This is a review and detailed measurements of the
RME UFX III
professionnal Interface
(ADC, DAC, Headphones Amp).
The UFX III is quite recent, as it was launched around march 2023.
Normal price is around 2700€.
I purchased mine new.
Presentation
The UFX III is the current top of the RME interfaces line.
Here is a quick comparison of the different models in the range.
(I collated this list myself, so please forgive me if there is any mistake)
(Number within ( ) means the physical input or output is shared with other functionalities)
As one may see, even if the number of analog inputs and outputs is limited, this is a quite powerful interface, allowing up to 94 inputs and 94 ouptuts.
Rear panel is quite busy.
The only visible difference with the UFX II, the next model down in the range, is the MADI inputs and outputs and the USB III connection.
This is quite important to me, since I wanted to cascade it with the excellent RME 12Mic-D microphone preamp I already own.
With a MADI connection both directions, I can get a total Dante and Totalmix integration.
This allows me to record in parallel all 16 microphone inputs (12+4) on a network-connected PC through Dante and also locally with Durec on a USB drive as a backup.
Measurements
Measurements were performed mainly with my usual RME ADI-2/4 Pro SE.
On occasion, the UFX III itself was used to add gain and mesure low noise values.
I used a mix of AudioPrecision APx 500 Flex 8.1.2 and Virtins MultiInstrument 3.9.9.6 softwares.
Thanks to AudioPrecision for letting me try this software for a few weeks.
Main goal in using an audio interface is to record music.
So, unlike what's the usual order here on ASR, let's start with the most important part for that purpose.
RME UFX III - Inputs (ADC) measurements
Input sensitivity range
One of the first things to know when using an interface or a microphone preamp is its gain range.
For a digital audio interface, we'd rather look at the range of sensitivities, since there is no such thing as a normalized "Gain".
EDIT: If you prefer to have X values incerasing from left to right, see in attachment. I kept it here in decreasing value order, since that's the order of gain increase.
The X scale is in dBu.
For reference, I added the RME ADI-2/4 Pro SE - which is a line-level only interface - and the Yamaha AD-8HR - a wide spread model in Pro audio.
We see that the microphone input range is very extended, from 18dBu (@0dBFS at 0dB gain) to -57dBu (@0dBFS 75dB gain).
-57dBu is around 1.1 mVrms. So you may reach the input's maximum level at that gain setting with just 1.1 mV rms.
That's a lot of gain, really.
RME is following EBU (European Broadcasting Union) standard, which recommends 18dBu @0dBFS as the reference for microphone gain values.
(Note that every interface vendor may use his own rule for that. So it's important to refer to voltage sensitivity for comparison)
Instrument is different: It's unbalanced and 21dBu is reached for a "8 db" gain marking, so reference seems to be 29dBu.
Rear Line inputs use 2 discrete range values: 13dBu and 19dBu.
SINAD (Inputs)
SINAD is a good indicator of the device's engineering quality.
You can't reach "excellent" SINAD without proper attention to details.
Of course, here, SINAD at 4 Vrms is less relevant.
(Amir uses 4V because he standardizes for HiFi use. A different focus.)
But let's have a look, still.
Here, with Microphone input at gain 0dB (4v = -3.7dBFS )
OK, that's ranking in "Excellent" category in Amir's ADC chart.
But wait. We have a line input too.
At 4V, the line input's SINAD value is almost identical to the Mic input's at 0dB.
With 6V on line input, we get
Let's compare the different inputs
THD+N (inputs)
(THD+N is exactly -SINAD. So you just change the sign of the value and you have the SINAD value)
Vertical offset between curves gives us the different noise levels.
We also see that the distorion increases as level approaches full scale (0dBFS) for mic and inst inputs.
However, distortion here will remain inaudible, at -100dB.
(I've seen interfaces, from other reputable brands, distort completely above -10dBFS or so.)
Anyway, good practice recommends recording with an average level around -20 or -18dBFS.
