Mackie HM-400 Rack-Mountable, 4-Channel Headphone Amplifier
The Mackie HM-400 is a rack-mountable, 4-channel headphone amplifier designed to provide versatile headphone amplification for artists, musicians, and engineers monitoring through headphones in live stage applications and home, project, commercial, and mobile-recording studios. It features a stereo main output via XLR and 1/4" jacks and twelve 1/4" TRS stereo headphone outputs—three per channel—fed by a customizable blend of inputs.
One stereo main input via XLR and 1/4" jacks can be mixed with a per-channel 1/4" stereo aux input. Each channel offers 2-band EQ for quick tone shaping, stereo balance or main/aux input mix control, and output level adjustments. Also on each channel are switches for muting left and/or right signals and operating in stereo or mono. 7-segment LED meters display main input and per-channel output levels.
Features:
The HM-400 ships with an IEC power cable and occupies 1 RU in a standard 19" rack.
Distribute signal to up to twelve pairs of headphones
Occupies 1 RU
One stereo main input via XLR or 1/4" jacks
One 1/4" stereo aux input per channel
One stereo main output via XLR or 1/4" jacks
Three 1/4" headphone outputs—one on the front panel and two on the rear—per channel fed by an output level control
2-band EQ per channel for quick treble and bass adjustments
Per-channel Balance knob allows control of left/right level balance or aux/main input mix
Switches on each channel for L/R mute and St/2-Ch (stereo/mono) mode
7-segment LED metering for input and each output channel
Heavy-gauge steel chassis for rugged durability
Specifications:
Number of Channels: 4
Input Connections: 2 x XLR 3-pin balanced (one stereo pair)
2 x 1/4" TRS balanced (one stereo pair, also accepts 1/4" TS unbalanced)
1 x 1/4" TRS stereo unbalanced for main input
4 x 1/4" TRS stereo unbalanced for aux inputs
Output Connectors: 2 x XLR 3-pin balanced (one stereo pair)
2 x 1/4" TRS balanced (one stereo pair, also accepts 1/4" TS unbalanced)
12 x 1/4" TRS stereo unbalanced headphone outputs
Maximum Input Level: Main Input: +15 dBu
Aux Input: +20 dBu
Maximum Output Level: Headphone Outputs: 550 mW per channel at 47 Ohms (+21 dBu)
Input Impedance: Main Input: 20 kOhms balanced, 10 kOhms unbalanced
Aux Input: 10 kOhms unbalanced
Output Impedance: Headphone Outputs: 3 Ohms unbalanced
Gain Range: Main Input: -66 to +18 dBu
Function Controls: Power on/off
Main level knob
L/R mute switches per channel
Stereo/2-Ch switches per channel
2-band EQ per channel
Balance knob per channel
Output knob per channel
Frequency Response: 20 Hz to 20 kHz (±1 dB)
THD: <0.01% (+4 dBu, 1 kHz, unity gain)
Noise: -66 dB
CMRR: Main Input: >42 dB at 1 kHz
Display: 1 x input level meter
4 x output level meters
Power Requirement: 100 to 120 VAC, 50/60 Hz, 24 W
220 to 240 VAC, 50/60 Hz, 24 W
Power Connector: 1 x 3-pin IEC male, 250 VAC, 10 A
Construction Material: Heavy-gauge steel chassis
Dimensions (H x W x D): 1.8 x 19.0 x 8.8"
Weight: 8 lb
