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!
The loudness of your headphones will vary depending on their design and their input impedance. The output impedance of the HP4 is 51Ω (ohms), and it will work fine with professional and consumer headphones but the volume will differ depending on which type of headphone you use.
Headphones with lower input impedances will generally be louder than higher-impedance headphones. (In this case, louder does not mean better!) Most professional headphones have impedances between 150Ω and 600Ω. Consumer headphones for CD players and the like often have impedances between 8Ω and 32Ω.
Broadcast headphones are specialized, and you are unlikely to use them with an HP4; their impedances are typically between 1.5 kΩ (kilohms) and 2 kΩ.
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 adjust the overall headphone level, sum the stereo signals to mono, and mute the rear-panel Monitor outputs.
The Monitor Mute button mutes the main rear-panel outputs. This is handy when recording in front of a computer and studio monitors, especially when you don’t have a hardware mixer, because you can mute the signal going to the monitors rather than turn down the monitor level.
The headphone outputs remain active when the Monitor Mute button is engaged.
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.
- 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
- Compact 1/3U rack-mount chassis
- Sealed, detented, metal rotary controls
- External 16 VAC power supply