1 Topic by sirhans (edited by sirhans 2020-04-27 15:45:15)

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Topic: Fireface UFX+ -10dBV noise floor higher than Fireface 800 (!)

After many years I decided to upgrade from an old Fireface 800 to a Fireface UFX+. Spending more than twice as much as back then, I expected a serious upgrade. Sadly upon reading the manual I was shocked to find there is no longer a switchable -10dBV sensitivity! It instead recommends to use 9 dB gain on the +4 preset.

Sure enough, this raises the noise floor by 9dB, as it appears to be a purely digital gain. The resulting noise floor is about 5 dB worse than on my old Fireface 800 and 10 dB worse in higher frequencies (96 kHz operating mode). And even without gain it's only 5 dB better than with the old interface.

I would be okay with the mere 5 dB improvement but 5 dB degradation? I'm very disappointed to say the least. Why one has to cut corners on a 2000+ EUR flagship product is beyond me.

After looking up the other manuals, it would appear this same problem affects the UFX II, only the old UFX seems to still have the actual electronical switching to -10dBV.

Edit: And at frequencies approaching 96 kHz in 192 kHz operating mode, the noise floor is a whopping 15 dB higher with -10 dBV level and 5 dB higher at normal +4 level. Jesus Christ.

2 Reply by MC

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Re: Fireface UFX+ -10dBV noise floor higher than Fireface 800 (!)

AD converters have moved on with less THD, less noise and lower latency (FF800: 43 samples, UFX+: 12.6 samples). The 'issue' with higher frequency noise in double and quad speed has been explained in both manuals, Fireface 800 and Fireface UFX+, including the differences:

FF800: But when activating the DS and QS mode, the displayed noise level will rise from -109 dB to -104 dB at 96 kHz, and –82 dB at 192 kHz.

FF UFX+: But when activating the DS and QS mode, the displayed noise level will rise from -113 dB to -105 dB at 96 kHz, and –79 dB at 192 kHz.

About -10 dBV: due to the better SNR of the used ADC it made sense to no longer fully support this low (and unusual) line level in discrete hardware (also typical -10 dBV equipment has a much higher noise floor, or worse SNR, than the UFX+ offers). Instead we added features that make more sense in real world usage. Example: Did you notice that you can switch the I/O Ref Level PER CHANNEL, independently, and this for both inputs and outputs?

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Matthias Carstens
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Re: Fireface UFX+ -10dBV noise floor higher than Fireface 800 (!)

Thanks for the answer.

Those quotes from the manual do hint at the problem, yes, but to be quite honest, from my point of view, this little note somewhere in the manual is not adequate to make it clear to a potential buyer what a potential downgrade is to be expected. And it's not really much of an explanation either, just a mention of the problem.

I understand the point about the improved SNR, but it's a mere 4 or 5 dB improvement, whilst the gain knob raises the noise floor by 9 dB, so in -10 dbV mode, there's a 4 or 5 dB downgrade even without DS or QS mode. And in QS, in the high frequency range, I end up with effectively around 15 dB more noise.

Take a look: https://www.audiosciencereview.com/forum/index.php?attachments/2020-04-27-21_14_25-adobe-audition-png.60731/

So I have between 5-15 dB downgrade in noise floor compared to a 16 year old (!) unit, after paying more than double the price. And your justification for it is that the new unit is better. Sorry, that doesn't make sense to me. If the new unit's noise floor was improved across the entire frequency range, and was improved by 15 dB instead of 5, then that explanation would be valid to me, but I don't see how it is this way.

The -10 dBv level is not unusual at all either in my humble non-professional opinion. It's what all the consumer hardware uses, for example good old amplifiers/phono preamps output this. The manual also mentions that the front inputs are meant for unbalanced input. I tried those too, but for those I needed about 24 dB of the digitally controlled gain, which again raised the noise floor to where it was barely worth it, and also introduced several spikes i the frequency spectrum.

Again, I've seen better results from an old Steinberg interface that you can buy used for under 200 bucks now.

