Phonitor One

The audiophile headphone amplifier

with innovative Phonitor Matrix and outstanding sound quality.

Monitoring in highest sound quality.
Create perfect mixes on headphones – thanks to the Phonitor Matrix.

number one in sound

For us the sound is always in the foreground. When it sounds good, we like to listen. To get such a sound, you need experience and technical finesse. We have incorporated both into the Series One.

The design of the amplification stages

The preamplifier stage

Two Burr-Brown OPA 2134 SoundPlus™ operational amplifiers provide the pre-amplification. These are specially designed for audiophile circuits and are characterized by extremely low noise and minimal distortion of only 0.00008%.

Thanks to a true FET stage, the OPA 2134 achieves a slew rate of 20V/µs, making it a high-speed operational amplifier. This has an immediate positive effect on the liveliness of the playback.

In addition, low capacitance film capacitors are installed in the signal path as bypass capacitors of the coupling capacitors, which ensures a more precise transmission of the high-frequency signal components.
The excellent Panasonic ‘Electric Double Layer’ gold electrolytic capacitors are used as coupling capacitors. They offer the highest storage capacity of all capacitor technologies

The output stage

The output stage of the headphone amplifier is designed as a push-pull amplifier in class AB mode. The bipolar transistors share the amplification of the positive and negative half-waves, which produces a higher gain and a higher output voltage than in Class A operation, where only one transistor amplifies both half-waves.

The output stage transistors are thermally coupled and thus run particularly coherently, which contributes to a consistent and stable sound image.

The power supply has a buffer circuit with low source resistance, ensuring generous current reserves even when operating low-impedance headphones.  

The Revolution: Phonitor Matrix

The Phonitor Matrix is the revolution in the headphone amplifier.

It enables mixing and mastering engineers to create perfect mixes on headphones, which will translate perfectly to all types of stereo speaker systems.

With the Phonitor Matrix, you can create mixes on headphones that sound just like on speakers.

But the Phonitor Matrix is not only designed for professional use in the studio.
It also enables the hifi enthusiast to enjoy music on headphones, like if it was played back on speakers.

How is this possible?

Music is normally produced and mixed for playback on stereo speakers.

Listening on headphones is different from listening on loudspeakers. The biggest difference is the lack of crossing signals of the sound signal from the left speaker to the right ear and from the right speaker to the left ear.

These crossing signals are missing in conventional headphone listening, because there are no signals crossing from one side of the headphones to the other. This results in an unnaturally wide stereo stage and sound sources are not played back at their correct position in the stereo spectrum.

The SPL Phonitor Matrix can correct this false stereo image with an analog circuitry.

The Phonitor Matrix parameters

The two main parameters of the Phonitor Matrix are Crossfeed and Angle:

• Crossfeed determines the crossing signals of the channels.
• Angle determines the opening angle of the stereo image.

The “Crossfeed” parameter of the Phonitor One is continuously adjustable via the crossfeed control.
The “Angle” parameter is fixed at the studio standard of 30°.

To perfect the listening experience, the level of the sound sources centered in the stereo image must be attenuated when the Phonitor Matrix is activated. The result is that not only the position of all sound sources is correctly located, but also their volume. 

For the Phonitor One, this parameter, which we call “Center” for the Phonitor Matrix, is fixed at a -1 dB cut, which is the best choice for an authentic representation of the soundstage.

During conventional listening on headphones, our brain can compensate a certain level of false playback representation – but this is very exhausting and leads to listening fatigue.

Two line inputs

The Phonitor One offers two analog stereo inputs
(TRS and RCA).

Input devices with an analog output signal, such as CD players, mixers, synthesizers or an analog tape machine/tape deck, can be connected balanced (TRS jacks) or unbalanced (RCA) to the analog line inputs.

If a computer, tablet or smartphone is to be connected directly digitally, it is worth taking a look at the Phonitor One with USB input and state-of-the-art 32-bit DA converter.

Perfectly adjusted

At a regular listening volume, the volume control should be in the one o’clock position. This gives you an ideal control path for listening quieter and louder.

