New (2021) RME Fireface UCX II

[enricoclaudio]

Trying to decide if it's worth spending $1400 more on a UFX+ or go with the UCX II, switching from an Apollo Twin X (I rarely use UAD plugins and need more I/O plus latency is mediocre - both the UCX II and UFX+ would be a step up).

8 inputs + 8 over ADAT would be the max I use any time soon (sampler with 8 outs, a couple of other instruments and an Eventide H3000 would be the max simultaneous use) so the UCX II is fine there.

The only negative I see for the added expense is the UCX II's DA dynamic range being lower than either the Apollo line or the UFX+ (118dBA vs 115dBA) but I'm having a hard time quantifying what that might mean in real world terms.

One line of thinking is that I go with the UCX II (selling my Apollo makes it an even swap) now and if a TB3 (or TB4 or whatever the future holds) UFX+ replacement comes along in a couple of years that would be an upgrade path if I found myself wanting to.

I own the UA Apollo Twin USB Duo, Apogee Quartet and RME UCX II, the Apogee Quartet is now for sale and the Apollo Twin stays as backup. The RME UCX II floor noise is ridiculous low compared to the Quartet and the Twin DUO. Not to mention that TotalMix makes other audio interfaces UI look like toys. If you don't need/use UAD plugins, then the UCX II is the way to go. Also agree that latency in the UCX II is so much better than on the Apollo Twin. I use mostly the Apollo Twin as audio interface for a live streaming rig with WireCast Pro and what I find convenience is the big volume knob with LEDs all around which is great if you need to make volume changes on the fly while live streaming, but that is a very particular case/use. For everything else, the UCX II is better.

 

[jirodreams]

I went ahead and ordered a UCX II - the decision helped by one being available and no ETAs on UFX+ with my usual shops.

 

[Helicopter]

I really need one of these in my life, but my budget for stuff I don't need has to recover a bit before I pull the trigger.

Who's gonna offer one to Amir for testing in the meantime?

 

[Taswegian]

I use mostly the Apollo Twin as audio interface for a live streaming rig with WireCast Pro and what I find convenience is the big volume knob with LEDs all around which is great if you need to make volume changes on the fly while live streaming, but that is a very particular case/use. For everything else, the UCX II is better.

How does the UCX II and TotalMix perform for live streaming? It is one of my main intended purposes for the unit if I purchase it, secondary to live recording of guitar/vocals.

 

[enricoclaudio]

How does the UCX II and TotalMix perform for live streaming? It is one of my main intended purposes for the unit if I purchase it, secondary to live recording of guitar/vocals.

Sound wise, it works great. But I find the Apollo Twin just a bit more convenient due the big centered knob with LEDs all around that show volume level. As example, I also have one Apollo Twin at work (big church in Houston) that I also use with WireCast Pro and changing levels between worship and sermon is super easy because visually due the all around LEDs you can see where the volume level is. My streaming guy loves it. You can also purchase the RME ARC which has a big centered knob but it doesn't have the LEDs all around. For changing volume on the fly I do prefer physical knobs than a mouse over software. My streaming guy has 2 x 27" Dell Monitors. In one is only WireCast Pro Preview and Program windows and on the second monitor all the monitoring software, including Vimeo, Church website and UAD Software to monitor channel levels and clipping but volume levels are changed with the physical knob in the Apollo Twin.

 

[Rja4000]

@Atanasi
First quick tests (Using the RME ADI-2 Pro fs R as a measurement device)
Only playing with settings from within Totalmix

The UCX II looks very stable and TotalMix is really a joy to use.

 

[Trell]

@Atanasi
First quick tests (Using the RME ADI-2 Pro fs R as a measurement device)
Only playing with settings from within Totalmix

The UCX II looks very stable and TotalMix is really a joy to use.


View attachment 153264

View attachment 153263

For the Main output I had hoped there would be a increase in overall level of SINAD for +4dBu compared to +13dBu, similar to the difference between +13dBu and +19dBu.

