JMF Audio - precision means Musicality

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DXC2.2 MKII digital to analog converter

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At the time the first version of the DXC2.2 came out it settled a new reference in digital to analog audio conversion. It was acclaimed worldwide for its great musicality and fidelity; sounding more open, more “analog”. The world's first 768kHz DAC! But after the development of the PRS1.5 analog preamplifier, the time had come to give the DXC2.2 a follow-up. The DXC2.2 MKII with its new functionalities would be the digital counterpart of the PRS1.5 analog preamplifier, so it was decided they would share the same look and feel. Moreover, the DXC2.2 MKII, PRS1.5 and HQS1050 power amplifiers are based on the same 10mm thick machined aluminum chassis, for an elegant product line.

The 768kHz DAC: 4x the limit of Bluray and 8x the equivalent of SACD! > DXC2.2 MKII is ultra high performance, universal, future proof yet clean and simple to use. > MCLK3 locking mechanism is JMF Audio’s smart answer to clocking issues with transports. > USB module permits bit-perfect operation with isolation and local synchronization! > DA768 conversion rates of 705.6 and 768kHz allows PCM audio to outperform DSD (SACD)! > DMSS super symmetrical conversion on gold plated substrate is precision analog piece of art!

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> Using a standard link, MCLK3 extracts an incredibly detailed and natural sound from transports! The main digital audio board handles the standardized audio inputs and receives the USB module as an add-on. It also embeds the reference master clocks. Because JMF Audio believes that digital electronics in an audio converter is all a matter of analog design (clocks are analog components by nature), great care was taken in the development of this new main digital audio board incorporating many innovative features. The 2 SPDIF and 2 AES-EBU audio standard inputs are independent and galvanically isolated. The clock and data recovery from the audio source is done by the newly designed proprietary MCLK3 vari-speed 3-stage-locking mechanism that takes reference from the local master clocks through the MCDC master clock distribution circuits. The MCDC feature 2 ultra-low-jitter shielded master clocks made-to-measure for JMF Audio. One is used as reference for input sampling rates multiple of 44.1kHz and the other is used for sampling rates multiple of 48 kHz. As opposed to the conventional PLL (phase lock loop) circuits found in other hi-end DACs, MCLK3 provides a much higher resolution, which guarantees an ultra low jitter dependence and contributes to the absence of granularity, the natural wide open sound, the dynamics and “analog” feel that one can enjoy with the DXC2.2 MKII. Indeed, other DACs are either slaves to the SPDIF / AES-EBU (or I2S) inputs (i.e. dependent on source’s jitter), or they employ complex external clocking techniques (clock links are senstive to EMI which results in jitter, synchronization PLLs add jitter). > Unrivaled precision timing! High resolution is nothing without perfect timing. MCLK3 with the precision local master clocks is JMF Audio’s smart solution: robustness to EMI and jitter, less cables, universality! It means the best sound quality is assured with a SPDIF or AES-EBU connection! The implementation of the key concepts presented above has resulted in the printed circuit board design itself to be a work of art. It is a multilayer design and all critical traces are impedance controlled. It has to be noted that the 176.4 and 192kHz sampling rates are supported over a standard single wire SPDIF or AES-EBU connection, whereas some professional DACs require uncommon or dual wire connections. *Please note that the JMF Audio's forthcoming transport will play SACD and Bluray discs (Pure Audio 192kHz) and connect to the DXC2.2-MKII using an AES-EBU interface.

> The DXC2.2 MKII's USB module offers the highest quality way to enjoy files from your computer! The USB module allows the connection of an audio server, typically a personal computer on which an audio

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software player has been installed*. As explained in the previous paragraph, the USB module is an add-on to the main digital audio board. The USB module is extractible from the chassis, which makes the DXC2.2 MKII open to potential upgrades to follow future computer audio interface standards. In order to make the DXC2.2 MKII immune to the electromagnetic interferences that could come from the computer via the USB link, the USB module features a galvanic isolation. There is no physical link between the computer and the audio circuits. Moreover the USB module is enclosed in an aluminum shield case to prevent any radiation. The USB module is powered by the DXC2.2 MKII through a dedicated power supply. Data over the USB interface are transferred by packets, as opposed to SPDIF and AES-EBU interfaces that carry data continuously. This is a real issue because with an audio converter, a continuous data transfer is necessary to ensure uninterrupted music. The USB interface as such represents the worst of jitter and has never been considered by JMF Audio as a viable interface for high quality audio. Instead the USB module of the DXC2.2 MKII operates asynchronously with the computer for the highest quality audio**. The main digital audio board’s master clocks are the timing references and the USB communication is bidirectional. The DXC2.2 MKII’s USB module requests samples to the computer and provides them continuously to the main digital audio board at the local precision master clock’s rate. The DXC2.2 MKII is master over the USB interface for a time-perfect, zero jitter audio transmission! The USB audio module is clocked by the master clocks through the MCDC master clocks distribution circuits described in the previous paragraph. One reference clock is used for the audio inputs multiple of 44.1kHz (44.1, 88.2, 176.4) and another is used for the inputs multiple of 48 kHz (48, 96, 192). The USB module can operate in Audio Class 1 and 2, selected at the back of the device. Audio Class 2 is for performance (plug and play on MAC computers, with provided driver for Windows computers).

