JMF Audio HQS6002 stereo power amplifier
|Sensibility||All models have the same voltage gain (which eases multi-amplification)|
|Common mode rejection||CMRR 100dB, basado en criterios psicoacústicos desde 2012.|
|Output power RMS||
|Noise floor and hum||Better than -125dB (mono) -122dB (stereo) un-weighted 1kHz (meas. dating 2012)|
|Bandwidth||3Hz to 100 kHz (-3dB), 3Hz to 40kHz (0dB)|
Driving the loudspeakers… Caring for the music…
The JMF Audio HQS power amplifiers have been acclaimed for their high output power combined with a faithful, natural rendering of music. Since 1988, the most influential audio professionals, such as American studio designer Tom Hidley, and world-class studios (Nashville, New-York, London, Capri, Tokyo, Paris…) have trusted the HQS power amplifiers to monitor the quality of the recordings and productions, with great pleasure of listening.
While it first met with success in the studios, the JMF Audio technology was humbly aimed at celebrating music, for all music lovers.
Jean-Marie Fusilier designed and built the HQS power amplifiers without the preconceptions, the marketing considerations, the deadlines or budgets that generally limit commercial designs. Being an expert engineer in high-frequency, infra-red and power electronics, Jean-Marie Fusilier approached audio differently, by passion, with pragmatism, and developed innovative solutions. These set the fundamentals of the make JMF Audio, established in 1985.
The JMF Audio founder desired a lively yet controlled rendering for all types of musics… Even with high sensitivity loudspeakers, this meant significant driving force, precision and very low noise floor. The tube technology which he used to cherish was therefore left aside. Regarding the solid-state technology, it was common belief that only a pair of matched output transistors could lead to musicality, which was still only suitable for intimistic listening.
Jean-Marie Fusilier took up the challenge to design a high output power amplifier offering a superb musicality.
The philosophy behind the JMF Audio HQS power amplifiers can be summarized as follows:
> A huge reserve of energy for instant delivery at the output on fortissimo. Achieved with the proprietary RPS concept involving bespoke toroidal transformers and bespoke high performance capacitors.
> High voltage electronics for superior headroom and higher efficiency. A linear amplification by design, a short signal path starting with a precision trimmed balanced input stage. These are key features of the LDA driver board, the center piece.
> High current output capability for best possible control, allowing the amplification structure not to rely on compensations such as feedback loops, yet featuring a high damping factor by nature. The base of the proprietary MTP concept.
A philosophy as set in the beginning and still followed today, sometimes with the exact same components…
Complementing the major aspects, the details are of significant importance regarding the musical result:
Since their introduction, the JMF Audio HQS power amplifiers have taken advantage of the long researches of their designer on the sound neutrality of passive components, semiconductors and materials as well as on the amplification structure allowing fast response, stability and linearity at every stage. The JMF Audio HQS power amplifiers utilize selected and uncommon components for audio applications: high frequency precision transistors, matched differential pairs, bespoke passive components, selected and noble materials…
Due to the requirements for specific components from the aeronautic, aerospace and fast-train industries located in France, some companies have specialized in providing custom parts. Thanks to our initial activities in high-frequency electronics, as told in the History of the brand, we have collaborated for over 30 years with such specialists, which allowed JMF Audio to obtain the bespoke components and parts, especially passive, that best suited our criteria, for serving music.
The JMF Audio HQS power amplifiers are able to deliver formidable currents, with serenity. Large signals never happen to mask small signals. Possibly unique…
We have pointed out that the reaction of the loudspeakers (the counter electromotive force) was a commonly underestimated phenomenon. The loudspeakers have to be under control. In living rooms, at moderate listening levels, the JMF Audio HQS power amplifiers allow an ample rendering of music, in an absolute comfort.
JMF Audio defines dynamics as linearity down to the lowest levels, especially when the message is complex. This is another aspect that we consider very important. Linearity allows the reproduction of the least details, the subtle ambiances and the wide and coherent natural sound stage as caught at the recording. A challenge…
And especially desirable when enjoying music at moderate levels. The notes last longer with JMF Audio power amplifiers.