Your point about the improvements in the GUI is well seen, and this is probably why I might just keep the unit since I gave away the old one and I love the drivers and stability and finally being able to use USB, but I still feel incredibly let down and have a good amount of regret about the buying decision. I thought initially that it might be a faulty unit, but I guess I know better now.

4 Reply by vinark (edited by vinark 2020-04-28 11:40:25)

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Re: Fireface UFX+ -10dBV noise floor higher than Fireface 800 (!)

Just try this.... Look at the noise floor of your unit at -10db. Write it down. Then connect a -10db device like a cd player turned on and look at the noise floor again.
In practice I have nothing I can connect to my AD that has a lower noise floor then -100db by a big  margin. Lots of -80db gear and a running mic is even worse. The only thing that outputs at -110db is my DA LOL.
Also noise figures don't tell it all. Also have a listen to the noise. I don't have both units so can't do it but I am almost certain the new units noise will sound more benign. Some older units sound like a percolator albeit at -110db
I am not trying to argue with you and I am not from RME, but just give you some much needed peace of mind.
Cheers
Vincent

Vincent, Amsterdam
https://soundcloud.com/thesecretworld
BFpro fs, 2X HDSP9652 ADI-8AE, 2X HDSP9632

5 Reply by sirhans (edited by sirhans 2020-04-28 11:52:28)

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Re: Fireface UFX+ -10dBV noise floor higher than Fireface 800 (!)

Thanks vinark, your point is valid in principle and this is very true for at least the lower frequency spectrum, however with my old stereo amplifier - a Marantz unit - connected, the noise floor was still where it was before I powered it on in the higher frequencies. Talking about the old FF800, but it ofc also applies now. There's not that much high frequency content that these output I think.

I'm not even talking about audible, just to make it clear. This high frequency stuff isn't audible of course. But I also like playing around with slowing down stuff recorded at high sample rates, for example by reinterpreting 192 kHz recordings as 48 kHz, and then the noise would come into the audible range with a high enough listening level.

I realize that this is good enough for making a good sounding recording. But, you know, I can get a unit that sounds good for a tenth of the price. In the very least I didn't expect a downgrade from what I had before. I want to do some digitizations for archival and for that I want every last bit of fidelity, also because you never know what kind of technology will come out in a few decades (speaking of machine learning etc) that will be able to do something nice to the recording with the high frequency stuff preserved. Better safe than sorry I think.

With that said, can someone recommend a good ADC unit I could buy to connect to this to get decent -10 dBV performance? Sadly it's hard to find charts showing the 192 kHz performance of various units. For example I thought the MOTU 8A and related devices might be good, but I can't find any 192 kHz data on those either.

Was actually considering buying the MOTU 1248 first (half the price) which had slightly better performance than the UFX+ but I ended up deciding that the additional handful of dB of improvement isn't worth forgoing RME drivers etc. Had I known what awaits me with the -10 dBV stuff and high frequency noise I might have just decided to go for the MOTU.

6 Reply by MC

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Re: Fireface UFX+ -10dBV noise floor higher than Fireface 800 (!)

> But I also like playing around with slowing down stuff recorded at high sample rates, for example by reinterpreting 192 kHz recordings as 48 kHz, and then the noise would come into the audible range with a high enough listening level.

Did you read the above, or just looked scared and confused at your FFT diagrams? You just got -79 dB of noise instead of -82 dB. Where does this justify all your statements? And why are these 3 dB more a problem of audibility when the other is not?

For mastering purposes and such the ADI-2 Pro is the best ADC we have to offer. Read chapter 34.9 of its manual, it even includes a FFT of this same topic (some other RME manuals show this as well). Here the noise value is -92 dB @ 192 kHz, the best you can get these days. There is no ADC anymore that does linear noise up to 96 kHz.

http://www.rme-audio.de/download/adi2profsr_e.pdf

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Matthias Carstens
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Re: Fireface UFX+ -10dBV noise floor higher than Fireface 800 (!)

