Pro Co HJ4P 4-Channel Headphone Junction Box
The Pro Co HJ4P 4-Channel Headphone Junction Box is designed to provide trouble-free distribution and control of audio signals from stereo power amplifiers to up to four sets of headphones.
Pro Co HJ4P 4-Channel Headphone Junction Box Details
The Pro Co HJ4P 4-Channel Headphone Junction Box is designed to provide trouble-free distribution and control of audio signals from stereo power amplifiers to up to four sets of 150-600Ω stereo headphones (lower impedance phones may be used with some loss in power efficiency). The HJ4P is intended primarily for use in recording or broadcast studios to deliver cue or foldback mixes to groups of musicians or vocalists. It may also be used in sound reinforcement systems where headphones for hearing-impaired individuals are required.
The XLR-type input and loop- through connectors are compatible with most studio cue system outputs, and permit the HJ4P to be connected with standard low-impedance microphone cables. The loop-through function allows multiple HJ4Ps to be "?daisy-chained" if necessary. The STEREO/MONO and LEFT/RIGHT switches allow the HJ4P to be used to select either a stereo cue mix, or either of two monaural mixes. This is very useful in tracking sessions when, for example, the drummer may require a drastically different mix from the rest of the musicians. This feature could be used in bilingual sound reinforcement applications, with the speaker"?s voice on one channel and a translator"?s on the other. The LEFT VOL and RIGHT VOL controls allow stereo balancing to be individually tailored, and by switching to MONO and turning one VOL control to minimum a mix can be delivered to one ear only, leaving the other free for "?natural" listening.
The four 1/4" (6.3mm) headphone outputs are individually isolated with resistors to prevent the amplifier output from momentary short-circuits when plugging in or out, thus eliminating annoying pops from the cue system. Resistive isolation also prevents one defective set of headphones from affecting the levels of the others, or from completely "?shorting out" the system.
The HJ4P is ruggedly constructed of 16 gauge steel, painted with durable black semigloss epoxy paint, and has all controls and connectors clearly identified with white silkscreened labels. All components are of top-grade quality, including the sealed "?J"-style level controls and the miniature "?rocker" switches. The heavy base and non-skid feet prevent tip-over problems, and the enclosure design effectively recesses all controls and connectors to prevent accidental damage.
Pro Co HJ4P 4-Channel Headphone Junction Box Features
- For Studio Cue Systems or Sound Reinforcement
- XLR Input and Loop Out
- LEFT/RIGHT Switch Selects 1 of 2 Mono Mixes
- Mil-Spec Left and Right Volume Controls
- Resistive Isolation Protects Amplifier
- Heavy-Duty Steel Enclosure
Pro Co HJ4P 4-Channel Headphone Junction Box Controls
- AMP IN: Female 3-pin XLR-type connector accepts signals from unbalanced speaker-level sources (power amplifier outputs)
- LOOP OUT: Male 3-pin XLR-type connector for "?daisy-chain" connection of multiple HJ- 4P units using standard microphone cables.
- STEREO/MONO: Rocker switch selects stereo mode (left input drives left side of headphones, right input drives right side) or mono mode (one input drives both sides of phones).
- LEFT/RIGHT: Rocker switch selects which input drives both sides of phones when MONO mode is selected. (Has no effect in STEREO mode.)
Pro Co HJ4P 4-Channel Headphone Junction Box Specifications
- INPUT IMPEDANCE: > 6ohm (MONO mode, 4 sets of 8 ohm stereo headphones). > 30 ohm (MONO mode, 4 sets of 600 ohm stereo headphones).
- OUTPUT IMPEDANCE: Nominally 47 ohm
- POWER EFFICIENCY: Approximately 15% (8 ohm headphones). Approximately 93% (600 ohm headphones).
- ABSOLUTE MAXIMUM OUTPUT LEVEL
- Approximately 340 milliwatt (8 ohm headphones).
- Approximately 25.5 watt (600 ohm headphones).
- Outputs current-limited by 2.0 watt 47 ohm resistors to approximately 200 milliampere. Exceeding these limitations will cause destruction of these resistors and possible damage to the HJ4P.
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