Benchmark HPA4, LA4 Instruction Manual

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Benchmark HPA4

Instruction Manual

Reference Stereo Headphone Ampli f ier

and

Reference Line Amplifier

with

Relay Gain and Input Contr o l

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Safety Information

Fuses

CAUTION: FOR CONTINUED FIRE

HAZARD PROTECTION ALWAYS REPLACE THE FUSES WITH THE CORRECT SIZE AND TYPE (T 0.5A 250V 5 X 20 MM – LITTELFUSE® SLO-BLO EQUIVALENT). THE FUSE DRAWER INCLUDES TWO FUSES. ALWAYS REPLACE BOTH FUSES AT THE SAME TIME.

AC Input Voltage Range

NOTE: THE HPA4 IS EQUIPPED WITH A

UNIVERSAL POWER SUPPLY. THERE IS NO VOLTAGE SELECTION SWITCH. AC VOLTAGE RANGE IS 88-264 VAC, 50-60 HZ. THE PRODUCT MAY ALSO BE OPERATED FROM DC POWER OVER A VOLTAGE RANGE OF 125-373 VDC.

Power Cord

CAUTION: ALWAYS USE A GROUNDED

POWER CORD. THE PRODUCT IS EQUIPPED WITH A STANDARD IEC POWER ENTRY MODULE. USE AN IEC POWER CORD THAT IS EQUIPPED WITH THE APPROPRIATE CONNECTOR FOR YOUR LOCATION. CORDS ARE AVAILABLE FROM YOUR DEALER.

HXP218.500 OR

Modifications

CAUTION: DO NOT SUBSTITUTE PARTS

OR MAKE ANY MODIFICATIONS WITHOUT THE WRITTEN APPROVAL OF BENCHMARK MEDIA SYSTEMS, INC. MODIFICATION MAY CREATE SAFETY HAZARDS AND VO I D THE WARRANTY.

CAUTION: CHANGES OR MODIFICATIONS

NOT EXPRESSLY APPROVED BY BENCHMARK MEDIA SYSTEMS COULD VOID THE USER'S AUTHORITY TO OPERATE THE EQUIPMENT UNDER FCC REGULATIONS.

Repairs

CAUTION: DO NOT SERVICE OR REPAIR

THIS PRODUCT UNLESS PROPERLY QUALIFIED. ONLY A QUALIFIED TECHNICIAN SHOULD PERFORM REPAIRS.

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Contents

Safety Information 2

Fuses 2 AC Input Voltage Range 2 Power Cord 2 Modifications 2 Repairs 2

Front Panel 5 Rear Panel 5 Features 6 Quick Start Guide 7

Main Screen 7 Balance Controls 8 Screen Navig a t ion 9 Display Settings 10

Remote Control 11 Front Panel Controls 12 Connecting Other Audio Components 13

Use Balanced Interfaces When Possible 13 Balanc ed XLR Signal Levels 13 Selecting Components for Your System 13 Use the 12V Trigger Connections 13

Connecting Benchmark Components 14

Benchmark AHB2 Power Amp 14 Benchmark DAC 14

HPA4 System Overview 24

The Ultimate Headphone Amplifier 24 The Ultimate Line Amplifier 24 Relay-Controlled Gain Stages 24 Balance Controls 24 100% Analog Signal Path 24 Fully-Balanced Signal Paths 24 Differential Amplifiers 24 Powerful Headphone Output 25 Dual Headphone Outputs 25 Ultra-Wide Bandwidth 25 Rotary Encoder 25 Convenience Features 25 12V Trigger 26 Auto-On Function 26 Casework 26 Equipment Placement 26 Auto-Ranging Power Supply 26

Audio Line Inputs 27

Balanced XLR Interfaces 27 Unbalanced RCA Interfaces 27 Input Level Matching 27

Audio Line Outputs 27

Unity Gain at 0 dB 27

15.8 dB Offset Balanced vs. Unbalanced 27

Headphone Outputs 28

Driving Two Sets of Headphones 28 Standard 1/4" TRS Connector 28 High Performance XLR4 Connector 28

Basic Features 15

Input Selection 15 Volume Control 15 Balance Adjust 15 MUTE Function 15

-20 dB DIM Function 15

Advanced Features (Settings Screens) 16

Settings Menu Screens 16 DISPLAY Settings 17 INPUT SETUP 19 RENAME INPUT 19 VOLUME SETUP 19 SETTINGS LOCK 19 POWER Settings 20 REMOTE Settings 21 ABOUT Screens 22 SPLASH SCREEN 22 RESET Screens 23

THX-888 Amplifier 29

Headphone and Hearing Warnings 29 Soft-Start Circuit 29 Protection Circuits 29

Advanced Feature Details 30

PRESET Mode 30 Auto-On Function 30 Bi-directional 12V Trigger 30 Software Version Identification 31

Performance Graphs 32

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Specifications 50

THX-888 Headphone Outputs 50 Balanced Analog Outputs 50 Unbalanced Analog Outputs 51 Balanced Analog Inputs 51 Unbalanced Analog Inputs 51 Status Display 52 AC Power Requirements 52 Dimensions 52 Weight 52 Model Numbers 52

AC Power-Entry and Fuse Module 53 Regulatory Compliance 54

FCC Notice (U.S. Only) 54 RoHS Compliant Information 54 CE Certificate of Compliance 55

Warranty Inf o rmation 56

Benchmark 1-Year Warranty 56 Benchmark Ext en ded Warranty Options 57 Notes on Warranty Repairs 57

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Front Panel

Rear Panel

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Features

 THX-888 Headphone Amplifier with THX AAA™ Technology  Benchmark Line Amplifier  256-Step Fully-Balanced Relay Gain Contro l , 0.5 dB Steps  Precision Timed Relay Closures  Precision Metal Film Resistors  Gold-Contact Relays  Balanced and Unbalanced I/O  6 Watts into 16 Ohm Headphones  11.5 Vrms into 300 Ohm Headphones  0.1 Hz to 500 kHz frequency respon se  SNR > 135 dB  THD < 125 dB (0.00006%) under full load  Short-Circuit Protection on Headphone Amplifier  DC Protection on Headphone Amplifier  Over-Voltage Protection on Headphone Amplifier  Over-Current Protection on Headphone Amplifier  Thermal Protection on Headphone Amplifier  Full-Color 3.5" Capacitive Touch Screen  IR Remote Control (optional)  2 Balanced Stereo Line Inputs  2 Unbalanced Stereo Line Inputs  Balanced Stereo Line Output  Unbalanced Stereo Line Output  Balanced Mono Sum Output  12V Trigger I/O – two bi-directional 12V trigger ports  AUTO-ON Function - can be programmed to turn on when AC is applied  Power Switch – very low standby power , <0.5 W at 120 VAC  High-Efficiency Low-Noise Power Supplies – 100-240 VAC, 50-60 Hz  Meets FCC Class B and CE emissions requirements  Tested for immunity to radiated and conducted RF interference

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Quick Start Guide

Main Screen

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Balance Controls

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Screen Navigation

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Display Settings

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Remote Control

Turns the HPA4 on. Any devices

both).

OFF

Turns the unit off. A ny devices turn off in a controlled sequence.

VOLUME

Turns the volume up or down.

selected output group(s).

-20 dB

Toggles the -20 dB DIM function.

selected output group(s).

MUTE

Toggles the MUTE function.

selected output group(s).

INPUT

ARROWS

Scrolls through the enabled inputs on the HPA4.

Selects input D1 on DAC if connected.

Selects input D2 on DAC if connected.

Selects input D3 on DAC if connected.

Selects input D4 on DAC if connected.

USB

Selects USB input on DAC if connected.

Analog

Selects analog input(s) on DAC if connected.

The remote control is designed to control the HPA4 and any Benchmark D/A converter that supports remote control.

The bottom six input selection buttons select the DAC inputs if the DAC MODE is enabled (on the REMOTE setup screen).

The HPA4 inputs are controlled with the INPUT ARROWS.

slaved to the 12V TRIGGER will also turn on in a controlled sequence.

If the HPA4 is ON, this button toggles the OUTPUT GROUP SELECTION (headphone, line, or

slaved to the 12V TRIGGER will

The chart at the right summarizes the functions of the IR remote control.

ARROWS

DIM

Volume up cancels MUTE and DIM.

Volume will only be adjusted on

DIM will only be toggled on

MUTE will only be toggled on

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Front Panel Controls

POWER

Turns the unit on or of f.

remain on at all times) .

VOLUME

Adjusts the volume in 0.5 dB

both).

The front panel features a color touch screen, a power switch and a volume knob.

The volume knob includes a push switch that can be used to select which output group will be controlled by the knob rotation.

(button)

(knob)

Any devices slaved to the 12V TRIGGER will also turn on or

off in a controlled sequence.

If AUTO-ON is enabled, the

POWER button will toggle MUTE on and off (the unit will

steps.

The knob features an acceleration function. Rotate the knob quickly and the volume will change in larger steps.

Tip: The IR remote sensor is located just to

the right of the power switch. Keep this sensor unobstructed if you will be using the optional remote control.

Tip: When AUTO-ON is enabled, a switched

AC outlet can be used to turn your system on and off. The 12V TRIGGER I/O can be used as a trigger output to control the power state of additional components.

The chart at the right summarizes the functions of the power button and volume knob.

Volume up automatically cancels DIM and MUTE.

Volume will only be adjusted on selected output group(s).

Push the volume knob to select which output group(s) will be controlled (headphone, line, or

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Connecting Other Audio Components

Use Balanced Interfaces When Possible

When possible, use balanced interfaces to connect the primary devices in your system. Balanced interfaces offer significant performance advantages due to the diffe rential signals and higher voltage lev els. In most cases, balanced interfaces will reduce noise in your system.