> DA768 conversion rates of 705.6 and 768kHz allows PCM audio to outperform DSD (SACD)! > DMSS super symmetrical conversion on gold plated substrate is precision analog piece of art! The new digital to analog conversion board named DA768 converts zeros and ones to physical magnitude with the highest precision for the best musicality. The DA768 certainly is the masterpiece of the DXC2.2 MKII. The printed circuit board is a multilayer design featuring the famous PGP gold plating finish developed by JMF Audio in the early 90’s. This special finish requires all the components to be mounted and soldered by hand by a specialist. Given the components’ fine pitch, this work is similar to jewelry and watchmaking.

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The typical JMF Audio power supply design was improved on this new DA768 board to present an unprecedented stability. The audio data provided by the main digital audio board described previously are oversampled to rates as high as 705.6kHz or 768kHz depending on the input, whereas the other hi-end DACs on the market convert at 192kHz maximum for the great majority and at 384kHz for a few others. The higher conversion rates have two benefits: the DA768 employs a non-destructive sampling image rejection digital filter and features the purest post-conversion analog stage. This makes a big difference in the perceived sound quality and it could be stated that the DXC2.2 MKII offers the main advantage of DSD to PCM audio regarding the digital to analog conversion! The DA768’s DMSS (Dual-Mono Super Symmetrical) precision conversion stage backed with ultra high precision analog circuitry ensures unparalleled conversion linearity. The lowest level information that represent the slightest nuances in the performers’ play and the most subtle ambiances are perfectly extracted and correlated to the main musical content, which results in extraordinary sound homogeneity. The DA768 features a volume control in the digital domain so the DXC2.2 MKII can be directly connected to a power amplifier. On the analog section, the new DA768 embeds a passive level attenuator which is remotely controlled by the HIGH/LOW switch at the back of the device. The output level range can then be adjusted according to the driven devices’ sensitivity. And, when the DXC2.2 MKII is used with variable volume control, setting the output level attenuation permits to turn the volume up and thus to optimize the conversion resolution and signal to noise ratio. Although super symmetrical by design, the DA768 includes a final unbalancing stage for the single ended outputs. Both single ended (RCA) and balanced (XLR) outputs feature high output drive capability to actually drive the modulation cables. The balanced XLR outputs are impedance matched with the JMF Audio CM4 modulation cables and with the PRS1.5 and HQS power amplifiers’ input stages for an increased three dimensional sound stage perception.

> The DXC2.2 MKII was designed to be a timeless jewel! After selection on technical aspects, refined selection on measurement, the final decision on absolutely all the audio components that the DXC2.2 MKII contains has been taken after long listening tests in the JMF Audio's studio. JMF Audio’s research and development investment in the remake (MKII) of the DAC series lasted over one year, with a total dedication and the will to make the best the smart way. Again, precision means musicality!

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Features: SPDIF inputs

2 (IN1, IN2)

AES-EBU inputs

2 (IN3, IN4)

USB inputs

1 (IN0)

Unbalanced output

1 stereo

Balanced output

1 stereo

Volume display

[30] to [99] in variable volume (no display in full-output)

Mode of operation

variable volume / fixed full output (for use with preamp)

Source display

[i0] to [i4]

Source selection, shortcut

quick toggling between USB and preferred SPDIF/AES

Remote control

IR remote control, all functions

Ground connection (earth) optional

dia. 4mm banana type

Massive aluminum volume control button / double bearing / massive aluminum compartment / smooth rotation Massive anodized aluminum chassis, mounted on special damped and anti skidding JMF Audio feet Specifications: Main digital audio board Input interface

all inputs electrically independent / galvanic isolation

SPDIF inputs impedance, min. and max. level

75 ohms, 0.2V .. 5V

AES-EBU inputs impedance, min. and max. level

110 ohms, 0.2V .. 10Vpp differential

Clock recovery mechanism

MCLK3 proprietary vari-speed 3-stage-locking mechanism with reference to the local master clocks

Clocking system

master DAC concept with 2 made-to-measure ultra low jitter master clocks in MCDC proprietary clock circuits

Supported resolutions

16..24bits/ 32, 44.1, 48, 88.2, 96, 176.4, 192 kHz

De-emphasis

de-emphasis 50/15us automatic, seemless

USB Module Input interface

entirely shielded module / galvanic isolation

USB connection type

USB 2.0 High Speed compliant

USB Audio Class

Audio Class 1 or 2 selected with switch at the back

Synchronization

asynchronous, DAC master through MCDC clock circuits, specific ASIO driver provided for Windows

Supported resolutions

16..24 bits / 44.1, 48, 88.2, 96, 176.4, 192 kHz

DAC section

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Digital to analog conversion technology

DA768 w/ DMSS topology on proprietary PGP multilayer gold plated substrate

True digital to analog conversion rate

705.6 kHz or 768.0 kHz depending on input

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JMF Audio - precision means Musicality

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Total harmonic distortion plus noise at full output

0.0008 % at 1kHz typical** (bw. 22Hz .. 22kHz)

True audio dynamics (EIAJ measurement)

130 dB typical** (real! no auto-mute function!)