In order to obtain an optimal control range even with very powerful headphones, the output level of the headphone amplifier can be attenuated by activating the -10 dB DIP switch.

Power Supply

Good sound always starts with the power supply. This is where you lay the foundation for the performance of the entire device. Although we “only” supply a 12 V plug-in power supply unit, the secondary power supply inside generates a voltage level of +/-17 Volts for the analog audio sections with which professional levels of up to +22.5 dB can be achieved!

An elaborate low-drop operating voltage regulation provides more “juice” and regulates cleanly even when the maximum operation voltage is reached.

The Phonitor One delivers full power when used with the included 1.5 A power supply.

Just switch it on and enjoy the great sound. The ON-switch puts the Phonitor One into operation.

Number One in Sound

With the Series One – just as with all other SPL devices – we develop not only according to plan, but also by ear from the very beginning.

Many important components are installed on the circuit boards using Through-hole technology. This way we can ensure that we can use the best sounding components.

For audio professionals and discerning listeners alike, achieving the purest, most accurate headphone monitoring experience is essential. The SPL Audio Phonitor One headphone amplifier is designed precisely for those who demand uncompromising sound quality and precise control over their listening environment. Whether mixing, mastering, or simply enjoying music at home, this amplifier delivers a natural, spacious sound that replicates the experience of listening to speakers in a well-treated room, directly through your headphones.

One of the standout features of the Phonitor One is its innovative crossfeed control. Traditional headphone listening often suffers from an unnatural stereo image, where sounds can feel disjointed or overly isolated in each ear. The Phonitor One’s crossfeed circuit blends the left and right channels in a way that mimics speaker listening, reducing listener fatigue and providing a more realistic, comfortable audio experience. This means you can work longer and with greater accuracy, hearing details as they would be perceived in a professional studio environment.

In addition to crossfeed, the Phonitor One offers customizable speaker angle and center level controls for each channel. The speaker angle adjustment lets you simulate the typical positioning of studio monitors, fine-tuning how the soundstage is perceived. This helps in making better mixing decisions by accurately representing stereo width and instrument placement. The center level control enhances or reduces the signal in the center channel, which is invaluable for balancing vocals or lead instruments in your mix. Together, these features provide precise spatial control, allowing you to tailor the listening experience exactly to your needs.

Connectivity is straightforward and versatile. The Phonitor One supports two stereo analog inputs via 1/4″ TRS jacks and a dual RCA stereo input, ensuring compatibility with a wide range of audio sources such as audio interfaces, mixers, or even consumer devices. Its single stereo output via a 1/4″ TRS headphone jack supports most professional headphones, delivering up to 3.09 pounds of solid, desktop-grade construction that will stay firmly in place during use. The included 12 V DC power supply guarantees stable and clean power delivery, which is critical for maintaining audio fidelity without unwanted noise or distortion.

Weighing just over three pounds and built in a compact desktop form factor, the Phonitor One is both portable and robust enough to withstand daily professional use. Its intuitive controls are accessible and responsive, allowing for quick adjustments without interrupting your workflow. These practical details make it an excellent choice not only for studio professionals but also for audiophiles seeking a high-quality desktop headphone amplifier that enhances every detail of their music.

Use cases for the Phonitor One extend from critical listening environments such as mixing and mastering studios to high-end home setups. For mixing engineers, it provides a reliable tool to accurately assess stereo imaging and balance, ensuring mixes translate well across various playback systems. Audiophiles will appreciate the natural soundstage recreation and detailed, fatigue-free listening experience it offers. Its versatility and sonic precision make it an indispensable component for anyone serious about audio quality.

In summary, the SPL Audio Phonitor One headphone amplifier elevates headphone listening to a new standard of realism and comfort. With its sophisticated crossfeed technology, customizable spatial controls, and professional-grade build quality, it offers unmatched precision and usability. Priced at ₹57,740, it represents a worthwhile investment for those who demand critical listening accuracy and a natural, speaker-like headphone experience. Choose the Phonitor One and listen with confidence, knowing your sound is as true as it gets.