Balanced XLR Signal Levels

The HPA4 Supports Professional Signal Levels

The XLR line inputs and ou t p ut s on the HPA4 support very hig h +28 dBu signal levels. These high levels are used in professional studio environments because of the high performance that comes with using higher voltages. All Benchmark products support professional signal levels. Benchmark DACs and power amplifiers wil l in t e rface to the HPA4 using peak signal levels between +22 dBu and +24 dBu.

When possible, select devices that have professional-level XLR interfaces. These will usually have better SNR specifications than devices with consumer-level XLR interfaces. This difference in SNR is often about 10 dB. Look for high signal levels when purchasing audio components and check the SNR specifications.

Use the 12V Trigger Connections

Trigger ports can be used to sequence the power-up and power-down operations so that all of your components turn on and off with a single switch. The trigger ports can also eliminate the loud pops that can occur when devices are turned on or off in the wrong sequence.

The trigger ports on the HPA4 are bidirectional and can be connected to inputs or outputs on other devices. All Benchmark trigger ports are bi-directional. Most other products will have dedicated trigger inputs or outputs.

If you want the HPA4 to control your system, connect the HPA4 trigger ports to the trigger inputs on the other dev i ces. When the HPA4 turns on, the other dev ices will follow.

The HPA4 Also Supports Consum er S ig n a l Levels

The stepped gain controls in the HPA4 have excellent noise performance and provide a wide dynamic range. This allows the simultaneous use of consumer-level and professional-level balanced interfaces. Professional XLR interfaces are usually 10 dB hotter than consumer-level XLR interfaces. The stepped gain control in the HPA4 can easily provide a 10 dB boost or cut without sacrificing performance.

If you want to use another device as a trigger master, connect its trigger output to one of the trigger ports on the HPA4. When this other device turns on or off, the HPA4 will follow.

In an all-Benchmark system, jus t connect the trigger ports in a star or daisy chain. The system can be turned on or off using the power switch on any Benchma rk device. This is one of the advantages provided by Benchmark's bi-directional trigger ports.

Selecting Components for Your System

Select devices with balanced XLR inputs and outputs. Balanced interfaces are vastly superior to unbalanced RCA interfaces.

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Connecting Benchmark Components

Benchmark AHB2 Power Amp

1. Set the SENSITIVITY switch on the

AHB2 to 22 dBu (switch in the down position).

2. Connect either trigger port on the

AHB2 to eith er trigger port on the HPA4. If you are using two AHB2

amplifiers in bridged mono, the second amplifier can be connected to an unused trigger port on the HPA4 or the other amplifier.

3. C onnect the left and right XLR outputs on the HPA4 to the left and right XLR inputs on the amplifier. If you are using two amplifiers in bridged mono mode, connect the cables to the MONO input on each amplifier.

4. If you are using a single AHB2, set the MODE switch on the back of the amplifier to STEREO. If you are using two AHB2 amplifiers, set the MODE on each to MONO.

Tip: If you turn the system on or off using

the HPA4 or the remote control, the amplifier s will follow. If you will be listening to headphones and you wish t o turn off the amplifiers, you can d o this: Just press the POWER buttons on each amplifier and they will turn off without turning off the HPA4.

Tip: If you want to shut down the entire

system using the POWER switch on an amplifier, you will need to press and hold the switch for 3 seconds.

can be used to turn the entire system on or off in a sequenced fashion.

3. Use XLR cables to connect the DAC to Input 1 on the HPA4. This input supports a special DAC compatibility mode.

4. If your DAC has a 'DAC-ONLY MODE', enable this mode. This will bypass the VOLUME, MUTE and DIM controls on the DAC.

5. If your DAC does not have a 'DACONLY MODE', set every input on the DAC to 'HT' mode, or 'CALIBRATED' mode. This will bypass the volume control on the DAC, but IR remote MUTE and DIM controls may still be active on some DAC models.

If you have a Benchmark DAC with remote control, the HPA4 has a special mode of operation that allows both devices to be controlled from a single remote. If your Benchmark DAC has remote control, follow this additional step:

6. Go to the REMOTE settings screen on the HPA4 and select 'BENCHMARK DAC ON XLR1'. The Benchmark IR remote control will now control both devices. The HPA4 will pro v id e volume control and switching between analog inputs. The DAC will provide switching between digital inputs.

Tip: Use the dedicated digital input select

buttons (USB, D1, D2, D3 and D4) to select digital inputs on the DAC. Use the INPUT scroll buttons on the remote to select analog inputs on the HPA4. Use the dedicated ANALOG button on the remote to sel ect the analog inputs on the DAC (if a ny).

Benchmark DAC

1. Set the XLR output attenuators in the DAC to 0 dB. You will need to open the cover on the DAC if these jumpers need to be changed.

2. If your DAC has a trigger port, connect it to either port on the HPA4. This trigger connection provides a control link so that the remote, DAC or HPA4

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Tip: We recommend using the direct analog

inputs on the HPA4 before using the analog inputs on the back of the DAC. The direct connections on the back of the HPA4 will provide better performance.

Tip: Use the VOLUME UP key on the remote

if you wish to release the MUTE and DIM on all devices.

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Basic Features

MUTE Function

Input Selection

Use the input selection arrows to scroll through the enabled inputs. These arrows are displayed on the HOME screen and are also available on the REMOTE.

Volume Control

The volume of the headphone and line output groups can be adjusted independently. The bar graphs show the current volume settings. The volume controls are enabled when the bar graph(s) are highlighted.

Select the OUTP UT G R OUP(S)

Press the volume knob or touch the bar graphs to select the OUTPUT GROUP that you would like to adjust (headphones, line or both). If you are using the remote, press the ON button to toggle between output groups.

The headphone output and line output groups have separate MUTE buttons on the touch screen. Each MUTE button is highlighted in red when the output group is muted.

When MUTE is toggled on, the audio is immediately muted. When MUTE is toggled off, the volume will fade back up to the original level.

The MUTE key on the remote will mute the selected output group(s).

Tip: Turn the VOLUME up to release MUTE

and return to the prior volume setting.

-20 dB DIM Function

The DIM function reduces the level of the selected output group(s) by 20 dB. When DIM is toggled on, the volume fades down by exactly 20 dB. When DIM is toggled off, the volume fades back up to the original lev e l.

Adjust the volume

Rotate the volume knob or use the remote control to adjust the volume of the selected output group(s).

Balance Adjust

Press the BAL button on the HOME screen to change the L/R balance of the headphone and/or line outputs. These are independently adjustable.

The volume bar graph will be displayed in yellow when DIM is on.

Tip: Turn the VOLUME up to release DIM

and return to the prior volume setting.

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Advanced Features (Settings Screens)

Press the gear icon on the HOME screen to access the advanced features.

If the advanced features have been locked, a locked gear icon will be displayed on the HOME screen. Press and hold the locked gear icon for 3 seconds to access the advanced features.

Settings 2

Settings Menu Screens

• Power (Auto-On, Trigger)

Settings 1

• Display Settings

• Input Setup

• Lock/Unlock Advanced Settings

• Remote (IR Enable, DAC Mode)

• About (System Information)

Settings 3

• Reset Advanced Settings

• Full Factory Reset

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DISPLAY Settings

Display Settings 1

• Maximum Screen Brightness

• Screen Brightness when Dimmed

DISPLAY Settings 2

• Screen Dim Timer

• 'WAKE ON VOLUME' Function

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DISPLAY Settings 3

• Display Sleep Timer (screen off)

• Menu Timer (return to home page)

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INPUT SETUP

VOLUME SETUP

• Rename Inputs

• Disable/Enable Inputs

• Volume Setup for Each Input

• Volume Preset - Enable/Disable

• Boost Adjust (input volume offset)

RENAME INPUT

• Input Name Edit

SETTINGS LOCK

• Lock/Unlock Advanced Settings

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POWER Settings

• Auto-On - Enable/Disable

• 12V Trigger Mode

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REMOTE Settings

• Enable IR Remote Control

• Integrate with Benchmark DAC

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ABOUT Screens

ABOUT THX

ABOUT

• Firmware Version (hardware drivers)

• Software Version (touch screen)

ABOUT BENCHMARK

• Benchmark Contact Information

• THX AAA™ Technology Information

SPLASH SCREEN

• Unit is Turning On or Off, Audio is Muted

• May be manually enabled from ABOUT screen (this does not mute the audio, touch the screen to exit).

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RESET Screens

FACTORY RESET

RESET SETTINGS

• Reset all Advanced Settings Except Input Names

• Reset all Advanced Settings Including Input Names

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HPA4 System Overview

The Ultimate Headphone Amplifier

Benchmark Media Systems, Inc. and THX, Ltd. have partnered to introduce the Benchmark HPA4 headphone/line amplifier featuring TH X Achromatic Audio Amplifier (AAA™) technology.

THX AAA™ reduces harmonic, intermodulation, and crossover distortion by 20 to 40 dB to guarantee a realistic and fatigue-free listening experience. It accomplishes this using a patented feedforward topology to null conventional distortion and noise mechanisms, resulting in the world's most linear amplifier. THX AAA™ allows the amplifier to reach its maximum output power and sound pressure level (SPL) without producing the distortion that normally accompanies increased output levels in traditional amplifiers.

Featuring the flagship THX-888 amplifier design, the revolutionary HPA4 headphone amplifier incorporates the same THX AAA™ technology that Benchmark uses in the AHB2 power amplifier. The HPA4 delivers sonic perfection. Hear the music without any contamination from electronic noise or distortion. The HPA4 delivers power, audio fidelity, speed and accuracy over an utterly silent background.

The Ultimate Line Amplifier

The THX-888 amplifier is driven by a Benchmark line amplifier that features relay gain control, relay input selection, and relay muting. It is designed to deliver the lowest possible distortion and noise over a wide range of volum e set tings. We believe that the HPA4 line amplifier is the fin est available at any price.