Another interesting plot is THD+N vs Level for Mic preamp at different gain settings
Here we see mainly the difference in noise, as expected.
We see also that this distortion behaviour close to max level we've seen above is only there for levels >15dBu or so (>4V).
Not a typical Microphone level.
We see also the diminushing return of adding gain: the noise benefit between 35dB gain and 75dB gain is not that big.
So you may as well keep a lower gain (and more margin to avoid overloads with peaks) and just push the level later in digital without huge noise penalty.
Dynamic range (Inputs)
First, Mircophone input at 0dB gain
(AES-17 - 20Hz-20kHz - 997hz signal at -60dBFS - CCIR-2k weighting)
Higher is better
Note: This is CCIR-2k weighted, to compare with Amir's measurements.
Here are the different values
So we get almost 120dB dynamic range (A weigthed) on Mic input.
EIN - Noise (Mic Inputs)
One of the key performance factors for microphone preamp is the noise.
If we've seen above that the dynamic range at high input level and 0dB gain is high, what about at low level and higher gain?
EIN stands for "Equivalent Input Noise".
EIN measurement is done with a 150 ohm resistor between pin 2 and 3.
I compensate for room temperature fluctuation vs 20°C.
BW is 20Hz-20kHz
As the device heats, the resistor also heats, so values here may fluctuate 0.1dB or even 0.2dB.
We'll measure it for several gain values:
Black plot is un-weighted noise.
Superposed Red plot is noise with A weighting.
130.2dB A-weigthed
128.2dB unweighted
This is state of the art level.
Note that EIN is always best at Max gain.
Noise profile is also quite flat, with low 50Hz mains peak.
(Some preamps have more noise at low or high frequencies.)
Above, we see that with a gain giving full scale for 10mV, EIN is almost identical to the maximum gain.
Another excellent achievement.
At a gain giving full scale for 100mV, EIN is degraded a bit, which is normal.
It' remains very good, which is the sign of an excellent mic preamp implementation.
As we've said above, in the THD+N vs level section, the noise difference is just 2dB between 75dB gain and 36dB gain.
EIN at 0dB is not really relevant.
But we see Noise Level is confirming our previous Dynamic range measurements, at 119.99dB (A).
(You have to reverse sign to compare to DR)
Here is how EIN evolves with gain
When the curve becomes horizontal, there's nothing to be gained in terms of noise by increasing the gain.
From 63dB of gain, the curve is a straight line.
And here is a comparison with other mic preamps
Lower is better
(A-weighting values - Reference gain = gain for 100mV @0dBFS = 36dB gain on the UFX III)
The graph speaks for itself.
(For the curious, we see here how the Yamaha AD8HR works: it has a very limited effective gain range, 24dB or so, then a pad is engaged - the vertical peak - then 24dB again, then a second pad, and again the 24dB.
The results are not great, but it does provide a very wide range at low cost. If you listen carefully, you can hear the relay engage at both thresholds).
Frequency response (Inputs)
Another key peformance factor is a flat frequency response.
For line level, this is usually perfect.
For Instrument input, we see a deviation though.
We see -0.47dB at 20kHz
(Most probably not an issue for instrument pickups, which are typically bandwidth limited anyway.)
For mic inputs, this may also vary with Mic preamp gain
At max gain, we see the highest deviation
(Remember, at 75dB gain, we have a maximum acceptable signal of 1mV.
This is very very low.
And boosting 0.5dB at 20kHz at mixing stage if required won't be noticed, anyway.)
But at a gain that gives 0dBFS with 10mV (56dB gain), this is mostly gone.
Deviation is not significant at that gain and below.
Overall, this performance is excellent.
Linearity (Inputs)
Intermodulation distortion (Inputs)
Multitone (Inputs)
This is Mic input.
Line input is a copy/paste.
THD vs Frequency (Inputs)
We mostly see high frequency noise at play here.
(Continued in next post)
RME UFX III
professionnal Interface
(ADC, DAC, Headphones Amp).