True signal to noise ratio (full output, XLR)

130 dBA typical at 1kHz** (real! no auto-mute!)

Output impedance

50 ohms RCA and XLR

Output level range control

passive attenuators, remotely controlled

Maximum output level

+20dBu (7Vp) XLR switch HIGH / 0dBu XLR sw. LOW +14dBu (4Vp) RCA sw. HIGH / -5dBu RCA sw. LOW

Volume control

70 steps of 1dB, digital at the conversion stage

Main power supply Mains voltage range

100..240VAC

Power supply isolation

Two levels of electromagnetic shielding

Internal power supply distribution

Proprietary QUAD-STAR-POWER

Power consumption

< 25W in operation (< 1W in standby)

**Dynamics and SNR measurements with 4th order low pass filter at 22kHz for accurate value. Measured performances with Audio Precision Dual Domain equipment. Important notice: Many modern DACs automatically activate an auto-mute function during supposed silences... Measures of SNR and dynamics may thus be impressive (incredible), but they do not reflect reality (music)... Characteristics are subject to change with product evolution, without notice.

Models: DXC2.2-MKII

Stereo unit

Product described here

DXC6.10-MKII

Modular: multichannel and/or DSP (PSL / PSL-X)

See product page

Clients' comments: Mr. Martin (HQS7001, PRS1.5, CM4, DXC2.2-MKII) former user of DCS with external clock: "I plugged in the DXC2.2 MKII last Saturday and the listening is staggering. Same feeling as with the change of preamp. The mids are realy worthy of JMF Audio (French Musical Jewel) and the listening in general shows unequalled presence, fullness and sweetness. [...] The Mahler's 10th symphony played with my Kalista (CD transport) has reached a never imagined level of dynamics, sound stage and analog feel..." Mr. D.H. (HPM500, HQS9001, PRS1.5, DXC2.2-MKII) former DXC version 1 owner, after comparison demo: "Great and clear improvement, superb sound stage and musicality (AES-EBU and USB), I look forward to receiving mine" Mr. K.F. (HQS9001, PRS1.5, DXC2.2-MKII) Asia, hi-end audio equipment importer: "Yes we have received the DXC2.2-MKII. The sound is amazing! We appreciate the ability to play 24bit/192kHz files as well as CDs through JMF Audio's technology." Mr. J.D. (HQS6002, DXC2.2-MKII, CM4, DP2, PC3) France, JBL speakers, formerly using Jeff Roland, Wadia, Audioquest: "I don't define myself as an audiophile since I don't listen to jazz or classical, but anyway, the difference [with my previous equipment] is stunning! I rediscover all my recordings... I have purchased a lot of new CDs and DVDs since! I also subscribed to an online music service [stream to the DAC] which made me discover talented artists, in hi-res!" Mr. S.R: (DXC2.2-MKII) "CDs sound so natural, open! Definitely forgot about SACDs! [...] The results with Bluray discs at 24/96, 24/176, 24/192 are excellent." Mr. J-R (professional musician and producer): "I only trusted vinyl records. I had never liked CDs. But with JMF Audio, there is no so-called 'digital sound'. It is extremely aired, lively, full. We were shocked..." Mr. J.S (DXC2.2): "I auditioned the DXC2.2 several years ago. The sound was really 'analog'. Unfortunately I could not afford it. So a dealer sold me the three unit MSB stack. It is good, it is precise, but there is not the life of the JMF. I finaly

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found a second hand unit when you released the MKII. Precision is one thing, but the DXC2.2 goes much further than that." After visit at JMF Audio: "We have the feeling that music is played slower, that the musicians are relaxed. [...] Today we listened to Music!" Mr. Rinder (HQS2400, SR4, CM4, DXC2.2) on JBL speakers : "The DAC is wonderful, so musical! It is strange but I feel like the musicians are in my living room" Mr. Stephan (HQS6002, SR4, CM4, DXC2.2) : "I never thought so much could be gained from digital"

Revisions: No revision on MKII. MKII does not mean a change of painting, it is a complete new design (chassis, boards, power supplies, features). Previous models: (discontinued) DXC2.2C

Improved power supplies and groundings

DXC2.2B

Improved power supplies

DXC2.2

Initial release (2006)

© JMF Audio ® 1985-2015 rev. 20/04/15 - All rights reserved - Tous droits réservés

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