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Intel Nuc motherboard ADC quality

Willem

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I have just ordered a new Intel Nuc (i7 10th generation) to be used in an Akasa Turing FX fanless case. This will serve as my home office computer, for work, but also as an audio source. One of my professional applications is speech recognition because at times I suffer from rsi. For this and for videoconferencing I use a Sennheiser me3 speech microphone as one of the best for speech recognition (and better means a lower recognition error rate). With my current pretty old PC I use an external mono usb ADC as that was recommended to avoid the mediocre performance of motherboard audio, and noise in particular. Since I have lent that external ADC to my wife who now teaches a lot online, I wonder if I should buy another external DAC, or whether motherboard ADCs such as in this NUC are now good enough. Over the years I noticed that motherboard audio has improved from often pretty atrocious to quite decent at times. Are there any measuremtns for these quite popular motherboards?
 

pozz

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Are there any measuremtns for these quite popular motherboards?
It's a good question. I wonder what kind of SNR and level is required for effective speech recognition.
 

AnalogSteph

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The ADC itself is rarely the part to be worried about (certainly not for speech), though performance at 48 kHz may prove measurably better than at 44.1. IME (which is mostly with almost 10-year-old Realtek chips), assuming there aren't any ground routing issues, it is most often a noisy microphone bias supply that tends to dominate even the mediocre mic input noise density.

So if you do want to get fancy, an external preamp for such consumer electret mics would be the way to go. These are surprisingly rather less common than you might think. Note: I've seen one with USB supply - always use an external charger for one of these to minimize the otherwise inevitable ground loop issues.
 
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Willem

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I have much of my information from: https://www.speechrecsolutions.com/ They argue that you need a good external ADC, but my guess is that that is primarily because the inside of a PC is a noisy environment. In their experience recognition accuracy suffers from a slow computer, an inferior microphone (solved with this quite professional Sennheiser ME3 that sits close to your mouth and is very good at excluding extraneous noise) and from the noise of an internal ADC of suboptimal quality. They claim that in their experience the buddy 7 g usb adapter is the best usb ADC for this: https://store.speechrecsolutions.com/buddy-7g-usb-adapter-p41.aspx I don't need this for my audio out as that goes into an ODAC.
I now ask because I have surrendered my ADC and mic to my wife whose students are more than pleased that their teacher uses such a good microphone (the most important piece of kit for online teaching). It does not look like I will get it back:), so I wondered if I can get equally good results if I use another ME3 with my new computer's internal ADC, or whether I need an external ADC.
 

AnalogSteph

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The microphone and placement thereof is about 90% of the story. Otherwise, recording speech does not present any major challenges in terms of dynamic range or lack of distortion. I would assume that anything detrimental to speech recognition would be blatantly obvious when listening to the recording, whether that be waterfall levels of noise, heavy-handed noise reduction algorithms or severe clipping / distortion.

So I suggest that you get another of them ME3s, plug it into the NUC's mic input, check / adjust input device settings (Windows 10 makes you jump through some hoops to get to them but the still exist), do some test recordings @48 kHz and see how those turn out. (If you find noise reduction to be turned on by default, turn it off for now. Analog input gain should be around +20 dB, perhaps +30.) Should you find them rather too noisy even with analog input gain at maximum, obtain a suitable external microphone preamp.

What you are calling an "ADC" isn't just that - in fact, the mic input also has to provide a low-noise bias supply to power the electret capsule, and audio ICs will also provide a preamplifier stage with several different gains being software-selectable (e.g. 0 / +10 / +20 / +30 dB). Only then does the signal end up at an analog multiplexer to make its way to the actual ADC, which these days should generally be capable of something at least approaching "CD quality", way better than what you need. I've heard some dubious USB microphone ADCs but onboard chips have generally be fine, maybe with some attention paid to your choice of sample rate (48 kHz is generally fine, 44.1 may prove more problematic).

As I said previously, both the bias supplies and input preamps tend to have their limits in terms of noise, so for best performance turning down input gain and driving the input from an external preamp tends to be advisable, hence my suggestions to this effect. This should not generally be necessary for speech recognition, but would be useful e.g. when recording voiceovers. While noise reduction can improve the subjective result substantially if necessary and applied carefully, I would prefer having to do little more than some minimal noise gating.
 

DVDdoug

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I don't know about that motherboard. Noise from the preamp is a common problem but if you're not getting excess hiss it's probably OK. And sometimes the preamp will clip (and sometimes clip asymmetrically) before the ADC clips.

The other (often bigger) issue for high-quality recording or other "serious audio" is that the mic input on a computer isn't compatible with stage/studio mics (which have balanced connections). And pro studio condenser mics need 48V phantom power.

