Grace Design kommer snart med m903 (http://www.gracedesign.com/products/m903/m903.htm) som er etterfølgeren til m902.
Nyhetsbrev desember 2010: http://www.gracedesign.com/newsletter/dec10/newsletter12_10.htm
Informasjon fra Hifisentralen:
Nyhetsbrev desember 2010: http://www.gracedesign.com/newsletter/dec10/newsletter12_10.htm
http://www.gracedesign.com/products/m903/m903.htm
Ten years ago, we launched the model 901 headphone amplifier. 4 years later, the m902, which set the standard for a new category of compact, precision playback tools. Today, we proudly unveil the m903, which is simply the most refined and feature rich headphone amp, DAC and compact monitor controller available.
The m903 keeps everything great about its predecessors, adds some useful new features, and ups the ante with even more breathtaking audio performance. A new volume control provides higher headroom and lower distortion and noise. New generation DAC's and ultra-low noise balanced current to voltage converter yields even more musical performance compared to the m902. Improved s-lock PLL circuitry delivers even lower phase noise and jitter. An improved power supply isolates headphone amplifiers, line amplifiers, DAC's and digital logic, resulting in lower noise and distortion.
Perhaps the most exciting improvement is the all new high speed USB interface. This cutting edge technology provides a completely asynchronous data transfer mode which allows for bit-perfect USB playback with zero interface induced jitter. This new interface affords standard driverless USB Class 1 operation on Windows and Mac up to 24bit/96kHz and USB Class 2 audio for 24bit/192kHz operation on Windows and Mac (drivers needed for 192kHz operation under Windows). This is computer-based audiophile playback, perfected.
New crossfeed circuitry is even more useful and includes a gentle compensation to eliminate the perceived loss of low frequency content. Both balanced and unbalanced line outputs are now standard, with individual volume controls for each. We have even included a mono mode for checking a mix for phase issues or simply monitoring in mono. These improvements cement the m903 as the perfect compact, audiophile grade monitor controller, even for larger scale production environments with more than one set on monitors.
A full complement of analog and digital inputs are provided (balanced, unbalanced, AES3, S/PDIF, TOSLINK and USB), which are selectable via a precision rotary front panel switch. And we offer an updated optional infrared remote control, which provides essential control for anyone working out of reach of their m903.
Advancing the tradition of unmatched audio performance and functionality, the m903 is now the ultimate solution for high resolution audio playback. From the very top mastering engineers to the most discerning audiophiles it is a must for anyone searching to discover new depths in music and sound.
Available soon!
Features
- Balanced and unbalanced analog inputs
- 24bit/192kHz digital stereo inputs- AES3, S/PDIF, TOSLINK and USB
- High speed USB interface - completely asynchronous transfer mode allows for bit-perfect playback with zero interface induced jitter
- Driverless operation on Windows & Mac up to 96kHz/24bit
- Supports USB Class 2 audio specification for 192kHz/24bit operation on Windows & Mac (drivers needed for 192kHz operation under Windows)
- New generation DAC's and ultra low noise balanced current to voltage converter yields more musical performance compared to the m902
- Mono mode for checking mix phase issues (or listening to Pet Sounds)
- s-Lock phase lock loop sample clock regeneration for ultra-low jitter and rock solid digital stability
- High-current transimpedance headphone amplifier circuitry built to effortlessly drive low impedance headphones
- Balanced and unbalanced variable level analog line outputs
- Improved power supply architecture isolates headphone power amplifiers, line amplifiers, DAC's and digital logic
- Precision level control with a 99.5dB range in 0.5 dB steps
- Channel level matching accuracy of 0.05dB
- Improved x-feed circuit eliminates perceived loss of low frequency content
- Optional infrared remote control available
- Internal linear power supply with custom wound toroidal transformer
- Sealed gold contact relays used for all signal switching
- Five year transferable warranty on parts and labor
På Head-Fi har bruker mbgrace (Michael) gitt utdypende informasjon:SPECIFICATIONS D/A CONVERTER
- Input Sample Rate: 32, 44.1, 48, 88.2, 96, 176.4, 192kHz
- http://www.head-fi.org/forum/thread/521166/grace-design-m903-reference-headphone-amplifier-dac-monitor-controller/15#post_7045051
- http://www.head-fi.org/forum/thread/521166/grace-design-m903-reference-headphone-amplifier-dac-monitor-controller/15#post_7064939
Hi All,
Just got back from AES in San Francisco and finally have a couple of minutes to myself. I thought I would tell a little about what is inside the m903. Basically there is no stone left unturned in the m903. Admittedly the specifications we published look a lot like the m902. I have yet to sit down at the Audio Precision and make official measurements for all of the performance parameters yet. The numbers you see are indicated as "preliminary" and are conservative. I will update them as we get closer to releasing production units.
Anyway, here is a list of some of the circuit changes from the m902 design. Sorry if some if this gets too technical.
DAC.
We are using the PCM1798 as the DA converter. I think this is a brilliantly musical DAC. It may not have the same noise numbers as the 1792/4 but it doesn't draw 350mW either. This is important in the m903 since the DAC analog power supply is in the form of a shunt regulator.
Following the PCM1798 is a new current to voltage (I/V) converter based on an unlikely suspect: THAT1570. This is actually a low noise front end amplifier for microphones and utilizes a current feedback architecture. While the I/V converter in the m902 was a current feedback amplifier the THAT1570 has substantially lower noise and lower distortion.
