Professional Fidelity Mastering Grade Listening

Welcome

Thank you for choosing the Phonitor x. The Phonitor x is the ultimate headphone amplifier, offering connections for headphones operated both balanced and unbalanced. With up to 3.7 W output power, it delivers impressive performance.

The Phonitor x is not just a headphone amplifier but also an excellent preamplifier capable of driving power amplifiers or active speakers.

VOLTAIR technology, also known as SPL 120V Rail Technology within the Professional Fidelity series, makes the Phonitor x an outstanding device in terms of dynamic range, signal-to-noise ratio, and headroom, delivering an exceptional sound experience with invincible serenity, transparency, and realness.

Front View

The front panel features the following controls and indicators:

• 1 Standby: Power on/off switch.
• 2 VU Meters: Display input levels.
• 3 Phonitor Matrix On/Off: Activates or deactivates the Phonitor Matrix.
• 4 Crossfeed: Adjusts the interaural level difference.
• 5 Angle: Adjusts the interaural time difference related to speaker placement.
• 6 Laterality: Compensates for perceived volume differences between channels.
• 7 Volume: Main volume control.
• 8 Analog Source: Selects between analog inputs (XLR/RCA).
• 9 Digital Source: Selects between digital inputs (USB, coaxial, optical).
• 10 Mode Switch: Selects between Stereo, Stereo with Laterality, and Mono modes.
• 11 Output/Mute Switch: Selects output (Loudspeakers/Headphones) or mutes the output.
• 12 Balanced Headphone: Balanced headphone output.
• 13 Standard Headphone: Standard headphone output.

The unit also features input selection knobs for SOURCE (USB, Optical, Coaxial, XLR, RCA) and a DIGITAL input selector.

Rear View

The rear panel includes:

• 13 Mains Switch: Power switch.
• 14 Mains Voltage: Input for power cord, with voltage selection (115V/230V).
• 15 Analog Audio Inputs: XLR and RCA inputs.
• 16 Digital Audio Inputs: USB, coaxial, and optical inputs.
• 17 IR PGM Volume: For IR remote control programming.
• 18 AMP CTL: Amplifier control connection for remote power on/off.
• 19 Audio Outputs: XLR and RCA line outputs.

The rear panel also shows fuse information, voltage selection instructions, DIP switch settings, and wiring details for XLR and RCA connections.

Bottom View

The bottom of the unit features DIP switches (20) for configuration.

VOLTAIR – 120V Rail Technology

VOLTAIR is SPL's 120V Rail Technology. Audio signals are processed with +/-60V DC, offering twice the voltage of discrete operational amplifiers and four times that of semiconductor operational amplifiers. This technology provides outstanding technical and sonic performance, characterized by superior dynamic range, headroom, and the reproduction of fine details for a relaxed, natural audio experience.

Comparisons

The Phonitor x's VOLTAIR technology is compared to other circuits, demonstrating its advantages in operating voltage and maximum audio level. Higher operating voltage positively impacts dynamic range, distortion limit, and signal-to-noise ratio.

dB scales represent exponential increases. A 3 dB increase corresponds to doubling acoustic power, +6 dB to doubling sound pressure level, and +10 dB to doubling perceived loudness. VOLTAIR technology offers performance twice that of common components in terms of maximum level and dynamic range, with values approximately 10 dB higher. THD measurements show a difference of over 3 dB compared to OPA134 at 36V, equating to over 50% improvement in sound pressure level.

Diagrams:

• Operating Voltage vs. Max. Audio Level: Bar charts show that SPL-OP@120V achieves a higher maximum audio level (141.4 dBu) compared to OPA 134@30V (124.2 dBu) and OPA 134@36V (129.1 dBu).
• Dynamic Range and THD&N: Bar charts compare dynamic range and THD&N values for different amplifier circuits. SPL-OP@120V shows a dynamic range of 33.2 dBu and THD&N of -114.2 dB, outperforming OPA 134@36V (22.5 dBu, -111.7 dB) and OPA 134@30V (21.5 dBu, -106 dB).