The UFX III is quite recent, as it was launched around march 2023.
Normal price is around 2700€.
I purchased mine new.
Presentation
The UFX III is the current top of the RME interfaces line.
Here is a quick comparison of the different models in the range.
(I collated this list myself, so please forgive me if there is any mistake)
(Number within ( ) means the physical input or output is shared with other functionalities)
As one may see, even if the number of analog inputs and outputs is limited, this is a quite powerful interface, allowing up to 94 inputs and 94 ouptuts.
Rear panel is quite busy.
The only visible difference with the UFX II, the next model down in the range, is the MADI inputs and outputs and the USB III connection.
This is quite important to me, since I wanted to cascade it with the excellent RME 12Mic-D microphone preamp I already own.
With a MADI connection both directions, I can get a total Dante and Totalmix integration.
This allows me to record in parallel all 16 microphone inputs (12+4) on a network-connected PC through Dante and also locally with Durec on a USB drive as a backup.
Measurements
Measurements were performed mainly with my usual RME ADI-2/4 Pro SE.
On occasion, the UFX III itself was used to add gain and mesure low noise values.
I used a mix of AudioPrecision APx 500 Flex 8.1.2 and Virtins MultiInstrument 3.9.9.6 softwares.
Thanks to AudioPrecision for letting me try this software for a few weeks.
Main goal in using an audio interface is to record music.
So, unlike what's the usual order here on ASR, let's start with the most important part for that purpose.
RME UFX III - Inputs (ADC) measurements
Input sensitivity range
One of the first things to know when using an interface or a microphone preamp is its gain range.
For a digital audio interface, we'd rather look at the range of sensitivities, since there is no such thing as a normalized "Gain".
EDIT: If you prefer to have X values incerasing from left to right, see in attachment. I kept it here in decreasing value order, since that's the order of gain increase.
The X scale is in dBu.
For reference, I added the RME ADI-2/4 Pro SE - which is a line-level only interface - and the Yamaha AD-8HR - a wide spread model in Pro audio.
We see that the microphone input range is very extended, from 18dBu (@0dBFS at 0dB gain) to -57dBu (@0dBFS 75dB gain).
-57dBu is around 1.1 mVrms. So you may reach the input's maximum level at that gain setting with just 1.1 mV rms.
That's a lot of gain, really.
RME is following EBU (European Broadcasting Union) standard, which recommends 18dBu @0dBFS as the reference for microphone gain values.
(Note that every interface vendor may use his own rule for that. So it's important to refer to voltage sensitivity for comparison)
Instrument is different: It's unbalanced and 21dBu is reached for a "8 db" gain marking, so reference seems to be 29dBu.
Rear Line inputs use 2 discrete range values: 13dBu and 19dBu.
SINAD (Inputs)
SINAD is a good indicator of the device's engineering quality.
You can't reach "excellent" SINAD without proper attention to details.
Of course, here, SINAD at 4 Vrms is less relevant.
(Amir uses 4V because he standardizes for HiFi use. A different focus.)
But let's have a look, still.
Here, with Microphone input at gain 0dB (4v = -3.7dBFS )
OK, that's ranking in "Excellent" category in Amir's ADC chart.
But wait. We have a line input too.
At 4V, the line input's SINAD value is almost identical to the Mic input's at 0dB.
With 6V on line input, we get
Let's compare the different inputs
THD+N (inputs)
(THD+N is exactly -SINAD. So you just change the sign of the value and you have the SINAD value)
Vertical offset between curves gives us the different noise levels.
We also see that the distorion increases as level approaches full scale (0dBFS) for mic and inst inputs.
However, distortion here will remain inaudible, at -100dB.
(I've seen interfaces, from other reputable brands, distort completely above -10dBFS or so.)
Anyway, good practice recommends recording with an average level around -20 or -18dBFS.
Another interesting plot is THD+N vs Level for Mic preamp at different gain settings
Here we see mainly the difference in noise, as expected.
We see also that this distortion behaviour close to max level we've seen above is only there for levels >15dBu or so (>4V).
