HP4

Now Hear This!
Are you and your session players and bandmates tired of straining to hear underpowered headphones? We were too. That’s why Jim Odom and his jambalaya-fueled team of engineers designed 150 mW headphone amps for the HP4 headphone-distribution system.

These headphone amps are not just loud enough for session and stage use, they’re loud enough to explode the oysters in a Po’ Boy sandwich. Yet the sound is clear and clean, with a wide dynamic range. At last, everybody will be able to hear—assuming they are capable of hearing. Be careful with that level control!

Simplicity is the HP4’s hallmark. You get left and right line inputs, left and right line outputs with level control, and the four headphone outs. You can globally mute the headphone outs, adjust the overall headphone level, sum the stereo signals to mono, and mute the rear-panel Monitor outputs.

The HP4 can sit on a tabletop or can be screw-mounted to a standard rack tray (not included), where it requires just 1/3 rackspace. And if your needs grow, you can use the line outputs to feed the inputs of a second HP4 or an HP60. Chain as many headphone systems as you need.

So listen up! Quit struggling with mediocre headphone amps. Get the HP4 and hear everything loud and clear. You owe it to your music.

Features:

Input/Output

• 4 screaming-loud (150 mW per channel) stereo ¼” headphone outputs (front panel)
• 2 balanced ¼” line outputs (monitor outputs)
• 2 balanced ¼” line inputs

Meters, Controls, and Features

• Headphone level control for each channel
• Mono summing switch for each channel
• Monitor level control
• Monitor mute switch
• Daisy-chain multiple units via monitor outputs

Physical

• Compact 1/3U rack-mount chassis
• Sealed, detented, metal rotary controls
• External 16 VAC power supply

Inputs

• Connector Type ¼” TRS, balanced
• THD+N 0.0025%, 1 kHz, unity gain 
• Max Input Level +18 dBu, <0.5% thd+n,="" unity="">
• Input Impedance 10 kΩ
• Frequency Response 20 Hz - 20 kHz, ±0.5dB

Monitor Outputs

• Connector Type ¼” TRS, asymmetrical, impedance-balanced
• THD+N 0.0025%, 1 kHz, unity gain 
• Max Output Level +18 dBu, <0.5%>
• Output Impedance 51Ω
• Frequency Response 20 Hz - 20 kHz, ±0.5dB

Headphone Outputs

• Connector Type ¼” TRS, stereo
• Max Output Power 130 mW/Ch., <0.5% thd+n,="" 60ω="">
• Frequency Response 20 Hz - 20 kHz, ±0.5 dB, 60Ω load
• Headphone Impedance Working Range 32Ω - 600Ω

Power

• External Adapter Type +12 VDC, 1000 mA, center pin positive

Physical

• Dimensions 1/3U rack-mount (with standard rack tray, not included)
• Height 1.75” (44.45 mm)
• Depth 5.5" (139.7 mm)
• Width 5.5” (139.7 mm)
• Weight 5 lbs (2.27 kg)