Phonitor Matrix

Basics of stereo listening

When listening to speakers, sound from the right is perceived by both ears, with a time delay, lower level, and reduced frequency range for the opposite ear. This is due to the speed of sound (approx. 340 m/s) and the physical obstruction of the head, which reflects and absorbs sound.

Our brain determines sound direction via time delay (interaural time difference) and level difference (interaural level difference).

Stereo listening with a "traditional" headphone preamplifier

Traditional headphone amplifiers often miss the delayed and quieter signal from the opposite side, creating an unnatural sound that stresses the brain. This can lead to an exaggerated stereo width, placing instruments outside their intended positions. The Phonitor Matrix corrects these unnatural effects.

How does the Phonitor Matrix work?

The Phonitor Matrix creates a speaker-like listening experience on headphones by calculating time and level differences with specific frequency responses. This allows the brain to correctly identify sound direction, placing instruments accurately within the stereo image, similar to studio mixing. It minimizes hearing fatigue compared to traditional headphone amplifiers.

Angle

The ANGLE switch adjusts the interaural time difference, simulating different speaker placements. Settings range from 20° to 55°.

Diagram: A diagram illustrates various speaker placements around a listener's head, with angles marked (20°, 30°, 40°, 55°).

Crossfeed

Crossfeed defines the interaural level difference, approximating the influences of room size, reflection, and absorption characteristics. Six crossfeed values are available.

Diagrams: Graphs show frequency-corrected level difference and time difference at max. Crossfeed and 30° Angle.

Interaural level and time differences are frequency-corrected due to the non-linear way the head reflects and absorbs sound.

Setting of Crossfeed and Angle

Both Crossfeed and Angle parameters define interaural level and time differences. To reproduce accurate speaker placement, first select the ANGLE parameter closest to your speaker setup, then choose the recommended CROSSFEED parameter (e.g., Angle: 30°, Crossfeed: 3).

Factors like loudspeaker type, room acoustics, and individual perception influence stereo listening. The Phonitor x offers six switch positions to fine-tune Crossfeed for optimal speaker playback matching.

Diagram: Images of the Angle and Crossfeed control knobs.

Table: Settings of Crossfeed and Angle

Adjustment of the Phonitor Matrix

Use the CROSSFEED switch (4) and ANGLE switch (5) to adjust headphone playback to match your room and loudspeaker setup.

1. Play familiar audio material and go to your usual listening spot.
2. Toggle between headphones and loudspeakers using the OUTPUT switch (11).
3. Set the ANGLE switch according to your loudspeaker placement (see page 14).
4. Set the CROSSFEED switch to the value that best matches your familiar speaker-listening sound.
5. Listen to instruments panned in the stereo field; they should appear in the same positions on headphones.

Diagrams: Images of the Mute/Output switch, Angle knob, and Crossfeed knob.

Matrix On/Off

The MATRIX switch (3) activates or deactivates the Phonitor Matrix. The matrix is available for headphone outputs only; Speaker Outputs (19) are not affected.

Source Selection

The Phonitor x functions as a preamplifier with up to five audio sources. It features two analog stereo inputs (XLR and RCA) and can be equipped with a DA converter for USB, coaxial, and optical digital inputs.

• Select analog sources (RCA or XLR) using the SOURCE switch (8).
• Select digital sources (USB, coaxial, optical) using the DIGITAL switch (9).

Signals at the analog RCA input are amplified from HiFi to studio level, equalizing levels when switching between XLR and RCA (if a studio signal is present at XLR).

Diagram: Illustrates analog (XLR, RCA) and digital (USB, Optical, Coaxial) source connections.

Output Selection

The OUTPUT switch (11) routes the input signal to loudspeakers or headphones. The Mute position silences outputs, illuminating the VU meters in red. The loudspeaker setting routes the signal to both analog audio outputs (RCA and XLR).

