Building upon the success of the original, the SPL Phonos duo is a professional RIAA phono preamplifier with a pair of balanced and unbalanced stereo inputs and outputs. The Phonos duo is compatible with both moving magnet (MM) and moving coil (MC) cartridge systems.
The design utilizes SPL's 120V rail technology to ensure high headroom and crystal-clear performance, while the RIAA filter utilizes the legendary Douglas-Self design for outstanding phono sound.
MM & MC
Moving Magnet
- Moving magnet cartridges generate a voltage by moving a magnet between copper coils. In order to achieve the best possible linearity of the frequency and phase response, the capacitance is modified to adjust the cartridge.
- Phonos duo offers six different capacities for this adjustment: 12, 47, 100, 150, 220, and 330pF.
Moving Coil
- The moving coil cartridge is also a small electromagnetic generator. However, the magnets are firmly anchored, and the coils move between the magnets. This concept is exactly the opposite of the moving magnet cartridge. Consequently, it is not the capacitance, but the impedance that is the decisive parameter in matching the cartridge.
- Phonos duo offers six different impedances for this adjustment: 20, 50, 100, 220, 500 ohms, and 1 kilohms.
Balanced I/O
- Phonos duo offers two pairs of stereo inputs and outputs. A pair of balanced inputs and outputs with XLR connectors and a pair of unbalanced inputs and outputs with RCA connectors.
- The INPUT switch on the front of the Phonos duo can be used to switch between the two stereo inputs.
- The output signal is always present in parallel at both output, regardless of the selected input.
Connections
- Gold-plated RCA sockets are available for connecting the turntable and for outputting to a preamplifier such as the Director Mk2 or the Elector.
- A ground connection for the turntable is designed as banana plug socket. The ground lead can be either clamped or plugged in.
- Phonos duo also features a switch on the rear panel labeled GND LIFT. This ground-lift function can be used to eliminate ground loops by isolating the internal ground from the housing ground when the switch is pressed.
Panel Controls
Perfect Level
- The GAIN switch can be used to set the pre-amplification; in other words, the output level of the Phonos duo. There are three values to choose from:
- In the “Low” position, the amplification for MM systems is +30 dB and for MC systems +50 dB. This is ideal in combination with standard HiFi devices that operate with a reference level of -10 dBV. In switch position, “Med”, the amplification is increased by 10 dB (MM = +40 dB, MC = +60 dB).
- If the switch is in the “High” position, the gain is increased by a further 10 dB (MM = +50 dB, MC = +70 dB). This means that the output level is approximately as loud as that of modern DA converters at a reference level of 0 dBfs = 15 dBu.
Rumble
- The rumbling of the turntable‘s drive mechanism is amplified by the high amplification of the bass range due to RIAA equalization in playback. The Phonos duo offers a switchable subsonic filter to remove this rumble.
Mono
- The MONO switch can be used to select whether the stereo input signal should be output as a regular stereo signal or summed to mono (switch in the On position). This is useful, for example, when using a mono system to play mono records.
Mute
- The MUTE switch can be used to mute all outputs.
On
- The Phonos duo can be switched-on with the ON switch (switch is in the upper position).
Douglas Self Design
- The RIAA equalization of the Phonos was developed according to the recommendations of Douglas Self
- Idea: many small capacities instead of a few large capacities
- Advantages: the capacitors charge and discharge faster, which results in better resolution and faster impulse response
- Only audiophile Styroflex capacitors are used in the entire RIAA equalizer
- About the person: Douglas Self is a British electronics engineer with a strong penchant for audio. He holds honorary degrees from Cambridge University and teaches psychoacoustics at the University of Sussex
VOLTAiR Technology
- The 120V technology works with ±60V. To be able to handle such a high voltage, SPL has developed special proprietary operational amplifiers that can operate with a DC voltage of ±60V: the SPL 120V SUPRA operational amplifiers. This high voltage would destroy conventional components and operational amplifiers.
- The 120V technology achieves exceptional technical specifications and sonic benefits. Technically, in terms of dynamic range, signal-to-noise ratio and headroom. Sonically, in terms of richness of detail and an absolutely relaxed listening experience.
- SPL devices with VOLTAiR technology can handle input levels of +32.5 dBu thanks to the higher internal operating voltage of ±60 volts, thus offering 12 dB more headroom over ±15 audio devices. All components consequently operate continuously in the optimum operating range, resulting in a very pleasant, natural, and relaxed sound experience. So, you can enjoy your music in every detail.