Relay-Controlled Gain Stages

The relay-controlled gain stages provide 256 volume steps in precise 0.5 dB increments. These gain stages feature the finest goldcontact relays available.

Relay closures are precisely timed to deliver silky-smooth volume changes. No other relaycontrolled gain stage offers this level of precision or performance.

The HPA4 includes 4 independent fullybalanced 256-step volume controls: two for the L&R headphone outputs, and two for the L&R line outputs. To make this all happen, the HPA4 includes a total of 64 precision relays.

Balance Controls

The line and headphone outputs feature independent balance controls that are adjustable in 0.5 dB steps.

100% Analog Signal Path

The HPA4 is 100% analog. It is designed to be driven from an external D/A converter or an external analog so urce. The HPA4 is designed to provide the ultimate analog signal path between inputs and outputs. The HPA4 eclipses the performance of typical high-end preamplifiers by achieving much lower noise and distortion.

Fully-Balanced Signal Paths

The internal signal paths are fully balanced. The inputs are routed to a balanced pair of precision differential amplifier s. These drive two sets of fully-balanced 256-step volume controls. The balanced outputs from the volume controls drive the headphone amplifier and line output drivers.

Differential Amplifiers

The HPA4 features precision differential amplifiers on all inputs. These reject common-mode noise, common-mode distortion and common-mode interference. This feature is especially important when using D/A converters that lack their own differential amplifiers.

Benchmark D/A converters include differential amplifiers, but many competing converters

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lack these stages which remove the commonmode distortion produced by D/A chips.

Powerful Headphone Output

The THX-888 amplifier in the HPA4 can cleanly deliver high power and current into low-impedance headphones. It can also deliver the high voltage required by very lowsensitivity headphones.

High Power

The HPA4 delivers 6 Watts into 16 Ohms. Best of all, there is no increase in THD when driving low-impedance h eadphones. The THX AAA™ technology keeps the output distortion free while driving very difficult low-impedance loads.

High Current

Low-impedance headphones may also require high current due to difficult phase a ngles presented by non-resistive driver loading. The HPA4 can provide peak currents exceeding

1.5 amps. This is more than enough current to drive difficult headphones with ease.

Ultra-Wide Bandwidth

The frequency response of the HPA4 extends from 0.1 Hz to 500 kHz. This extended range keeps the phase response extremely accurate over the entire audio band. The entire audio spectrum is delivered with the proper timing.

Bass is delivered with the correct timing relative to other frequencies. Most audio products deliver the bass slightly late. Bass that arrives late tends to mask highfrequency details. In contrast, bass that arrives with the correct timing will sound deep, full and well damped. For this reason, all Benchmark products feature low-frequency extension to 0.1 Hz.

The extreme 500 kHz high-frequency extension delivered virtually perfect timing at the high end of the audio spectrum. High frequencies are delivered with precise timing relative to low and mid frequencies. In addition, the left-right differential phase is virtually perfect at 20 kHz. These timing characteristics preserve the precise placement of voices within a well-defined 3D stereo image.

High Voltage

High-impedance headphones may not draw much power or much current, but they may demand high drive voltages. The HPA4 delivers 11.9 Vrms into 300-Ohm headphones. This is plenty of voltage to drive headphones with very low sen sitivities.

Dual Headphone Outputs

The HPA4 features a traditional 1/4" TRS headphone jack and a 4-pin XLR jack.

The 4-pin jack provides separate r eturns for the left and right channels. Each output channel is driven differentially relative to its return pin on the 4-pin jack.

We recommend using the 4-pin jack because the XLR connector provides lower contact resistance than the TRS connector.

Rotary Encoder

The volume control knob features a highquality optical encoder that is rated for he a vy use. An acceleration feature makes it easy to move through the 256 volume steps while maintaining 0.5 dB/step resolution. A press of the control knob toggles between headphone volume, line volume, or both.

Convenience Features

The HPA4 includes independent on-screen mute buttons for the headphone and line outputs. Both can also be muted with the volume knob or with the optional remote control.

The HPA4 includes an on-screen -20 dB dim button that fades the level down by 20dB. This function provides a temporary volume reduction and an easy return to the previous

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listening level. This control makes it easy to transition between a normal listenin g level and a background level. The DIM function is also accessible from the optional remote control.

Inputs may be renamed and unused inputs may be disabled. Input levels can be trimmed to provide input-to-input level matching.

Screen brightness is adjustable and timers can be set to dim or shut off the display. The setup screen can be locked to prevent access to advanced features.

12V Trigger

Equipment Placement

Locate the HPA4 where the side panels are exposed to air. These panels help dissipate heat and should not be obstructed.

The IR sensor for the remote control is located to the right of the power switch on the front panel. Make sure this is visible from your listening position.

The HPA4 does not emit strong magnetic fields and for this reason, it will not create interference with audio devices that are placed above or below the HPA4.

The HPA4 has two trigger ports. These can be connected to other audio components so that the entire audio syst em can turn on and off in a sequenced f as hio n. The HPA4 will pull the trigger I/O to 12 volts DC while the HPA4 is on. If the HPA4 is off and an external device pulls the trigger I/O to 12 volts, the HPA4 will turn on.

The trigger ports are bi-directional by default, but they can be configured as inputs or outputs.

Auto-On Function

The HPA4 can be programmed to automatically turn on when AC power is applied.

Casework

The HPA4 is available with a black or silver faceplate and is designed to match the Benchmark AHB2 power amplifier. It occupies the same footprint as the Benchmark DAC1, DAC2 and DAC3 converters. The case features a milled faceplate and milled sides. Top, bottom, and rear panels are made from thick aluminum and feature a brushed texture. The HPA4 is built to last and will be a fine addition to your listening space.

Please note that most power amplifiers emit strong magnetic fields. In most cases, the HPA4 should not be stacked directly above or below a power amplifier. Allow at least a few inches of space above or below a power amplifier. The magnetic fields produced by the power amplifier may interfere with the

HPA4. One exception is the Benchmark AHB2 power amplifier. The HPA4 can be

stacked directly above or below an AHB2 without any risk of m agnetic interference from the power amplifier.

The HPA4 can also be stacked directly above or below Benchmark DAC2 or DAC3 converters. The older DAC1 series converte rs emit stronger magnetic fields and should not be stacked directly above or below the HPA4.

Auto-Ranging Power Supply

The internal power supply automatically senses the AC line voltage. There are no settings or fuses to change for international operation. Select a grounded IEC power cord that matches the AC outlets in your country.

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Audio Line Inputs

The HPA4 features two stereo balanced XLR analog inputs and two stereo unbalanced RCA analog inputs.

Balanced XLR Interfaces

Balanced interfaces use higher signal levels and for this reason, they provide better signal to noise ratios. Balanced interfaces also provide immunity from ground loop induced hum and buzz. In general, balanced interfaces are vastly superior to unbalanced. Select products with balanced interfaces a nd avoid the use of unbalanced interfaces whenever possible.

Unbalanced RCA Interfaces

Given the widespread consumer use of unbalanced RCA inter connects, we have made every effort to extract the highest possible performance from these antiquated consumer audio interconnects.

The unbalanced RCA inputs on the HPA4 are connected to balanced receivers. These balanced receivers provide significant immunity to ground loop induced hum and buzz. This topology provides the RCA inputs with some of the advantages of fully-balanced interfaces. Nevertheless, unbalanced interfaces can never match the full performance of professional-grade balanced interfaces.

15.8 dB default boost doesn't work in your system, individual inputs can be trimmed by +/- 10 dB in 0.5 dB steps using the BOOST function. The boost value does not impact the audio performance. It is equivalent to automatically rotating the volume control when the input is changed. The boost value changes the way the vo lume is numerically displayed.

Tip: We recommend using professional-grade

balanced XLR interconnects that provide +24 dBu at 0 dBFS. Consumer-grade balanced XLR interconnects operate at levels that are about 10 dB lower (4 Vrms or +14.2 dBu at 0 dBFS). Consumer RCA interconnects operate at levels that are about 16 dB lower (2 Vrms or 8.2 dBu at 0 dBFS). High signal levels and diffe rential signal ing are essential in highresolution audio systems. RCA interconnects will limit system performance.

Audio Line Outputs

The HPA4 features a stereo pair of balanced XLR outputs and a stereo pair of unbalanced RCA outputs. It also includes a balanced mono sum output. The mono sum can be used to drive a powered subwoofer.

The balanced outputs are designed to operate at professional levels (+24 dBu at 0 dBFS).

The unbalanced outputs are designed to operate at consumer levels (2 Vrms at 0 dBFS).

If your D/A converter and/or power amplifier lack balanced interfaces, it is a good indication that these devices are not true high-resolution audio products. Look for professional-grade balanced interfaces that support 24 dBu signal levels.

Input Level Matching

By default, the unbalanced inputs on the HPA4 are automatically boosted by 15.8 dB so that they will match the level of the professional-grade balanced inputs. If the

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 27

Unity Gain at 0 dB

If the volume control is set to 0 dB, the XLR output levels will be identical to the XLR input levels feeding the system. Likewise, the RCA output levels will be identical to the RCA input levels feeding the system.

15.8 dB Offset Balanced vs. Unbalanced

Balanced outputs are 15.8 dB hotter than the unbalanced outputs. Balanced inputs are assumed to be 15.8 dB hotter than unbalanced.

Page 28

Headphone Outputs

The left-hand jack is

The right-hand jack is

channel.

the headphone plug. Gold plated plugs are highly recommended.

The traditional 1/4" TRS connector uses the sleeve as a common ground for the left and right channels. This connection carries twice the current carried by the other contacts. High contact resistance at the sleeve connection can cause distortion on both channels.

a traditional 1/4" TRS headphone jack. The L & R channels share a common return.

a 4-pin XLR headphone jack that features dedicated returns for each

Driving Two Sets of Headphones

The HPA4 has more than enough power and output current to drive two sets of headphones simultaneously. The two headphone jacks can be used simultaneously, but the two sets of headphones need to have simila r sensitivities. If the sensitivities are different, one set of headphones will play louder than the other.

