SPL HPm

500 Series Headphone Amplifier for Monitoring

SPL
SKU: 47817

500 Series Headphone Monitor Amplifier

  • 500 Series Headphone Amplifier, Dual-Slot Module
  • Two headphone outputs with independent volume control
  • Analog Phonitor Matrix with continuous Crossfeed, Angle, and Center Level
  • Class AB push-pull output stage with thermally coupled transistors
  • Stereo/Mono/Mute selector and phase reversal for listening to Mid and Side signals separately
  • Power supply with buffer circuit to drive even low-impedance headphones with ample headroom

The SPL HPm is a 500 Series headphone monitoring amplifier that combines two independent headphone outputs and the Phonitor Matrix—SPL’s analog technology that ensures headphone mixes sound accurate even when played back through speakers—into a dual-slot module. It’s the ideal solution for those who already have a 500 Series rack and want to add high-quality headphone monitoring for mixing, mastering, recording, or working in tandem with an artist.

Two Class AB headphone amplifiers in the 500 Series module

The output stage is a Class AB push-pull amplifier: the bipolar transistors divide the amplification of the positive and negative half-waves, achieving higher gain and a higher output voltage compared to a Class A circuit with a single transistor. The output transistors are thermally coupled and operate with exceptional consistency, resulting in a stable and consistent sound image.

Ample current reserve even with low-impedance headphones

The power supply incorporates a low-source-resistance buffer circuit, which ensures ample current reserve even with low-impedance headphones. The two outputs each have their own volume control, so you and another person can listen at the same time, each at your own volume level.

Phonitor Matrix: Headphone mixes optimized for speakers

Music is mixed with speaker playback in mind, where sound from the left speaker also reaches the right ear and vice versa. With headphones, these crosstalk signals are absent: the result is an unnaturally wide stereo image, with vocals and instruments placed in the wrong positions. The Phonitor Matrix corrects this representation using an analog circuit, so decisions made in headphones regarding panning, reverb, and levels translate correctly to any stereo system.

Crossfeed, Angle, and Center Level

Crossfeed, which is continuously adjustable, determines how much signal is routed from one channel to the opposite ear. Angle sets the spread angle of the virtual speakers to one of three positions—20°, 30°, and 40°—with 30° as the studio standard. Center Level attenuates the center of the stereo image by -0.5, -1, or -1.5 dB to ensure that the volume of central sources is also correct; the reference value is -1 dB. Listening becomes more natural and less tiring, even during long sessions.

Stereo/Mono/Mute and Mid/Side Listening

The signal can be switched between stereo and mono, while the Mute position silences the headphone outputs. Phase inversion rotates the left or right channel by 180°. By combining these two functions, you can listen to the Mid and Side signals separately: in Mono mode with phase inversion enabled, you hear only the Side signal; without phase inversion, you hear only the Mid signal. This control has become standard for many mixing and mastering engineers.

SPL HPm Technical Specifications

  • Type: Headphone amplifier with Phonitor Matrix
  • Format: 500 Series module, dual-slot
  • Input and output: balanced
  • Headphone outputs: 2 x 6.35 mm (1/4") TRS jacks, independent volume
  • Output stage: Class AB push-pull, thermally coupled transistors
  • Phonitor Matrix: Continuous crossfeed, Angle 20°/30°/40°, Center Level -0.5/-1/-1.5 dB
  • Controls: Stereo/Mono/Mute, L or R phase inversion
  • Maximum input and output level: 21 dBu
  • Input impedance: 10 kΩ
  • Output impedance: 150 Ω
  • Common-mode rejection: > 82 dB
  • Frequency response (-3 dB): 10 Hz – 100 kHz
  • THD+N (0 dBu, 10 Hz – 22 kHz): 0.03%
  • Noise (A-weighted): -92.3 dB
  • Dynamic range: 113 dB
  • Maximum headphone output level: +18 dBu (600 Ω), +15 dBu (300 Ω), +5 dBu (32 Ω)
  • Weight: 0.8 kg
  • Weight with packaging: 0.9 kg

€ 399,00 € 335,29 + VAT

  • Available on request
  • Clock icon Normally shipped in 10-15 working days
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