• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

RME UFX III Audio Interface review

Tovarich007 said:
what means exactly EIN and why is this criteria so important ?
Click to expand...
One of the most audible aspect of amplifying small signals - like the output signal from a low sensitivity microphone when the source is far or not very loud - is noise.
In usual HiFi DACs and ADCs, we measure noise at a fixed "gain": That's what the Dynamic range value gives you.

But with a microphone preamp, this gain is not fixed.
The very goal of a microphone preamp is to amplify the signal to bring it above the ADC's noise level by a margin.
EIN (Equivalent Input Noise) helps us to understand how big this margin can be, comparing directly the noise as a voltage (usually expressed in dBu), so independently from the gain factor.

The noise is coming from 2 sources:
The source's noise : In the EIN, usually. a resistor of 150 Ohm is used as a "source".
This value is similar to a dynamic microphone impedance.
Of course, we don't want a microphone signal to mess the measurement, so we use a fix resistor instead.
The resistor itself is subject to Thermal noise (see here), so it contributes to the EIN noise.
At 20°C, a 150 Ohm resistor will have a thermal noise for a 20hz-20kHz bandwidth of 220 nVrms, or -130,92 dBu unweighted.

Then the preamplifier adds its own noise, which is what we want to evaluate.

As you may see in my measurements, the EIN at maximum gain under the same circumstances is at -128.2dBu.
If we deduct the resistor thermal noise, that's approx. 206 nVrms of noise added by the preamp itself (I compute this value and show it in the bottom right on each EIN measurement).
So less than the resistor's own noise.

As the gain decreases, this value will increase, since you'll be more and more limited by the ADC's noise.

In an ideal world, an ADC with an infinitely low noise level would not need a preamp.

Above a certain gain, the benefit of increasing the gain becomes too small, since we reach the preamp electronic's limits.
 
I am curious about the harmonics on the 4 V vs. 6 V input test. HD2 increases by about 8 dB, as it should, but HD3 decreased by a similar amount which is very unusual.

How did you generate the higher voltage? By cranking up the ADI's output? Other than compensation effects going on, I have no good handwaiving explanation.
 
capslock said:
I am curious about the harmonics on the 4 V vs. 6 V input test. HD2 increases by about 8 dB, as it should, but HD3 decreased by a similar amount which is very unusual.

How did you generate the higher voltage? By cranking up the ADI's output? Other than compensation effects going on, I have no good handwaiving explanation.
Click to expand...
I need to check, but, usually, for 4V, I use the RME ADI-2/4 Pro SE in 13dBu range and push the level to +1.5dB (which works), to reach 4V.
This gives a better SINAD figure because the noise is lower than with the 19dBu range - but distortion may be a bit higher.
For 6V, I use the ADI-2/4 in 19dBu range.
 
Last edited:
Excellent work, thanks a lot. I'm really curious how these results compare to the smaller RME UCX II and the Neumann MT 48.

Any chance making a similarly detailed "official" UCX II and Neumann mt48 reviews in the near future?
 
That was an epic review, a very professional test of a very professional product.

Should this sit under Audio Interfaces, perhaps?

Thanks, Nick
 
Another fantastic review @Rja4000 ! :cool:

Glad to see these contributions promoted to Home Page where they belong.
 
Can't thank you enough for this epic review! Even though most of the features of this device are only useful for professionals, most of the so-called "High-End-Manufacturers" should be ashamed when it comes to quality AND the price!!! I would still be blind without ASR....
 
RME device getting measured by RME device.

1718618008277.png
 
ozonepaul said:
Excellent work, thanks a lot. I'm really curious how these results compare to the smaller RME UCX II and the Neumann MT 48.

Any chance making a similarly detailed "official" UCX II and Neumann mt48 reviews in the near future?
Click to expand...
I have the UCX II.

I was looking to measure the Neumann, since I'm curious.
It's one of those multi-path ADCs we see around.
I was not conviced so far, but this one may be better.
If anyone has a Neumann or Merging, lives in EU and is OK to let me measure it, please reach to me :)
 
@Rja4000: I find it interesting that - looking at the DA impulse response - RME seems to have implemented a IIR "SD Sharp" filter rather than the usual "technically correct" FIR filter. Can you confirm this (just for interest)?
Could the reason be lower latency vs the FIR implementation?
Did you also measure the AD filter impulse response?

BR, Mark
 
markstein said:
@Rja4000: I find it interesting that - looking at the DA impulse response - RME seems to have implemented a IIR "SD Sharp" filter rather than the usual "technically correct" FIR filter. Can you confirm this (just for interest)?
Could the reason be lower latency vs the FIR implementation?
Did you also measure the AD filter impulse response?

BR, Mark
Click to expand...
Usually audio interfaces use these filters for lower latency. I think you'll find most interfaces use that type filter.
 
markstein said:
@Rja4000: I find it interesting that - looking at the DA impulse response - RME seems to have implemented a IIR "SD Sharp" filter rather than the usual "technically correct" FIR filter. Can you confirm this (just for interest)?
Could the reason be lower latency vs the FIR implementation?
Did you also measure the AD filter impulse response?

BR, Mark
Click to expand...
I just know what you see.

You may want to ask @MC_RME to confirm, but I think @Blumlein 88 is correct: the reason is probably to keep latency low.

Given the measurements, it seems to work just fine, anyway.
 
Thank you both for your feedback.

I will not bother MC with this question - asked just out of curiosity.

I am in contact with him regarding two other issues:
- There seems to be an issue with RoomEQ implementation, at least with my specific workspace, and when switching input sample rate. RME confirmed this, and there might - hopefully - be a firmware update soon addressing this.
- The specifics of PEQ implementation are currently not documented. RME uses proportional Q, so when using multisuboptimzer you may choose "RBJ" PEQs.

RME so far was very supportive with my requests! See the RME forum for more details.
 
markstein said:
The specifics of PEQ implementation are currently not documented. RME uses proportional Q, so when using multisuboptimzer you may choose "RBJ" PEQs.
Click to expand...
RME's EQ implementation is quite classic.
Q (or bandwidth) is not taken at -3dB versus peak gain but at half gain.

This matches AutoEQ's custom filter.
I think it also matches REW's generic EQ.
Topping D50 III EQ also matches this definition.
I don't know for sure for Roon, but I hope it's the same.

When an EQ is proposed, I think it's important to check the compatibility, as I've done in my D50 III review.

Any details on this is welcome.
 
You must log in or register to reply here.

Similar threads

R
How to measure EIN (Equivalent Input Noise) of an interface's Mic preamp
5 6 7
Replies
132
Views
10K
Sokel
Sokel
markstein
Microphone preamp instead of phono preamp
2
Replies
31
Views
3K
somebodyelse
S
jerryfreak
Deity PR-2 Portable Audio Recorder
Replies
15
Views
4K
JJKM
J
B
Quick Review: Topping E2X2 OTG
Replies
5
Views
1K
jdjung
J
Douk Audio
Douk Audio VU2PRO Needs Your Opinions!--The Upgraded Version of Douk Audio VU2.
2 3
Replies
53
Views
4K
gargouille
G
Back
Top Bottom