The main purpose of the second connector is to provide a high-performance alternative to the traditional TRS phone jack.

Standard 1/4" TRS Connector

With many TRS plugs we have found that the tip connectio n is somewhat less reliable than the ring connection. This means that there is a higher chance of distortion being added to the left channel.

Tip: If the TRS plug is gold plated, clean and

in good condition, the TRS jack can match the performance of the XLR4. When conditions are less than ideal, the TRS contact resistance can be the largest source of distortion in the entire HPA4 headphone system.

High Performance XLR4 Connector

The 4-pin XLR connector provides dedicated pins for the left and right returns. There are no shared connections . In the HPA4, the left and right outputs are differentially driven relative to their respective returns.

The separate returns eliminate any interaction between the channels. More importantly, the XLR4 connector provides much lower contact resistance than the traditional 1/4" TRS connector.

The HPA4 included a traditional 1/4" tip-ringsleeve (TRS) headphone jack. This provides a convenient output that is compatible with most headphone cords. Slightly higher performance is available from the XLR4 connector.

In our tests we have found that the TRS contacts can occasionally produce more distortion than the entire HPA4 headphone amplifier. We have selected one of the highest quality TRS jacks available, but the performance of the TRS jack is highly dependent upon the quality and condition of

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 28

Our tests have shown that XLR jack and plug combinations provide very reliable electrical connections. No measurable distortion was produced by the XLR4 connector in any of our tests.

Tip: The Volume Control simultaneously

adjusts the level for both headphone jacks. If two listeners will be simultaneously using the headphone outputs, we recommend using headphones with identical or very similar voltage sens itivitie s.

Page 29

THX-888 Amplifier

Protection Circuits

The headphone outputs are driven by the flagship THX-888 amplifier. This headphone amplifier incorporates the same patented THX AAA™ technology that Benchmark uses in the AHB2 power amplifier. The HPA4 is designed to deliver power, audio fidelity, speed and accuracy over an utterly silent background.

THX AAA™ reduces harmonic, intermodulation, and crossover distortion by 20 to 40 dB to guarantee a realistic and fatigue-free listening experience. It accomplishes this using a patented feedforward topology to null conventional distortion and noise mechanisms. THX AAA™ allows the amplifier to reach its maximum output power and sound pressure level (SPL) without producing the distortion that normally accompanies increased output levels in traditional amplifiers.

Headphone and Hearing Warnings

CAUTION: The THX-888 headphone

amplifier in the HPA4 is cap able of d elivering peak-to-peak voltages of about 25 Volts. It is also capable of delivering 1.5 Amps. These levels are high enough to damage most headphones (and your ears). Use caution when adjusting playback levels.

CAUTION: Do not drive a set of headphones

while they are sitting on a desk or stand. It is easy to accidentally overdrive them. This is especially true when you have set the headphones aside while listening to speakers. Mute or unplug your headp hones when they are not in use!

The THX-888 headphone amplifier has several circuits that are intended to protect the amplifier from overloads and short circuits. Fault cond itions will disable a pair of output relays which wi ll disconnect the amplifier from the output jacks. The output relays are only energized when all conditions are normal.

Over Current Protection

If the output current exceeds 1.5 Amps on either output channel, the protection re lays will disconnect the amplifier from the output jacks. The connection will be restored after a few seconds. The protection cycle will repeat if necessary. This protection mode may engage if headphones are plugged into the 1/4" TRS jack while audio is playing. TRS plugs can cause a temporary short-circuit condition while the plug is being inserted.

Clip Detection

If the headphone amplifier is driven into clipping, the protection relays will disconne ct the amplifier from the output jacks. If clipping ceases, the connection will be restored after a few seconds.

DC Detection

If DC is detected on the output of the headphone amplifier, the protection relays will disconnect the amplifier from the o utput jacks. This protection circuit is intended to protect the headphones in the unlikely event of a catastrophic component failure.

Soft-Start Circuit

The THX-888 uses relays to mute the headphone output until the power supplies have reached normal voltages.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 29

Temperature Limiting

If the THX-888 is severely overloaded for a period of time, component temperatures may start to climb. If safe operating temperatures are exceeded, the protection relays will disconnect the amplifier from the output jacks. After the drivers have cooled, the connection will be restored. This cooling cycle may take several minutes.

Page 30

Advanced Feature Details

PRESET Mode

The 12V TRIGGER I/O can be connected to the trigger input or output ports on a D/A converter, power amplifier, or both.

The PRESET mode sets the output level to a fixed level. There are separate presets for the headphone and line outputs. Each input has two preset buttons. One for the headphone outputs and one for the line outputs. These can be set on the VOLUME SETUP screen which is accessed from the INPUT SETUP screen.

Auto-On Function

The HPA4 can be programmed to automatically turn on whenever AC power is applied. This function allows automation using switched AC outlets. When AUTO-ON is enabled, the HPA4 cannot be turned off without removing AC power.

The AUTO-ON function is programmed on the POWER screen.

If AUTO-ON is enabled, the power switch will mute all of the outputs, but will not turn the unit off. Likewise, the OFF button on the remote will mute all of the outputs.

Tip: Turn the VOLUME up to release MUTE

and return to the prior volume setting.

Bi-directional 12V Trigger

Benchmark has reinvented the 12 volt trigger by adding bi-directional signaling. The trigger connection on the HPA4 can be used as an input, an output, or both. It is compatible with any common 12 volt trigger input or output.

The HPA4 can send a 12 Volt DC trigger signal to start other components in the system, or it can wake up in response to an externally generated trigger signal.

The trigger modes can be set using the

POWER screen.

Auto Trigger Mode

By default, the trigger ports are set to AUTO TRIGGER mode. In this mode, the HPA4

automatically configures its trigger I/O ports as inputs (slave) or outputs (master) as needed. This mode is recommended for most applications. In AUTO TRIGGER mode, the HPA4 will always turn other devices on and off. It will also respond when other devices force the trigger line high or low.

Master Trigger Mode - (Output Only)

In MASTER TRIGGER mode, the HPA4 will ignore external inputs to the trigger ports. The HPA4 will force the trigger ports to 12 volts DC when the unit is ON, and will force the ports to 0 volts while the unit is turning

OFF.

Slave Trigger Mode - (Input Only)

In SLAVE TRIGGER mode, the HPA4 will not drive the trigger ports. The ports will be configured for input only. The HPA4 will turn on and off in response to the trigger signal supplied by other system devices.

Typical Trigger Applications

The 12V TRIGGER I/O can be used to turn other audio components on when the HPA4 turns on. The HPA4 can also turn on and off in response to other connected components. The Benchmark bi-directional 12V Trigger is compatible with virtually all trigger systems.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 30

Typical trigger applications:

• HPA4 → Amplifier

• HPA4 → Amplifier → Amplifier

• HPA4 → DAC → Amplifier

Page 31

Bi-Directional Trigger Applications

Benchmark products support bi-directional communications over the trigger bus. Any Benchmark product connected to the bus can turn the entire system on or off. Be cause of the bi-directional design, any power butto n on a Benchmark HPA4, AHB2, or DAC can be used to start or stop the system.

The Benchmark device that starts the system will become the trigger master. If the trigger master is turned off, all slave devices will follow. If a slave device is turned off, all other devices will stay on.

If the HPA4 is used to turn the system on, any connected AHB2 amplifiers will become slave devices and they can be turned off without shutting down the HPA4. This feature makes it easy to turn the AHB2 amplifier(s) off when listening to headphones.

Slave devices can force the entire trigger bus to shut down if the POWER button or OFF button is pressed and held for 3 seconds.

Tip: Press and hold the POWER button on

any Benchmark device for 3 seconds to force a shutdown of the entire trigger-connected system.

Trigger Specifications

The Benchmark 12V TRIGGER I/O has a wide operating range to allow interfacing with most other DC trigger systems. It should only be used with trigger inputs that are designed to tolerate 12 VDC.

• 12 VDC 200 mA current-limited output

• Input responds to 3.3 V logic and

higher

• Maximum input voltage = 30 VDC

• Maximum reverse input voltage = -0.3

VDC

• Input Impedance = 20 k Ohms

• 1/8" (3.5 mm) TRS jack

• Tip = 12 Volt Trigger I/O

• Ring = no connection

• Sleeve = chassis ground

Caution: The 12V TRIGGER I/O is not an

audio connection! This i s a 12V DC connection for synchronizing the on and off sequencing of an entire audio system.

Tip: The trigger ports can be connected with

2-conductor or 3-conductor 1/8" (3.5 mm) cables. The 3rd conductor is not used. Benchmark products are supplied with 3conductor cables, but any mix of 2 and 3 conductor cables can be used.

Software Version Identification

The software and firmware versions are displayed on the ABOUT screen. The software drives the touch screen and the firmware programs the Xilinx FPGA hardware control system. The FPGA controls the power supplies, trigger ports, rotary volume knob, remote control and relays. The FPGA has the speed and precision required to execute precise timing of the make-before-break relay closures in the stepped volume control.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 31

Page 32

Performance Graphs

Audi o Precision

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Attenuator_THDvsGain_P15toN15.at27

ColorSweep Trace

Line Style Thick

Data Axis

Comment

1 1 Cya n Solid 4 Anlr.Level B

Left G ain dB r A

1 2

Green Solid 4

Distortion.Ch.1 Harm Sum1 Ratio Right THD dB

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

d B

-14

+14

-12

-10

-8

-6

-4

-2

+10

+12

d B

-14

+14

-12 -10

-8 -6 -4

-2

-0 +2

+4 +6

+10

+12

dBr A

Graph 1 - Stepped Gain Control - THD vs. Gain (-15 dB to +15 dB)

The relay-controlled stepped gain controls are a key feature of the HPA4. The headphone and line outputs have fully-independent controls. These stepped gain controls are designed to provide volume control over a wide operating range without adding any significant noise or distortion.

