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RME Babyface Pro FS Portable Interface Review

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#63
Input Impedance:
1 kOhm unbalanced, 2 kOhm balanced

Why, RME, why!? o_O
Because its XLR inputs 1-2 are primarily intended for microphones, where 2k Zin is pretty much standard. If you enable pads there (somewhat assumed for balanced line level sources), the impedance increases to 5.2k.
If you have some unbalanced sources to capture, you can connect it via two TS inputs 3-4, those has 1Mohm Zin.
 

P48

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#64
The IEC standard for 48V is 6.8 kOhm. Most professional microphones are somewhere between 150 Ohm and 300 Ohm. In terms of impedance bridging that is pretty much okay. Still, the higher the damping factor the better (less signal attenuation and distortion). Higher input impedances can be crucial for vintage or more affordable microphones. Hence, I see no reason why you should go for 2kOhm as a standard. It's practically less versatile.

Just as an inspiration:
http://www.sound-link.co.uk/pdf/AES 145 - Improving Audio Performance of Microphones Using a Novel Approach rev23.pdf
 

MC_RME

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#65
You should do a little market research to find out that 2 kOhm is indeed a 'standard' for mic inputs. Mentioning the 6.8 k from the phantom power supply is misleading, these don't serve as impedance load but as current source.
 

q3cpma

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#66
You should do a little market research to find out that 2 kOhm is indeed a 'standard' for mic inputs. Mentioning the 6.8 k from the phantom power supply is misleading, these don't serve as impedance load but as current source.
Sorry if this not the exact thread for this, but how long is the warranty on such interfaces? The manual only cites 6 months, which is "a bit" too low for my taste.
 

P48

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#67
You should do a little market research to find out that 2 kOhm is indeed a 'standard' for mic inputs. Mentioning the 6.8 k from the phantom power supply is misleading, these don't serve as impedance load but as current source.
Thanks for the hint!

Nevertheless, is there any reason for choosing such "low" resistors?

I found some measurements of entry level interfaces from Audient, Behringer, Motu, Focusrite and Komplete Audio by the way. Most of them come with 3kOhm. Not much of a improvement, though.
 

MC_RME

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#68
Sorry if this not the exact thread for this, but how long is the warranty on such interfaces? The manual only cites 6 months, which is "a bit" too low for my taste.
As the manual says warranty time is different per country. For example 2 years in US, Canada, South America, Europe. 5 years in UK.
 

MC_RME

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#69
Thanks for the hint! Nevertheless, is there any reason for choosing such "low" resistors?
Two things: dynamic mics operate better at lower load impedances. Of course there is a balance between good and too low. There are mic pres that offer selectable input impedance, between 3k and 1k in multiple steps (or so). I never bought into the idea that this causes significant sound changes, though.

The other thing is that a designer wants to build units that don't exhibit high noise the moment you unplug something from the input - bad user experience guaranteed. That's why line inputs often have around 10 kOhm input impedance. If the input is 'open' with nothing connected it is still terminated with said 10 kOhms. Using 1 MOhm instead noise would be high. Now with TRS jacks one can use additional contacts so when no plug is inserted the jack short circuits its pins to ground. The Babyface Pro does that as well (this is industry standard, IMHO). But on a XLR you don't have any switching contacts that could do that. Add the high gain of around 40 dB used for mic inputs and you see why such an input with higher impedance will cause dissatisfaction and lots of support requests, although basically this is a non issue (nothing plugged is no valid use case).
 
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MC_RME

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#70
Mass poster here :rolleyes:

As Amir is too busy I thought I add the missing measurement of the 3.5 mm TRS output. As I explained that one has near zero ohm output impedance and is limited to an output level 6 dB lower than the big TRS. As a result this output does not clip at highest level with a 32 Ohm load, reaches a bit better THD+N throughout, and maxes out at 91 mW (manual mentions 90 mW at 0.1% THD - as can be seen the THD is below 0.0006%).

The basics behind this design decision (power supply etc) I explained in an earlier post, but there is one more: the max level here, +7 dBu, equals the Low Power setting in the ADIs. And that one has been a good limit for many people using various phones.

THD+N Ratio vs Measured Level_ Babyface Pro FS Phones Out Cursor.PNG
 
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Be.

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#71
I wonder how this compares to the new budget motu offerings (m4 and m2). Hopefully you can test an M4 soon.
I am quite curious about this as well. I've been using a Babyface Pro (non-FS) since 2015. I had a MOTU Ultralite AVB for a while which I returned for a variety of reasons including random horrible crackling noise with Linux, requirement of a separate power supply, long bootup time (why should I ever wait for an audio interface's firmware to boot??), strange lag changing the sample rate, and the TRS jacks being packed so tightly that XLR adapters didn't fit in adjacent jacks. When I got a pair of Genelec 8030As, I could hear that the Babyface Pro sounds better than the MOTU Ultralite AVB, but the difference was small. If the Motu M4 holds up to the quality of the Ultralite AVB, the sound quality for the cost would be excellent, especially considering this new Babyface Pro FS is selling for $150 more than the Babyface Pro which I bought for $750 new.
 
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Music1969

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#72
Hi @MC_RME

For external DC power, the manual states 9-14 Vdc @ 1A minimum. Is that a 5.5 x 2.5 mm connector ?
 
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