The standard headphone output (13) has priority over the balanced headphone output (12). No signal is sent to the balanced output if headphones are plugged into the standard output.

Warning: Never connect a mono jack cable to the standard headphone output (front panel stereo jack). Ensure the stereo jack is fully inserted to prevent short circuits that could damage the amplifier.

Icon: A mute icon ? is shown next to the OUTPUT switch description.

MODE Switch

The MODE switch (10) allows selection between Stereo, Stereo with Laterality control, and Mono modes. In Mono mode, stereo channels are summed, and each is reduced by 6 dB to maintain loudness.

Laterality

Laterality refers to sound perception deviation between ears. The Laterality control (6) compensates for perceived volume differences due to hearing impairments. Unlike conventional balance controls, it increases one channel while attenuating the other (e.g., +2.25 dB for left, -2.25 dB for right). This control offers finer adjustment than standard balance controls.

Diagram: A circular control labeled 'LATERALITY' with 'Left', 'Center', and 'Right' positions.

VU Meters

The VU meters (2) display input levels from -20 dB to +5 dB, with 0 dB corresponding to +4 dBu. Sensitivity can be lowered by 10 dB via DIP switches, allowing levels up to +15 dB input to be displayed.

The VU meters feature ballistics optimized for visual perception and time calibration compliant with BBC requirements. The rise time to 0 dB is approximately 300 ms.

Diagram: Two VU meters showing scale markings.

AMP CTL (Amplifier Control)

Connect the Phonitor x's AMP CTL (18) to an SPL Performer s800 using a 3.5 mm mono mini jack cable to switch both units in and out of standby simultaneously. The Phonitor x offers two outputs (A and B) for connecting two Performer s800 units in bridge mode or bi-wiring.

Setting DIP switch 6 to ON enables the Performer s800 to enter standby when the output selection is set to Headphone.

Diagram: Shows the AMP CTL connection for remote power on/off.

IR Remote Control

The volume potentiometer can be controlled remotely via infrared (IR). The Phonitor x learns your remote control; no special remote is needed. You can assign unused buttons on existing remotes (e.g., CD player remote) for Volume Up/Down.

Learning Process:

• Set the OUTPUT switch (11) to Mute. VU meters will light up red.
• Press the PGM IR VOLUME button (17) on the rear; the Power LED will brighten.
• Point the remote at the VU meters (2). Press the desired button for Volume Down. The Power LED flashes once per push. Press repeatedly until the LED flashes three times quickly to confirm programming.
• Repeat for Volume Up. The learn mode ends automatically after the second button is learned.

Icons: Mute ?, Output ?.

DIP Switches

The DIP switches (20) on the bottom of the unit configure various settings:

Level Increase of the Headphone Output

• DIP switch 1: ON = Headphone output boosted to +22 dB.
• DIP switch 2: ON = Headphone output boosted to +12 dB.
• DIP switches 1 & 2: ON = Headphone output boosted to +24 dB.

These settings help drive power-hungry headphones.

Attenuate the Sensitivity of the VU Meters

• DIP switch 3: ON = Attenuates VU meter sensitivity by 10 dB. 0 dB on the VU meter then represents +10 dBu, allowing display of levels up to +15 dB input.

Slave Thru

DIP switches 4 and 5 allow the chosen input to pass directly to the outputs:

• DIP switch 4: ON = Input passes directly to XLR output, unaffected by volume control (Slave Thru).
• DIP switch 5: ON = Input passes directly to RCA output, unaffected by volume control (Slave Thru).

Standby of Connected Performer s800 Power Amp When Set to Headphone

DIP switch 6: ON = Units connected via AMP CTL (Performer s800 power amp) switch into standby to save power when the output selection is set to Headphone ?.

