install in accordance with the manufacturer's instructions. To avoid the risk of electric shock and damage, do not subject this product to any liquid/rain or moisture. Do not use this product when in close proximity to water. Do not install this product near any direct heat source. Do not block areas of ventilation. Failure to do so could result in fire. Keep product away from naked flames.
OFF: Denotes the product is turned off. WARNING Describes precautions that should be observed to prevent the possibility of death or injury to the user. CAUTION Describes precautions that should be observed to prevent damage to the product. Disposing of this product should not be placed in municipal waste and should be Separate collection.
IMPORTANT SAFETY INSTRUCTIONS
Read these instructions Follow all instructions Keep these instructions. Do not discard. Heed all warnings. Only use attachments/accessories specified by the manufacturer.

Power Cord and Plug

WARNING
Power Supply Ensure that the mains source voltage (AC outlet) matches the voltage rating of the product. Failure to do so could result in damage to the product and possibly the user. Unplug the product before electrical storms occur and when unused for long periods of time to reduce the risk of electric shock or fire. External Connection Always use proper ready-made insulated mains cabling (power cord). Failure to do so could result in shock/death or fire. If in doubt, seek advice from a registered electrician. Do Not Remove Any Covers Within the product are areas where high voltages may present. To reduce the risk of electric shock do not remove any covers unless the AC mains power cord is removed. Covers should be removed by qualified service personnel only. No user serviceable parts inside.
Do not tamper with the power cord or plug. These are designed for your safety. Do not remove Ground connections! If the plug does not fit your AC outlet seek advice from a qualified electrician. Protect the power cord and plug from any physical stress to avoid risk of electric shock. Do not place heavy objects on the power cord. This could cause electric shock or fire.

Cleaning

When required, either blow off dust from the product or use a dry cloth. Do not use any solvents such as Benzol or Alcohol. For safety, keep product clean and free from dust.

Servicing

Refer all servicing to qualified service personnel only. Do not perform any servicing other than those instructions contained within the User's Manual.

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

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 Use the HPA6 as a Headphone Amplifier 5.2 Use the HPA6 as Independent Power Amplifiers 5.3 The HPA6 in Studio Application 5.4 The HPA6 in Mono/Stereo Application 6. TECHNICAL SPECIFICATIONS....11 7. WARRANTY.....12

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. In parallel with the Headphone Outputs on the rear panel, the Headphone Output on the front panel is also used to output the signal of the individual channel.

2. FEATURE LIST

Signal Rack Unit 6 individual channels Common input gain control, and individual output gain control Up to 3 headphone outputs per channel Direct In and Headphone Output on the front panel for easy operation, esp. used in the rack mounting application Input and Output Level Meter Balance Control to mix up the Main In and the Aux In signal Main Outputs for chaining further HPA6 headphone amplifiers Maximum audio quality even at high volume levels Exceptionally rugged construction ensures long life and durability Universal and professional headphone amplification system for studio and stage application Manufactured under QS9000 certified quality system

3. CONTROL ELEMENTS

INPUT LEVEL(dBu)

OUTPUT LEVEL(dBu)

12 CLIP

R MAIN IN AUX BALANCED

0 OUTPUT GAIN HEADPHONE OUT
1 MAIN IN AUX BALANCED AUX IN OUTPUT GAIN HEADPHONE OUT
1 AUX MAIN IN BALANCED AUX IN OUTPUT GAIN HEADPHONE OUT
1 AUX BALANCED AUX IN OUTPUT GAIN HEADPHONE OUT

DIRECT IN

AUX IN MONO

ON HEADPHONE

6-Channel

AMPLIFIER

STEREO
INPUT GAIN MAIN SECTION CHANNEL 1 CHANNEL 2 CHANNEL 3 CHANNEL 4 CHANNEL 5 CHANNEL 6

Excluding 1 knob control, 1 jack and 8 LEDs for the common main section, the LTO HPA6 6-Channel Headphone Amplifier also contains 3 Push-button switches, 2 knob controls, 2 phone jacks and 4 LEDs for each individual channel.

3.1 The Front Panel

4 MAIN IN AUX BALANCED AUX IN MONO 0 6
OUTPUT GAIN HEADPHONE OUT
INPUT GAIN MAIN SECTION CHANNEL 1
1. Direct In Input The Direct In Input is used to feed the external program sources into the main signal path, comparing to the Main Input on the rear panel, this input presents the priority character. 2. Input Gain Control This control sets the input signal level coming from Main In. 3. Input Level Meter This meter tells you the level of the main input signal coming from Main/Direct In, and the range goes 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 The Left input signal will be muted if this switch is activated. 6. R Mute Switch The Right input signal will be muted if this switch is activated. 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 In parallel with the Headphone Output on the rear panel, this 1/4" TRS phone jack is also used to output the signal of the individual channel. 10. Balanced Control This control is used to set the proportion between the signal coming from Aux In Input and Main/Direct In Input. 11. Output Gain Control This control is used to adjust the output level of the individual channel. 12. Output Level Meter This 4-digit meter tells you the level of the output signal, and the range goes from -24dBu to +12dBu. In case of the Clip LED lights up, please turn down the Input Gain Control or/and the individual Output Gain Control to avoid any distortion.

