Setting up an RME Fireface UCX with the Axe-Fx II.

JSXtremist

JSXtremist

Inspired
Hello, I'm having trouble with noise and setting up an RME Fireface UCX with the Axe-Fx II. I would like to DI straight into the Fireface UCX, and loop the signal through the Axe-Fx II over SPDIF.

DI: guitar > Fireface UCX
wet: Fireface UCX > Axe-Fx II > Fireface UCX

Fireface USB Settings:
Sample Rate at 48000 Hz, and Current at 32000 Hz.
Clock Source at SPDIF coax, and Current at SPDIF.
SPDIF Coax input status at Sync and 32 kHz.

Axe-Fx Audio I/O Settings:
Main Input Source: SPDIF / AES
Word Clock: SPDIF / AES In
SPDIF / AES Select: SPDIF
 
Your interface should be set for internal clock source. The Axe relies on the incoming SPDIF/AES signal when word clock or main input source is set to SPDIF/AES.

I'm not sure what the 32 kHz means in what you've listed. The interface should be running at 48 kHz. Maybe everything will say 48 after you adjust clock source.
 
I've switched the Fireface UCX over to internal clock source to be greeted now with a different flavor of hiss and noise. o_O
 
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Yeah set everything to 48Khz. The axe is fixed at 48Khz. No idea what 32Khz is...
Also, make sure the Axe is set to be slave for the clock and the input is set to SPDIF.
 
Try turning down the level parameter in the preset's input/gate block. It's not unusual to have to do this after capturing a DI with another device.
 
Most noise is gone, but signal distortion still remains when going into the front of the Axe-Fx (it's Main Input Source to Analog Input 1) with SPDIF out to the Fireface UCX. So the DI into the Fireface UCX does seem to be introducing the noise issue.
 
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I sold my UFX last year so I cannot check this, but I remember the 32 kHz thing. This usually means both units are not in sync. You got to change something to make it sync, current should be 48 kHz.
 
The sample rate sync issue was solved by setting the UCX clock source to internal, as Bakerman suggested above. Now the UCX input status from the Axe-Fx shows the sample rate locked at 48 kHz over SPDIF coax. Thank you! :D
 
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After looking through the UCX manual, I discovered that only inputs #3 and #4 have the features necessary to support direct instrument signals. With the guitar now plugged into UCX input #3, the DI sounds satisfactory (no issues that I can hear), using these channel settings:
  • level reference set to +4 dBu (-10dBV and Lo Gain are also available)
  • "Inst" enabled, to change input impedance from 10 to 470 kOhm (Hi-Z)
  • gain set to around 8 dB (available range is 0-12 dB)
Comparing guitar DI vs Axe-Fx "dry" (all blocks off in grid), signal levels on the UCX:
  • Guitar DI peaks around -3 dB, heavy palm mutes on the guitar.
  • Axe-Fx SPDIF send and return both peak around -6 dB.
Now if I can just get the levels on the Axe-Fx and the SPDIF send and return setup properly. Signal overload (and massive distortion) is occurring once the Amp and Cab blocks on the Axe-Fx are engaged, unless I lower the SPDIF send on the UCX by about -32 dB. Help please, anyone? :coldsweat:
 
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JSXtremist said:
Now if I can just get the levels on the Axe-Fx and the SPDIF send and return setup properly. Signal overload (and massive distortion) is occurring once the Amp and Cab blocks on the Axe-Fx are engaged, unless I lower the SPDIF send on the UCX by about -32 dB. Help please, anyone? :coldsweat:
Click to expand...

That's one way to set level. Or you could leave the UCX send at 0 dB and reduce Axe input/gate block level parameter.

Figuring the "right" amount (for level as if you played guitar straight into Axe) would require additional testing but I wouldn't worry about that too much. You could just pick a slightly distorted preset you're familiar with, and make sure the reamp isn't sounding too clean or distorted.
 
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