This plot shows that the stepped gain control produces almost no measureable THD. Over a range of -15 dB to +15 dB, the THD is between -120 dB (0.0001%) and -140 dB (0.00001%) and is near the measurement limits of the AP2722 test system! This measurement includes the balanced input and output buffers. This is a virtually distortion-free signal path with gain control.

Notes:

• The cyan curve shows the gain and uses the left-hand (dBr A) scale to show the gain in dB. This scale is dB relative to the input level. The input level was 10 dBu throughout the test.

• The green curve shows the THD using a 1 kHz test tone. The THD is plotted in dB relative to the output level and uses the right-hand (dB) scale. The output level was adjusted from -5 dB to +25 dBu using the stepped attenuator.

• Balanced inputs to balanced outputs.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 32

Page 33

Graph 2 - Stepped Gain Control - Output Noise vs. Gain Setting

Audi o Precision

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Attenuator_SNR.at27

ColorSweep Trace Line Style

Thick Data Axis Comment Cursor1

Cursor2

1 Cya n Solid

4 Anlr. Level A

Left Gain -20.070 dBr A

+14.947 dBr A

2 Green Solid

4 Anlr.Am pl Right A-Weighted Output Noise

*-146.039 dBr *-133.045 dBr

-150

+10

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

-146.039

-133.045

d B

-150

+10

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

d B

-100

+10

-90

-80

-70

-60

-50

-40

-30

-20

-10

-20.07 +14.947

dBr A

dx=+35.017 dB

dy=-12.994 dB

The stepped gain control has a gain range of -112.5 to +15 dB in 0.5 dB steps. This plot shows the A-weighted output noise over a gain range of -100 dB to + 15 dB. The A-weighted output noise is plotted relative to the maximum balanced output level of 28 dBu. The signal to noise ratio at any gain setting is the difference between the two curves. At maximum gain, the SNR is 15 dB - (-133 db) = 148 dB. At a gain of -20 dB, the SNR is -20 dB - (-146 dB) = 126 dB. This test demonstrates the wide operating range of the fully-balanced low-impedance stepped gain controls.

Below a gain of -20 dB, the noise is determined by the thermal noise (Johnson noise) produced by the resistors in the stepped attenuator. Ea ch side of the balanced attenuator has an impedance of just 1210 Ohms. This means that the balanced output impedance of the attenuator is 2420 Ohms. This resistance determines the output noise of the balanced attenuators. At any gain less than -20 dB, the A-weighted noise floor of the stepped gain control in combination with the balanced output buffers is -146.5 dB relative to +28 dBu. In other words, the A-weighted output noise is -118.5 dBu. This is approximately equivalent to the thermal noise produced by a single 2.5 kOhm resistor. This shows that the active balanced output buffers d o not add any significant noise to the stepped gain control. The active output buffers are important because they provide low impedance drive to downstream devices (such as power amplifiers and the internal THX-888 headphone amplifier).

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 33

Page 34

Audi o Precision

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THDvsPowerl_BAL_IN_HPA_Out_16_Ohms.at27

ColorSweep Trace

Line Style Thick Data

Axis Comment

1 Green Solid

Distortion.Ch.1 Harm Sum1 Ratio Left

-130

-100

-128

-126

-124

-122

-120

-118

-116

-114

-112

-110

-108

-106

-104

-102

d B

6 500m

1.5 2 2.5 3 3.5

4.5 5

5.5

Graph 3 - THD vs. Output Power - Headphone Amplifier - 0 to 6 W into 16-Ohms

The THX-888 headphone amplifier is designed to drive heavy loads at high levels without an increase in THD. It is also virtually distortion-free at low signal levels and/or light loads.

This output power sweep shows that THD does not increase with output power. The THX-888 headphone amplifier stays extremely clean as the output power is swept from 60 mWatts to 6 Watts. Over this 100:1 range of power, the THD is virtually unchanged! The THD measures better than about -125 dB (0.000056%) over this wide range of output power into a 16-Ohm load. At the maximum rated output power or 6 Watts, THD measures about -127 dB (0.00004%).

This test demonstrates the effectiveness of the THX AAA™ technology in the THX-888 amplifier.

Notes:

• The scale on the left is dB THD relative to the output level.

• The test tone is 1 kHz. The test tone level was varied to sweep the output power from 0.06

Watts to 6 Watts.

• Balanced inputs to headphone outputs, volume control set at 0 dB.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 34

Page 35

Audi o Precision

07/16/18 12:27:53

THDvsFreq_BAL_IN_HPA_Out_16_Ohms_1Watt.at27

ColorSweep

Trace Line Style Thick

Data

Axis Comment

Source 2 Cursor1 Curs or2

1 2

Green Solid 4

Distortion.Ch.1 Harm Sum1 Ratio Left

L dB : 7.00000 =Swr.Ch. A Input -126.430 dB -120.588 dB

1 3

Green Solid 4 Distortion.Ch.1 Har m Sum1 Ratio

Right L % : 7.00000 =S wr .Ch. A Input

0.00005 % 0.00009 %

2 2 Red Solid

4 Distortion.Ch.1 Har m Sum1 Ratio Left

R dB : 8.00000 = S wr . Ch. A Input -125.405 dB - 121.412 dB

3 Red

Solid 4

Distortion.Ch.1 Harm Sum1 Ratio Right

R % : 8.00000 =Swr. Ch. A Input

*0.00005 % *0.00008 %

0.00004

0.001

0.00005

0.00006

0.00007

0.00008

0.00009

0.0001

0.0002

0.0003

0.0004

0.0005

0.0006

0.0007

0.0008

0.0009

0.00005

0.00008

-130

-100

-128

-126

-124

-122

-120

-118

-116

-114

-112

-110

-108

-106

-104

-102

20k 4k 6k 8k

10k

12k 14k

16k

18k

1.019k

10.01k

TTTT

dx=8.99100 kHz

dy=0.00003 %

Graph 4 - THD vs. Output Frequency - Headphone Amplifier - 20 Hz to 20 kHz Sweep

This frequency sweep shows that the THD remains extremely low when the frequency increases. The THX-888 headphone amplifier delivered this performance while driving a 16-Ohm load.

Notes:

• The scale on the left is dB THD relative to the output level.

• The output level is 1 Watt into 16-Ohms (4 Vrms, 14.3 dBu).

• The THD measurement bandwidth is 48 kHz.

• The test tone is swept from 20 Hz to 20 kHz.

• Balanced inputs to headphone outputs, volume control set at 0 dB.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 35

Page 36

Graph 5 - Frequenc y Respo nse - Line Amplifier

Audi o Precision

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Freq_Resp_Bal_Bal.at27

ColorSweep

Trace

Line Style Thick

Data Axis Comment

Cursor1 Cursor2

1 Red Solid

4 Anlr. Level A Left Line Out

*+0.003 dBr *+0.003 dBr

-3

-2.8

-2.6

-2.4

-2.2

-2

-1.8

-1.6

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

+0.2

+0.4

+0.6

+0.8

+0.003+0.003

200k

20 50

100

200

500

10k 20k 50k 100k

20.5k

dx=-20.480 kHz

dy=+0.000 dB

The -3 dB frequency response of the line amplifier extends from about 0.1 Hz to 500 kHz. This is well beyond the 10 Hz to 200 kHz range of our AP2722 measurement system. Over our 10 Hz to 200 kHz measurement range, the frequency response is perfectly flat.

The primary advantage of this wide frequency response is that it delivers a very precise phase response. Low bass is delivered with precise timing relative to the highest audible frequencies (and everything in between). Furthermore, the extreme bandwidth keeps the L/R differential phase nearly perfect. The result is an unrivaled stereo image with accurate placement of musical voices within a 3D sound stage.

Notes:

• The scale on the left (dBr A) is dB relative to the output level at 1 kHz. The test used a 0-dBu test tone. The small +/- 0.003 dB random variations shown are due to the measurement limitations of the AP2722.

• Balanced inputs to balanced line outputs, volume contro l set at 0 dB.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 36

Page 37

Audi o Precision

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Freq_Resp_Bal_HPA_300-Ohms.at27

ColorSweep Trace

Line Style Thick Data Axis

Comment Cursor1

Cursor2

1 1

Green Solid

4 Anlr.Level A

Left HP Out into 300 O hms

*-0.014 dBr *-0.850 dBr

-3

-2.8

-2.6

-2.4

-2.2

-2

-1.8

-1.6

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

+0.2

+0.4

+0.6

+0.8

-0.014

-0.85

200k 20

100 200 500 1k 2k 5k

10k

20k 50k

100k

20.5k

200k

dx=179.500 kHz

dy=-0.836 dB

Graph 6 - Frequenc y Respo nse - Headphone Amplifier - 300-Ohm Load

This plot is included to show that the frequency response of the headphone amplifier changes very little when the load impedance changes. The 16-Ohm re sponse (shown in Graph 7) is nearly identical to the 300-Ohm response shown in this graph.

Notes:

• The scale on the left (dBr A) is dB relative to the output level at 1 kHz. The test used a 0-dBu test tone.