3.2 The Rear Panel

AC INPUT
95-120V 60Hz or 210-240V 50Hz Rated Power Consumption 40W

110-120V 220-240V

TIP: L- CHANNEL RING: R- CHANNEL MIN. LOAD 100OHMS TIP/PIN 2 RING/PIN 3 SLEEVE/PIN 1 TIP/PIN 2 RING/PIN 3 SLEEVE/PIN 1 TIP/PIN 2 RING/PIN 3 SLEEVE/PIN 1

NEW 1 TIDE

TIP/PIN 2 RING/PIN 3 SLEEVE/PIN 1

NEW 3 2

TIDE 1
210-240V: T315mAL 250VAC 95-120V: 500mA 250VAC REPLACE FUSE WITH CORRECT TYPE ONLY
Apparaten skall anslutas till jordat uttag nar den ansluts till ett natverk
HEADPHONE OUT 6 HEADPHONE OUT 5 HEADPHONE OUT 4 HEADPHONE OUT 3 HEADPHONE OUT 2 HEADPHONE OUT 1

MAIN OUTPUT RIGHT

MAIN OUTPUT LEFT

MAIN INPUT RIGHT

MAIN INPUT LEFT
13. Fuse holder / Voltage selector You must be sure of the Voltage available in your Country because this is a Dual Voltage Unit. Voltage operation can be changed through the fuse protecting the power supply but this operation must be performed by a qualified Engineer.

220-240V

THIS IS SET FOR 110V AC TO 120V AC OPERATION
THIS IS SET FOR 220V AC TO 240V AC OPERATION
Please note the triangular markers on both sides of the fuse holder ( See figure above), to change the voltage pull the fuse holder out, rotate it 180 and push it back again. The operating voltage will be that indicated by one of the two triangular markers. 14. AC Inlet After the correct voltage has been set you can connect the AC plug to the unit and in the AC power socket. 15. Main Input Connectors These connectors are used to input the stereo signal. You can input the main signal via the balanced 1/4" TRS phone jack or XLR connector. 16. Main Output Connectors These connectors are used to output the stereo signal. You can output the main signal via the balanced 1/4" TRS phone jack or XLR connector. In some typical field, you can also use these connectors to interlink several Headphone Amplifiers for more groups monitor. 17. Headphone Out1 In Parallel with the Headphone Out on the front panel (for CH 1), these are the headphone outputs of Channel 1. 18. Headphone Out2 In Parallel with the Headphone Out on the front panel (for CHl 2), these are the headphone outputs of Channel 2. 19. Headphone Out3 In Parallel with the Headphone Out on the front panel (for CH 3), these are the headphone outputs of Channel 3. 20. Headphone Out4 In Parallel with the Headphone Out on the front panel (for CH 4), these are the headphone outputs of Channel 4. 21. Headphone Out5 In Parallel with the Headphone Out on the front panel (for CH 5), these are the headphone outputs of Channel 5. 22. Headphone Out6 In Parallel with the Headphone Out on the front panel (for CH 6), these are the headphone outputs of Channel 6.

220-240V 110-120V

110-120V
4. INSTALLATION & CONNECTION 4.1 Mains Connection
This is a dual voltage unit. Please ensure that the LTO HPA6 6-Channel Headphone Amplifier is set to the correct supply voltage before plugging the power cord into the wall outlet, use the same fuse as marked on the fuse holder at the AC power connection socket. Do not insert power cord into the unit until voltage has been correctly set. Do not plug the power cord into AC power until voltage has been correctly set. The mains connection of the LTO HPA6 6-Channel Headphone Amplifier is made by using the enclosed mains cord and a standard IEC receptacle. It meets all of the international safety certification requirements.

