SPL Phonos DUO Phono Preamplifier

SPL Phonos DUO Phono PreamplifierPhonos duo The RIAA Phono Preamplifier Twice as nice The SPL phono preamplifier Phonos duo expands the established SPL phono preamplifier Phonos with a pair of balanced stereo inputs and outputs. Phonos duo is thus even more versatile. Whether moving magnet (MM) or moving coil (MC) cartridge systems the SPL VOLTAiR technology and the RIAA filter in the legendary Douglas Self design form the fundament for an outstanding phono sound. Great design a must

Phonos duo

The RIAA Phono Preamplifier – Twice as nice

The SPL phono preamplifier Phonos duo expands the established
SPL phono preamplifier Phonos with a pair of balanced stereo inputs and outputs.
Phonos duo is thus even more versatile.

Whether moving magnet (MM) or moving coil (MC) cartridge systems –
the SPL VOLTAiR technology and the RIAA filter in the legendary Douglas-Self design
form the fundament for an outstanding phono sound.

Great design – a must have

Visually, the SPL Phonos duo Phono Preamplifier fits perfectly into the SPL HiFi line
Professional Fidelity – and is of course available in the three basic colors black, red or silver.

MM & MC

There are two cartridge systems for turntables:

Moving Magnet (MM) and Moving Coil (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 pF, 47 pF, 100 pF, 150 pF, 220 pF und 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 ohms, 50 ohms, 100 ohms , 220 ohms, 500 ohms and 1 kohm.

MC or MM ?

Moving coil cartridge systems are commonly regarded as the more audiophile systems, as they allow a faster and therefore a finer cartridge due to their low mass. They bring out the finest nuances of the record. The output voltage of a moving coil cartridge system is extremely low at just a few hundred microvolts and is therefore more sensitive to noise and induced hum.

The very low output voltage makes preamplifier design a challenge, because it has to be pre-amplified extremely noise-free. With up to 70 dB preamplification, Phonos duo offers one of the most powerful phono preamplifiers for moving coil systems. Thanks to SPL 120V technology, Phonos duo amplifies extremely low-noise, linear and phase-locked.

Moving coil cartridges have a very low inductance and impedance.

This means that the effects of cable capacitance (from the cartridge to the preamplifier) are not that significant. The impedance, however, is the relevant parameter here and can be set in six positions on the Phonos duo. The manufacturers specify the impedances of the cartridges. These should be followed as closely as possible.

Moving magnet cartridges, on the other hand, are more rugged and often less expensive.
The greater mass of the moving magnets causes more inertia, which results in less precise reading
of the record. However, modern moving magnet systems also use neodymium magnets, which have
a significantly lower mass. Such moving magnet systems can also keep up with
some moving coil systems in terms of accuracy.

Capacitance plays a significant role with moving magnet cartridges.

This means that the effects of cable capacitance (from the cartridge to the preamplifier)
can‘t be ignored here. The capacity for moving magnet cartridges can therefore be set to six values
on the Phonos duo to be optimally adapted to the system.

Tip:
If there is any doubt as to which capacitance corresponds to that of the cartridge, simply switch through the capacitances on the Phonos duo. As long as the high frequency range increases, the capacitance is lower than that of the cartridge. If the high frequency range reduces again, the capacitance is higher than that of the cartridge.

Free choice – balanced or unbalanced

Phonos duo offers two pairs of stereo inputs and outputs.
A pair of balanced inputs and outputs with XLR inputs and outputs 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.

Perfect level

The GAIN switch can be used to set the pre-amplification, i 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 (see RIAA equalization). 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).

RIAA Equalization

RIAA equalization is a specification for the recording and playback of records proposed by the Recording Industry Association of America (RIAA).

The RIAA equalization curves introduced a global de facto industry standard for vinyl records in 1954.

RIAA equalization uses pre-emphasis to reduce low frequencies and boost high frequencies when the record is cut (blue RIAA curve).

The bass is reduced by up to 20 dB to provide more space and longer record play time.
The high frequencies are boosted by up to 25 dB to increase the signal-to-noise ratio between the noise of the record media to the audio signal.

During playback, exactly the opposite happens in the Phonos. The de-emphasis filter (red RIAA curve) compensates for the pre-emphasis and the result
is a linear frequency response.

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.

Sounds good

With all devices of the Professional Fidelity series we develop not only according to plan, but also by ear. 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.

The VOLTAiR Technology

The 120V technology is our reference technology. The 120V technology is unique in the world. It operates at a DC voltage of 120 volts. This is four times that of IC-based semiconductor op-amps. In our Professional Fidelity series, we refer to this unsurpassed technology as VOLTAiR technology.

The highest possible audio quality requires the highest possible audio operating voltage.

The 120V technology works with +/-60 V. To be able to handle such a high voltage, we have developed special proprietary operational amplifiers that can operate with a DC voltage of +/-60 V: 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.

By the way, the “120V” in the name of the technology has nothing to do with the local mains voltage from the mains power socket. This is about the operating voltage inside the device with which the audio signals are processed.

The mains voltage from the mains power socket is transformed to the required secondary voltage in the device’s internal linear power supply with toroidal transformer. Rectifiers convert this AC voltage into DC voltage required in the audio device.

Slimmer is smarter

Replacing fuses and voltage selection

The replacement of fuses and the switching of mains voltages must only be performed by qualified technicians. Fuses must only be replaced with fuses of the same type and specifications.