DXC2.2 MKII digital to analog converter

MODELS

SPECIFICATIONS

TESTIMONIALS

REVISIONS

Converting bit streams to real signals...  Caring for the music...  

 

JMF Audio presents the 768kHz DAC, 4x the limit of Blu-ray and 8x the equivalent of SACD.

 

To the JMF Audio's 30 year expertise in analog audio electronics, recognized from American studios to Japanese music lovers, skills in psychoacoustics and an unique approach to digital circuits for the music were added through the founder's sons.

The first researches of JMF Audio in digital audio and signal conversion were conducted to meet internal needs, by passion and challenges. It was also about assessing the potential for improvement in a field commonly considered as close to perfection. The results quickly showed that by addressing points which importance has often been underestimated, the solutions that JMF Audio could develop favored the expression of the musical work. 

The digitization of the audio signal offers many advantages for transfer and storage. To enjoy listening, however, it is necessary to convert the digital codes into continuous signals evolving over time. JMF Audio is approaching so-called digital signal processing and the crucial step of its conversion, in an innovative way, in a globally analog way...

A converter (DAC) translates a quantized value into an analog magnitude at a time T. The music information will be extracted by successive high frequency conversions. The relative temporal stability between conversions is a key parameter. The time information can be provided by the disc drive or by the file server. It is based on clocks. But these clocks are analog components by nature, with their characteristics of phase jitter and spectral density power (variability of periodicity)...  

The highest temporal accuracy is therefore necessary to ensure a conversion that is faithful to the original. However, guaranteeing it with musicality is a challenge. For the DXC 2.2 MKII converter, JMF Audio has developed the concept of synchronization and local timing named MLCK3 based on its own clock circuits placed near the conversion stages, to ensure maximum signal integrity.

With the advent of the CD, the sampling frequency of the audio signal was defined at 44.1 kHz, which according to Shannon's theorem is sufficient to quantify the highest frequency signals audible to the human ear. Recording studios worked on higher frequencies such as 48kHz. DVD and Blu-ray formats allowed sampling frequencies up to 192 kHz. Increasing the sampling frequency at the recording would make it possible to quantify ultra-sonic harmonics of the musical instruments... The often ignored aspect is that this actually reduces the constraints on the spectral image rejection during the sampling, which makes the process more transparent by improving its impulse response...

Based on our psycho-acoustic studies on this phenomenon, JMF Audio has developed a conversion technology operating at 705 or 768kHz, which means 16 times better than the CD format, and still twice as high as the internal DXD format of some mastering machines. This is in order to ensure a faithful representation of the digitized information and to obtain a directly analog signal, because very fine, without the need for post filtering. A world first in 2003... An achievement with the DXC 2.2 MKII, named DA768.

 

These innovative technologies have lead to a rendering of atmospheres, nuances, soundstages and a fluidity of interpretations that is second to none.

 

> DXC 2.2 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, an analog piece of art.

> Via a standardized link, MCLK3 extracts an incredibly detailed and natural sound.

The main digital audio board handles the standardized audio S/PDIF and professional AES-EBU inputs and embeds the reference master clocks. The USB module comes as an add-on. Because JMF Audio believes that digital electronics in a DAC is a matter of analog design (clocks are analog components by nature), a special attention was paid on the development of this new main digital audio board incorporating many innovative features. The two S/PDIF and two AES-EBU audio inputs are independent and galvanically isolated. The clock and data recovery from the audio source is performed 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 circuits feature two shielded bespoke master clocks. 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. 

From the implementation of these concepts has resulted a digital electronic circuit board which serves the music.

> Unrivaled precision timing.  High resolution is nothing without precise time reference.

The MCLK3 principle contributes to the fluidity, to the natural rendering, to the true dynamics and “analog” feel that surprises the listener. The optimum is assured with a single S/PDIF or AES-EBU connection, simply, up to 176.4 and 192kHz sampling rates.

The JMF Audio DMT 3.7 transport plays SACD and Blu-ray Pure Audio discs (192kHz), PCM and DSD files and connects to the DXC 2.2-MKII using an AES-EBU interface. 

> The DXC 2.2 MKII's USB module offers the highest quality way to take advantage of files from your computer.

The USB module allows the connection of an audio server, typically a personal computer on which an audio 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 DXC 2.2 MKII open to upgrades to follow possible future computer audio interface standards. 

The USB module features a galvanic isolation, preventing the DXC 2.2 MKII from being subject to the electromagnetic interferences from the computer environment. This module is enclosed in an aluminum shield case and takes advantage of a dedicated power supply.

As opposed to the S/PDIF and AES-EBU interfaces that carry audio information continuously, data over the USB interface are transferred in packets. The USB module hence operates asynchronously with the computer, via a bi-directional communication. The samples are requested from the computer which provides them to the main digital audio board at the pace imposed by the DAC's local master clocks. 

> DA768's conversion rates of 705.6 and 768kHz allows PCM audio to outperform DSD (SACD).

The conversion section named DA768, another masterpiece and jewel inside the DXC 2.2 MKII, converts bitstreams into physical magnitude. The DMSS conversion architecture followed by an ultra high precision analog section ensures unparalleled conversion linearity. The very low level information that represents the subtle nuances in the artists' play and the most subtle ambiances are extracted and correlated to the musical content. This results in an extraordinary homogeneous rendering.

The DA768 board features discrete ultra-low noise level surface-mounted components and custom-made capacitors. All the components and connectors of the audio path have been selected based on technical and reliability criteria, as well as 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.

> DMSS super symmetrical conversion on gold plated substrate, analog piece of art.

