SPL AUDIO HPm The Headphone Monitoring Amplifier for 500 Series.
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Product Overview
Mastering-Grade Monitor Emulation for Your 500 Series Lunchbox
The SPL HPm addresses a fundamental flaw in headphone monitoring: the artificial, 180-degree stereo separation that places the left channel exclusively in the left ear and the right channel exclusively in the right ear. This "super-stereo" effect causes severe ear fatigue, skews panning decisions, and results in mixes that sound disjointed when played back on traditional loudspeakers.
The HPm solves this problem by bringing SPL’s revolutionary Phonitor Matrix to the 500 Series format. Hand-assembled in Germany, this single-slot module takes your stereo mix bus and applies intelligent, fully analog crosstalk and timing variables. This recreates the natural acoustic environment of an optimized studio control room, letting you mix, edit, and master on headphones with total confidence that your work will translate perfectly to any speaker system.
Product Description
The Proprietary Analog Phonitor Matrix:
Instead of using digital signal processing (DSP) or latency-inducing software plugins, the HPm utilizes a 100% analog passive filter network to emulate loudspeaker listening. When you listen to studio monitors, your left ear hears the left speaker first, and then the right speaker a fraction of a millisecond later at a slightly attenuated level and with a altered frequency response. The HPm mimics this natural acoustic phenomenon perfectly via hardware, correcting the unnatural stereo spread of headphones without altering the raw fidelity of your audio path.
Surgical Acoustic Stage Formatting Layout:
The streamlined front panel provides highly interactive controls designed to match your specific studio setup:
Crossfeed Control: A three-position switch that adjusts the amount of interaural level difference (crosstalk) between the channels. This simulates how much the sound from the opposite "virtual speaker" bleeds into each ear, depending on room size and speaker positioning.
Speaker Angle Switch: Offers three selectable angles (15°, 30°, and 45°) to simulate the physical toe-in placement of your monitors. Setting it to the standard 30° position establishes a perfect, textbook equilateral mixing triangle.
Center Level Compensation: When stereo signals are blended via crossfeed, the center image can sometimes experience a slight volume lift. The HPm automatically applies passive attenuation to the center channel to preserve a perfectly flat, linear volume balance.
Premium High-Current Dual Amplification and Mono Matrix:
The HPm features two independent headphone outputs on the front panel—one balanced 1/4" TRS jack and one balanced 3.5mm mini-jack—wired in parallel. Driven by a high-current, ultra-low distortion solid-state amplifier stage, it drives power-hungry, high-impedance studio headphones cleanly with massive dynamic headroom and tight low-end punch. Additionally, a dedicated Mono/Stereo switch lets you check phase relationships and center-image stability instantly, while a Mute switch kills the headphone outputs cleanly with zero pop noise.
Key Features
500 SERIES PHONITOR MODULE: Integrates SPL's legendary mastering-grade headphone amplifier matrix into a space-saving single-slot 500 series module.
ALL-ANALOG SPEAKER EMULATION: Uses passive hardware filters to replicate speaker-style crosstalk and localization, eliminating headphone ear fatigue.
3-STAGE CROSSFEED MATRIX: Selectable crossfeed levels let you adjust the virtual room ambiance and channel bleed to simulate different acoustic environments.
ADJUSTABLE SPEAKER ANGLES: Choose between 15°, 30°, or 45° speaker placements to mimic the physical layout of high-end control rooms.
HIGH-CURRENT HEADPHONE AMPS: Robust solid-state output stage drives high-impedance and low-impedance open/closed-back headphones with ease.
DUAL FRONT PARALLEL OUTPUTS: Outfitted with 1/4" (6.35mm) and 1/35" (3.5mm) balanced headphone jacks to accommodate any cable connector without adapters.
HARDWARE MONO & MUTE TOGGLES: Front-panel switches allow for immediate phase checks and safe, click-free audio muting.
PREMIUM GERMAN HARDWARE DESIGN: Handbuilt in Germany utilizing high-grade components, a 4mm aluminum faceplate, and solid-milled aluminum control knobs.
Technical Specifications
Feature
Specification
Device Type
Analog Headphone Monitoring Amplifier with Monitor Emulation Matrix
Form Factor
Single-Slot 500 Series Module Framework
Core Technology
Pure Analog Phonitor Matrix (Passive Level & Time-Delay Network)
Crossfeed Settings
3 Positions (Low, Medium, High Emulation Mapping)
Speaker Angle Parameters
3 Positions: 15° | 30° (Standard Equal) | 45°
Analog Audio Inputs
Fed directly via the 500 Series Rack Backplane Stereo Bus Slots