Specifications

Inputs

XLR inputs

• Neutrik XLR, balanced, Pin 2 = (+)
• Impedance: ca. 20 kohms
• CMR: -82 dBu (at 1 kHz)
• Max. Input level: +32.5 dBu

RCA inputs

• Unbalanced
• Impedance: ca. 10 kohms
• Max. Input level: +32.5 dBu

Digital inputs (optional) / sample rates

• Coaxial SPDIF (RCA) - sample rates PCM (kHz): 44.1, 48, 88.2, 96, 176.4, 192
• Optical TOSLINK (F06) – sample rates PCM (kHz): 44.1, 48, 88.2, 96
• USB (B) – sample rates PCM (kHz): 44.1, 48, 88.2, 96, 176.4, 192

Outputs

Balanced headphone output

• Neutrik 4-pin XLR connector
• Pin wiring: 1 = L (+), 2 = L (-), 3 = R (+), 4 = R (-)
• Impedance: 0.36 ohms
• Damping factor: 180 @ 40 ohms
• Frequency range: 10 Hz to 300 kHz (-3 dB)
• Crosstalk at 1 kHz: -90 dB
• THD & N: 0.00091 % (at 0 dBu, 1 kHz, 100 kohms load)
• Noise (A-weighted): -98 dBu
• Dynamic range: 130.5 dB

Standard headphone output

Warning: Never connect a mono jack cable to the standard headphone output (front panel stereo jack). Ensure the stereo jack is fully inserted, otherwise a short circuit might damage the headphone amplifier!

• 6.35 mm TRS connector
• Pin wiring: Tip = Left, ring = right, sleeve = GND
• Impedance: 0.18 ohm
• Attenuation factor: 180 @ 40 ohms
• Frequency range: 10 Hz to 300 kHz (-3 dB)
• Crosstalk at 1 kHz: -90 dB
• THD & N: 0.00091% (at 0 dBu, 1 kHz, 100 kohms load)
• Noise (A-weighted): -103 dB
• Dynamic range: 135.5 dB

Max. Output power (at +30 dBu @ 1 kHz)

• 2 x 1 W at 600 Ohm impedance
• 2 x 2 W at 300 Ohm impedance
• 2x 3.7 W at 120 Ohm impedance
• 2x 2.9 W at 47 Ohm impedance
• 2x 2.7 W at 32 Ohm impedance

Line outputs

• Neutrik XLR, balanced, Pin 2 = (+)
• RCA, unbalanced
• Frequency range: 4 Hz to 300 kHz (-3 dB)
• Crosstalk at 1 kHz: -106 dB
• THD & N: 0.00085 % (at 0 dBu, 1 kHz, 100 kohms load)
• Noise (A-weighted): -103.8 dB
• Dynamic range: 136.3 dB

Internal operating voltages

• Analog: +/- 60 V
• Digital: + 5 V and + 3.3 V (optional)

Power supply

• Mains voltage (switchable): 230 V AC / 50 Hz or 115 V AC / 60 Hz
• Fuses: 230 V: T 500 mA; 115 V: T 1 A
• Power consumption: max 40 VA
• Stand-by power consumption: 0.7 W

Dimensions (incl. feet)

(WxHxD) 10.94 x 3.94 x 12.99 in (278 x 100 x 330 mm)

Weight

• 9.48 lbs (4.3 kg), unit only
• 11.90 lbs (5.4 kg), shipping

Important Notes

Version 1.0 – 04/2016

Developer: Bastian Neu

This manual describes the product but offers no guarantee for specific characteristics or successful results. Unless stated otherwise, all information corresponds to the technical status at the time of delivery by SPL electronics GmbH. Design and circuitry are under continuous development and improvement; technical specifications are subject to change.

© 2016 SPL electronics GmbH. This document is the property of SPL and may not be copied or reproduced in any manner, in part or fully, without prior authorization by SPL. Sound Performance Lab (SPL) continuously strives to improve its products and reserves the right to modify the product described in this manual at any time without prior notice. SPL and the SPL Logo are registered trademarks of SPL electronics GmbH. All company names and product names in this manual are the trademarks or registered trademarks of their respective companies.

Declaration of CE Conformity

CE The construction of this unit is in compliance with the standards and regulations of the European Community.