With the DAC, the only issue is usually noise. If you're not getting excessive noise and you're getting enough "signal" you probably can't get an audible improvement. (Frequency response and distortion are almost always better than human hearing.)

 

Saidera

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What you are calling an "ADC" isn't just that - in fact, the mic input also has to provide a low-noise bias supply to power the electret capsule, and audio ICs will also provide a preamplifier stage with several different gains being software-selectable (e.g. 0 / +10 / +20 / +30 dB). Only then does the signal end up at an analog multiplexer to make its way to the actual ADC, which these days should generally be capable of something at least approaching "CD quality", way better than what you need. I've heard some dubious USB microphone ADCs but onboard chips have generally be fine, maybe with some attention paid to your choice of sample rate (48 kHz is generally fine, 44.1 may prove more problematic).

As I said previously, both the bias supplies and input preamps tend to have their limits in terms of noise, so for best performance turning down input gain and driving the input from an external preamp tends to be advisable, hence my suggestions to this effect. This should not generally be necessary for speech recognition, but would be useful e.g. when recording voiceovers. While noise reduction can improve the subjective result substantially if necessary and applied carefully, I would prefer having to do little more than some minimal noise gating.
The other (often bigger) issue for high-quality recording or other "serious audio" is that the mic input on a computer isn't compatible with stage/studio mics (which have balanced connections). And pro studio condenser mics need 48V phantom power.
Thanks to the E1DA Cosmos ADC I now know a little about ADCs. The OP asked 'whether motherboard ADCs such as in this NUC are now good enough'. I really want to know, and I think every remote worker who uses VoIP wants to know the answer.

So the microphone quality and placement is 90%; 10% remaining for the ADC (and yet if the ADC is terrible, no amount of microphone greatness is going to result in good sound) so I would suggest 75% for microphone and 25% for ADC.

So for plug in power mics, a low-noise bias supply is necessary, and then the ADC needs a pre-amp (if built-in version is noisy then get external microphone preamp), and then there's an analog multiplexer, and then an actual ADC which should capture CD 96dB. And we are all familiar with Realtek 'blue crab' sound which historically generally favours 48kHz playback and recording (indeed many laptops go so far as to turn off 44.1kHz support). We're assuming this motherboard ADC is Realtek-branded.

If it's a good Realtek chip, then the ADC DR might be around 110 dB, but if it's average, 90-100 dB is common. But ADC quality doesn't matter if it's fed with noise, so it's the bias supply and pre-amp along with a high quality mic that matters.
The average person who isn't involved in digital production does not own studio equipment. The most they could have is an IC Recorder from years back, or a PCM field recorder, various laptops and phones, some interfaces, a tape recorder, 3.5 mm mics, usb mics, headset mics and similar stuff.

For consumers, Sony still sells old stock 3.5 mm jack mics from the 80s and 90s used for tape recorders and cut off at 15 kHz, while audio-technica sells either 3.5 mm or USB (unknown quality ADC inbuilt) or XLR etc. None of these appear to be relevant for today's age. We don't even use USB ports that much. XLR is a bit beyond the average consumer in my imagination. 3.5 mm mic jacks are virtually gone now. Wireless bluetooth transmission of recorded sound tends to sound terrible due to compression and mic positioning (eg at the ears). Nothing here suits the current times without diminishing sound quality.

I read somewhere years ago that perhaps crinacle used the apple dongle's ADC via an adapter, because that ADC is the best among all USB-C dongles. I find this to be true. It's not studio quality, but it supports 24/48 PCM recording in mono and there's not that much noise or 'unrealistic sound' (which all other dongles tend to exhibit). Any headset with a TRRS jack (with a large and wide mic) you get for free when you buy a phone can be used, provided that its microphone sounds alright (eg Apple Earpods, Oppo Earpods copy, Samsung headsets etc) Because it's free, can be positioned close to your mouth, and is Apple iPhone communication quality, for voice recording it's what I now use. I think Apple and Cirrus worked out the right way to do the bias supply, pre-amp and ADC, and also the mini mic capsule of the headset which often sounds terrible.
 

600_OHM

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At the risk of turning this into a computer-nerd hijack, the Intel NUC's I've run have great quality builds and componentry very well supported by Linux. No need for a billion processes running like windows.

But yeah, the external dac or other external solution is always wise.

One possibility if you are a freak like me, is to run a distro that is capable of being put solely into ram, and not touching any hard drive or even ssd during the course of normal operation.

Like with the latest Knoppix 9.1. Usually installed to a fast usb to boot from. Use the "toram" option to play with if you have enough ram and see if it makes any difference.

erm - sorry about the computer nerd distraction here ...
 

Saidera

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Perhaps you could comment on what Realtek chip is used? Does it record 24/48 PCM?
 
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