SPL PHONITOR 3 + Exp. Rack

Phonitor Matrix Headphone Amplifier with Expansion Rack

• Headphone amplifier and analog monitor controller with SPL 120V (±60 V) technology, Expansion Rack included
• Expansion Rack for 19" rack mounting (2U), with a passive switch for four pairs of monitors
• Phonitor Matrix with Crossfeed, Angle, and Center Level for a stereo image in headphones similar to that of monitors
• Output power of 2 x 5 W into 250 Ω and 2 x 1 W into 32 Ω, source impedance of just 0.18 Ω
• THD+N of just 0.0003% and a dynamic range of 134.5 dB
• Three balanced XLR stereo inputs, VU meter, and 45 mm volume knob with ALPS RK27 potentiometer

The SPL Phonitor 3 with Expansion Rack is the rack-mount configuration of SPL’s headphone amplifier and monitor controller. The Phonitor 3, which combines 120V technology and Phonitor Matrix, comes with the Expansion Rack, which enables mounting in a standard 19" rack and includes a passive switch to control up to four pairs of speakers. It’s the ideal solution for mixing and mastering control rooms, post-production studios, and dubbing studios that want headphones and monitors under a single control system, with the unit neatly integrated alongside the rest of the outboard gear.

SPL Expansion Rack: 19" rack and four sets of monitors

The Expansion Rack houses the Phonitor 3 in a 19" x 2U enclosure and expands its connectivity. An integrated rotary switch routes the Phonitor 3’s stereo monitor output to four stereo XLR outputs: essentially adding three speaker outputs, allowing you to connect, for example, full-range, midfield, and nearfield monitors, and switch between them with a single gesture to check the mix on different systems.

Passive switching, with no electronics in the signal path

Switching is completely passive, with no active circuits in the signal path and no power supply. The signal reaching your monitors is the direct output from the Phonitor 3, with no additional stages that could alter its quality.

In a rack or on your desk

If you prefer to keep the Phonitor 3 on your desk with the switch within easy reach, you can remove the rack ears from the Expansion Rack and attach the Phonitor’s feet to the bottom of the rack. The Expansion Rack is also compatible with the Phonitor 3 DAC and SMC 7.1, which are mounted in the same way.

Phonitor Matrix: Mixing with Headphones Using the Monitor Perspective

With headphones, each ear hears only one channel, whereas with speakers, both ears receive sound from both speakers. The Phonitor Matrix recreates this natural crossfeed in analog form and restores accurate spatial perception. With three dedicated controls, you can tailor the soundstage to your needs: Crossfeed adjusts how much signal is sent to the opposite ear, Angle simulates the angle of the virtual speakers, and Center Level balances the level of sounds in the center. The result is panning, reverb, and level settings that translate accurately across any listening system.

SPL 120V Headphone Amplifier with 5 W per channel

SPL 120V technology operates at voltages of ±60 V and guarantees very wide headroom: maximum input and output levels of +32.5 dBu, a dynamic range of 134.5 dB, and THD+N of 0.0003%. The headphone output delivers 2 x 5 W into 250 Ω and 2 x 1 W into 32 Ω, with a source impedance of just 0.18 Ω: it drives both high-impedance studio headphones and less-efficient models with control and headroom, delivering precise bass and clean transients even at high volumes.

Linear power supply with shielded toroidal transformer

The internal linear power supply with a shielded toroidal transformer ensures stability and an interference-free noise floor—an essential requirement for critical listening during mixing and mastering.

Monitor controller for studio and mastering

Three balanced stereo XLR inputs allow you to connect multiple sources simultaneously—such as an audio interface, reference converter, and player—and switch between them in an instant. The monitor output, split by the Expansion Rack into four outputs, powers your active speakers or power amplifiers.

Controls for Mix Quality Assurance

L/R swap, independent phase inversion for each channel, and laterality control to correct the balance between left and right help you verify phase, balance, and stereo image consistency. The VU meters constantly display the input level, with selectable calibration to match your workflow standards.

45 mm volume knob with ALPS RK27

The 45 mm milled aluminum volume knob drives an ALPS RK27 “Big Blue” potentiometer, renowned for its precise channel tracking and smooth rotation.

Technical Specifications for the SPL Phonitor 3 with Expansion Rack

• Type: Headphone amplifier with monitor controller and Expansion Rack
• Analog technology: SPL 120V (±60 V)
• Inputs: 3 x balanced stereo XLR
• Headphone output: 6.35 mm (1/4") TRS jack
• Maximum input and output level: +32.5 dBu
• Input impedance (XLR): 20 kΩ
• Frequency response: 10 Hz – 100 kHz
• THD+N (headphone output, 1 kHz, 0 dBu): 0.0003%
• Dynamic range: 134.5 dB
• Output power: 2 x 5 W into 250 Ω, 2 x 1 W into 32 Ω
• Headphone output source impedance: 0.18 Ω
• Phonitor Matrix: Crossfeed, Angle, Center Level
• Controls: L/R swap, phase inversion per channel, lateralization
• VU meter with selectable calibration
• Volume knob: 45 mm, ALPS RK27 potentiometer
• Power supply: internal linear power supply with shielded toroidal transformer
• Mains voltage (selectable): 230 V AC / 115 V AC
• Power consumption: max 40 VA
• Phonitor 3 dimensions: 278 x 100 x 300 mm; weight 4.9 kg
• Expansion Rack: 1-to-4 passive switch, 1 x balanced stereo XLR input, 4 x balanced stereo XLR outputs
• Expansion Rack: 19" rack, 2U, removable rack ears
• Expansion Rack dimensions (W x H x D): 482 x 88 x 303 mm; weight 2.7 kg
• Expansion Rack Compatibility: Phonitor 3, Phonitor 3 DAC, SMC 7.1