The high pass filter section is now based on the OPA1612. Finally a low noise bipolar amplifier that sounds really good!
The DAC audio power supplies and the line input/output supplies have now been separated from the headphone amplifier power supplies. This reduces dynamic interaction between the headphone power amp and the DAC analog circuits when driving difficult headphone loads.
Clocks
For bi-phase encoded digital inputs (toslink, spdif, and AES3) the m903 employs the same clocking architecture as the m902 with some significant improvements. (I'll get to the USB section in a minute).
The s-Lock PLL contains new lower phase noise (jitter) VCXOs. As well, the phase comparator in the PLL has been upgraded to a low noise charge pump type circuit. (The HC9046 datasheet gives a nice treatment of this type of phase comparator). The overall PLL jitter rejection performance has been increased with a higher order loop filter which is now 18dB/octave.
This all boils down to lower jitter at the DAC compared to the m902.
Volume control
The m903 volume control is based on the Cirrus CS3318. This is a really advanced volume control! It has 7dB lower noise than the PGA4311 and it runs on +/-9V power supplies. The channel matching is really tight (within several hundredths of a dB).
Headphone amplifier
This is, after all, the core of the m903. The headphone amplifier is the same basic topology as the m902 but the output short circuit protection circuit has been moved out of the signal path and into the power supply lines. As mentioned above, the headphone amp now has it's own set of dedicated power supply regulators.
The crossfeed curcuit, which is licensed from Jan Meier, is a more sophisticated design than the one in the m902. It has some passive compensation that reduces the perception of loss of bass in some program material while maintaining the excellent upper register tonal transparency of the original circuit.
Line outputs
The m903 has both balanced and unbalanced outputs. (the m902 had one or the other) Each ouput has independent level control so you can hook up multiple speaker systems or you can use one set of outputs to feed a sub and the other for the main speakers. These outputs have a firmware setting for +/- 9.5dB output level trim for matching speaker efficiencies. There are also individual balance adjustments for each line output and power on preset level settings.
USB
the m903 now uses a completely galvanically isolated, asynchronous data transfer high speed USB interface. There is simply no PLL like *no* PLL.
Clocking data out of a buffer with a low noise fixed oscillator is the ideal digital audio playback architecture.
General
One thing we didn't do is change how the m903 looks for the most part. However, the white 7-segment leds are nice and clear and much easier to focus on from across the room. Oh, and the input selector switch is now a really nice Swiss made EAO rotary switch that has a very solid feel and will last for ever.
...one more thing, there is now a mono mode. This is probably a more practical feature in a music production environment but it will be fun for listening to Pet Sounds!
Cheers,
Michael
Det ser ut som om ProLyd er norsk importør:The crossfeed circuit is switched in and out of the signal path with a relay. When it is engaged a white LED illuminates on the front panel. The crossfeed can be turned on and off directly from the optional IR remote control or from the parameter edit menu at the front panel of the unit.
The m903 was not designed with an architecture to support minimum phase filter options.
The m903 uses the Wavelength Audio asynchronous technology.
Cheers,
Michael
- Grace Design m903: 14.595,- ink. mva.: http://www.prolyd.no/Avdelinger/pro...rence-headphone-amplifier--and--DAC-A903.aspx
- Grace Design m903 Fjernkontroll: 1090,- ink. mva.: http://www.prolyd.no/Avdelinger/pro...red-remote-control-unit-for-m903-A903RCU.aspx
Informasjon fra Hifisentralen:
vredensgnag skrev:Det viktigste, ved bruk av en headphone-amp i slik forbindelse, er hvordan den simulerer crossfeed fra L>R øret og R<L øret. Det gjør en Grace m902 (0g nå m903) så det er til å applaudere.
vredensgnag skrev:Og så er det en god del DACer som ikke har asynkron USB, og disse bør man unngå. Av den grunn ville jeg f.eks. ikke kjøpt en Grace m902 i dag, dersom det var utsikter til bruk av USB-tilkoblingen - Grace har implementert asynkron USB i m903. Men da m902 ble lansert var det ingen som reflekterte over behovet i forhold til USB.
I tillegg bør man vurdere om man vil ha galvanisk skille mellom datamaskin som potensiell støykilde og DAC. USB er mer sannsynlig overfører av f.eks. PSU-indusert støy - og det har selvsagt ingen ting med protokollen å gjøre, men med at det er fast kontakt.
totte skrev:Den har også galvanisk skille på usb-inngangen.ceroxol skrev:Leser at Grace m903 har lisensiert Wavelenght (Gordon Rankin) sin Streamlenght HS kode, samme som Ayre, Halide Design, Aesthetix.. Regner med det dukker opp en test på Computeraudiophile om ikke lenge.vredensgnag skrev:Grace har implementert asynkron USB i m903.
De første kommer til Prolyd ila 2 uker.
Man skrev:M903 har balansert ut. Jack.
totte skrev:Artig dette. Jeg har den helt nye Grace m903 hodetelefonforsterker/dac i bestilling (kommer kanskje før jul...). Denne har ulike digitalinnganger, inkludert s/pdif og asynkron og galvanisk isolert (i motsetning til på m902) usb-inngang. Jeg skal jammen få meg en slik kabel for å sammenligne mellom inngangene. Artig ja.
totte skrev:Hjemme i leiligheten har jeg nyinnkjøpte Sennheiser HD800 og Grace m903 i bestilling. Disse skal kobles sammen og drives av laptop med J.River og ikke utsettes for tweaking eller noe annet, men kun brukes til å lytte til.
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