User Manual

User's Guide MADIface XT © RME
101
Best USB 2 performance is achieved by connecting the XT to its own bus, which should be no
big problem as most USB 2.0 interfaces are a double bus design. A check in the Device Man-
ager can be done as follows:
Connect the MADIface to a USB 2 port
¾ Start the Device Manager, View set to Devices by Connection
¾ Select ACPI x86-based PC, Microsoft ACPI-Compliant System, expand PCI Bus
This branch normally includes two entries of a USB2 Enhanced Host Controller. A USB Root
Hub can be seen, which then connects all USB devices, including the MADIface. By reconnect-
ing to a different port this view shows at which of the two controllers the MADIface is connected.
With multiple devices it can be checked if they are connected to the same controller.
Furthermore this information can be used to operate an external USB drive without disturbing
the MADIface, by simply connecting the drive to the other controller.
It can also be used to check where and in what combination USB 3 is used. In fact many mod-
ern motherboards have an additional chip to the mostly found Intel chipset, adding further USB
3 ports. But documentation is often unclear about which port/socket is connected to which chip.
By connecting the MADIface XT and using the procedure above one can easily see the current
connection, ensuring the XT is really connected to the Intel chipset and not to some other flaky
one.
Especially with notebooks it can happen that all internal devices and all the sockets/ports are
connected to the same controller, with the second controller not used at all. In that case all de-
vices have to use the same bus and will interfere with each other.
A computer blocked for a short time – no matter if ASIO or WDM – will lose one or more data
packets. Such problems can only be solved by increasing the buffer size (latency).
30.5 External PCI Express
External PCI Express is the professional’s solution for an external audio interface which should
work as good as possible – and like an internal one. In simple words: using an Extender (PCI
Express card or ExpressCard) the internal PCI Express bus is buffered and made available
outside of the computer via special external PCIe cables. The whole system is standardized,
available and in use for many years, but so far limited to external chassis adding PCIe slots,
and usage in pro video applications. The XT is the first audio interface ever to use this tech-
nique, that guarantees the best performance and latency available among all the existing inter-
face formats (PCI, FireWire 400, FireWire 800, USB 2, USB 3).
Thunderbolt, which builds up on PCI Express, gives the same performance. Using a Thunder-
bolt to PCIe adapter box is both valid and does not degrade performance compared to E-PCIe.
Matrox offers such an adapter for their MXO2, adding significant cable length by using the
maximum length of E-PCIe (5 m) and Thunderbolt (2 m) at the same time. The similar Sonnet
Qio Thunderbolt interface unfortunately does not work, as its PCIe is locked to 5 GB/s mode,
which is not supported by the XT.
PCIe and ExpressCard extender cards from Matrox and Sonnet were tested by RME.
Matrox: MXO2 PCIe Host Adapter. MXO2 ExpressCard/34 Host Card.
Sonnet: Express Bus Extender PCIe 2.0 for Qio. PCIe 2.0 Bus Extender ExpressCard/34.
E-PCIe cable is made by Molex (see chapter 31) and available from various sources.
More information on these and other products can be found in the RME forum.