• Balanced inputs to headphone outputs, volume control set at 0 dB.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 37

Page 38

Audi o Precision

07/16/18 11:55:30

Freq_Resp_Bal_HPA_16-Ohms.at27

ColorSweep Trace

Line Style Thick Data Axis

Comment Cursor1

Cursor2

1 1

Green Solid

4 Anlr.Level A

Left HP Out into 16 O hms

*-0.125 dBr *-1.453 dBr

-3

-2.8

-2.6

-2.4

-2.2

-2

-1.8

-1.6

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

+0.2

+0.4

+0.6

+0.8

-0.125

-1.453

200k 20

100 200 500 1k 2k 5k

10k

20k 50k

100k

20.5k

200k

dx=179.500 kHz

dy=-1.328 dB

Graph 7 - Frequenc y Respo nse - Headphone Amplifier - 16-Ohm L oad

The -3 dB frequency response of the headphone amplifier extends well beyond the 10 Hz to 200 kHz range of our AP2722 measurement system. The response is -0.125 dB at 20 kHz and -1.45 dB at 200 kHz when driving a heavy 16-Ohm load. Compare this to Graph 6 (frequency response into 300 Ohms). The difference in frequency response due to the heavy 16-Ohm loading is minimal. The difference due to loading is only 0.1 dB at 20 kHz and 0.6 dB at 200 kHz.

Notes:

• The scale on the left (dBr A) is dB relative to the output level at 1 kHz. The test used a 0-dBu test tone.

• Balanced inputs to headphone outputs, volume control set at 0 dB.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 38

Page 39

Graph 8 - Differential P hase - Line Amplifier

Audi o Precision

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Differential_Phase_Bal_Bal.at27

ColorSweep Trace Line Style Thick Data Axis Comment

1 1 Green Solid 4 Anlr.Phase!Delta Left

-1

-0.9

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

+0.1

+0.2

+0.3

+0.4

+0.5

+0.6

+0.7

+0.8

+0.9

d e g

10 200k

20 50 100

200 500

1k 2k 5k 10k 20k

50k

100k

This plot shows the differential phase between the left and right channels. The extended 0.1 Hz to 500 kHz frequency resp onse keeps the phase response of the two channels well matched over the audio band. This plot shows that the differential phase is virtually perfect! Notice that the scale is highly expanded (+/- 1 degree). The slight bumps in the curve are due to the measurement limits of the AP2722 test station. This L/R phase matching is much be tter than the L/R phase matching in the AP2722 test station. To make this measurement, we had to create a correction curve for the AP2722. The correction curve removes the phase errors produced by the test equipment, allowing measurement of the line amplifier.

Notes:

• The vertical scale is the phase difference between the left and right channels.

• Balanced inputs to balanced outputs, volume control set at 0 dB.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 39

Page 40

Graph 9 - Differential P hase - Headphone Amp lifier - 300-Ohm Load

Audi o Precision

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Differential_Phase_Bal_HP_300_Ohms.at27

ColorSweep

Trace

Line Style Thick

Data Axis Comment

1 1

Green Solid 4 Anlr.Phase!Delta Left

-1

-0.9

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

+0.1

+0.2

+0.3

+0.4

+0.5

+0.6

+0.7

+0.8

+0.9

d e g

200k

20 50

100

200

500

10k 20k 50k 100k

This plot shows the differential phase betwee n the le ft and right headphone channels. The extended frequency response keeps the phase response of the two channels well matched over the audio band. This plot shows that the differential phase is virtually perfect! At 200 kHz, the differential phase error is only about 0.1 degree.

Notes:

• The vertical scale is the phase difference between the left and right channels.

• Balanced inputs to headphone outputs, volume control set at 0 dB.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 40

Page 41

Audi o Precision

07/13/18 15:49:14

FFT_Idle_Unity_Gain_Bal_Bal.at27

ColorSweep

Trace Line Style

Thick Data Axis

Comment Source 2

2 Green

Solid 4 Fft.Ch.1 Ampl Left

Left Line O utput : 1.00000 =S wr .Ch. A Input

Green Solid 4 Fft.Ch.1 Ampl Right

: 1.00000 =S wr .Ch. A Input

2 Red Solid 4 Fft.Ch.1 Ampl Left Right Line Output

: 2.00000 =S wr .Ch. A Input

Red

Solid 4

Fft.Ch.1 Ampl Right

: 2.00000 =S wr .Ch. A Input

2 Yellow

Solid 4

Fft.Ch.1 Ampl Left Mono Line Out put

: 3.00000 =S wr .Ch. A Input

3 3

Yellow Solid 4

Fft.Ch.1 Ampl Right : 3. 00000 = S wr.Ch. A Input

-180

-170

-160

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

-190

-180

-170

-160

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

2.5k 47.5k 5k 7.5k 10k 12.5k 15k 17.5k 20k 22.5k 25k

27.5k

30k

32.5k

35k 37.5k 40k 42.5k 45k

Graph 10 - FFT Idle Channel Noise - Balanced In to Balanced Out

The HPA4 is an exceptionally quiet line amplifier. This allows it to be inserted between a Benchmark DAC3 and an AHB2 power amplifier without degrading the noise performance of the system. This same line stage is used in front of the THX-888 headphone amplifier. The line stage provides volume control without degrading the perform a nce of the headphone amplifier.

Notes:

• The scale on the left (dBr A) is dB relative to +28 dBu. This is the maximum input and output level supported by the HPA4 line stage.

• The scale on the right (dBr B) is dB relative to +22 dBu. This is the input level required to drive an external AHB2 power amplifier to full output power. It is also the level required to drive the internal THX-888 to full output power.

• Balanced inputs to balanced line outputs, volume control set at 0 dB.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 41

Page 42

Graph 11 - FFT Idle Channel Noise - Balanced In to Headphone Out

Audi o Precision

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FFT_Idle_Unity_Gain_Bal_HPA.at27

Color

Sweep

Trace Line Style Thick

Data Axis Comment

Source 2

1 2 Green Solid 4

Fft.Ch.1 Ampl Left Left HP Output : 7.00000 =S wr .Ch. A Input

3 Green

Solid 4

Fft.Ch.1 Ampl Right

: 7.00000 =S wr .Ch. A Input

2 2

Red Solid 4

Fft.Ch.1 Ampl Left Right HP Output

: 8.00000 =S wr .Ch. A Input

3 Red Solid

4 Fft.Ch.1 Ampl Right

: 8.00000 =S wr .Ch. A Input

-170

-160

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

-180

-170

-160

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

2.5k 47.5k 5k 7.5k

10k

12.5k 15k

17.5k 20k

22.5k 25k

27.5k

30k 32.5k

35k 37.5k 40k 42.5k 45k

This graph shows the noise performance of the HPA4 from the balanced inputs to the output of the THX-888 headphone amplifier. This extraordinary performance keeps noise at inaudible levels, even when using high-efficiency headphones.

Notes:

• The scale on the left (dBr A) is dB relative to +28 dBu. This is the maximum input and output level supported by the HPA4 line stage.

• Balanced inputs to headphone outputs, volume control set at 0 dB.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 42

Page 43

Audi o Precision

07/13/18 10:02:46

FFT_Idle_Unity_Gain_Bal_Bal_Low_Freq.at27

ColorSweep

Trace Line Style

Thick Data Axis

Comment Source 2

Cursor1 Cursor2

1 2

Green Solid

4 Fft.Ch.1 Ampl Left

Left Line O ut : 1.00000 =Swr. Ch. A Input

-150.645 dBr A -150.464 dBr A

Green Solid 4 Fft.Ch.1 Ampl Right

: 1.00000 =S wr .Ch. A Input *-144.645 dBr

*-144.464 dBr

2 2 Red Solid 4

Fft.Ch.1 Ampl Left Right Line Out : 2.00000 =Swr.Ch. A Input -149.889 dBr A

-149.685 dBr A

Red Solid

Fft.Ch.1 Ampl Right

: 2.00000 =S wr .Ch. A Input -143.889 dBr B -143.685 dBr B

2 Yellow Solid

4 Fft.Ch.1 Ampl

Left Mono Line Out

: 3.00000 =S wr .Ch. A Input -150.113 dBr A -150.050 dBr A

3 3 Yellow

Solid 4 Fft.Ch.1 Ampl Right

: 3.00000 =S wr .Ch. A Input -144.113 dBr B

-144.050 dBr B

-180

-170

-160

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

-144.645-144.464

-190

-180

-170

-160

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

20 400 40 60 80 100 120 140 160 180 200 220

240

260

280

300 320 340 360 380

180.196 300.02

dx=119.824 Hz

dy=+0.182 dB

Graph 12 - AC Line-Related Hum - Line Amplifier

This FFT plot shows that AC line-related hum is 150 dB below the maximum output level of +28 dBu (use the left-hand dBr A scale)! The AC line frequency was 60 Hz in this test.

This plot also shows that AC line-related hum is 144 dB below the maximum input level of the internal THX-888 and an externally connected AHB2 power amplifier. These levels are so low that they will not impact the system SNR through the internal THX-888 or an external AHB2.

Notes:

• The scale on the left (dBr A) is dB relative to +28 dBu. This is the maximum input and output level supported by the HPA4 line stage.

• Balanced inputs to balanced line outputs, volume control set at 0 dB.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 43

Page 44

Graph 13 - AC Line-Related Hum - Headphone Output

Audi o Precision

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FFT_Idle_Unity_Gain_Bal_HPA_Low_Freq.at27

Color

Sweep

Trace Line Style Thick

Data Axis Comment

Source 2 Cursor1

Cursor2

1 2 Green Solid

4 Fft.Ch.1 Ampl Left Left HP Output : 7.00000 =Swr. Ch. A I nput

*-157.763 dBr *-159.010 dBr

1 3

Green

Solid 4

Fft.Ch.1 Ampl Right

: 7.00000 =S wr .Ch. A Input -151.763 dBr B -153.010 dBr B

2 Red

Solid 4

Fft.Ch.1 Ampl Left Right HP Output

: 8.00000 =S wr .Ch. A Input -170.357 dBr A -171.347 dBr A

2 3

Red Solid 4

Fft.Ch.1 Ampl Right : 8. 00000 = S wr.Ch. A Input

-164.357 dBr B -165.347 dBr B

-170

-160

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

-180

-170

-160

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

-157.763

-159.01

20 400

80 100

120 140

160 180

200

220 240

260 280

300 320 340 360 380

180.196 300.02

dx=119.824 Hz

dy=-1.247 dB

7.00000

This FFT plot shows that AC line-related hum is at least 152 dB below the THX-888 headphone amplifier's maximum output level of +22 dBu (use the r ight-hand dBr B scale)!