Not a typical Microphone level.
We see also the diminushing return of adding gain: the noise benefit between 35dB gain and 75dB gain is not that big.
So you may as well keep a lower gain (and more margin to avoid overloads with peaks) and just push the level later in digital without huge noise penalty.
Dynamic range (Inputs)
First, Mircophone input at 0dB gain
(AES-17 - 20Hz-20kHz - 997hz signal at -60dBFS - CCIR-2k weighting)
Higher is better
Note: This is CCIR-2k weighted, to compare with Amir's measurements.
Here are the different values
So we get almost 120dB dynamic range (A weigthed) on Mic input.
EIN - Noise (Mic Inputs)
One of the key performance factors for microphone preamp is the noise.
If we've seen above that the dynamic range at high input level and 0dB gain is high, what about at low level and higher gain?
EIN stands for "Equivalent Input Noise".
EIN measurement is done with a 150 ohm resistor between pin 2 and 3.
I compensate for room temperature fluctuation vs 20°C.
BW is 20Hz-20kHz
As the device heats, the resistor also heats, so values here may fluctuate 0.1dB or even 0.2dB.
We'll measure it for several gain values:
- Maximum gain (75dB gain here)
- Gain for sensitivity = 10mV rms @0dBFS (56dB gain here)
- Gain for sensitivity = 100mV rms @0dBFS (36dB gain here)
- Minimum gain (0dB gain here(
Black plot is un-weighted noise.
Superposed Red plot is noise with A weighting.
130.2dB A-weigthed
128.2dB unweighted
This is state of the art level.
Note that EIN is always best at Max gain.
Noise profile is also quite flat, with low 50Hz mains peak.
(Some preamps have more noise at low or high frequencies.)
Above, we see that with a gain giving full scale for 10mV, EIN is almost identical to the maximum gain.
Another excellent achievement.
At a gain giving full scale for 100mV, EIN is degraded a bit, which is normal.
It' remains very good, which is the sign of an excellent mic preamp implementation.
As we've said above, in the THD+N vs level section, the noise difference is just 2dB between 75dB gain and 36dB gain.
EIN at 0dB is not really relevant.
But we see Noise Level is confirming our previous Dynamic range measurements, at 119.99dB (A).
(You have to reverse sign to compare to DR)
Here is how EIN evolves with gain
When the curve becomes horizontal, there's nothing to be gained in terms of noise by increasing the gain.
From 63dB of gain, the curve is a straight line.
And here is a comparison with other mic preamps
Lower is better
(A-weighting values - Reference gain = gain for 100mV @0dBFS = 36dB gain on the UFX III)
The graph speaks for itself.
(For the curious, we see here how the Yamaha AD8HR works: it has a very limited effective gain range, 24dB or so, then a pad is engaged - the vertical peak - then 24dB again, then a second pad, and again the 24dB.
The results are not great, but it does provide a very wide range at low cost. If you listen carefully, you can hear the relay engage at both thresholds).
Frequency response (Inputs)
Another key peformance factor is a flat frequency response.
For line level, this is usually perfect.
For Instrument input, we see a deviation though.
We see -0.47dB at 20kHz
(Most probably not an issue for instrument pickups, which are typically bandwidth limited anyway.)
For mic inputs, this may also vary with Mic preamp gain
At max gain, we see the highest deviation
(Remember, at 75dB gain, we have a maximum acceptable signal of 1mV.
This is very very low.
And boosting 0.5dB at 20kHz at mixing stage if required won't be noticed, anyway.)
But at a gain that gives 0dBFS with 10mV (56dB gain), this is mostly gone.
Deviation is not significant at that gain and below.
Overall, this performance is excellent.
Linearity (Inputs)
Intermodulation distortion (Inputs)
Multitone (Inputs)
This is Mic input.
Line input is a copy/paste.
THD vs Frequency (Inputs)
We mostly see high frequency noise at play here.
(Continued in next post)
Attachments
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