SPL Phonos RIAA Phono Preamp with VOLTAiR Tech

Description

RIAA Phono Preamplifier with VOLTAiR technology

Phonos is a preamplifier for record players using either
moving magnet (MM) or moving coil (MC) cartridges. The equalization curve
is according to RIAA and suitable for all vinyl records since 1954. The RIAA
filter is designed after Douglas Self.

With up to 70 dB gain for MC cartridges and 51 dB gain for
MM cartridges Phonos belongs to the most powerful phono preamplifiers.

 

• 120 V
  rail phono preamplifier for record players

• RIAA
  equalization (after Douglas Self)

• Suitable
  for MM (Moving Magnet) and MC (Moving Coil) cartridges

• Max.
  preamplification: 51dB (MM); 70dB (MC)

• Capacitances
  for MM: Off, 150 pF, 220 pF and 330 pF

• Impedances
  for MC: 100, 220, 470; 2k2, 4k7 and 10 kohms

• Styroflex
  condensers used throughout the RIAA equalizer

• Switchable
  Gain: Normal, -10 dB, +4 dB

• Gold-plated
  RCA in- and outputs

• Audio
  ground connection for record player

• Switchable
  rumble filter (Subsonic)

• Linear
  power supply with toroidal transformer

• Made
  in Germany 

 

The technical basis of all Professional Fidelity
units is our proprietory 120 V Rail Technology, which we also call VOLTAiR
technology. The name makes reference to the unequalled high voltage of 120 V
(+/-60 V DC) and the huge dynamic range of over 140 dB that goes with it.

RIAA equalization

RIAA equalization is a specification for the recording and
playback of phonograph records, established by the Recording Industry
Association of America (RIAA). The RIAA equalization curve was intended to
operate as a de facto global industry standard for records since 1954.

The purposes of the RIAA equalization,
which is a form of pre-emphasis on recording and de-emphasis on
playback, are to permit greater recording times by decreasing the mean
width of each groove, to improve sound quality, and to reduce the groove damage
that would otherwise arise during playback.

A recording is made with the low frequencies reduced and the
high frequencies boosted, and on playback the opposite occurs. The net result
is a flat frequency response, but with attenuation of high frequency noise such
as hiss and clicks that arise from the recording medium.

The RIAA equalization curves for recording (blue) and
playback (red) of vinyl records. The recording curves perform the inverse
function, reducing low frequencies and boosting high frequencies.

RIAA equalization has transition points in three places:
75 µs, 318 µs and 3180 µs, which correspond to 2122 Hz,
500 Hz and 50 Hz (rounded values). 

 

Transition Frequencies	Time Constants	Relative Level
50 Hz	3180 µs	-17 dB
500 Hz	318 µs	-3 dB
1000 Hz	159 µs	0 dB
2120 Hz	75 µs	+3 dB

 

The construction of the RIAA equalizer follows a design made
by Douglas Self. In this design larger single capacities are exchanged against
smaller multiple capacities.

MM and MC

There are two primary methods a modern cartridge uses to
generate current. These are moving magnet (MM) and moving coil (MC)
configurations.

Moving Magnet

Moving magnet cartridges tend to produce lush, mellow sound.
By moving a magnet within copper coils a small voltage is created. MM
cartridges sport very high inductance and impedance. In the latter, cable
capacitance can negatively affect the flatness of frequency response and
linearity of phase response. Phonos offers a selection of four capacities to
fine tune the flatness of the frequency response or to willingly increase high
frequencies in playback. The capacities are 150pF, 220pF and 330pF. In the OFF
position the capacitance is determined by the cable capacitance.

Moving Coil

The MC design is again a tiny electromagnetic generator, but
(unlike an MM design) with the magnet and coils reversed. The resulting
signal is only a few hundred microvolts, and thus more easily swamped by noise,
induced hum, etc. Thus it is more challenging to design a preamplifier with
the extremely low noise inputs needed for moving-coil cartridge. Phonos
provides a 20dB higher preampfification for the MC stage compared to the MM
stage.

MC cartridges offer very low inductance and impedance, which
means that the effects of capacitance (in the cable that goes from the
cartridge to the preamp) are negligible. The impedance of cartridge can be set
in six values: 100, 220, 470, 2.2k, 4.7k, and 10kOhm. If in doubt which
impedance matches the cartridge’s impedance you can empirically determine the
value for the flattest frequency response.

Subsonic filter

Rumble from the playback turntable’s drive mechanism is
amplified by the low frequency boost that occurs on playback. The Phonos offers
a switchable Subsonic filter to eliminate the rumble.

Gain

The preamplification is switchable and offers three values
for MM and MC.

The Normal gain is +47dB (MM) and +66 (MC).

In the -10dB position the Phonos produces enough output
level for standard consumer electronics products operating on -10dBV.

In the +4dB position the output is equally loud as modern DA
converters at 0dBfs = +15dBu.

Professional Fidelity
• Pro-Fi-Serie

Phonos is part of our Pro-Fi series of products. Pro-Fi
stands for Professional Fidelity and it expresses that these products have
their roots in professional studio technology being optimized for high-fidelity
music playback.

We love simple elegance and a certain level of
understatement. Therefore we renounce over-dimensioned housing milled out
of a solid block and other mostly price-driving attributes of many high-end
products. Our background is come from professional studio technology, where
inner values and audio performance count the most.

Mastering studios give your records and CDs the final
tough – with SPL 120 V technology. And because the Phonos is built with the
same technology it belongs to best phono preamplifiers on the planet. With its
extraordinary specifications and enormous headroom Phonos plays back audio in
the most relaxed and uncompromized fashion.

VOLTAiR is the synonym for our 120V Rail Technology within
the Professional Fidelity series.

The audio signals are processing with an unequalled +/-60V
DC.

The Sound

120V Rail Technology is our reference
technology developed and manufactured to run on an operating voltage of
120 volts, which corresponds to twice that of discrete operational amplifiers
and four-times that of semiconductor operational amplifiers.

120V Rail Technology reaches outstanding technical and
sonic performances. Technically especially in terms of dynamic range and
headroom and sonically especially in reproducing the finest details and
delivering a totally relaxed sounding audio experience. Music sounds absolutely
natural and hearing fatigue is drastically reduced.

Even the best audio measuring equipment arrives at the
boundaries. In same situations we ended up just measuring the Audio Precision
Cascade 2 measuring device and we cannot say how good the 120V Rail Technology
actually performs.

Comparisons

The direct relation between operating level and maximum
level is fundamental for the classification: the higher the operating level,
the higher the maximum level a circuit can handle. And since virtually all
essential acoustic and musical parameters depend on this relation, a higher
operating voltage also has a positive impact on the dynamic range, distortion
limit and signal-to-noise ratio.

Do bear in mind that dB scales do not represent linear but
rather exponential increases. A 3dB increase corresponds to doubling the
acoustic power, +6dB correspond to twice the sound pressure level, and +10dB
correspond to twice the perceived loudness.

When it comes to volume, the 120V Rail Technology exhibits a
performance, in regard to maximum level and dynamic range, that is twice that
of common components and circuits given that its values are approximately 10dB
higher.

THD measurements of the 120V op-amp show a difference of
more than 3dB compared to the OPA134 at 36V — in terms of sound pressure level,
that corresponds to an improvement of more than 50%.

The operating level most commonly used for audio equipment
is 30 volts.