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HPA-4
2
4 CHANNEL HEADPHONE/AMPLIFIER/LINE DISTRIBUTOR
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With extensive switching functions, extreme efficiency, and unmatched sound quality, the ultra-versatile HPA-4 is a universal 4-channel
multi-purpose headphone amplifier/line distribution system—perfect for the most demanding professional stage and studio applications.
FEATURES
TABLE OF CONTENTS
Congratulations on your choice of headphone/amplifier/line distributor — you have purchased one of the finest stereo headphone/am-
plifier/line distributors on the market today. This unit was developed using the expertise of professional sound engineers and working
musicians. You will find that your new NADY AUDIO HPA-4 has superior performance and greater flexibility than any other headphone/
amplifier/line distributors in its price range. Please read this manual carefully to get the most out of your new unit.
Thanks for selecting NADY AUDIO as your choice in headphone/amplifier/line distributor.
• Four totally independent stereo high-power headphone ampli-
fier/line distribution channels in a convenient single rack pack-
age—an ingenious, easy-to-operate unit allowing a maximum
variety of both useful monitoring and stereo line level signal dis-
tribution options.
• Input Source Select switches and Phone and Line 1/4" TRS ste-
reo outputs on each channel, and 4 independent stereo input
sections (each with servo-balanced L & R 1/4"TRS jacks) en-
able independent selection of any of the 4 stereo signals for
each headphone amp/line distribution channel. This allows se-
lecting from up to 4 completely independent monitor signals for
each set of headphones connected to the HPA-4 for optimum
monitoring flexibility or 4 separate choices for each channel’s
Line Output for enabling many useful, simple audio switching/
routing solutions.
• Separate Volume control for each channel adjusts the level to
both Phone and parallel Line outputs
• Easily expandable for optimum versatility in any application—up
to four HPA-4’s can be daisy chained for additional fully select-
able headphone/line distribution requirements
• No-compromise circuit design, stringently selected tight-toler-
ance components and low-noise, extremely linear or amps for
reference-quality, transparent audio with maximum headroom
even at extremely high headphone volume levels
• High-quality, rugged construction for maximum reliability
• Shielded internal dual regulated power supply with
~115V(60Hz)/~230V(50Hz) select switch and fused IEC power
cord connector
FEATURES ................................................................................. 2
WARNING ................................................................................... 3
INSTALLATION .......................................................................... 4
FRONT & REAR PANEL CONNECTIONS ................................ 5
CONTROLS & INDICATORS ..................................................... 5
APPLICATIONS.......................................................................... 6
1. Using the HPA-4 as a headphone amplifier .......................... 6
2. Using the HPA-4 as a line distribution unit ............................ 6
3. Daisy chaining multiple HPA-4’s together for additional
headphone/line distribution requirements ............................. 6
SPECIFICATIONS ...................................................................... 6
NOTES ........................................................................................ 7