PHS 7.2 Phono, £24,000
The PHS 7.2 and PHS 7.3 are dual-mono and symmetrical phono preamplifiers, featuring JMF Audio’s unique precision balanced input stage design and innovative ALP and ALP-EM linearization technologies. These phono preamplifiers can handle up to 2 (PHS 7.2) or 3 (PHS 7.3) tone-arms or record players. Their advanced hand-calibrated balanced input stage and high gain take full advantage of low-level moving coil cartridges, without the need for step-up transformers.
The innovative input module interfaces provide 16 resistive and 16 capacitive loads for each input and corresponding cartridge, for precise dampening and tuning of the upper range of frequencies to achieve a linear overall response. The load settings are assigned to each input which allows seamless switching from one tone-arm to another. The record collector oriented PHS 7.3 features a special mono mode and three optimized alternative compensation curves for the enjoyment of pre-RIAA era recordings.
JMF Audio products are designed to be references and to last. The base of these instruments is safe and modular. Upgrades are proposed for the original owner to take advantage of the results of our continuous research and development efforts, without the need for product change
JMF WRITES:
“Selecting the source, processing the micro signal… Caring for the music…
Behind every JMF Audio product development lies music lovers’ motivation. While most historical recordings have been remastered and transferred to modern formats, we felt that the digital versions failed to carry the emotion and ambiances in their integrality. That the recordings from the golden era had to be enjoyed in the format they were intended for.
JMF Audio’s knowhow in analog had been recognized in world-class recording studios as well as by audio connoisseurs for more than 30 years. The definitive phono pre-amplifier’s circuits would be developed capitalizing on our experience and our latest innovations. As the PHS phono pre-amplifier would inherit from several of the PRS 1.5 line-level pre-amplifier’s aspects, the project could have been expected to be completed in less time than usual for JMF Audio. The research and development and the manufacturing of specific components eventually required some additional years of dedication… and lead to two models.
Minute signal extraction and faithfulness to the music being major challenges to achieve.
The PHS phono preamplifiers were finally unveiled, and the performances were beyond the initial expectations… Whichever the recording era, the JMF Audio PHS Instruments for the music® reveal the vinyl record as a format capable of utmost musicality, involvement, liveliness, and ultimately serving the music.”
“I can hear the JMF Audio gene from the first note, which is natural, solid, great dynamics and unlimited energy. This is indeed a masterpiece of phonostage! I heard about the development of this preamplifier years ago. The final product is far beyond my expectation. I can definitely hear the effort/time being spent on the final product. Thanks for bringing such enjoyment to my listening. Listening to a DMM record with the JMF Audio PHS 7.2 now, sounds like tape to me! Very happy to see that 3 years wait is totally worth it.”
“But despite all the excitement of the music and the images it evokes in us, the PHS 7.2 guides us with the utmost calm, unshakable, through threatening waters.”
The JMF Audio PHS reference phono pre-amplifiers feature a dual mono design, fully balanced circuitry, short signal path, and rely on the innovative ALP linearization (Intellectual Property registration).
> ALP is a purely passive linearization filter that compensates for the RIAA recording curve with precision.
> ALP features zero distortion, infinite headroom, by design.
> ALP is sealed and shielded under a machined block of aluminum of Orose® grade.
> ALP is built around bespoke made components and JMF Audio made components.
> ALP is buffered by JMF Audio’s SSA Super Symmetrical Analog technology involving hand calibrated input and output stages.
In addition to the main aspects, the details are of significant importance regarding the musical result:
PHS 7.3’s dual mono design with JMF Audio’s proprietary PGP 24 carat gold analog printed circuit boards embedding the proprietary ALP-EM record linearization filters. Components are populated on the top and on the bottom of the boards for optimal signal traces length.
For improved immunity to vibrations, each channel’s assembly is mounted on its own sub-chassis and benefits from dedicated suspensions.
Each printed circuit board is made up of more than 700 parts.