One thing to keep in mind is that you don't need to record at 192khz to slow down. Since there is almost certain no info above 20khz in what you record anyway, unless you record bats with specialized equipment. Slowing down is a really nice sounddesign thing indeed, I have a yamaha sampler that is really good at interpolating at lower octaves.
I am not 100% sure but I think the noise at higher freqs is not an RME thing. I am sure MC can give you a honest answer about this. I remember reading that the downside of recording at higher rates is reduced accuracy (noise?).
If someone who reades this has some tips for reading, please do.
Cheers again

Vincent, Amsterdam
https://soundcloud.com/thesecretworld
BFpro fs, 2X HDSP9652 ADI-8AE, 2X HDSP9632

8 Reply by sirhans (edited by sirhans 2020-04-28 15:27:37)

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Re: Fireface UFX+ -10dBV noise floor higher than Fireface 800 (!)

A fuller comparison:
https://i.imgur.com/Fso12n6.png

For reference: The MR816 you can get under 200 bucks. Sadly I don't have a 192 kHz test for that one anymore. The Korg Audio Kontrol 1 is a shitty little device that I got for 20 bucks used. I'm not saying that it's better than the UFX+ ofc, it's cheap crap, but in a certain area even that one has less high frequency noise than the UFX+.

You just got -79 dB of noise instead of -82 dB.

Nope. I did a simple playback in Adobe Audition of my old FF800 @ 192 kHz and of the FF UFX+ @ 192 kHz. The level meter showed -71 dB for the FF800, but for the UFX+ it showed -58. That's actually a total of 13 dB more noise unweighted, unless I'm doing some wrong math.

Edit: I'd also like to add that the Adi-2 Pro is hardly comparable. It costs more than an entire used FF800 for merely 2 inputs (as far as I understand it) and I'm not sure if it has a switchable -10 dbV equivalent either. I know it has some switchable levels, but I'm not that well versed with the different dB scales. Of course the Adi-2 Pro performance is magnificent, but at that price point we may as well be comparing to something like the Lynx Hilo.

@vinark

Once I built myself a little microphone thingy that could go up to 96 kHz (or close to). Was a lot of fun. Anyway, as I said, you're right - I won't notice unless I do crazy stuff like this or recording bats. But you know, if I pay 2000+ EUR for an audio interface, I better be able to record bats to be honest. Especially if the older model that now goes for 500 EUR could record bats no problem. I'm being rhetorical, but you hopefully get the point.

If I just wanted a "good enough" input, I would have just gotten myself another one of those cheap Steinbergs for 10% of the price. Compared to the FF800, am I expected to pay a 300+% premium for the ability to be able to switch the input level per channel while having a 13 dB degradation in noise floor in 192 kHz operating mode? It's nice features, don't get me wrong, and I praise and respect whoever did the drivers and GUI, but ADC quality is much more important than those little upgrades imo. There was nothing wrong with the FF800 GUI.

Sorry for being so salty, it's not directed at you vinark, rather at the people who made these design decisions.

Edit: Pardon, it's of course a NI Audio Kontrol 1, not a Korg.

9 Reply by MC

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Re: Fireface UFX+ -10dBV noise floor higher than Fireface 800 (!)

> The level meter showed -71 dB for the FF800, but for the UFX+ it showed -58.

Peak level. We hear and measure in RMS.

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Matthias Carstens
RME

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Re: Fireface UFX+ -10dBV noise floor higher than Fireface 800 (!)

Okay I'm not that knowledgeable. I did an average RMS measurement in Audition as well:
-72 for the UFX+
-85 for the FF800

Still 13 dB difference.

11 Reply by MC

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Re: Fireface UFX+ -10dBV noise floor higher than Fireface 800 (!)

> I did a simple playback in Adobe Audition of my old FF800 @ 192 kHz and of the FF UFX+ @ 192 kHz

The values mentioned in the manual can be easily verified with the level meters in TotalMix FX, set to RMS. No software needed at all. They show -79 dBFS at both LoGain and +4 dBu mode with nothing connected at the inputs.

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Matthias Carstens
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