4.2 Audio connection

The HPA6 6-Channel Headphone Amplifier presents with balanced XLR connectors and 1/4" TRS phone jack and it can be interfaced by several ways to support a variety of applications without any signal loss. a. Wiring Configuration Either the 1/4" TRS (Tip-Ring-Sleeve) phone jack or the XLR servo connector can be wired in balanced and unbalanced modes, which will be determined by the actual application status. Please wire your systems as the following examples: For 1/4" Phone jack

Tip Sleeve

TS Type Unbalanced

TRS Type Balanced

TRS Type Unbalanced

For XLR connector

Pin2 (+) Pin3 (-) (Linked to Pin1 manually, Pin1 ( ) Pin3 (-) ) Pin1 ( )

Pin2 (+)

XLR Type Unbalanced

XLR Type Balanced

b. In Line Connection For these applications, the HPA6 6-Channel Headphone Amplifier provides XLR connectors and 1/4" TRS phone jack to easily interface with most professional audio devices. Follow the configuration examples below for your particular connection.

Balanced

SLEEVE RING TIP

TIP RING SLEEVE

Tip Ring Sleeve 3 Tip Ring Sleeve

Tip Ring Sleeve 2 3

Unbalanced

Tip Ring Sleeve Tip

Sleeve

TIP SLEEVE

Cent r e Screen Tip Sleeve Tip Ring Sleeve Cent r e Screen Centre Screen 3

SLEEVE TIP

Sleeve Tip Ring

Sleeve Tip Sleeve

Tip Ring

Sleeve 3

4.3 Rack Mounting
The most secure mounting is on a universal rack shelf available from various rack manufactures or your music dealer. The HPA6 6-Channel Headphone Amplifier fits into one standard 19" rack unit of space. Please allow at least an additional 4" depth for the connectors on the rear panel. Be sure that there is enough air space around the unit for sufficient ventilation and please do not place the HPA6 6-Channel Headphone Amplifier on high temperature devices such as power amplifiers etc. to avoid overheating.

5. APPLICATION

This section introduces some typical applications of your LTO HPA6 6-Channel Headphone Amplifier. Please reserve your time to well understand the control elements ( see Chapter 3 ) and the following application examples, so as to be able to fully exploit the HPA6 6-Channel Headphone Amplifier.
5.1 Use the HPA6 as a Headphone Amplifier
This is the basic application for HPA6 6-Channel Headphone Amplifier. While using the HPA6 as a Headphone Amplifier, please apply the program source to Main / Direct In Inputs, and connect the headphone cable to one of the appropriate outputs. Ensure the Balanced Control adjusted to the complete counter-clockwise position, and turn up the Input Gain control. The Input Gain control is used to boost or attenuate the general volume of all the headphones, while the individual Output Gain controls are used to set the desired channel volume. Three headphones can be connected per channel each time, but, please be sure that the resulted connection impedance must over 100ohms, otherwise, the output amplified signal may sound a little offensive, in terms of long time fault condition usage, the headphone amplifiers will be finally damaged or distorted. If you still need further headphone ports or more groups headphone amplifier, please interlink any number of HPA6 via the Main outputs. In parallel with the Headphone Output on the rear panel, the Headphone Output on the front panel is also used to output the signal of the individual channel, such function proves to be very useful esp. in the rack mounting application.

Headphone output2 Headphone output1

Headphone output4

Headphone output6

Headphone output3

Headphone output5
R MAIN IN AUX BALANCED AUX IN

5 MONO

Direct in program source
5.2 Use the HPA6 as Independent Power Amplifiers
Instead of using the HPA6 as the Headphone Amplifier, in many particular circumstances, it can also be conducted as the independent power amplifiers, as for this kind of application, please turn the Balanced Control to complete clockwise. By setting the Balanced Control to AUX position, the Main signal will then be muted, only the signals coming from Aux In Input can be routed to the headphone amplifiers circuit. So, now, you can apply up to six independent stereo program sources to the mixing console, and consequently, six different and individual monitor facilities for up to six musicians can be created.
Headphone output2 Headphone output1 Headphone output4 Headphone output61

AUX in 1

AUX in 2

AUX in 3

AUX in 4

AUX in 5

AUX in 6
5.3 The HPA6 in Studio Application
Generally, the Aux In Inputs are used to feed a further input signal, which can be mixed with the Main/Direct In signal via Balanced Control, so that, well understood this function, you can get the wonderwork in the studio field. Normal practice, if you want to record a vocal track which is intended to ride on an already existing background musical tracks, take it easy, just use the Main Input to feed the musical background signals, and input the Vocal signal through Aux In.
Background musical signals