The HQS3200-UPM, the mono power amplifiers that propelled JMF Audio in the world class recording studios in 1988, were renowned for being extremely natural sounding, revealing the details yet being able to deliver huge currents, providing a lot of headroom. The JMF Audio’s HQS power amplifiers were awarded in Japan as the best audio amplification technology, in every category. Consequently, JMF Audio never felt necessary to present an amplifier to a contest in the following 30 years.
Present models bring the listener yet closer to the artists with precision, beauty of timbres, nuances and respect of ambiances… The last revision F introduced for the 30th anniversary of the recognition in Swiss studios are, in our opinion, a summit.
The LDA mono driver board, the center piece and jewel inside the power amplifier, is in charge of voltage amplification of the delicate incoming line signal by a factor of over 30dB. Since 1985, the driver stage has featured the innovative and still unrivaled hand calibrated precision input stage, enabling 100dB of common mode rejection of interferences carried by the input cables, this means more than 30 times better than found in professional balanced circuitry. This parameter having been enhanced by integrating psychoacoustic criteria starting from 2012.
Un-balanced incoming signals automatically take advantage of the symmetrical amplifications structure. The proprietary DC coupling allows a direct signal path (cutoff below 3Hz with offset error detection). These features have been common to all designs and have taken advantage of improvements with time, on technical and sound quality aspects.
A total of 6 adjustment points require manual calibration after a 100 hour burn-in period on each driver board.
The LDA mono driver board features metal case ulta low noise discrete components (military grade), bespoke capacitors on the power supplies (made in France), temperature compensated current biasing. Every components and connectors on the audio path have been selected for their reliability and on listening for their natural sound characteristics.
The JMF Audio proprietary PGP pure gold finish of the multi layer printed circuit board is incompatible with the automated processes. The hundreds of components populating both sides of the board are hand mounted and soldered one by one by our specialized technicians with JMF Audio’s bespoke solder, using a magnifying glass. A work of art that recalls jewels manufacturing.
The proprietary MTP type output stage, in charge of the signal amplification in current, employs multiple selected transistors (42 per channel on the HQS 9001) which have their own biasing (hybrid, class A on small signals since 2009), thermal compensation, fail-safe circuit. The biasing being independently calibrated to match the transistors and associated driver board’s characteristics.Thanks to the naturally stable design of the power amplifiers, the output stages provide a pure direct path, without the added inductive component that is normally mandatary in solid state designs.
The JMF Audio elements are entirely hand crafted in our workshops and pass severe tests. Since revision D, every power amplifier has even been verified by listening in our studios after an operational period of over 100 hours, so as to ensure its future owner will receive the best.
– RPS ultra stable power supplies. Specifically made to measure capacitors and toroidal transformers.
– LDA ultra linear and direct amplification structure (featuring PGP gold).
– DCS servo, direct coupling, no capacitor link on the amplification path.
– DPO direct output design: naturally stable amplification design requiring no output inductance.
– MTP output stage: multiple transistors, individually controlled, 330A capability for HQS9001.
– TRB temperature regulated circuits (with quick thermal stabilization starting from revision C)
– PGP specific gold plated analog audio boards (LDA amplification an MTP output stage).
– SCD sealed case design (no dust can enter), passive cooling (option silent heatsink cooling fan)
– Ultra low noise floor (and cross talk on stereo version).
– LSS made to measure dia. 6mm output terminals (120A rated!) with specific PGP gold
– Automatic detection and protection against input offset, too high frequency, high temperature, overload.
– Vu meter for input signal magnitude monitoring (switchable starting from revision F).
– Hand wired, soldered and mounted. Drastic control and selection of all components.
– All models feature the same voltage gain, which definitely facilitates multi amplifiers setups (active setups).
– All power amplifiers are upgradable to the last revision (starting from revision B, new chassis).