Like a recording studio microphone:
A phono cartridge is an electromechanical component that converts variations in records’ grooves into variations of electrical signal. Similarly, a microphone converts variations of air pressure into variations of electrical signal.
Both these sensors are made of a coil that needs to be connected to a signal amplifier. The signals are of very low magnitude and need to be protected against electromagnetic interference before amplification. This is why microphones have always been connected through shielded balanced interconnections in the recording studio world. For cost reasons related to consumer applications and also because the original cartridges were of moving magnet type, phono interconnections have been widely made through un-balanced links with RCA connectors.
The greatest care should be taken with nowadays precision moving coil cartridges that output low level signals. Since phono cartridges are balanced by design, the JMF Audio PHS phono pre-amplifiers handle them as studio microphones:
The PHS phono pre-amplifiers take advantage of JMF Audio’s innovative and still unrivaled hand calibrated precision balanced input stage technology which allows up to 100dB of interference rejection and consequently protects the least micro detail of music picked-up from the record. Moreover, the calibration method integrates psychoacoustic criteria.
The interface is ideally made with a JMF Audio phono cable from the tone-arm’s through DIN to XLR or RCA (hot-cold) to XLR. Optionally the PHS pre-amplifier can be ordered with input IN1 wired as RCA for the tone-arms that feature an attached cable. The signal would take advantage of the balanced input stage as well.
Multiple inputs and optimal cartridge loading:
The PHS phono pre-amplifiers can handle several tone-arms or record players through dedicated inputs. The load settings are assigned to each input which allows seamless switching from one tone-arm to another.
Quite a few modern cartridges feature rigid cantilevers and tend to present an un-even response with a significant rise of magnitude at the upper frequencies. Low value resistive loading is commonly admitted as the only way to obtain an acceptable response from these cartridges. The JMF Audio PHS phono pre-amplifiers propose an alternative through combined resistive and capacitive loading for precise dampening and tuning of the upper range of frequencies and achieve a linear overall response. By releasing the constraints on the cartridge, the musical rendering shows greater openness and liveliness. The load value being dependent on the cartridge, the setting is located near the corresponding input, which ensures the shortest signal path. All inputs load settings are easily controllable at sight from the rear panel.
High gain:
The JMF Audio PHS phono pre-amplifiers feature as high as 75dB of gain for the modern moving coil cartridges that require more amplification. A lever on the front panel allows to adapt the gain to suit MM and MC cartridges, the overall system’s gain or the line pre-amplifier’s sensitivity.
Absolute phase:
To compensate from recordings made out-of-phase and/or to match with next amplification stages which balanced connections follow a former standard, the PHS phono preamplifiers feature an absolute signal phase control.
No additional electronic circuits or components are involved for absolute signal phase control in the PHS phono pre-amplifiers, ensuring total transparency without change in performance.
Subsonic filter:
Very low frequency content, usually due to record wrap, recording flaw or acoustic induced vibrations, may alter the musical rendering along with putting unnecessary high demand on the power amplification. Elimination of the lowest frequencies is made possible by activating the subsonic filter with the Filter push button.
The processing is purely passive and no additional electronic circuits are involved for the subsonic filtering in the PHS phono pre-amplifiers.
PHS 7.3 dual-mono phono pre-amplifier – Orose® silver
The PHS phono pre-amplifiers have taken advantage of the result of JMF Audio’s long researches on the sound neutrality of passive components, semiconductors and materials, as described in the pages related to the HQS power amplifiers. The JMF Audio PHS phono pre-amplifiers utilize selected and uncommon components for audio applications: instrumentation metal-case semiconductors, proprietary printed circuits boards substrates…
Due to the requirements for specific components from the aeronautic, aerospace and fast-train industries located in France, some companies have specialized in manufacturing custom parts. Thanks to our initial activities in high-frequency electronics, as told in the History of the Brand, we have collaborated with such specialists for over 30 years, which has allowed JMF Audio to obtain made to measure components and parts, especially passive, that best suited our criteria, for the music.