Notes:

• The scale on the left (dBr A) is dB relative to +28 dBu. This is the maximum input and output level supported by the HPA4 line stage.

• Balanced inputs to headphone outputs, volume control set at 0 dB.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 44

Page 45

Graph 14 - FFT 1 kHz Tone at 22 dBu - Line Amplifier - Balanced to Balanced

Audi o Precision

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FFT_1kHz_Bal_Bal.at27

ColorSweep

Trace Line Style Thick Data Axi s

Comment

Source 2 Cursor1

Cursor2

Green

Solid 4

Fft.Ch.1 Ampl Left Left Line Out

: 1.00000 =S wr .Ch. A Input -124.094 dBr B

-146.609 dBr B

2 2

Red Solid 4

Fft.Ch.1 Ampl Left Right Line Out

: 2.00000 =S wr .Ch. A Input -126.729 dBr B

-141.285 dBr B

2 Yellow Solid 4

Fft.Ch.1 Ampl Left Mono Line Out

: 3.00000 =S wr .Ch. A Input *-128.219 dBr *-144.566 dBr

-190

-180

-170

-160

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

-128.219

-144.566

2k 32k

4k 6k 8k 10k

12k 14k

16k

18k 20k

22k

24k 26k

28k 30k

3.01493k

5.01822k

dx=2.00329 kHz

dy=-16.347 dB

This plot shows that the THD produced by the line amplifier is extremely low, even when delivering a very high 22 dBu output. The third harmonic measures better than -124 dB (0.00006%) on all balanced outputs! The 5th harmonic measures better than -141 dB (0.000009%) on all balanced outputs!

Notes:

• The scale on the left (dBr B) is dB relative to +22 dBu. This is the signal level required to drive an external AHB2 power amplifier to full output power. It is also the level required to drive the internal THX-888 to full output power. It is also the level of the test tone.

• Balanced inputs to balanced line outputs, volume control set at 0 dB.

• The 1 kHz fundamental has b een removed using a notch filter . This filter increases the

resolution of the AP2722 test system.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 45

Page 46

Audi o Precision

07/13/18 11:45:55

FFT_1kHz_Ubal_Ubal.at27

ColorSweep Trace Line Style

Thick Data Axis Comment Source 2

Cursor1 Cursor2

2 Green

Solid 4

Fft.Ch.1 Ampl Left L RCA Out

: 5.00000 =S wr .Ch. A Input *-119.172 dBr *-118.128 dBr

2 2

Red Solid 4

Fft.Ch.1 Ampl Left R RCA Out : 6.00000 =Swr.Ch. A Input

-118.981 dBr B -118.977 dBr B

-190

-180

-170

-160

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

-119.172

-118.128

32k

10k

12k

14k

16k

18k

20k

22k

24k

26k

28k

30k

2.01329k3.01493k

dx=1.00164 kHz

dy=+1.044 dB

Graph 15 - FFT 1 kHz Tone at 1.6 Vrms - Li ne Amplifier - Unbalanced to Unbalanced

This plot shows the performance of the unba lanced inputs and outputs. The input level is 1.6 Vrms which is the level required to produce 22 dBu on the balanced o utputs. This level was selected to match the operating point used in Graph 14.

If you compare Graph 6 (unbalanced) to Graph 5 (balanced) you can see that the unbalanced inputs and outputs perform very well in terms of THD. However, the SNR is slightly reduced due to the much lower signal levels used with unbalanced interconnects.

Notes:

• The scale on the left (dBr B) is dB relative to 1.6 Vrms. It is also the level of the test tone.

• Unbalanced inputs to unbalanced line outputs, volume control set at 0 dB.

• The 1 kHz fundamental has b een removed using a notch filter . This filter increases the

resolution of the AP2722 test system.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 46

Page 47

Audi o Precision

07/13/18 10:40:31

FFT_1kHz_Bal_HPA_16_Ohms.at27

ColorSweep Trace Line Style

Thick Data Axis Comment Source 2

Cursor1 Cursor2

2 Green

Solid 4

Fft.Ch.1 Ampl Left L HP Out into 16 O hms

: 7.00000 =S wr .Ch. A Input -130.396 dBr B -126.744 dBr B

2 2

Red Solid 4

Fft.Ch.1 Ampl Left R HP Out into 16 O hms : 8.00000 =S wr .Ch. A Input

*-127.591 dBr *-134.156 dBr

-190

-180

-170

-160

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

-127.591

-134.156

32k

10k

12k

14k

16k

18k

20k

22k

24k

26k

28k

30k

2.01329k3.01493k

dx=1.00164 kHz

dy=-6.565 dB

Graph 16 - FFT 1 kHz Tone at 22 dBu - Hea dphone Amplifier - 6 W into 16-Ohms

This plot shows that the THD produced by the THX-888 headphone amplifier is ex tremely low, even when delivering a very high 22 dBu output into a low-impedance 16-Ohms load. The output power is 6 Watts per channel. The 2nd harmonic measures better than -127.5 dB (0.00004%) under full rated load! The 3rd harmonic measures better than -126.5 dB (0.000005%)! This test demonstrates the effectiveness of the THX AAA™ with feed-forward error correction.

Notes:

• Balanced inputs to headphone outputs, volume control set at 0 dB.

• The 1 kHz fundamental has been removed using a notch filter. This filter increases the

resolution of the AP2722 test system.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 47

Page 48

Graph 17 - FFT 10 kHz Tone at 22 dBu - L i ne Amplifier

Audi o Precision

07/13/18 10:59:10

FFT_10kHz_Bal_Bal.at27

ColorSweep

Trace Line Style Thick Data Axi s

Comment

Source 2 Cursor1

Cursor2

Green

Solid 4

Fft.Ch.1 Ampl Left Left Line Out

: 1.00000 =S wr .Ch. A Input *-130.406 dBr

*-124.343 dBr

2 2

Red Solid 4

Fft.Ch.1 Ampl Left Right Line Out

: 2.00000 =S wr .Ch. A Input -124.132 dBr B

-125.049 dBr B

2 Yellow Solid 1

Fft.Ch.1 Ampl Left Mono Line Out

: 3.00000 =S wr .Ch. A Input -130.115 dBr B -124.568 dBr B

-190

-180

-170

-160

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

-130.406

-124.343

2k 32k

4k 6k 8k 10k

12k 14k

16k

18k 20k

22k

24k 26k

28k 30k

20.0429k 29.9967k

dx=9.95384 kHz

dy=+6.064 dB

This plot shows that the THD produced by the line amplifier is extre mely low, even when delivering a very high 22 dBu output. The 2nd and 3rd harmonics each measure better than -124 dB (0.00006%)! This test shows that THD does not increase when reprod ucing high frequencies.

Notes:

• Balanced inputs to balanced line outputs, volume control set at 0 dB.

• The 10 kHz fundamental has been removed using a notch filter. This filter increases the

resolution of the AP2722 test system.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 48

Page 49

Audi o Precision

07/13/18 11:03:28

FFT_10kHz_Bal_HPA_16_Ohms.at27

ColorSweep Trace Line Style

Thick Data Axis Comment Source 2

Cursor1 Cursor2

2 Green

Solid 4

Fft.Ch.1 Ampl Left L HP Out into 16 O hms

: 7.00000 =S wr .Ch. A Input *-131.738 dBr *-123.982 dBr

2 2

Red Solid 4

Fft.Ch.1 Ampl Left R HP Out into 16 O hms : 8.00000 =S wr .Ch. A Input

-125.997 dBr B -123.818 dBr B

-190

-180

-170

-160

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

-131.738

-123.982

32k

10k

12k

14k

16k

18k

20k

22k

24k

26k

28k

30k

20.0429k

29.9967k

dx=9.95384 kHz

dy=+7.755 dB

Graph 18 - FFT 10 kHz Tone at 22 dBu - Headphone Amplifier - 6 W into 16-Ohms

This plot shows that the THX-888 headphone amplifier stays extremely clean, even when delivering 6 Watts at 10 kHz! The output level is 22 dBu (9.8 Vrms). The load impedance is 16 Ohms. Under these extreme high slew rate conditions, the 2nd and 3rd harmonics measure better than about -124 dB (0.00006%) into a difficult 16-Ohm load! This test demonstrates the effectiveness of the THX AAA™ technology which includes feed-forward error correction.

Notes:

• Balanced inputs to headphone outputs, volume control set at 0 dB.