Headphone Output 1

Main Input

5 MONO MONO

AUX In 1 Vocal signal
5.4 The HPA6 in Mono / Stereo Application
The HPA6 6-Channel Headphone Amplifier can be switched between the Mono and Stereo operational mode via Mode Switch control. Press the Mode Switch for Mono application, the Mono LED (8) lights up. In Mono application, the input two signals are combined together and the resulting mono signal routes to both the Left and Right Headphone Out Outputs.
6. TECHNICAL SPECIFICATIONS
AUDIO INPUT MAIN input Connectors Type Impedance Max.input level CMRR AUX IN and DIRECT IN input Connectors Type Impedance Max.input level CMRR AUDIO OUTPUT Connectors Type Impedance Max. output level SYSTEM SPECIFICATIONS Frequency response S/N THD POWER AMPLIFIER Max.output power Min.output impedance Max.gain FUNCTION CONTROLS Input level Balanced per channel Output level per channel FUNCTION SWITCHES Left mute Right mute Mode INDICATORS Input level Output level POWER SUPPLY Mains voltage USA/Canada U.K./Australia Europe Power consumption Fuse Main connection PHYSICAL Dimension Net weight 483(W) 217(D) 44(H)mm(19" 8.54" 1.7") 2.9kg(6.39lb) 40W 95-120V~: T500mA L/210-240V~: T315mA L Standard IEC receptacle 120V , 60Hz 240V~, 50Hz 230V~, 50Hz 8-digit LED display: -24/-18/-12/-6/0/+6/+12/ +18dBu 4-digit LED display: -24/0/+12dBu/CLIP mutes the left signal of the respective channel mutes the right signal of the respective channel switches channel to mono variable mix between aux and main signal variable +21dBm 100Ohms +20dB 10Hz to 50kHz,+/-3dB >90dB, unweighted, 22 Hz to 22kHz (>95dB @ +4dBu) 0.005% typ.@+4 dBu, 1kHz, Gain 1 XLR and 1/4" jack balanced /unbalanced dependent on the input impedance +21 dBu balanced and unbalanced XLR and 1/4" jack RF filtered, servo balanced input 50 kOhms balanced, 25 kOhms unbalanced +21 dBu balanced and unbalanced (unity gain) typ.40 dB, >55 dB @ 1kHz 1/4" TRS (tip=left, ring=right, sleeve=ground) unbalanced 25 kOhms unbalanced +21 dBu unbalanced (unity gain) typ,40 dB, >55 dB @ 1 kHz

7. WARRANTY

1. WARRANTY REGISTRATION CARD To obtain Warranty Service, the buyer should first fill out and return the enclosed Warranty Registration Card within 10 days of the Purchase Date. All the information presented in this Warranty Registration Card gives the manufacturer a better understanding of the sales status, so as to purport a more effective and efficient after-sales warranty service. Please fill out all the information carefully and genuinely, miswriting or absence of this card will void your warranty service. 2. RETURN NOTICE 2.1 In case of return for any warranty service, please make sure that the product is well packed in its original shipping carton, and it can protect your unit from any other extra damage. 2.2 Please provide a copy of your sales receipt or other proof of purchase with the returned machine, and give detail information about your return address and contact telephone number. 2.3 A brief description of the defect will be appreciated. 2.4 Please prepay all the costs involved in the return shipping, handling and insurance. 3. TERMS AND CONDITIONS 3.1
LTO warrants that this product will be free from any defects in materials and/or workmanship for a period of 1 year from the purchase date if you have completed the Warranty Registration Card in time.
3.2 The warranty service is only available to the original consumer, who purchased this product directly from the retail dealer, and it can not be transferred. 3.3 During the warranty service, LTO may repair or replace this product at its own option at no charge to you for parts or for labor in accordance with the right side of this limited warranty. 3.4 This warranty does not apply to the damages to this product that occurred as the following conditions: Instead of operating in accordance with the user's manual thoroughly, any abuse or misuse of this product. Normal tear and wear. The product has been altered or modified in any way. Damage which may have been caused either directly or indirectly by another product / force / etc. Abnormal service or repairing by anyone other than the qualified personnel or technician. And in such cases, all the expenses will be charged to the buyer. 3.5 In no event shall LTO be liable for any incidental or consequential damages. Some states do not allow the exclusion or limitation of incidental or consequential damages, so the above exclusion or limitation may not apply to you. 3.6 This warranty gives you the specific rights, and these rights are compatible with the state laws, you may also have other statutory rights that may vary from state to state.

SEIKAKU TECHNICAL GROUP LIMITED No. 1, Lane 17, Sec. 2, Han Shi West Road, Taichung 40151 Taiwan http://www.altoproaudio.com Tel: 886-4-22313737 email: alto@altoproaudio.com Fax: 886-4-22346757 All rights reserved to ALTO. All features and content might be changed without prior notice. Any photocopy, translation, or reproduction of part of this manual without written permission is forbidden. Copyright c 2005 SEIKAKU GROUP

NF 00893-2.3