RME Fireface 400
The RME Fireface 800 was the first FW device, which was no worse than the external RME interfaces that required a digital PCI or Cardbus controller for a PC connection.
According to the manufacturer, the Fireface 400 is not just the little brother of the Fireface 800. It is a completely newly designed device. It is the only device in its class with active jitter suppression, stand-alone functionality, complete controllability from the front panel, highly flexible I/Os in professional quality, and an unsurpassed 648-channel matrix router - at sample rates up to 192 kHz.
RME Fireface 400 features:
- TotalMix: 648-channel mixer with 42-bit internal resolution
- MIDI controlled stand-alone operation
- Up to three Fireface 400/800 units can operate in parallel
- Analog inputs: 6 x 1/4" TRS (4 x Line, 2 x Line/Instrument), 2 x XLR/TRS Combo (2 x Mic/Line) All inputs are servo-balanced
- Analog outputs: 6 x 1/4" TRS, servo-balanced, DC-coupled signal path. 1 x 1/4" TRS, unbalanced
- Digital I/O: 1 x ADAT, SPDIF
- MIDI: 2 x MIDI I/O via breakout cable (4 x DIN)
- Support for sample rates up to 192 kHz
- Two digitally controlled Mic Preamps in high-end quality
- Two balanced universal inputs for line and instrument signals
- SteadyClock for maximum jitter suppression and clock refresh
- Simple stand-alone operation with rotary encoder and front panel display
- TotalMix: 648-channel mixer with 42-bit internal resolution
- 54 Level Meter Peak/RMS, hardware-calculated
- Full mobility by Bus Power support
- Windows and Mac compatibility
The DSP-based TotalMix mixer allows fully independent routing and mixing of all 18 input and output channels to all 18 physical outputs. Up to 9 totally independent stereo sub-mixes simply mean unrivalled monitoring facilities. The mixer can be completely MIDI controlled via the Mackie-compatible controller.
Eight ADAT channels are available simultaneously with the analog channels. The coaxial SPDIF I/O , which is fully AES/EBU compatible, also works up to 192 kHz.
Technical properties of RME Fireface 400
(according to the updated User's Manual)
ADC (Inputs 5-8):
- DR: 113 dBA, 110 dB
- THD: < -100 dB (< 0.001 %)
- THD+N: < -98 dB (< 0.0012 %)
- Crosstalk: > 110 dB
DAC (Outputs 1-6):
- DR: 113 dBA @ 44.1 kHz, 110 dB
- THD: -100 dB, < 0.001 %
- THD+N: -96 dB, < 0.0015 %
- Crosstalk: > 110 dB
This device uses the latest two AKM AK4620A stereo codecs that unite DAC and ADC in a single package. The AK4620A is positioned for professional sound cards, DAW, and other equipment. The codec supports up to 24-bit 192 kHz for recording and playback. Signal to noise ratio is 100 dB, dynamic range - 113/115 dBA. The DAC uses the AKM Advanced Multi-Bit delta-sigma architecture to obtain low modulator noise - practically flat noise spectrum up to 80 kHz. Filters at switch-selectable capacitors provide resistance to jitter of the master clock. The ADC has the AKM Enhanced Dual-Bit architecture to reach a relatively large dynamic range. There is a digitally controlled (IPGA) amplifier at the input. Digital filters have a linear phase.
Digital interface:
- Clocks: Internal, at digital inputs: ADAT, SPDIF, word clock. Optional LTC/Video in
- Low Jitter Design: < 1 ns in PLL mode, all inputs
- internal clock: 800 ps, Random Spread Spectrum
- Jitter suppression of external clocks: > 30 dB (2.4 kHz)
- Effective clock jitter influence on AD and DA conversion: near zero
- PLL ensures zero dropout, even at more than 100 ns jitter
- Digital Bitclock PLL for trouble-free varispeed ADAT operation
- Supported sample rates: 28 kHz up to 200 kHz
The list of famous users of RME products:
http://www.rme-audio.de/en_artists.php
Although the Firewire interface looks very attractive and provides high bandwidth, it poses some problems in the audio tasks. Immediate access to data and maximum speed of transferring sound buffers in small chunks are more important to sound devices than theoretical bandwidth. It's also important to have as little overheads as possible - bandwidth losses to transfers of ancillary data of standard protocols. CPU load generated by the interface also plays an important role, it has a direct effect on the minimal signal latency.
It's praiseworthy that RME have a special section in the official web site (Technical Background) to publish some technical details.
The manufacturer explains that there are fundamental differences in the RME architecture and Firewire products from other manufacturers. External audio Firewire devices usually use a general-purpose Firewire chip and a separate I/O controller with minimal functionality. Manufacturers sometimes add a DSP effect processor. But there appears a problem of limited data exchange rate between a device and a computer along the entire interface chain. Thus, the standard approach leads to a limitation on the number of simultaneous channels as well as on the signal transmit time.
RME designed a proprietary solution for the Firewire interface. The core is packaged into FPGA, which allows to improve its performance and fix bugs by updating its firmware. DSP is implemented inside FPGA to process routing signals in TotalMix or to measure signal levels. On the physical level, the company uses Texas Instruments chips - the best solution for the Firewire interface. In order to avoid problems, it's also recommended to use a TI-based firewire controller to plug the Fireface. The RME web site publishes a list of recommended and inadvisable controllers. The latter are manufactured by unknown Chinese manufacturers with serious mistakes in their circuitry.
The drivers support the following operating systems: Windows 2000 SP4, XP, XP 64, Vista, Vista 64, Mac OS X, and Mac OS X x86.
Bundle:
- Fireface 400
- Cable IEEE1394a (FW400), 4 m (full-size 6-pin connectors)
- MIDI breakout cable (2 inputs, 2 outputs)
- Power supply
- Printed manual in English/German
- Driver CD
- Optical cable (TOSLINK), 2 m
The box also contains a leaflet with the following warning:
Firewire devices can be powered up and shut down any time (hot switching). Since its appearance, this advantage of Firewire have misled many people and caused the death of a great many devices. Web research brings up innumerable numbers of hard drives and computers that were damaged when users connected interface cables.
The main problem is that the Firewire cable also has power wires. Brief voltage surges appear when you plug or unplug a device. They break through wire isolation and damage delicate electronic components.
Of course, this problem can be minimized with special measures (protective diodes at the input, smooth power supply, etc), but it cannot be eliminated. Hot switching always poses a threat, if a device is powered from the bus.
So RME recommend avoiding hot switching!
Plug the Fireface 400 to Firewire only when a computer and the Fireface are powered off. And you will avoid the above-mentioned problems.
According to RME, manufacturers of chips for Firewire audio interfaces (BridgeCo, Philips AV LLC) have a vague idea as to what professional interfaces need. In particular, their chips lack the following features that are offered exclusively by RME products:
- Lock to external signals in realtime
- Support for varipitch/varispeed
- Offset-free record/playback
- Support for multiple units
- Support for sample rates up to 192 kHz
- Change of the buffer size in real-time