Featuring a deactivatable volume control, the DXC 2.2 MKII can directly control a power amplifier. In fact, the output stages inherit technologies employed in the PRS 1.5 preamplifier. In the pure analog section, the new DA768 board embeds a passive attenuator controlled by the HIGH / LOW switch located on the rear panel. The output level range can be adjusted according to the sensitivity of the driven device. When the DXC 2.2 MKII is used with variable volume, enabling the output attenuation optimizes the conversion resolution and the dynamic range.

> The DXC 2.2 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 DXC 2.2 MKII contains has been taken after long listening tests in the JMF Audio's studio. From the remake (MKII) of the DAC series up to its current revision (see bottom of page), JMF Audio’s investment in research and development has been continuous.

 

The JMF Audio DAC, faithful to the music.

The JMF Audio elements are entirely hand crafted in our workshops and pass severe tests. Since revision B, every DXC 2.2 MKII 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.

About MQA by Bob Stuart:

We are pleased to announce that the JMF Audio digital to analog converters are compatible with the MQA's most important aspect by nature. Indeed, JMF Audio has designed DACs converting as high as 768kHz for all input rates in order to present a sharp "analog like" impulse response, since 2003...

When playing an MQA-CD or file, including an estimated compensation of the blurring effect on the recording side, the result would be unhindered by the DXC2.2 MKII.

MQA also includes a data size reduction feature for easier download and storage, which is mostly interesting for portable audio devices and streaming. When playing MQA files, unfolding should be done with the computer/server.

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 hold by a double bearing in a machined aluminum compartment for smooth rotation. Machined 10mm thick anodized and brushed 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
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 
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.

 

Present models:
DXC 2.2 -MKII Stereo unit Product described here
DXC 6.10 -MKII Modular: multichannel and/or DSP (PSL / PSL-X) See product page

Owners' comments:

The JMF Audio DXC2.2 MKII has seduced music lovers from all areas. Whether these experienced audiophiles and sound engineers used to defend tube based designs or whether they used to trust famed brands in solid-state technology, they have found in the JMF Audio DAC the precision, timbres rightness, amplitude, greatness in the presentation of music.

We are thankful to the enthusiastic JMF Audio instruments-for-the-music owners for their feedbacks, comments and the wish for some of them to get the information published. 

However it has been decided to limit the comments on this page to just a few. Music enthusiasts are invited to discover and experience for themselves. JMF Audio would be pleased to guide and advise a representative.

Please refer to the Contact page and our Policy.

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Mr. Martin (HQS7001, PRS1.5, CM4, DXC2.2-MKII)

"I plugged in the DXC2.2 MKII last Saturday and the listening is staggering. Same feeling as with the change of preamplifier. The mid frequencies 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 [French made highly regarded CD transport] has reached a never imagined level of dynamics, sound stage and analog feel..."

 

Mr. Yu (HQS6002, PRS1.5, DXC2.2 MKII) Singapore:

"Just want to let you know that I have received the unit [DXC2.2 MKII] yesterday and just completed the connection about three hours ago. Listened to the first piece of classical music and feel like I was transposed to the concert hall! Thank you. [...] .

 

Mr. Chan (DXC 2.2 MKII), Hong Kong, 2015:

"I have to say thank you for your great and amazing DAC! Its performance is over my expectation... It is very natural, open and with very good resolution! Thank you very much again for your great product !!"  (e-mail feedback)

 

Mr. W.Ng., first owner of the DMT3.7 with DXC2.2-MKII combo in Hong-Kong (including DP5 AES-EBU cable):

"I must write to congratulate you guys for an amazing creation in the transport [and DAC]. Totally amazing. I now use it all the time from my array of other sources. Truly stunning." (e-mail feedback)

 

Mr. C. N., France, DXC 2.2 MKII-D converter (associated with DMT 3.7 transport and DP5-B AES-EBU link):

"I am eagerly listening to the source that I have purchased from JMF Audio. [...] All this gives a lot of realism, but with naturalness, without effects of hardness or excess of precision. I have no doubt that this is the player, but also its association with the DAC (DXC 2.2 MKII-D) and DP5-B cable that are non-destructive of all these signals provided by the transport. The sound engineers will have to deliver the best and our ears to stay young..."   (via e-mail, 1 month after reception of the instruments)

 

Mr. M. Ma. Hong Kong, already owner of a JMF Audio DMT 3.7 transport, purchased the DXC 2.2 MKII -D (2018)

"[The DXC 2.2 MKII-D] sounds incredible, so dense, so natural, so musical..."  (e-mail feedback)

 

Mr. Marvel, Marvel Music, Hong Kong, DXC2.2 MKII-D associated with DMT 3.7 transport, 2018:

"The JMF Audio's source outperfoms our previous reference SACD player by a wide margin".  

 

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Revisions history on model MKII:

 

DXC 2.2 MKII -D Major upgrade, 2017. Inheritance from the revision D of the PRS1.5 preamplifier.

> Read the first impressions in New York studios

DXC 2.2 MKII -C Major upgrade. Finalization and homogenization of the global isolation and shielding concept initiated in 1985. Applies to all JMF Audio products.
DXC 2.2 MKII -B Minor upgrade.

JMF Audio products are designed to be references and to last. The base of these instruments is safe and modular. Upgrades are proposed for clients to take advantage of the results of our continuous research and development efforts, without the need for product change. It means "details", but details make the differences and can lead to the exceptional. The device revision (B, C, D...) is indicated by a silver badge located on the rear panel and is linked to the product serial number in JMF Audio's tracking files. 

> More information about our upgrade policy.

MKII means a complete new design (chassis, shematics, components, circuit boards, power supplies, features).

Previous models: 

DXC 2.2 -C Improved power supplies and groundings
DXC 2.2 -B Improved power supplies
DXC 2.2  Initial release (2006)

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