The JMF Audio’s proprietary PGP 24 carat gold printed circuit board substrate is incompatible with the automated processes. The hundreds of components populating both sides of the boards are hand mounted and soldered one by one by our specialized technicians using JMF Audio’s specific solder, under a magnifying glass. A process that requires skills and patience and results in the application of jewels manufacturing methods.
A total of 8 adjustment points are hand calibrated on each pre-amplifier after 100 hours of operation at the manufacture.
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The PLS linear power supply technology from JMF Audio is now part of the PHS phono pre-amplifiers. It is the result of over a decade of research and development on the mains current (PCD 302 and PCD 102). It is based on a dedicated and made to measure low-noise and low-vibration toroidal transformer of the same technology as the large transformers that have equipped the JMF Audio power amplifiers for long.
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The JMF Audio Instruments for the music® are entirely hand crafted in our workshops and pass stringent tests. Every manufactured pre-amplifier has been verified by listening in our studios after an operating period of over 100 hours and placed in comparison with our references.
The dual chassis design, with the Orose® enclosure made of 10 to 16mm thick anodized and brushed aluminum parts, lays on JMF Audio’s proprietary decoupling feet. Whichever the chosen anodizing color Silver or Black, the engravings are filled with rose-gold and the controls, inserted in guided cylinders for smooth operation, are precisely machined in solid blocks of steel. The toggle switches, individually housed in a metal frame, are made in France to JMF Audio’s specifications.
Each PHS phono pre-amplifier is delivered with an Owner’s Manual containing the warranty terms and registration information.
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Number of outputs
3 (2 balanced, 1 un-balanced)
Number of inputs
2
Original input module types
MC/MM (x2)
Analog circuit board technology
PGP 24 carat gold
Linearization filter type
ALP
Linearization passive components
Precision grade (made in France to JMF Audio’s specifications)
Recording curves
RIAA
Subsonic filter
Yes
Hand calibrated inputs and outputs
Yes
balanced and adaptive
Input stage type
Technical specifications:
Connectors
XLR metal case, gold contacts | RCA metal case, gold contacts
Input impedance range
defined by input module type and settings
RIAA deemphasis curve conformance
+/- 0.05dB (1k..20kHz), +/- 0.1dB (20Hz..20kHz)
Interference rejection on the inputs
100dB typ.
Output impedance
Gain range
50 ohms
0, -10, -20dB (ctrl. with front panel switch)
Maximum gain output/input
75dB (low level MC cartridge)
Enclosure
Orose® up to 16mm thick machined anodized aluminum, machined steel buttons and rose-gold
Dimensions
482 wide (front panel) x 320 deep x 106 high mm including feet (19” x 12.6” x 4.2” high)
Net weight
14 kg (31 lbs), version B
Finishes
Silver or Black anodizing
200mV (typ. MM cart), 20mV (typ. MC cart), Gain min
Maximum input level
10V (+22dBu) into 10k ohms load
Maximum output level
1Hz..150kHz (intentionally limited for RF immunity)
Global circuits bandwidth
>96dBA (10V output, Gain min, typ. MC cart, IN1)
Signal to noise ratio (SNR)
<0.002% (10V output 1kHz, Gain min, BW.20kHz)
Total harmonic distortion (THD)
>100dB (10V output 1kHz, Gain min)
Channel separation
0 / 180° (ctrl. with front panel switch)
Phase range
Subsonic filter
-12dB/oct, 13Hz (ctrl. with front panel button)
100V, 120V, 220-240V AC – 50/60Hz (according to country of destination), version B
AC mains power supply
<25W, version B
Power consumption
Measurements with Audio Precision APX555 equipment. Voltage values are RMS. Specifications are based on the manufactured products at date of writing and may change with product evolution.
Versions history:
B
The PLS linear power supply technology from JMF Audio is now part of the PHS 7.3 and PHS 7.2. It is the result of over a decade of research and development on the mains current (PCD 302 and PCD 102). It is based on a dedicated and made to measure low-noise and low-vibration toroidal transformer of the same technology as the large transformers that have equipped the JMF Audio power amplifiers for long.
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