Perhaps @MC_RME can give some input on this.

 

[Rja4000]

For the Main output I had hoped there would be a increase in overall level of SINAD for +4dBu compared to +13dBu, similar to the difference between +13dBu and +19dBu.

Perhaps @MC_RME can give some input on this.

Let me first double check

 

[Rja4000]

More measurements for Analog Output
(NB: Volts are not measured but computed)

SINAD @4V output (+19dBu range)

SINAD @2V Balanced output (+13dBu range)

SINAD @1.23V (+4dBu range)

For comparison
SINAD @1.23V (+13dBu range)
We see clearly it's the same, but noise drops by 9dB vs 0dBFS (which means electronic noise level remains the same, so 4dBu range is done by gain reduction in the digital domain, IMO)

 

[AnalogSteph]

We see clearly it's the same, but noise drops by 9dB vs 0dBFS (which means electronic noise level remains the same, so 4dBu range is done by gain reduction in the digital domain, IMO)

NACK. The harmonics are substantially different, so I do think the DAC itself is near 0 dBFS. My guess is analog noise from the output stage is the dominating factor. Bit of a bummer but oh well. -98.5 dBu worth of output noise (~9.2 µV) is hardly what you would call exciting.

You may want to drag out your mic preamp to double-check... I mean, the ADI-2 Pro FS should manage -115 dBu input noise in the +4 dBu setting but just in case.

 

[Rja4000]

More measurements for Analog output...

31 bands 192kHz 13dBu range

31 bands 192kHz 19dBu range

Frequency response (in black)
compared to RME ADI-2 Pro fs R loopback in Red
(Fast Frequency Response signal @96kHz)

 

[Rja4000]

NACK. The harmonics are substantially different, so I do think the DAC itself is near 0 dBFS. My guess is analog noise from the output stage is the dominating factor. Bit of a bummer but oh well. -98.5 dBu worth of output noise (~9.2 µV) is hardly what you would call exciting.

You may want to drag out your mic preamp to double-check... I mean, the ADI-2 Pro FS should manage -115 dBu input noise in the +4 dBu setting but just in case.

I don't think so.
I think that's the RME ADI-2 Pro fs R ADC that raises the distortion (we're close to the limit of 4dBu Input range)


I've added some measurements where we have the RME UCX II Analog output in black compared with the RME ADI-2 Pro fs R Output in Red
(NB: In previous measurements, the RME ADI-2 Pro fs R was set in "Mono" input mode, still lowering the Noise and increasing its own ADC SINAD by a few dBs)

SINAD compared @4dBu output and input level

SINAD compared @4dBu output and 13dBu input level

 

[Rja4000]

It's even better if I lower level by 2dB, so that input level of the RME ADI-2 Pro fs R is in its optimal range

First SINAD with output around 2dBu
Black is RME UCX II Analog output @4dBu DAC range
Red is RME ADI-2 Pro fs R Main output @4dBu DAC range
ADC is RME ADI-2 Pro fs R in 4dBu range

Then the same with both DAC levels set to 13dBu range
and level lowered by 9dB in the software to keep the Voltage

We see that, for the UCX II, THD and SNR remain the same.
While with the ADI-2 Pro fs R, SNR decreases.
That clearly indicates that the output range impact (+4dBu vs +13dBu) on the UCX II SINAD is null

 

[AnalogSteph]

Looks like you're right. Seems a bit silly to even include the +4 dBu output range then, but oh well... more of a convenience thing than anything else, I guess. Maybe the input side only offering +13 and +19 dBu should have been a clue.

About 103 dB(A) ref. +4 dBu is still quite sufficient, mind you. I can't think of many monitors more critical than the Genelec 8010A, and those still have the -10 dB DIP switch for an input sensitivity of +4 dBu for 100 dB @ 1 m, which would put noise from the RME at -3 dB SPL A-wtd @ 1 m... quite arguably less than the Genelecs' own noise (spec <=+5 dB(A) at 1 m).

