• dtr
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Topic: UCX analog DC output, voltage?

Hi there,

I'm trying to find info on what levels of DC signals my UCX can output. I need to drive lasers that accept a range of -5 to +5V. Input more than that and they will get damaged. Less and I will not get the full range of power and motion.

I assumed the UCX can output DC as RME states the outputs are DC-coupled. I'm in doubt now as I read that on other Fireface models only the headphone out is truly DC coupled. Can anyone confirm what is the status on the UCX? And what max voltages it is outputting? (I wish I had a scope to measure...)

Tanx and best, Dieter

2 Reply by dtr (edited by dtr 2013-11-04 15:31:45)

  • dtr
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Re: UCX analog DC output, voltage?

Measuring with a basic multimeter it seems like the signal starts at around 2V and quickly drops off (the peak is likely higher but the multimeter too slow to catch it). So no DC.

My MOTU 828mk2 does maintain a steady 4.54V.

3 Reply by MC

  • MC
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Re: UCX analog DC output, voltage?

We never stated that the analog outputs can output DC. Only the headphone output can.

Regards
Matthias Carstens
RME

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  • dtr
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Re: UCX analog DC output, voltage?

Thanks for your reply.
You are right. I must have confused it with the specs of other Fireface models. Can you confirm that devices like the FF800 that state "Output DA: 8 x 1/4" TRS, servo-balanced, DC-coupled signal path. 1 x 1/4" TRS unbalanced" can output DC? If so, what voltage?

5 Reply by MC

  • MC
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Re: UCX analog DC output, voltage?

No, they can't. 'DC-coupled signal path' means that the internal path from DAC over several filter and gain amps to the output is completely free of coupling capacitors. But to protect the unit against DC and damage from outside signals there is one big capacitor directly at the output socket, which of course prevents to output DC signals. Units without such a protection don't have them because it is better, it is because they wanted to save space and money.

The phones output is a different topic because of its very low impedance. The required capacitor would be extremely big, and usually a protection at this kind of output is not required. That's why most (not all) of our units have DC-capability there.

Regards
Matthias Carstens
RME

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  • dtr
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Re: UCX analog DC output, voltage?

Thanks for clarifying.