[LAU] RME Babyface Pro questions

Fons Adriaensen fons at linuxaudio.org
Sat Mar 2 21:19:35 CET 2019

On Wed, Feb 27, 2019 at 11:57:56AM -0500, Joe Hartley wrote:
> My biggest concern is about phantom power, as I'd seen a mention that
> PP is only settable from the TotalMix software, which is a no-op in CC mode.
> I'm also interested in any "gotchas" or anecdotes about living with this
> unit under Linux.

I'm still very happy with my Babyface Pro. Got another one at work.

Phantom power on the mic inputs can be controlled on the device
itself, so also in CC mode.

Two 'gotchas', neither of them serious if you know they exist:

1. Analog inputs 3 and 4 (TRS) are *unbalanced*, somewhat unexpected
on a device in this price range. OTOH, analog outputs 1 and 2 *are*
balanced, with both pins 2 and 3 of the XLR being actively driven, 
and the signal on pin 3 being inverted. But this is *not* a 
'pseudo-floating' balanced output in the sense that shorting one
of the two pins to ground will make the other one compensate so
you still have the same voltage between pins 2 and 3 (as on some
other RME gear). The signals on pins 2 and 3 are independent.
The result is that if you use a standard XLR->XLR or XRL->TRS
cable to an unbalanced input (e.g. analog inputs 3 and 4), you 
are shorting output pin 3 to ground, and the output driver may
or may not not like that. 

2. As soon as a valid signal appears on the ADAT input this
becomes the master sample clock, there is no way to change that
in CC mode. The result is that if you connect ADAT out to ADAT in
(e.g. for testing, but also indirectly), the sample clock goes
kinetic as it tries to sync to itself and fails.

As said, neither of these is a showstopper as long as you are
aware of them. 

Another thing to watch out for: The gain of ADAT output channels
1 and 2 can be set on the unit itself, the maximum is +6 dB as
in totalmix. The others, 3..8, are always at 0 dB in CC mode.
So if you want the same gain on all 8 channels don't forget
to check 1 and 2. Hit me a few times when doing beamforming
using the ADAT outs.



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