 

[knkkskknk]

I have a ADI-2 Dac FS, how does the headphone amp/dac on this unit compare to UCX II?

Do you think I'd notice a difference? (I don't use too expensive headphones, I have Slate's VSX, and AKG K712)
I upgraded to the ADI-2 DAC and noticed a big difference in 3D imaging and improvement in sound over my cheap 100$ interface. But I'm having too much of a hassle switching between interfaces to record guitar/microphone and stuff. Would prefer an AIO unit like this.

Also how is the DI input on this for recording guitar? and Mic pres? Do you think they're a step up from a babyface atleast?

 

[Rja4000]

I have a ADI-2 Dac FS, how does the headphone amp/dac on this unit compare to UCX II?

Do you think I'd notice a difference?

You'd loose some flexibility on the EQ, mainly:
For the Phones output, you "just" have 3 EQ bands, including Bass+Trebble
vs
5 parametric + Bass+Trebble + "Loudness" on the RME ADI-2 DAC.

Output is powerful enough for me with my Focal Elegia.
I don't have test resistors at hand, so I can't test the output power now.

For the rest, I think the internal components for Mic and instrument are the same then the Babyface.
I will measure more on the inputs this week-end.

You have more DSP power, though, I guess, allowing dynamics (compression/ expansion) that are missing on the Babyface.

 

[Rja4000]

More measurements of the UCX II

DAC side

Dashboard 4Vrms
Not state of the art, but good enough for the usecase.

Jitter
(Source = USB, but we get exactly the same from AES)
Updated to align wth Amir's 16 frames average

Level Linearity
Nothing to worry about

IMD vs Level

32 tones
No issue

This one is using Amir's APx555 test file
32nd tone isn't displayed, since it's at 14Hz

Filter @48kHz

THD vs Frequency @4Vrms

NB: I ran this one twice, and I got those strange peaks at 40Hz and 60Hz on each run
I'll try to find what's going on here

Square wave

This is at maxmum output level (19dBu)
We see that the overshoot is not truncated, whih is good.



Dashboard @4V in Loopback mode
(DAC + ADC = RME UCX II)
We clear more than required CD SINAD for the loopback.
Good news if you want to insert an external analog effect, which will most likely perform much worse than this.

 

[Rja4000]

Measurements above are for Line output

 

[AnalogSteph]

ilter @48kHz

That's hardly doing anything. I mean, ~24 dB filter ultimate? My guess is it's still overloaded.

THD vs Frequency @4Vrms

NB: I ran this one twice, and I got those strange peaks at 40Hz and 60Hz on each run
I'll try to find what's going on here

Hmm. I can't help but notice that 60 Hz x 2 = 40 Hz x 3 = 120 Hz, which could be a power supply related thing. That said, your spectra previously were clear of mains stuff, so....

Square wave

This is at maxmum output level (19dBu)
We see that the overshoot is not truncated, whih is good.

There's still some funny business going on though, note the glitches whenever it ought to be hitting the first Gibbs peak after transition. The same at +13 dBu might be interesting to tell whether it's the filter / DAC or the analog side.

Measurements above are for Line output

It would certainly be interesting how the mic inputs are doing. (EIN at 75/60/40/20 dB shorted or 150R, THD(f) or IMD(f) at -1 dBFS for at least a few of them.)

 

[MC_RME]

I reported the same issue. I’m also running macOS 11.5.2 in my 2017 27” iMac. I’m guessing this is not a “Hot Plugged” audio interface. Which is not an issue for me as I leave it ON 24/7.

It is a device that supports hot-plugging or surprise removal. But Apple seems to have issues with that. You might try our latest driver plus macOS 11.6.

https://forum.rme-audio.de/viewtopic.php?pid=176090#p176090