• The 10 kHz fundamental has been removed using a notch filter. This filter increases the

resolution of the AP2722 test system.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 49

Page 50

Specifications

THX-888 Headphone Outputs

Test conditions: 1 kHz test tone, Output Level = +21 dBu, Unity Gain (unless noted)

Number of Headphone Outputs

Output Connector - Differential Drive

Gold-Pin Neutrik™ XLR4 - female

Output Connector - Common Ground Return

1/4" Neutrik™ TRS Jack

SNR

135 dB, A-Weighted 131 dB, 20 Hz to 20 kHz

Output Noise

< 2.45 uV, 20 Hz to 20 kHz

Frequency Response

-0.006 dB at 10 Hz

-3 dB at 0.1 Hz and 500 kHz

Output Impedance

Near 0 Ohms

Maximum Output Power and Voltage

6 Watts into 16 Ohms, 9.8 Vrms

440 mW into 300 Ohms, 11.5 Vrms

Maximum Output Current (protection thres hold)

1.5 Amps

Crosstalk, XLR4 Output

-133 dB@1kHz, -115 dB@10kHz

THD, 16-Ohm Load

-125 dB, 0.00006%, 16-Ohm Load

THD+N, 20 kHz BW, 16-Ohm load

-115 dB, 0.00018%

Volume Control Range

Mute, -112 dB to +15 dB in 0.5 dB steps

Balance Control Range

+/- 6 dB in 0.5 dB steps

Balanced Analog Outputs

Test conditions: 1 kHz test tone, Output Level = +24 dBu, Unity Gain (unless noted)

Number of Balanced Analog Outputs

3 (left, right, mono sum)

Output Connectors

Gold-Pin Neutrik™ XLR - male

SNR

137 dB, A-Weighted 135 dB, 20 Hz to 20 kHz

Output Noise

< 2.1 uV, 20 Hz to 20 kHz

Frequency Response

-0.005 dB at 10 Hz

-3 dB at 0.1 Hz and 500 kHz

Output Impedance

60 Ohms

Maximum Output Level

+28 dBu, 19.5 Vrms

THD

-126 dB, 0.00005%

THD+N, 20 kHz BW

-115 dB, 0.00018%

Volume Control Range (with 0 dBFS digita l in put)

Mute, -112 dB to +15 dB in 0.5 dB steps

Balance Control Range

+/- 6 dB in 0.5 dB steps

-0.014 dB at 20 kHz

2.6 Watts into 45 Ohms, 10.8 Vrms 640 mW into 200 Ohms, 11.3 Vrms

-0.001 dB at 20 kHz

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 50

Page 51

Unbalanced Analog Outputs

Test conditions: 1 kHz test tone, Input Level = 2 Vrms, Unity Gain (unless noted)

Number of Unbalanced Analog Outputs

2 (left, right)

Output Connectors

Gold RCA - female

SNR

116 dB, A-Weighted 108 dB, 20 Hz to 20 kHz

Output Noise

< 8 uV, 20 Hz to 20 kHz

Frequency Response

-0.008 dB at 10 Hz

-0.005 dB at 20 kHz

-3 dB at 0.1 Hz and 500 kHz

Output Impedance

30 Ohms

Maximum Output Level

+12.2 dBu, 3.2 Vrms

Volume Control Range (with 0 dBFS digita l in put)

Mute, -112 dB to +15 dB in 0.5 dB steps

Balance Control Range

+/- 6 dB in 0.5 dB steps

Balanced Analog Inputs

Number of Unbalanced Analog Inputs

4 (2 stereo pairs)

Input Connectors

Gold-Pin Neutrik™ XLR - female

Input Impedance

>50 k Ohms

Maximum Input Level

+28 dBu, , 19.5 Vrms

Input Selection and M ut ing

Gold-Contact Relays

Input State when Power is Off

Inputs are Disconnected using Relays

Unbalanced Analog Inputs

Number of Unbalanced Analog Inputs

4 (2 stereo pairs)

Input Connectors

Gold RCA - female

Input Impedance

>50 k Ohms

Maximum Input Level

+12.2 dBu, 3.2 Vrms

Input Selection and M ut ing

Gold-Contact Relays

Input State when Power is Off

Inputs are Disconnected using Relays

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 51

Page 52

AC Power Requirements

Nominal Operating Range

100 – 240 VAC, 50 - 60 Hz

Min/Max Operating range

90 – 260 VAC, 47 - 63 Hz

Power

< 0.5 Watts Standby 28 Watts Maximum

Fuses (2 required)

5x20 mm, 0.5 A 250 V Slo-Blo® Type

Dimensions

Form Factor

½ Rack Wide, 2 RU High

Depth - excluding knob and connectors

8.33” (220 mm)

Overall Depth - including knob and connectors

9.33” (237 mm)

Width

8.65” (220 mm)

Height - excluding feet

3.47" (88 mm)

Height - including feet

3.88” (99 mm)

Weight

HPA4 only

8 lb.

HPA4 with remote, power cord and manual

9 lb.

Shipp ing weight

12 lb.

Model Numbers

The HPA4 model number is 450-17200-XXX

XXX is a code for the chassis color

Status Display

Type

3.5" Color TFT with Capacitive Touch

Volume Indication - Headphone Output

Bar Graph and dB Gain

Volume Indication - Line Output

Bar Graph and dB Gain

MUTE Indicator

One for Headph on e, One for Line

-20 dB DIM Indicator

Common for Both Output Groups

Input Name

8-Character, User Programmable

Input Connector Display

Input Number, Connector Type

15 Watts Typical Program

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 52

Page 53

AC Power-Entry and Fuse

Fuses

Module

Input Voltage Range

Caution: For continued fire hazard

protection always replace the fuses with the correct size and type (T 0.5A 250V, 5 x 20 mm – Littelfuse® Slo-Blo HXP218.500 or equivalent). The fuse drawer includes two fuses. Always replace both fuses at the same time.

Note: The HPA4 is equipped with a universal

power supply. There is no voltage selection switch. AC voltage range is 100 to 240 VAC, 50 to 60 Hz.

Power Cord

Note: The AC power input uses a standard

IEC type connector. One USA-compatible power cord is included with the HPA4. IEC style power cords in country-specific configurations are available in your localit y.

Caution: Always use a grounded power

cord. The HPA4 is equipped with a standard IEC power entry module. Use an IEC power cord that is equippe d w ith the appropriate connector for your location. Cords are available from your dealer.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 53

Page 54

Regulatory Compliance

ercury (Hg), Hexavalent Chromium (Cr VI), and flame

FCC Notice (U.S. Only)

NOTICE: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:

• Reorient or relocate receiving antenna.

• Increase the separation between the equipment and receiver.

• Connect the equipment into an outlet on a circuit different from that to which the receiver is

connected.

• Consult the dealer or an experienced radio/TV technician for help.

This device complies with Part 15 of the FCC rules. Opera tion is subject to the following two conditions:

1. This device may not cause harmful interference.

2. This device must accept any interference received including interference that may cause undesired operation.

NOTICE: Changes or modifications not expressly approved by the party responsible for compliance could void the user's authority to operate the equipment.

RoHS Compliant Information

This statement clarifies Benchmark Media Systems, Inc. product compliance with the EU’s (European Union) directive 200 2/95/EC, or, RoHS (Restrictions of Hazardous Substances).

As of July 01, 2006, All Benchmark Media Systems, Inc. products placed on the European Union market are compliant (containing quantity limit weight less than or equal to 0.1% (1000 ppm) of any homogeneous Lead (Pb), M retardant Polybrominated Biphenyls (PBB) or Po lybrominated Diphenyl Ethers (PBDE)).

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 54

Page 55

CE Certificate of Compliance

Note: The HPA4 model number is 450-17200-XXX where XXX is a code for the chassis color.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 55

Page 56

Warranty Information

Benchmark 1-Year Warranty

The Benchmark 1-Year Warranty

Benchmark Media Systems, Inc. warrants its products to be free from defects in material and workmanship under normal use and service for a period of one year from the date of delivery.

This warranty extend s only to the original purchaser. This warranty does not apply to fuses, lamps, batteries, or any products or parts that have been subjected to misuse, neglect, accident, modification, or abnormal operating co nditions.

In the event of failure of a product under this warranty, Benchmark Media Systems, Inc. will repair, at no charge, the product returned to its factory. Benchmark Media Systems, Inc. may, at its option, replace the product in lieu of repair. If the failure has been caused by misuse, neglect, accident, or, abnormal operating conditions, repairs will be billed at the normal shop rate. In such cas es , an est imate will be submitted before work is started, if requested by the customer.

The foregoing warranty is in lieu of all other warranties, expressed or implied, including but not limited to any implied warranty of merchantability, fitness or adequacy for any particular purpose or use. Bench mark Media Systems, Inc. shall not be liable for any special, incidental, or consequential damages, and reserves the right to change this information without notice. This limited warranty gives the consumer-owner specific legal rights, and there may also be other rights that vary from state to state.

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 56

Page 57

Benchmark Extended Warranty Options

The Benchmark Extended 5-Year Warranty *

Benchmark Media Systems, Inc. optionally ex tends the standard 1-year warranty to a period of five years from the date of delivery.

*For the extended warranty to become effective, the original purchaser must register the product at the time of purchase either by way of the enclosed registration card or through the product registration section of the Benchmark Me dia Systems, Inc. website. This optional warranty applies only to products purchased within the US and Ca na da and is extended only to the original purchaser.

Attempts to deliberately deface, mutilate, or remove the product's label will render this warranty void. Benchmark will not honor warranties for any products dis ingenuously purchased on the US or Canadian markets for export. The terms of the extended warranty are subject to change without notice. For products purchased outside the US and Canada, please refer to the Extended Two 2-Year International Warranty.

The Benchmark Extended 2-Year International Warranty **

Benchmark Media Systems, Inc. optionally ex tends the standard 1-year warranty to a period of two years from the date of delivery.

**For the extended warranty to become effective, the original purchaser must register the product at the time of purchase either by way of the enclosed registration card or through the product registration section of the Benchmark Me dia Systems, Inc. website. This optional warranty applies only to products purchased outside the US and Canada and is extended only to the original purchaser.

Attempts to deliberately deface, mutilate, or remove the product's label will render this warranty void. Benchmark will not honor warranties for any products disingenuously purchased on the US or Canadian markets for export. The terms of the extended warranty are subject to change without notice. For products purchased in within the US and Canada, plea se refer to the Extended Five 5-Year Warranty.

Notes on Warranty Repairs

An RMA (return merchandise authorization) number, issued by our Customer Service Department, is required when sending products for repair.

They must be shipped to Benchmark Media Systems prepaid and prefe rably in their original shipping carton with the RMA number clearly visible o n the exterior of the packaging. A letter should be included giving full details of the difficulty.

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Benchmark Media Systems, Inc.

203 East Hampton Place, STE 2

Syracuse, NY 13206

USA

PHONE: +1-315-437-6300

FAX: +1-315-437-8119

benchmarkmedia.com

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 58