RME Audio Babyface User Manual - page 9
RME Tech Info Babyface Class Compliant
9
7. Useful notes
Stand-Alone Mode
As one wants to place the USB power supply not beside the Babyface, but further away into a power
outlet, a cheap USB cable extension, male to female, might be used to bridge the distance.
Unfortunately our (and our customer’s) experience is that most of these USB extensions are not only
cheap, but cheap. They cause a voltage drop that is enough to let the Babyface not initialize correctly,
or malfunction in certain situations. The workaround here is to still use an external power supply. Once
the Babyface is started the external power socket works. You can use a badly working extension cable
just to turn on the unit via USB buspower. After that it will get all the power that it needs from the
external power supply via the Babyface power socket.
Class Compliant Mode
You might get tempted to not use any external power supply at all. Indeed the Babyface runs bus
powered via typical USB power supplies quite well. Unfortunately some current intensive situations
like switching phantom power on, or plugging a condenser mic into the already powered mic input, can
cause a communication dropout. It seems like the spike of drawn current is detected by the iPad and
causes it to shortly disable the CC-device. Therefore we strongly recommend to always use a stable
external power supply. Then such effects do not show up with the iPad.
Mobile Operation
USB buspower can be delivered by a rechargeable battery as well. These days LiPo batteries with
USB ports are very popular, usually used to charge your mobile gadgets on the go. They are
lightweight, have an astonishing capacity, can be recharged quickly many times, and are not
expensive. And they have a USB port. We tried one of those small 4,200 mAh for around 20 Euros.
The Babyface worked for more than 6 hours while playing music from the iPad.